draft-ietf-pce-pcep-09.txt   draft-ietf-pce-pcep-10.txt 
Networking Working Group JP. Vasseur, Ed. Networking Working Group JP. Vasseur, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Intended status: Standards Track JL. Le Roux, Ed. Intended status: Standards Track JL. Le Roux, Ed.
Expires: May 19, 2008 France Telecom Expires: August 14, 2008 France Telecom
November 16, 2007 February 11, 2008
Path Computation Element (PCE) communication Protocol (PCEP) Path Computation Element (PCE) Communication Protocol (PCEP)
draft-ietf-pce-pcep-09.txt draft-ietf-pce-pcep-10.txt
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Abstract Abstract
This document specifies the Path Computation Element communication This document specifies the Path Computation Element Communication
Protocol (PCEP) for communications between a Path Computation Client Protocol (PCEP) for communications between a Path Computation Client
(PCC) and a Path Computation Element (PCE), or between two PCEs. (PCC) and a Path Computation Element (PCE), or between two PCEs.
Such interactions include path computation requests and path Such interactions include path computation requests and path
computation replies as well as notifications of specific states computation replies as well as notifications of specific states
related to the use of a PCE in the context of Multiprotocol Label related to the use of a PCE in the context of Multiprotocol Label
Switching (MPLS) and Generalized (GMPLS) Traffic Engineering. The Switching (MPLS) and Generalized (GMPLS) Traffic Engineering. PCEP
PCEP protocol is designed to be flexible and extensible so as to is designed to be flexible and extensible so as to easily allow for
easily allow for the addition of further messages and objects, should the addition of further messages and objects, should further
further requirements be expressed in the future. requirements be expressed in the future.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
Table of Contents Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Architectural Protocol Overview (Model) . . . . . . . . . . . 5 4. Architectural Protocol Overview (Model) . . . . . . . . . . . 5
4.1. Problem . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Problem . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.2. Architectural Protocol Overview . . . . . . . . . . . . . 6 4.2. Architectural Protocol Overview . . . . . . . . . . . . . 6
4.2.1. Initialization Phase . . . . . . . . . . . . . . . . . 7 4.2.1. Initialization Phase . . . . . . . . . . . . . . . . . 7
4.2.2. Path computation request sent by a PCC to a PCE . . . 8 4.2.2. Path Computation Request Sent By a PCC to a PCE . . . 8
4.2.3. Path computation reply sent by the PCE to a PCC . . . 9 4.2.3. Path Computation Reply Sent By The PCE to a PCC . . . 9
4.2.4. Notification . . . . . . . . . . . . . . . . . . . . . 11 4.2.4. Notification . . . . . . . . . . . . . . . . . . . . . 11
4.2.5. Error . . . . . . . . . . . . . . . . . . . . . . . . 12 4.2.5. Error . . . . . . . . . . . . . . . . . . . . . . . . 13
4.2.6. Termination of the PCEP Session . . . . . . . . . . . 13 4.2.6. Termination of the PCEP Session . . . . . . . . . . . 13
5. Transport protocol . . . . . . . . . . . . . . . . . . . . . . 13 4.2.7. Intermitent versus Permanent PCEP Session . . . . . . 14
5. Transport Protocol . . . . . . . . . . . . . . . . . . . . . . 14
6. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . . . 14 6. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . . . 14
6.1. Common header . . . . . . . . . . . . . . . . . . . . . . 14 6.1. Common header . . . . . . . . . . . . . . . . . . . . . . 15
6.2. Open message . . . . . . . . . . . . . . . . . . . . . . . 15 6.2. Open Message . . . . . . . . . . . . . . . . . . . . . . . 15
6.3. Keepalive message . . . . . . . . . . . . . . . . . . . . 16 6.3. Keepalive Message . . . . . . . . . . . . . . . . . . . . 16
6.4. Path Computation Request (PCReq) message . . . . . . . . . 17 6.4. Path Computation Request (PCReq) Message . . . . . . . . . 17
6.5. Path Computation Reply (PCRep) message . . . . . . . . . . 18 6.5. Path Computation Reply (PCRep) Message . . . . . . . . . . 18
6.6. Notification (PCNtf) message . . . . . . . . . . . . . . . 20 6.6. Notification (PCNtf) Message . . . . . . . . . . . . . . . 20
6.7. Error (PCErr) Message . . . . . . . . . . . . . . . . . . 21 6.7. Error (PCErr) Message . . . . . . . . . . . . . . . . . . 21
6.8. Close message . . . . . . . . . . . . . . . . . . . . . . 21 6.8. Close Message . . . . . . . . . . . . . . . . . . . . . . 22
7. Object Formats . . . . . . . . . . . . . . . . . . . . . . . . 22 7. Object Formats . . . . . . . . . . . . . . . . . . . . . . . . 22
7.1. PCE TLV Format . . . . . . . . . . . . . . . . . . . . . . 22 7.1. PCE TLV Format . . . . . . . . . . . . . . . . . . . . . . 22
7.2. Common object header . . . . . . . . . . . . . . . . . . . 22 7.2. Common Object Header . . . . . . . . . . . . . . . . . . . 23
7.3. OPEN object . . . . . . . . . . . . . . . . . . . . . . . 24 7.3. OPEN Object . . . . . . . . . . . . . . . . . . . . . . . 24
7.4. RP Object . . . . . . . . . . . . . . . . . . . . . . . . 25 7.4. RP Object . . . . . . . . . . . . . . . . . . . . . . . . 25
7.4.1. Object definition . . . . . . . . . . . . . . . . . . 25 7.4.1. Object Definition . . . . . . . . . . . . . . . . . . 26
7.4.2. Handling of the RP object . . . . . . . . . . . . . . 28 7.4.2. Handling of the RP Object . . . . . . . . . . . . . . 28
7.5. NO-PATH Object . . . . . . . . . . . . . . . . . . . . . . 28 7.5. NO-PATH Object . . . . . . . . . . . . . . . . . . . . . . 28
7.6. END-POINT Object . . . . . . . . . . . . . . . . . . . . . 31 7.6. END-POINT Object . . . . . . . . . . . . . . . . . . . . . 31
7.7. BANDWIDTH Object . . . . . . . . . . . . . . . . . . . . . 32 7.7. BANDWIDTH Object . . . . . . . . . . . . . . . . . . . . . 32
7.8. METRIC Object . . . . . . . . . . . . . . . . . . . . . . 33 7.8. METRIC Object . . . . . . . . . . . . . . . . . . . . . . 33
7.9. Explicit Route Object . . . . . . . . . . . . . . . . . . 36 7.9. Explicit Route Object . . . . . . . . . . . . . . . . . . 36
7.10. Route Record Object . . . . . . . . . . . . . . . . . . . 36 7.10. Reported Route Object . . . . . . . . . . . . . . . . . . 37
7.11. LSPA Object . . . . . . . . . . . . . . . . . . . . . . . 37 7.11. LSPA Object . . . . . . . . . . . . . . . . . . . . . . . 37
7.12. Include Route Object Object . . . . . . . . . . . . . . . 39 7.12. Include Route Object Object . . . . . . . . . . . . . . . 39
7.13. SVEC Object . . . . . . . . . . . . . . . . . . . . . . . 39 7.13. SVEC Object . . . . . . . . . . . . . . . . . . . . . . . 39
7.13.1. Notion of Dependent and Synchronized path 7.13.1. Notion of Dependent and Synchronized Path
computation requests . . . . . . . . . . . . . . . . . 39 Computation Requests . . . . . . . . . . . . . . . . . 39
7.13.2. SVEC Object . . . . . . . . . . . . . . . . . . . . . 41 7.13.2. SVEC Object . . . . . . . . . . . . . . . . . . . . . 41
7.13.3. Handling of the SVEC Object . . . . . . . . . . . . . 42 7.13.3. Handling of the SVEC Object . . . . . . . . . . . . . 42
7.14. NOTIFICATION Object . . . . . . . . . . . . . . . . . . . 43 7.14. NOTIFICATION Object . . . . . . . . . . . . . . . . . . . 43
7.15. PCEP-ERROR Object . . . . . . . . . . . . . . . . . . . . 46 7.15. PCEP-ERROR Object . . . . . . . . . . . . . . . . . . . . 46
7.16. LOAD-BALANCING Object . . . . . . . . . . . . . . . . . . 50 7.16. LOAD-BALANCING Object . . . . . . . . . . . . . . . . . . 50
7.17. CLOSE Object . . . . . . . . . . . . . . . . . . . . . . . 51 7.17. CLOSE Object . . . . . . . . . . . . . . . . . . . . . . . 51
8. Manageability Considerations . . . . . . . . . . . . . . . . . 52 8. Manageability Considerations . . . . . . . . . . . . . . . . . 52
8.1. Control of Function and Policy . . . . . . . . . . . . . . 52 8.1. Control of Function and Policy . . . . . . . . . . . . . . 52
8.2. Information and Data Models . . . . . . . . . . . . . . . 54 8.2. Information and Data Models . . . . . . . . . . . . . . . 54
8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 54 8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 54
8.4. Verifying Correct Operation . . . . . . . . . . . . . . . 54 8.4. Verifying Correct Operation . . . . . . . . . . . . . . . 54
8.5. Requirements on Other Protocols and Functional 8.5. Requirements on Other Protocols and Functional
Componentssection . . . . . . . . . . . . . . . . . . . . 55 Components . . . . . . . . . . . . . . . . . . . . . . . . 55
8.6. Impact on Network Operation . . . . . . . . . . . . . . . 55 8.6. Impact on Network Operation . . . . . . . . . . . . . . . 55
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 55 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 55
9.1. TCP Port . . . . . . . . . . . . . . . . . . . . . . . . . 55 9.1. TCP Port . . . . . . . . . . . . . . . . . . . . . . . . . 55
9.2. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . 55 9.2. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . 55
9.3. PCEP Object . . . . . . . . . . . . . . . . . . . . . . . 55 9.3. PCEP Object . . . . . . . . . . . . . . . . . . . . . . . 56
9.4. Notification Object . . . . . . . . . . . . . . . . . . . 57 9.4. RP Object . . . . . . . . . . . . . . . . . . . . . . . . 57
9.5. PCEP Error Object . . . . . . . . . . . . . . . . . . . . 57 9.5. Notification Object . . . . . . . . . . . . . . . . . . . 58
9.6. CLOSE Object . . . . . . . . . . . . . . . . . . . . . . . 58 9.6. PCEP-ERROR Object . . . . . . . . . . . . . . . . . . . . 58
9.7. PCEP TLV format . . . . . . . . . . . . . . . . . . . . . 59 9.7. CLOSE Object . . . . . . . . . . . . . . . . . . . . . . . 59
9.8. NO-PATH-VECTOR TLV . . . . . . . . . . . . . . . . . . . . 59 9.8. NO-PATH Object . . . . . . . . . . . . . . . . . . . . . . 60
10. PCEP Finite State Machine (FSM) . . . . . . . . . . . . . . . 59 9.9. METRIC Object . . . . . . . . . . . . . . . . . . . . . . 60
11. Security Considerations . . . . . . . . . . . . . . . . . . . 66 9.10. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . . 61
11.1. PCEP Authentication and Integrity . . . . . . . . . . . . 66 9.11. NO-PATH-VECTOR TLV . . . . . . . . . . . . . . . . . . . . 61
11.2. PCEP Privacy . . . . . . . . . . . . . . . . . . . . . . . 67 10. Security Considerations . . . . . . . . . . . . . . . . . . . 61
11.3. Protection against Denial of Service attacks . . . . . . . 67 10.1. PCEP Authentication and Integrity . . . . . . . . . . . . 62
11.4. Request input shaping/policing . . . . . . . . . . . . . . 67 10.2. PCEP Privacy . . . . . . . . . . . . . . . . . . . . . . . 62
12. Authors' addresses . . . . . . . . . . . . . . . . . . . . . . 68 10.3. Protection Against Denial of Service Attacks . . . . . . . 62
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 69 10.3.1. Protection Against TCP DoS Attacks . . . . . . . . . . 62
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 69 10.3.2. Request Input Shaping/Policing . . . . . . . . . . . . 63
14.1. Normative References . . . . . . . . . . . . . . . . . . . 69 11. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 63
14.2. Informative References . . . . . . . . . . . . . . . . . . 69 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 65
Appendix A. PCEP Variables . . . . . . . . . . . . . . . . . . . 71 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 72 13.1. Normative References . . . . . . . . . . . . . . . . . . . 65
Intellectual Property and Copyright Statements . . . . . . . . . . 73 13.2. Informative References . . . . . . . . . . . . . . . . . . 65
Appendix A. PCEP Finite State Machine (FSM) . . . . . . . . . . . 67
Appendix B. PCEP Variables . . . . . . . . . . . . . . . . . . . 74
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 74
Intellectual Property and Copyright Statements . . . . . . . . . . 76
1. Terminology 1. Introduction
[RFC4655] describes the motivations and architecture for a Path
Compuation Element (PCE) based model for the computation of
Multiprotocol Label Switching (MPLS) and Generalized (GMPLS) Traffic
Engineering Label Swtich Paths (TE LSPs). The model allows for the
separation of PCE from Path Computation Client (PCC), and allows for
the cooperation between PCEs. This necessitates a communication
protocol between PCC and PCE, and between PCEs. [RFC4657] states the
generic requirements for such a protocol including the requirement
for using the same protocol between PCC and PCE, and between PCEs.
Additional application-specific requirements (for scenarios such as
inter-area, inter-AS, etc.) are not included in [RFC4657], but there
is a requirement that any solution protocol must be easily extensible
to handle other requirements as they are introduced in application-
specific requirements documents. Examples of such application-
specific requirements are [RFC4927],
[I-D.ietf-pce-interas-pcecp-reqs] and [I-D.ietf-pce-inter-layer-req].
This document specifies the Path Computation Element Communication
Protocol (PCEP) for communications between a PCC and a PCE, or
between two PCEs, in compliance with [RFC4657]. Such interactions
include path computation requests and path computation replies as
well as notifications of specific states related to the use of a PCE
in the context of MPLS and GMPLS Traffic Engineering.
PCEP is designed to be flexible and extensible so as to easily allow
for the addition of further messages and objects, should further
requirements be expressed in the future.
2. Terminology
Terminology used in this document Terminology used in this document
AS: Autonomous System. AS: Autonomous System.
Explicit path: full explicit path from start to destination made of a Explicit path: Full explicit path from start to destination made of a
list of strict hops where a hop may be an abstract node such as an list of strict hops where a hop may be an abstract node such as an
AS. AS.
IGP area: OSPF area or IS-IS level. IGP area: OSPF area or IS-IS level.
Inter-domain TE LSP: A TE LSP whose path transits across at least two Inter-domain TE LSP: A TE LSP whose path transits at least two
different domains where a domain can either be an IGP area, an different domains where a domain can be an IGP area, an Autonomous
Autonomous System or a sub-AS (BGP confederations). System or a sub-AS (BGP confederations).
PCC: Path Computation Client: any client application requesting a PCC: Path Computation Client: any client application requesting a
path computation to be performed by a Path Computation Element. path computation to be performed by a Path Computation Element.
PCE: Path Computation Element: an entity (component, application or PCE: Path Computation Element: an entity (component, application or
network node) that is capable of computing a network path or route network node) that is capable of computing a network path or route
based on a network graph and applying computational constraints. based on a network graph and applying computational constraints.
PCEP Peer: an element involved in a PCEP session (i.e. a PCC or a PCEP Peer: an element involved in a PCEP session (i.e. a PCC or a
PCE). PCE).
TED: Traffic Engineering Database that contains the topology and TED: Traffic Engineering Database that contains the topology and
resource information of the domain. The TED may be fed by IGP resource information of the domain. The TED may be fed by IGP
extensions or potentially by other means. extensions or potentially by other means.
TE LSP: Traffic Engineering Label Switched Path. TE LSP: Traffic Engineering Label Switched Path.
Strict/loose path: mix of strict and loose hops comprising of at Strict/loose path: mix of strict and loose hops comprising at least
least one loose hop representing the destination where a hop may be one loose hop representing the destination where a hop may be an
an abstract node such as an AS. abstract node such as an AS.
Within this document, when describing PCE-PCE communications, the Within this document, when describing PCE-PCE communications, the
requesting PCE fills the role of a PCC. This provides a saving in requesting PCE fills the role of a PCC. This provides a saving in
documentation without loss of function. documentation without loss of function.
2. Introduction
[RFC4655] describes the motivations and architecture for a PCE-based
model for the computation of MPLS and GMPLS TE LSPs. The model
allows for the separation of PCE from PCC, and allows for the
cooperation between PCEs. This necessitates a communication protocol
between PCC and PCE, and between PCEs. [RFC4657] states the generic
requirements for such protocol including the requirement for using
the same protocol between PCC and PCE, and between PCEs. Additional
application-specific requirements (for scenarios such as inter-area,
inter-AS, etc.) are not included in [RFC4657], but there is a
requirement that any solution protocol must be easily extensible to
handle other requirements as they are introduced in application-
specific requirements documents. Examples of such application-
specific requirements are [RFC4927],
[I-D.ietf-pce-interas-pcecp-reqs] and [I-D.ietf-pce-inter-layer-req].
This document specifies the Path Computation Element communication
Protocol (PCEP) for communications between a Path Computation Client
(PCC) and a Path Computation Element (PCE), or between two PCEs, in
compliance with [RFC4657]. Such interactions include path
computation requests and path computation replies as well as
notifications of specific states related to the use of a PCE in the
context of MPLS and GMPLS Traffic Engineering.
PCEP is designed to be flexible and extensible so as to easily allow
for the addition of further messages and objects, should further
requirements be expressed in the future.
3. Assumptions 3. Assumptions
[RFC4655] describes various types of PCE. PCEP does not make any [RFC4655] describes various types of PCE. PCEP does not make any
assumption and thus does not impose any constraint on the nature of assumption and thus does not impose any constraint on the nature of
the PCE. the PCE.
Moreover, it is assumed that the PCE gets the required information so Moreover, it is assumed that the PCE has the required information
as to perform the computation of TE LSP that usually requires network (usually including network topology and resource information) so as
topology and resource information. Such information can be gathered to perform the computation of a path for a TE LSP. Such information
by routing protocols or by some other means, the gathering of which can be gathered by routing protocols or by some other means. The way
is out of the scope of this document. in which the information is gathered is out of the scope of this
document.
Similarly, no assumption is made on the discovery method used by a Similarly, no assumption is made about the discovery method used by a
PCC to discover a set of PCEs (e.g. via static configuration or PCC to discover a set of PCEs (e.g., via static configuration or
dynamic discovery) and on the algorithm used to select a PCE. For dynamic discovery) and on the algorithm used to select a PCE. For
the sake of reference [RFC4674] defines a list of requirements for reference, [RFC4674] defines a list of requirements for dynamic PCE
dynamic PCE discovery and IGP-based solutions for such PCE discovery discovery and IGP-based solutions for such PCE discovery are
are specified in [I-D.ietf-pce-disco-proto-ospf] and specified in [RFC5088] and [RFC5089].
[I-D.ietf-pce-disco-proto-isis].
4. Architectural Protocol Overview (Model) 4. Architectural Protocol Overview (Model)
The aim of this section is to describe the PCEP model in the spirit The aim of this section is to describe the PCEP model in the spirit
of [RFC4101]. An architecture protocol overview (the big picture of of [RFC4101]. An architecture protocol overview (the big picture of
the protocol) is provided in this section. Protocol details can be the protocol) is provided in this section. Protocol details can be
found in further sections. found in further sections.
4.1. Problem 4.1. Problem
The PCE-based architecture used for the computation of MPLS and GMPLS The PCE-based architecture used for the computation of path for MPLS
TE LSP is described in [RFC4655]. When the PCC and the PCE are not and GMPLS TE LSPs is described in [RFC4655]. When the PCC and the
collocated, a communication protocol between the PCC and the PCE is PCE are not collocated, a communication protocol between the PCC and
needed. PCEP is such a protocol designed specifically for the PCE is needed. PCEP is such a protocol designed specifically for
communications between a PCC and a PCE or between two PCEs in communications between a PCC and a PCE or between two PCEs in
compliance with [RFC4657]: a PCC may use PCEP to send a path compliance with [RFC4657]: a PCC may use PCEP to send a path
computation request for one or more TE LSP(s) to a PCE and the PCE computation request for one or more TE LSPs to a PCE and the PCE may
may reply with a set of computed path(s) if one or more path(s) that reply with a set of computed paths if one or more path(s) can be
satisfy the set of constraints can be found. found that satisfies the set of constraints.
4.2. Architectural Protocol Overview 4.2. Architectural Protocol Overview
PCEP operates over TCP, which fulfils the requirements for reliable PCEP operates over TCP, which fulfils the requirements for reliable
messaging and flow control without further protocol work. messaging and flow control without further protocol work.
Several PCEP messages are defined: Several PCEP messages are defined:
- Open and Keepalive messages are used to initiate and maintain a - Open and Keepalive messages are used to initiate and maintain a
PCEP session respectively. PCEP session respectively.
- PCReq: a PCEP message sent by a PCC to a PCE to request a path - PCReq: a PCEP message sent by a PCC to a PCE to request a path
computation. computation.
- PCRep: a PCEP message sent by a PCE to a PCC in reply to a path - PCRep: a PCEP message sent by a PCE to a PCC in reply to a path
computation request. A PCRep message can either contain a set of computation request. A PCRep message can either contain a set of
computed path(s) if the request can be satisfied or a negative reply computed paths if the request can be satisfied, or a negative reply
otherwise in which case the negative reply may also indicate the if not. The negative reply may indicate the reason why no path could
reason why no path could be found. be found.
- PCNtf: a PCEP notification message either sent by a PCC to a PCE or - PCNtf: a PCEP notification message either sent by a PCC to a PCE or
a PCE to a PCC to notify of a specific event. a PCE to a PCC to notify of a specific event.
- PCErr: a PCEP message sent upon the occurrence of a protocol error - PCErr: a PCEP message sent upon the occurrence of a protocol error
condition. condition.
- Close message: a message used to close a PCEP session. - Close message: a message used to close a PCEP session.
The set of available PCE(s) may either be statically configured on a The set of available PCE(s) may be either statically configured on a
PCC or dynamically discovered. The mechanisms used to discover one PCC or dynamically discovered. The mechanisms used to discover one
or more PCE(s) and to select a PCE are out of the scope of this or more PCEs and to select a PCE are out of the scope of this
document. document.
A PCC may have PCEP sessions with more than one PCE and similarly a A PCC may have PCEP sessions with more than one PCE and similarly a
PCE may have PCEP sessions with multiple PCCs. PCE may have PCEP sessions with multiple PCCs.
4.2.1. Initialization Phase 4.2.1. Initialization Phase
The initialization phase consists of two successive steps (described The initialization phase consists of two successive steps (described
in a schematic form in Figure 1): in a schematic form in Figure 1):
1) Establishment of a TCP connection (3-way handshake) between the 1) Establishment of a TCP connection (3-way handshake) between the
PCC and the PCE. PCC and the PCE.
2) Establishment of a PCEP session over the TCP connection. 2) Establishment of a PCEP session over the TCP connection.
Once the TCP connection is established, the PCC and the PCE (also Once the TCP connection is established, the PCC and the PCE (also
referred to as "PCEP peers") initiate a PCEP session establishment referred to as "PCEP peers") initiate PCEP session establishment
during which various session parameters are negotiated. These during which various session parameters are negotiated. These
parameters are carried within Open messages and include the Keepalive parameters are carried within Open messages and include the Keepalive
timer, the Deadtimer and potentially other detailed capabilities and timer, the Deadtimer and potentially other detailed capabilities and
policy rules that specify the conditions under which path computation policy rules that specify the conditions under which path computation
requests may be sent to the PCE. If the PCEP session establishment requests may be sent to the PCE. If the PCEP session establishment
phase fails because the PCEP peers disagree on the session parameters phase fails because the PCEP peers disagree on the session parameters
or one of the PCEP peers does not answer after the expiration of the or one of the PCEP peers does not answer after the expiration of the
establishment timer, the TCP connection is immediately closed. establishment timer, the TCP connection is immediately closed.
Successive retries are permitted but an implementation should make Successive retries are permitted but an implementation should make
use of an exponential back-off session establishment retry procedure. use of an exponential back-off session establishment retry procedure.
Keepalive messages are used to acknowledge Open messages and once the Keepalive messages are used to acknowledge Open messages, and once
PCEP session has been successfully established, Keepalive messages the PCEP session has been successfully established, Keepalive
may be exchanged between PCEP peers to ensure the liveness of the messages may be exchanged between PCEP peers to ensure the liveness
PCEP session. of the PCEP session.
A single PCEP session can exist between a pair a PCEP peers. Only one PCEP session can exist between a pair a PCEP peers at any
one time.
Details about the Open message and the Keepalive messages can be Details about the Open message and the Keepalive message can be found
found inSection 6.2 and Section 6.3 respectively. inSection 6.2 and Section 6.3 respectively.
+-+-+ +-+-+ +-+-+ +-+-+
|PCC| |PCE| |PCC| |PCE|
+-+-+ +-+-+ +-+-+ +-+-+
| | | |
|---- Open message --->| | Open msg |
| | |-------- |
|<--- Open message ----| | \ Open msg |
| \ ---------|
| \/ |
| /\ |
| / -------->|
| / |
|<------ Keepalive|
| --------|
|Keeplaive / |
|-------- / |
| \/ |
| /\ |
|<------ ---------->|
| | | |
: :
: :
| | | |
|---- Keepalive ----->|
| | | |
|<--- Keepalive -------| |<--- Keepalive ------|
| | | |
|---- Keepalive ------>|
Figure 1: PCEP Initialization phase (initiated by a PCC) Figure 1: PCEP Initialization phase (initiated by a PCC)
(Note that the exchange of Keepalive messages is optional) (Note that once the PCEP session is established, the exchange of
Keepalive messages is optional)
4.2.2. Path computation request sent by a PCC to a PCE
4.2.2. Path Computation Request Sent By a PCC to a PCE
+-+-+ +-+-+ +-+-+ +-+-+
|PCC| |PCE| |PCC| |PCE|
+-+-+ +-+-+ +-+-+ +-+-+
1)Path computation | | 1)Path computation | |
event | | event | |
2)PCE Selection | | 2)PCE Selection | |
3)Path computation |---- PCReq message--->| 3)Path computation |---- PCReq message--->|
request sent to | | request sent to | |
the selected PCE | | the selected PCE | |
Figure 2: Path computation request Figure 2: Path Computation request
Once a PCC has successfully established a PCEP session with one or Once a PCC has successfully established a PCEP session with one or
more PCEs, if an event is triggered that requires the computation of more PCEs, if an event is triggered that requires the computation of
a set of path(s), the PCC first selects one or more PCE(s). Note a set of paths, the PCC first selects one or more PCE. Note that the
that the PCE selection decision process may have taken place prior to PCE selection decision process may have taken place prior to the PCEP
the PCEP session establishment. session establishment.
Once the PCC has selected a PCE, it sends a path computation request Once the PCC has selected a PCE, it sends the PCE a path computation
to the PCE (PCReq message) that contains a variety of objects that request to the PCE (PCReq message) that contains a variety of objects
specify the set of constraints and attributes for the path to be that specify the set of constraints and attributes for the path to be
computed. For example "Compute a TE LSP path with source IP computed. For example "Compute a TE LSP path with source IP
address=x.y.z.t, destination IP address=x'.y'.z'.t', bandwidth=B address=x.y.z.t, destination IP address=x'.y'.z'.t', bandwidth=B
Mbit/s, Setup/Hold priority=P, ...". Additionally, the PCC may Mbit/s, Setup/Hold priority=P, ...". Additionally, the PCC may
desire to specify the urgency of such request by assigning a request desire to specify the urgency of such request by assigning a request
priority. Each request is uniquely identified by a request-id number priority. Each request is uniquely identified by a request-id number
and the PCC-PCE address pair. The process is shown in a schematic and the PCC-PCE address pair. The process is shown in a schematic
form in figure 2. form in Figure 2.
Details about the PCReq message can be found in Section 6.4 Details about the PCReq message can be found in Section 6.4
4.2.3. Path computation reply sent by the PCE to a PCC 4.2.3. Path Computation Reply Sent By The PCE to a PCC
+-+-+ +-+-+ +-+-+ +-+-+
|PCC| |PCE| |PCC| |PCE|
+-+-+ +-+-+ +-+-+ +-+-+
| | | |
|---- PCReq message--->| |---- PCReq message--->|
| |1) Path computation | |1) Path computation
| |request received | |request received
| | | |
| |2)Path successfully | |2)Path successfully
| |computed | |computed
| | | |
| |3) Computed path(s) sent | |3) Computed path(s)
| |sent
| |to the PCC | |to the PCC
|<--- PCRep message ---| |<--- PCRep message ---|
| (Positive reply) | | (Positive reply) |
Figure 3a: Path computation request with successful path computation Figure 3a: Path Computation Request With Successful
Path Computation
+-+-+ +-+-+ +-+-+ +-+-+
|PCC| |PCE| |PCC| |PCE|
+-+-+ +-+-+ +-+-+ +-+-+
| | | |
| | | |
|---- PCReq message--->| |---- PCReq message--->|
| |1) Path computation | |1) Path computation
| |request received | |request received
| | | |
| |2) No Path found that | |2) No Path found that
| |satisfies the request | |satisfies the request
| | | |
| |3) Negative reply sent to | |3) Negative reply sent to
| |the PCC (optionally with | |the PCC (optionally with
| |various additional | |various additional
| |information) | |information)
|<--- PCRep message ---| |<--- PCRep message ---|
| (Negative reply) | | (Negative reply) |
Figure 3b: Path computation request with unsuccessful path computation Figure 3b: Path Computation Request With Unsuccessful
Path Computation
Upon receiving a path computation request from a PCC, the PCE Upon receiving a path computation request from a PCC, the PCE
triggers a path computation, the result of which can either be: triggers a path computation, the result of which can either be:
o Positive (Figure 3-a): the PCE manages to compute a path that o Positive (Figure 3-a): the PCE manages to compute a path that
satisfies the set of required constraints, in which case the PCE satisfies the set of required constraints, in which case the PCE
returns the set of computed path(s) to the requesting PCC. Note returns the set of computed paths to the requesting PCC. Note
that PCEP supports the capability to send a single request that that PCEP supports the capability to send a single request that
requires the computation of more than one path (e.g. computation requires the computation of more than one path (e.g., computation
of a set of link-diverse paths). of a set of link-diverse paths).
o Negative (Figure 3-b): no path could be found that satisfies the o Negative (Figure 3-b): no path could be found that satisfies the
set of constraints. In this case, a PCE may provide the set of set of constraints. In this case, a PCE may provide the set of
constraints that led to the path computation failure. Upon constraints that led to the path computation failure. Upon
receiving a negative reply, a PCC may decide to resend a modified receiving a negative reply, a PCC may decide to resend a modified
request or take any other appropriate action. request or take any other appropriate action.
Details about the PCRep message can be found in Section 6.5. Details about the PCRep message can be found in Section 6.5.
4.2.4. Notification 4.2.4. Notification
There are several circumstances whereby a PCE may want to notify a There are several circumstances in which a PCE may want to notify a
PCC of a specific event. For example, suppose that the PCE suddenly PCC of a specific event. For example, suppose that the PCE suddenly
gets overloaded thus potentially leading to unacceptable response gets overloaded, potentially leading to unacceptable response times.
times. The PCE may want to notify one or more PCCs that some of The PCE may want to notify one or more PCCs that some of their
their requests (listed in the notification) will not be satisfied or requests (listed in the notification) will not be satisfied or may
may experience unacceptable delays. Upon receiving such experience unacceptable delays. Upon receiving such notification,
notification, the PCC may decide to redirect it(s) path computation the PCC may decide to redirect its path computation requests to
request(s) to another PCE should an alternate PCE be available. another PCE should an alternate PCE be available. Similarly, a PCC
Similarly, a PCC may desire to notify a PCE of a particular event may desire to notify a PCE of a particular event such as the
such as the cancellation of pending request(s). cancellation of pending requests.
+-+-+ +-+-+ +-+-+ +-+-+
|PCC| |PCE| |PCC| |PCE|
+-+-+ +-+-+ +-+-+ +-+-+
1)Path computation | | 1)Path computation | |
event | | event | |
2)PCE Selection | | 2)PCE Selection | |
3)Path computation |---- PCReq message--->| 3)Path computation |---- PCReq message--->|
request X sent to | |4) Path computation request X sent to | |4) Path computation
the selected PCE | |triggered the selected PCE | |request queued
| | | |
| | | |
5) Path computation| | 5) Path computation| |
request X cancelled| | request X cancelled| |
|---- PCNtf message -->| |---- PCNtf message -->|
| |6) Path computation | |6) Path computation
| |request X cancelled | |request X cancelled
Figure 4: Example of PCC notification (cancellation notification) sent to a PCE Figure 4: Example of PCC Notification (Cancellation
Notification)
Sent To a PCE
+-+-+ +-+-+ +-+-+ +-+-+
|PCC| |PCE| |PCC| |PCE|
+-+-+ +-+-+ +-+-+ +-+-+
1)Path computation | | 1)Path computation | |
event | | event | |
2)PCE Selection | | 2)PCE Selection | |
3)Path computation |---- PCReq message--->| 3)Path computation |---- PCReq message--->|
request X sent to | |4) Path computation request X sent to | |4) Path computation
the selected PCE | |triggered the selected PCE | |request queued
| | | |
| | | |
| |5) PCE gets overloaded | |5) PCE gets overloaded
| | | |
| | | |
| |6) Path computation | |6) Path computation
| |request X cancelled | |request X cancelled
| | | |
|<--- PCNtf message----| |<--- PCNtf message----|
Figure 5: Example of PCE notification (cancellation notification) sent to a PCC Figure 5: Example of PCE Notification (Cancellation
Notification) Sent To a PCC
Details about the PCNtf message can be found in Section 6.6. Details about the PCNtf message can be found in Section 6.6.
4.2.5. Error 4.2.5. Error
PCEP Error messages are sent when a protocol error condition is met The PCEP Error message (also referred to as a PCErr message) is sent
(e.g. unknown object, non supported object, policy violation, ...). in several situations: when a protocol error condition is met or when
the request is not compliant with the PCEP specification (e.g.,
reception of a malformed message, reception of a message with a
mandatory missing object, policy violation, unexpected message,
unknown request reference, ...).
+-+-+ +-+-+ +-+-+ +-+-+
|PCC| |PCE| |PCC| |PCE|
+-+-+ +-+-+ +-+-+ +-+-+
1)Path computation | | 1)Path computation | |
event | | event | |
2)PCE Selection | | 2)PCE Selection | |
3)Path computation |---- PCReq message--->| 3)Path computation |---- PCReq message--->|
request X sent to | |4) Path computation request X sent to | |4) Reception of a
the selected PCE | |triggered => Policy the selected PCE | |malformed object
| |violation ! | |
| |5) Request discarded | |5) Request discarded
| | | |
|<-- PCErr message ---| |<-- PCErr message ---|
| | | |
Figure 6: Example of Error message (policy violation) sent by a PCE Figure 6: Example of Error message Sent By a PCE To a PCC
In Reply To The Reception Of a Malformed Object
Details about the PCErr message can be found in Section 6.7. Details about the PCErr message can be found in Section 6.7.
4.2.6. Termination of the PCEP Session 4.2.6. Termination of the PCEP Session
When one of the PCEP peers desires to terminate a PCEP session it When one of the PCEP peers desires to terminate a PCEP session it
first sends a PCEP Close message and then closes the TCP connection. first sends a PCEP Close message and then closes the TCP connection.
If the PCEP session is terminated by the PCE, the PCC clears all the If the PCEP session is terminated by the PCE, the PCC clears all the
states related to pending requests previously sent to the PCE. states related to pending requests previously sent to the PCE.
Similarly, if the PCC terminates a PCEP session the PCE clears all Similarly, if the PCC terminates a PCEP session the PCE clears all
pending path computation requests sent by the PCC in question as well pending path computation requests sent by the PCC in question as well
as the related states. A Close message can only be sent to terminate as the related states. A Close message can only be sent to terminate
a PCEP session if the PCEP session has previously been established. a PCEP session if the PCEP session has previously been established.
In case of TCP connection failure, the PCEP session is immediately In case of TCP connection failure, the PCEP session is immediately
terminated. terminated.
Details about the Close message can be found in Section 6.8. Details about the Close message can be found in Section 6.8.
5. Transport protocol 4.2.7. Intermitent versus Permanent PCEP Session
An implementation may decide to keep the PCEP session alive (and thus
the corresponding TCP connection) for an unlimited time (this may for
instance be appropriate when path computation requests are sent on a
frequent basis so as to avoid to open a TCP connection each time a
path computation request is needed, which would incur additional
processing delays). Conversely, in some other circumstances, it may
be desirable to systematically open and close a PCEP session for each
PCEP request (for instance when sending a path computation request is
a rare event).
5. Transport Protocol
PCEP operates over TCP using a well-known TCP port (to be assigned by PCEP operates over TCP using a well-known TCP port (to be assigned by
IANA). This allows the requirements of reliable messaging and flow IANA). This allows the requirements of reliable messaging and flow
control to be met without further protocol work. control to be met without further protocol work.
An implementation may decide to keep the TCP connection alive for an
unlimited time (this may for instance be appropriate when path
computation requests are sent on a frequent basis so as to avoid to
open a TCP connection each time a path computation request is needed,
which would incur additional processing delays). Conversely, in some
other circumstances, it may be desirable to systematically open and
close the TCP connection for each PCEP request (for instance when
sending a path computation request is a rare event).
6. PCEP Messages 6. PCEP Messages
A PCEP message consists of a common header followed by a variable A PCEP message consists of a common header followed by a variable
length body made of a set of objects that can either be mandatory or length body made of a set of objects that can either be mandatory or
optional. In the context of this document, an object is said to be optional. In the context of this document, an object is said to be
mandatory in a PCEP message when the object MUST be included for the mandatory in a PCEP message when the object MUST be included for the
message to be considered as valid. A PCEP message with a missing message to be considered as valid. A PCEP message with a missing
mandatory object MUST trigger an Error message (see Section 7.15). mandatory object MUST trigger an Error message (see Section 7.15).
Conversely, if an object is optional, the object may or may not be Conversely, if an object is optional, the object may or may not be
present. present.
A flag referred to as the P flag is defined in the common header of A flag referred to as the P flag is defined in the common header of
each PCEP object (see Section 7.2) that can be set by a PCEP peer to each PCEP object (see Section 7.2). When this flag is set in an
enforce a PCE to take into account the related information during the object in a PCReq, the PCE MUST take the information carried in the
path computation. For example, the METRIC object defined in object into account during the path computation. For example, the
Section 7.8 allows a PCC to specify a bounded acceptable path cost. METRIC object defined in Section 7.8 allows a PCC to specify a
The METRIC object is optional but a PCC may set a flag to ensure that bounded acceptable path cost. The METRIC object is optional, but a
such constraint is taken into account. Similarly to the previous PCC may set a flag to ensure that the constraint is taken into
case, if such constraint cannot be taken into account by the PCE, the account. In this case, if the constraint cannot be taken into
PCE MUST trigger an Error message. account by the PCE, the PCE MUST trigger an Error message.
For each PCEP message type, rules are defined that specify the set of For each PCEP message type, rules are defined that specify the set of
objects that the message can carry. We use the Backus-Naur Form objects that the message can carry. We use the Backus-Naur Form
(BNF) to specify such rules. Square brackets refer to optional sub- (BNF) (see [RFC4234]) to specify such rules. Square brackets refer
sequences. An implementation MUST form the PCEP messages using the to optional sub-sequences. An implementation MUST form the PCEP
object ordering specified in this document. messages using the object ordering specified in this document.
6.1. Common header 6.1. Common header
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ver | Flags | Message-Type | Message-Lenght | | Ver | Flags | Message-Type | Message-Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: PCEP message common header Figure 7: PCEP Message Common Header
Ver (Version - 3 bits): PCEP version number. Current version is Ver (Version - 3 bits): PCEP version number. Current version is
version 1. version 1.
Flags (5 bits): no flags are currently defined. Unassigned bits are Flags (5 bits): no flags are currently defined. Unassigned bits are
considered as reserved and MUST be set to zero on transmission. considered as reserved and MUST be set to zero on transmission.
Message-Type (8 bits): Message-Type (8 bits):
The following message types are currently defined (to be confirmed by The following message types are currently defined (to be confirmed by
IANA). IANA).
skipping to change at page 15, line 19 skipping to change at page 15, line 37
2 Keepalive 2 Keepalive
3 Path Computation Request 3 Path Computation Request
4 Path Computation Reply 4 Path Computation Reply
5 Notification 5 Notification
6 Error 6 Error
7 Close 7 Close
Message-Length (16 bits): total length of the PCEP message expressed Message-Length (16 bits): total length of the PCEP message expressed
in bytes including the common header. in bytes including the common header.
6.2. Open message 6.2. Open Message
The Open message is a PCEP message sent by a PCC to a PCE and a PCE The Open message is a PCEP message sent by a PCC to a PCE and a PCE
to a PCC in order to establish a PCEP session. The Message-Type to a PCC in order to establish a PCEP session. The Message-Type
field of the PCEP common header for the Open message is set to 1 (To field of the PCEP common header for the Open message is set to 1 (To
be confirmed by IANA). be confirmed by IANA).
Once the TCP connection has been successfully established, the first Once the TCP connection has been successfully established, the first
message sent by the PCC to the PCE or by the PCE to the PCC MUST be message sent by the PCC to the PCE or by the PCE to the PCC MUST be
an Open message as specified in Section 10. Any message received an Open message as specified in Appendix A. Any message received
prior to an Open message MUST trigger a protocol error condition and prior to an Open message MUST trigger a protocol error condition and
the PCEP session MUST be terminated. The Open message is used to the PCEP session MUST be terminated. The Open message is used to
establish a PCEP session between the PCEP peers. During the establish a PCEP session between the PCEP peers. During the
establishment phase the PCEP peers exchange several session establishment phase the PCEP peers exchange several session
characteristics. If both parties agree on such characteristics the characteristics. If both parties agree on such characteristics the
PCEP session is successfully established. PCEP session is successfully established. TOTO
Open message Open message
<Open Message>::= <Common Header> <Open Message>::= <Common Header>
<OPEN> <OPEN>
The Open message MUST contain exactly one OPEN object (see The Open message MUST contain exactly one OPEN object (see
Section 7.3). Various session characteristics are specified within Section 7.3).
the OPEN object. Once the TCP connection has been successfully
established the sender MUST start an initialization timer called Various session characteristics are specified within the OPEN object.
OpenWait after the expiration of which if no Open message has been Once the TCP connection has been successfully established the sender
received it sends a PCErr message and releases the TCP connection MUST start an initialization timer called OpenWait after the
(see Section 10 for details). expiration of which if no Open message has been received it sends a
PCErr message and releases the TCP connection (see Appendix A for
details).
Once an Open message has been sent to a PCEP peer, the sender MUST Once an Open message has been sent to a PCEP peer, the sender MUST
start an initialization timer called KeepWait after the expiration of start an initialization timer called KeepWait after the expiration of
which if neither a KeepAlive message has been received nor a PCErr which if neither a KeepAlive message has been received nor a PCErr
message in case of disagreement of the session characteristics, a message in case of disagreement of the session characteristics, a
PCErr message MUST be sent and the TCP connection MUST be released PCErr message MUST be sent and the TCP connection MUST be released
(see Section 10 for details). (see Appendix A for details).
The KeepWait timer has a fixed value of 1 minute. The KeepWait timer has a fixed value of 1 minute.
Upon the receipt of an Open message, the receiving PCEP peer MUST Upon the receipt of an Open message, the receiving PCEP peer MUST
determine whether the suggested PCEP session characteristics are determine whether the suggested PCEP session characteristics are
acceptable. If at least one of the characteristic(s) is not acceptable. If at least one of the characteristic(s) is not
acceptable by the receiving peer, it MUST send an Error message. The acceptable by the receiving peer, it MUST send an Error message. The
Error message SHOULD also contain the related Open object: for each Error message SHOULD also contain the related Open object: for each
unacceptable session parameter, an acceptable parameter value SHOULD unacceptable session parameter, an acceptable parameter value SHOULD
be proposed in the appropriate field of the Open object in place of be proposed in the appropriate field of the Open object in place of
the originally proposed value. The PCEP peer MAY decide to resend an the originally proposed value. The PCEP peer MAY decide to resend an
Open message with different session characteristics. If a second Open message with different session characteristics. If a second
Open message is received with the same set of parameters or with Open message is received with the same set of parameters or with
parameters that are still unacceptable, the receiving peer MUST send parameters that are still unacceptable, the receiving peer MUST send
an Error message and it MUST immediately close the TCP connection. an Error message and it MUST immediately close the TCP connection.
Details about error message can be found in Section 7.15. Details about error message can be found in Section 7.15.
If the PCEP session characteristics are acceptable, the receiving If the PCEP session characteristics are acceptable, the receiving
PCEP peer MUST consequently send a Keepalive message (defined in PCEP peer MUST send a Keepalive message (defined in Section 6.3) that
Section 6.3) that would serve as an acknowledgment. serves as an acknowledgment.
The PCEP session is considered as established once both PCEP peers The PCEP session is considered as established once both PCEP peers
have received a Keepalive message from their peer. have received a Keepalive message from their peer.
6.3. Keepalive message 6.3. Keepalive Message
A Keepalive message is a PCEP message sent by a PCC or a PCE in order A Keepalive message is a PCEP message sent by a PCC or a PCE in order
to keep the session in active state. The Message-Type field of the to keep the session in active state. The Keepalive message is also
PCEP common header for the Keepalive message is set to 2 (To be used in response to an Open message to acknowledge that an Open
confirmed by IANA). The Keepalive message does not contain any message has been received and that the PCEP session characteristics
object. are acceptable. The Message-Type field of the PCEP common header for
the Keepalive message is set to 2 (To be confirmed by IANA). The
Keepalive message does not contain any object.
PCEP has its own keepalive mechanism used to ensure of the liveness PCEP has its own keepalive mechanism used to ensure of the liveness
of the PCEP session. This requires the determination of the of the PCEP session. This requires the determination of the
frequency at which each PCEP peer sends keepalive messages. frequency at which each PCEP peer sends Keepalive messages.
Asymmetric values may be chosen; thus there is no constraint Asymmetric values may be chosen; thus there is no constraint
mandating the use of identical keepalive frequencies by both PCEP mandating the use of identical keepalive frequencies by both PCEP
peers. The DeadTimer is defined as the period of time after the peers. The DeadTimer is defined as the period of time after the
expiration of which a PCEP peer declares the session down if no PCEP expiration of which a PCEP peer declares the session down if no PCEP
message has been received (keepalive or any other PCEP message: thus, message has been received (Keepalive or any other PCEP message: thus,
any PCEP message acts as a keepalive message). Similarly, there is any PCEP message acts as a Keepalive message). Similarly, there is
no constraints mandating the use of identical DeadTimers by both PCEP no constraints mandating the use of identical DeadTimers by both PCEP
peers. The minimum KeepAlive timer value is 1 second. peers. The minimum KeepAlive timer value is 1 second.
Keepalive messages are used to acknowledge an Open message if the Keepalive messages are sent at the frequency specified in the OPEN
receiving PCEP peer agrees on the session characteristics and to object carried within an Open message according to the rules
ensure the liveness of the PCEP session. Keepalive messages are sent speciifed in Section 7.3. Because any PCEP message may serve as
at the frequency specified in the OPEN object carried within an Open Keepalive, an implementation may either decide to send Keepalive
message. Because any PCEP message may serve as Keepalive an messages at fixed intervals regardless on whether other PCEP messages
implementation may either decide to send Keepalive messages at fixed might have been sent since the last sent Keepalive message, or may
intervals regardless on whether other PCEP messages might have been decide to differ the sending of the next Keepalive message based on
sent since the last sent Keepalive message or may decide to differ the time at which the last PCEP message (other than Keepalive) was
the sending of the next Keepalive message based on the time at which sent.
the last PCEP message (other than Keepalive) has been sent.
Note that sending Keepalive messages to maintain the session alive is Note that sending Keepalive messages to keep the session alive is
optional and PCEP peers may decide to not send Keepalive messages optional and PCEP peers may decide to not send Keepalive messages
once the PCEP session is established. once the PCEP session is established in which case the peer that does
not receive Keepalive messages does not expect to receive them and
MUST NOT declare the session as inactive.
Keepalive message Keepalive message
<Keepalive Message>::= <Common Header> <Keepalive Message>::= <Common Header>
6.4. Path Computation Request (PCReq) message 6.4. Path Computation Request (PCReq) Message
A Path Computation Request message (also referred to as a PCReq A Path Computation Request message (also referred to as a PCReq
message) is a PCEP message sent by a PCC to a PCE so as to request a message) is a PCEP message sent by a PCC to a PCE to request a path
path computation. The Message-Type field of the PCEP common header computation. A PCReq message may carry more than one path
for the PCReq message is set to 3 (To be confirmed by IANA). computation request. The Message-Type field of the PCEP common
header for the PCReq message is set to 3 (To be confirmed by IANA).
There are two mandatory objects that MUST be included within a PCReq There are two mandatory objects that MUST be included within a PCReq
message: the RP and the END-POINTS objects (see section Section 7). message: the RP and the END-POINTS objects (see section Section 7).
If one of these objects is missing, the receiving PCE MUST send an If one or both of these objects is missing, the receiving PCE MUST
error message to the requesting PCC. Other objects are optional. send an error message to the requesting PCC. Other objects are
optional.
The format of a PCReq message is as follows: The format of a PCReq message is as follows:
<PCReq Message>::= <Common Header> <PCReq Message>::= <Common Header>
[<SVEC-list>] [<SVEC-list>]
<request-list> <request-list>
where: where:
<svec-list>::=<SVEC>[<svec-list>] <svec-list>::=<SVEC>[<svec-list>]
<request-list>::=<request>[<request-list>] <request-list>::=<request>[<request-list>]
<request>::= <RP> <request>::= <RP>
<END-POINTS> <END-POINTS>
[<LSPA>] [<LSPA>]
[<BANDWIDTH>] [<BANDWIDTH>]
[<BANDWIDTH>]
[<metric-list>] [<metric-list>]
[<RRO>] [<RRO>[<BANDWIDTH>]]
[<IRO>] [<IRO>]
[<LOAD-BALANCING>] [<LOAD-BALANCING>]
where: where:
<metric-list>::=<METRIC>[<metric-list>] <metric-list>::=<METRIC>[<metric-list>]
The SVEC, RP, END-POINTS, LSPA, BANDWIDTH, METRIC, RRO, IRO and LOAD- The SVEC, RP, END-POINTS, LSPA, BANDWIDTH, METRIC, RRO, IRO and LOAD-
BALANCING objects are defined in Section 7. The special case of two BALANCING objects are defined in Section 7. The special case of two
BANDWIDTH objects is discussed in details in Section 7.7. BANDWIDTH objects is discussed in detail in Section 7.7.
6.5. Path Computation Reply (PCRep) message 6.5. Path Computation Reply (PCRep) Message
The PCEP Path Computation Reply message (also referred to as a PCRep The PCEP Path Computation Reply message (also referred to as a PCRep
message) is a PCEP message sent by a PCE to a requesting PCC in message) is a PCEP message sent by a PCE to a requesting PCC in
response to a previously received PCReq message. The Message-Type response to a previously received PCReq message. The Message-Type
field of the PCEP common header is set to 4 (To be confirmed by field of the PCEP common header is set to 4 (To be confirmed by
IANA). IANA).
The PCRep message MUST contain at least one RP object. For each
reply that is bundled into a single PCReq message, an RP object MUST
be included that contains a Request-ID-number identical to the one
specified in the RP object carried in the corresponding PCReq message
(see Section 7.4 for the definition of the RP object).
A PCRep message may contain a set of computed path(s) corresponding
to either a single path computation request with load-balancing (see
Section 7.16) or multiple path computation requests originated by a
requesting PCC. The PCRep message may also contain multiple
acceptable paths corresponding to the same request.
The bundling of multiple replies to a set of path computation The bundling of multiple replies to a set of path computation
requests within a single PCRep message is supported by PCEP. If a requests within a single PCRep message is supported by PCEP. If a
PCE receives non-synchronized path computation requests by means of PCE receives non-synchronized path computation requests by means of
one or more PCReq messages from a requesting PCC it MAY decide to one or more PCReq messages from a requesting PCC it MAY decide to
bundle the computed paths within a single PCRep message so as to bundle the computed paths within a single PCRep message so as to
reduce the control plane load. Note that the counter side of such an reduce the control plane load. Note that the counter side of such an
approach is the introduction of additional delays for some path approach is the introduction of additional delays for some path
computation requests of the set. Conversely, a PCE that receives computation requests of the set. Conversely, a PCE that receives
multiple requests within the same PCReq message MAY decide to provide multiple requests within the same PCReq message MAY decide to provide
each computed path in separate PCRep messages or within the same each computed path in separate PCRep messages or within the same
PCRep message. PCRep message. A PCRep message may contain positive and negative
replies.
A PCRep message may contain a set of computed path(s) corresponding
to either a single path computation request with load-balancing (see
Section 7.16) or multiple path computation requests originated by a
requesting PCC. The PCRep message may also contain multiple
acceptable paths corresponding to the same request.
The PCRep message MUST contain at least one RP object. For each
reply that is bundled into a single PCReq message, an RP object MUST
be included that contains a Request-ID-number identical to the one
specified in the RP object carried in the corresponding PCReq message
(see Section 7.4 for the definition of the RP object).
If the path computation request can be satisfied (the PCE finds a set If the path computation request can be satisfied (the PCE finds a set
of path(s) that satisfy the set of constraint(s)), the set of of paths that satisfy the set of constraints), the set of computed
computed path(s) specified by means of ERO object(s) is inserted in paths specified by means of ERO objects is inserted in the PCRep
the PCRep message. The ERO object is defined in Section 7.9. Such a message. The ERO is defined in Section 7.9. The situation where
situation where multiple computed paths are provided in a PCRep multiple computed paths are provided in a PCRep message is discussed
message is discussed in detail in Section 7.13. Furthermore, when a in detail in Section 7.13. Furthermore, when a PCC requests the
PCC requests the computation a set of paths for a total amount of computation of a set of paths for a total amount of bandwidth by
bandwidth of X by means of a LOAD-BALANCING object carried within a means of a LOAD-BALANCING object carried within a PCReq message, the
PCReq message, the ERO of each computed path may be followed by a ERO of each computed path may be followed by a BANDWIDTH object as
BANDWIDTH object as discussed in section Section 7.16. discussed in section Section 7.16.
If the path computation request cannot be satisfied, the PCRep If the path computation request cannot be satisfied, the PCRep
message MUST include a NO-PATH object. The NO-PATH object (described message MUST include a NO-PATH object. The NO-PATH object (described
in Section 7.5) may also comprise other information (e.g reasons for in Section 7.5) may also contain other information (e.g, reasons for
the path computation failure). the path computation failure).
The format of a PCRep message is as follows: The format of a PCRep message is as follows:
<PCRep Message> ::= <Common Header> <PCRep Message> ::= <Common Header>
<response-list> <response-list>
where: where:
<response-list>::=<response>[<response-list>] <response-list>::=<response>[<response-list>]
<response>::=<RP> <response>::=<RP>
skipping to change at page 20, line 30 skipping to change at page 20, line 30
where: where:
<attribute-list>::=[<LSPA>] <attribute-list>::=[<LSPA>]
[<BANDWIDTH>] [<BANDWIDTH>]
[<metric-list>] [<metric-list>]
[<IRO>] [<IRO>]
<metric-list>::=<METRIC>[<metric-list>] <metric-list>::=<METRIC>[<metric-list>]
6.6. Notification (PCNtf) message 6.6. Notification (PCNtf) Message
The PCEP Notification message (also referred to as the PCNtf message) The PCEP Notification message (also referred to as the PCNtf message)
can either be sent by a PCE to a PCC or by a PCC to a PCE so as to can be sent either by a PCE to a PCC, or by a PCC to a PCE, to notify
notify of a specific event. The Message-Type field of the PCEP of a specific event. The Message-Type field of the PCEP common
common header is set to 5 (To be confirmed by IANA). header is set to 5 (To be confirmed by IANA).
The PCNtf message MUST carry at least one NOTIFICATION object and may The PCNtf message MUST carry at least one NOTIFICATION object and MAY
contain several NOTIFICATION objects should the PCE or the PCC intend contain several NOTIFICATION objects should the PCE or the PCC intend
to notify of multiple events. The NOTIFICATION object is defined in to notify of multiple events. The NOTIFICATION object is defined in
Section 7.14. The PCNtf message MAY also contain an RP object (see Section 7.14. The PCNtf message MAY also contain RP objects (see
Section 7.4 when the notification refers to a particular path Section 7.4 when the notification refers to particular path
computation request. computation requests.
The PCNtf message may be sent by a PCC or a PCE in response to a The PCNtf message may be sent by a PCC or a PCE in response to a
request or in an unsolicited manner. request or in an unsolicited manner.
The format of a PCNtf message is as follows: The format of a PCNtf message is as follows:
<PCNtf Message>::=<Common Header> <PCNtf Message>::=<Common Header>
<notify-list> <notify-list>
<notify-list>::=<notify> [<notify-list>] <notify-list>::=<notify> [<notify-list>]
<notify>::= [<request-id-list>] <notify>::= [<request-id-list>]
<notification-list> <notification-list>
<request-id-list>:==<RP><request-id-list> <request-id-list>::=<RP><request-id-list>
<notification-list>:=<NOTIFICATION><notification-list> <notification-list>::=<NOTIFICATION><notification-list>
6.7. Error (PCErr) Message 6.7. Error (PCErr) Message
The PCEP Error message (also referred to as a PCErr message) is sent The PCEP Error message (also referred to as a PCErr message) is sent
when a protocol error condition is met. The Message-Type field of in several situations: when a protocol error condition is met or when
the PCEP common header is set to 6 (To be confirmed by IANA). the request is not compliant with the PCEP specification (e.g.,
reception of a malformed message, reception of a message with a
mandatory missing object, policy violation, unexpected message,
unknown request reference, ...). The Message-Type field of the PCEP
common header is set to 6 (To be confirmed by IANA).
The PCErr message is either sent by a PCC or a PCE in response to a The PCErr message is sent by a PCC or a PCE in response to a request
request or in an unsolicited manner. In the former case, the PCErr or in an unsolicited manner. If the PCErr message is sent in
message MUST include the set of RP objects related to the pending response to a request, the PCErr message MUST include the set of RP
path computation request(s) that triggered the protocol error objects related to the pending path computation requests that
condition. In the later case (unsolicited), no RP object is inserted triggered the error condition. In the later case (unsolicited), no
in the PCErr message. No RP object is inserted in a PCErr when the RP object is inserted in the PCErr message. For example, no RP
error condition occurred during the initialization phase. A PCErr object is inserted in a PCErr when the error condition occurred
message MUST contain a PCEP-ERROR object specifying the PCEP error during the initialization phase. A PCErr message MUST contain a
condition. The PCEP-ERROR object is defined in section Section 7.15. PCEP-ERROR object specifying the PCEP error condition. The PCEP-
ERROR object is defined in section Section 7.15.
The format of a PCErr message is as follows: The format of a PCErr message is as follows:
<PCErr Message> ::= <Common Header> <PCErr Message> ::= <Common Header>
<error-list> ( <error-object-list> [<Open>] ) | <error>
[<Open>] [<error-list>]
<error-list>:==<error>[<error-list>] <error-obj-list>::=<PCEP-ERROR>[<error-obj-list>]
<error>::=[<request-id-list>] <error>::=[<request-id-list>]
<error-obj-list> <error-obj-list>
<request-id-list>::=<RP>[<request-id-list>]
<error-list>::=<error>[<error-list>]
<request-id-list>:==<RP>[<request-id-list>] The procedure upon the receipt of a PCErr message is defined in
<error-obj-list>:==<PCEP-ERROR>[<error-obj-list>]
The procedure upon the reception of a PCErr message is defined in
Section 7.15. Section 7.15.
6.8. Close message 6.8. Close Message
The Close message is a PCEP message that is either sent by a PCC to a The Close message is a PCEP message that is either sent by a PCC to a
PCE or by a PCE to a PCC in order to close an established PCEP PCE or by a PCE to a PCC in order to close an established PCEP
session. The Message-Type field of the PCEP common header for the session. The Message-Type field of the PCEP common header for the
Close message is set to 7 (To be confirmed by IANA). Close message is set to 7 (To be confirmed by IANA).
Close message Close message
<Close Message>::= <Common Header> <Close Message>::= <Common Header>
<CLOSE> <CLOSE>
The Close message MUST contain exactly one CLOSE object (see The Close message MUST contain exactly one CLOSE object (see
Section 6.8). Section 6.8). If more than one CLOSE object is present, the first
MUST be processed and subsequent objects ignored.
Upon the receipt of a Close message, the receiving PCEP peer MUST Upon the receipt of a vlaid Close message, the receiving PCEP peer
cancel all pending requests and MUST close the TCP connection. MUST cancel all pending requests, it MUST close the TCP connection
and MUST NOT send any further PCEP messages on the PCEP session.
7. Object Formats 7. Object Formats
PCEP objects have a common format. They begin with a common object
header (see Section 7.2). This is followed by object-specific fields
defined for each different object. The object may also include one
or more type-length-value (TLV) encoded data sets. Each TLV has the
same structure as described in Section 7.1.
7.1. PCE TLV Format 7.1. PCE TLV Format
A PCEP object may include a set of one or more optional TLV(s). A PCEP object may include a set of one or more optional TLVs.
All PCEP TLVs have the following format: All PCEP TLVs have the following format:
Type: 2 bytes Type: 2 bytes
Lenght: 2 bytes Length: 2 bytes
Value Value: variable
A PCEP object TLV is comprised of 2 bytes for the type, 2 bytes A PCEP object TLV is comprised of 2 bytes for the type, 2 bytes
specifying the TLV length, and a value field. specifying the TLV length, and a value field.
The Length field defines the length of the value portion in bytes. The Length field defines the length of the value portion in bytes.
The TLV is padded to 4-bytes alignment; padding is not included in The TLV is padded to 4-bytes alignment; padding is not included in
the Length field (so a three bytes value would have a length of the Length field (so a three byte value would have a length of three,
three, but the total size of the TLV would be eight bytes). but the total size of the TLV would be eight bytes).
Unrecognized TLVs MUST be ignored. Unrecognized TLVs MUST be ignored.
IANA is requested to managed the PCEP Object TLV. IANA management of the PCEP Object TLV type identifier codespace is
described in Section 9.
7.2. Common Object Header
7.2. Common object header
A PCEP object carried within a PCEP message consists of one or more A PCEP object carried within a PCEP message consists of one or more
32-bit words with a common header which has the following format: 32-bit words with a common header which has the following format:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Object-Class | OT |Res|P|I| Object Length (bytes) | | Object-Class | OT |Res|P|I| Object Length (bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// (Object body) // // (Object body) //
| | | |
skipping to change at page 23, line 28 skipping to change at page 23, line 32
Object-Class (8 bits): identifies the PCEP object class. Object-Class (8 bits): identifies the PCEP object class.
OT (Object-Type - 4 bits): identifies the PCEP object type. OT (Object-Type - 4 bits): identifies the PCEP object type.
The Object-Class and Object-Type fields are managed by IANA. The Object-Class and Object-Type fields are managed by IANA.
The Object-Class and Object-Type fields uniquely identify each PCEP The Object-Class and Object-Type fields uniquely identify each PCEP
object. object.
Res flags (2 bits). Reserved field. This field MUST be set to zero Res flags (2 bits). Reserved field. This field MUST be set to zero
on transmission and MUST be ignored on receipt. on transmission and MUST be ignored on receipt. Unassigned bits are
considered as reserved. They MUST be set to zero on transmission and
MUST be ignored on receipt.
o P flag (Processing-Rule - 1-bit): the P flag allows a PCC to o P flag (Processing-Rule - 1-bit): the P flag allows a PCC to
specify in a PCReq message sent to a PCE whether the object must specify in a PCReq message sent to a PCE whether the object must
be taken into account by the PCE during path computation or is be taken into account by the PCE during path computation or is
just optional. When the P flag is set, the object MUST be taken just optional. When the P flag is set, the object MUST be taken
into account by the PCE. Conversely, when the P flag is cleared, into account by the PCE. Conversely, when the P flag is cleared,
the object is optional and the PCE is free to ignore it if not the object is optional and the PCE is free to ignore it.
supported.
o I flag (Ignore - 1 bit): the I flag is used by a PCE in a PCRep o I flag (Ignore - 1 bit): the I flag is used by a PCE in a PCRep
message to indicate to a PCC whether or not an optional object was message to indicate to a PCC whether or not an optional object was
processed. The PCE MAY include the ignored optional object in its processed. The PCE MAY include the ignored optional object in its
reply and set the I flag to indicate that the optional object was reply and set the I flag to indicate that the optional object was
ignored during path computation. When the I flag is cleared, the ignored during path computation. When the I flag is cleared, the
PCE indicates that the optional object was processed during the PCE indicates that the optional object was processed during the
path computation. The setting of the I flag for optional objects path computation. The setting of the I flag for optional objects
is purely indicative and optional. The I flag has no meaning in a is purely indicative and optional. The I flag has no meaning in a
PCRep message when the P flag had been set in the corresponding PCRep message when the P flag has been set in the corresponding
PCRep message. PCReq message.
If the PCE does not understand an object with the P flag set or If the PCE does not understand an object with the P flag set or
understands the object but decides to ignore the object, the entire understands the object but decides to ignore the object, the entire
PCEP message MUST be rejected and the PCE MUST send a PCErr message PCEP message MUST be rejected and the PCE MUST send a PCErr message
with Error-Type="Unknown Object" or "Not supported Object" along with with Error-Type="Unknown Object" or "Not supported Object" along with
the corresponding RP object. Note that if a PCReq includes multiple the corresponding RP object. Note that if a PCReq includes multiple
requests, only requests for which an object with the P flag set is requests, only requests for which an object with the P flag set is
unknown/unrecognized MUST be rejected. unknown/unrecognized MUST be rejected.
Object Length (16 bits). Specifies the total object length including Object Length (16 bits). Specifies the total object length including
the header, in bytes. The Object Length field MUST always be a the header, in bytes. The Object Length field MUST always be a
multiple of 4, and at least 4. The maximum object content length is multiple of 4, and at least 4. The maximum object content length is
65528 bytes. 65528 bytes.
7.3. OPEN object 7.3. OPEN Object
The OPEN object MUST be present in each Open message and MAY be The OPEN object MUST be present in each Open message and MAY be
present in a PCErr message. There MUST be only one OPEN object per present in a PCErr message. There MUST be only one OPEN object per
Open or PCErr message. Open or PCErr message.
The OPEN object contains a set of fields used to specify the PCEP The OPEN object contains a set of fields used to specify the PCEP
version, Keepalive frequency, DeadTimer, PCEP session ID along with version, Keepalive frequency, DeadTimer, PCEP session ID along with
various flags. The OPEN object may also contain a set of TLVs used various flags. The OPEN object may also contain a set of TLVs used
to convey various session characteristics such as the detailed PCE to convey various session characteristics such as the detailed PCE
capabilities, policy rules and so on. No TLVs are currently defined. capabilities, policy rules and so on. No TLVs are currently defined.
skipping to change at page 24, line 31 skipping to change at page 24, line 36
version, Keepalive frequency, DeadTimer, PCEP session ID along with version, Keepalive frequency, DeadTimer, PCEP session ID along with
various flags. The OPEN object may also contain a set of TLVs used various flags. The OPEN object may also contain a set of TLVs used
to convey various session characteristics such as the detailed PCE to convey various session characteristics such as the detailed PCE
capabilities, policy rules and so on. No TLVs are currently defined. capabilities, policy rules and so on. No TLVs are currently defined.
OPEN Object-Class is to be assigned by IANA (recommended value=1) OPEN Object-Class is to be assigned by IANA (recommended value=1)
OPEN Object-Type is to be assigned by IANA (recommended value=1) OPEN Object-Type is to be assigned by IANA (recommended value=1)
The format of the OPEN object body is as follows: The format of the OPEN object body is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ver | Flags | Keepalive | Deadtimer | SID | | Ver | Flags | Keepalive | DeadTimer | SID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Optional TLV(s) // // Optional TLV(s) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: OPEN Object format Figure 9: OPEN Object format
Ver (3 bits): PCEP version. Current version is 1. Ver (3 bits): PCEP version. Current version is 1.
Flags (5 bits): No Flags are currently defined. Unassigned bits are Flags (5 bits): No Flags are currently defined. Unassigned bits are
considered as reserved and MUST be set to zero on transmission. considered as reserved and MUST be set to zero on transmission.
Keepalive (8 bits): maximum period of time (in seconds) between the Keepalive (8 bits): maximum period of time (in seconds) between two
sending of PCEP messages. The minimum value for the Keepalive is 1 consecutive PCEP messages sent by the sender of this message. The
second. When set to 0, once the session is established, no further minimum value for the Keepalive is 1 second. When set to 0, once the
Keepalive messages need to be sent to the remote peer. A RECOMMENDED session is established, no further Keepalive messages are sent to the
value for the keepalive frequency is 30 seconds. remote peer. A RECOMMENDED value for the keepalive frequency is 30
seconds.
DeadTimer (8 bits): specifies the amount of time after the expiration DeadTimer (8 bits): specifies the amount of time after the expiration
of which the PCEP peer can declare the session with the sender of the of which the PCEP peer can declare the session with the sender of the
Open message down if no PCEP message has been received. The Open message down if no PCEP message has been received. The
DeadTimer MUST be set to 0 if the Keepalive is set to 0. A DeadTimer SHOULD be set to 0 and MUST be ignored if the Keepalive is
RECOMMENDED value for the DeadTimer is 4 times the value of the set to 0. A RECOMMENDED value for the DeadTimer is 4 times the value
Keepalive. of the Keepalive.
Example Example:
A sends an Open message to B with Keepalive=10 seconds and A sends an Open message to B with Keepalive=10 seconds and
Deadtimer=30 seconds. This means that A sends Keepalive messages (or Deadtimer=30 seconds. This means that A sends Keepalive messages (or
ay other PCEP message) to B every 30 seconds and B can declare the ay other PCEP message) to B every 10 seconds and B can declare the
PCEP session with A down if no PCEP has been received from A. PCEP session with A down if no PCEP message has been received from A
within any 30 second period.
SID (PCEP session-ID - 8 bits): unsigned PCEP session number that SID (PCEP session-ID - 8 bits): unsigned PCEP session number that
identifies the current session. The SID MUST be incremented each identifies the current session. The SID MUST be incremented each
time a new PCEP session is established and is mainly used for logging time a new PCEP session is established and is used for logging and
and troubleshooting purposes. troubleshooting purposes. There is one SID number in each direction.
Optional TLVs may be included within the OPEN object body to specify Optional TLVs may be included within the OPEN object body to specify
PCC or PCE characteristics. The specification of such TLVs is PCC or PCE characteristics. The specification of such TLVs is
outside the scope of this document. outside the scope of this document.
When present in an Open message, the OPEN object specifies the When present in an Open message, the OPEN object specifies the
proposed PCEP session characteristics. Upon receiving unacceptable proposed PCEP session characteristics. Upon receiving unacceptable
PCEP session characteristics during the PCEP session initialization PCEP session characteristics during the PCEP session initialization
phase, the receiving PCEP peer (PCE) MAY include an OPEN object phase, the receiving PCEP peer (PCE) MAY include an OPEN object
within the PCErr message so as to propose alternative acceptable within the PCErr message so as to propose alternative acceptable
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messages. The RP object is used to specify various characteristics messages. The RP object is used to specify various characteristics
of the path computation request. of the path computation request.
The P flag of the RP object MUST be set in PCReq and PCReq messages The P flag of the RP object MUST be set in PCReq and PCReq messages
and MUST be cleared in PCNtf and PCErr messages. If the RP objet is and MUST be cleared in PCNtf and PCErr messages. If the RP objet is
received with the P flag set incorrectely according to the rules received with the P flag set incorrectely according to the rules
states above, the receiving peer MUST send a PCErr message with states above, the receiving peer MUST send a PCErr message with
Error-type=10 and Error-value=1. The corresponding path computation Error-type=10 and Error-value=1. The corresponding path computation
request MUST be cancelled by the PCE without further notification. request MUST be cancelled by the PCE without further notification.
7.4.1. Object definition 7.4.1. Object Definition
RP Object-Class is to be assigned by IANA (recommended value=2) RP Object-Class is to be assigned by IANA (recommended value=2)
RP Object-Type is to be assigned by IANA (recommended value=1) RP Object-Type is to be assigned by IANA (recommended value=1)
The format of the RP object body is as follows: The format of the RP object body is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags |O|B|R| Pri | | Flags |O|B|R| Pri |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Request-ID-number | | Request-ID-number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Optional TLV(s) // // Optional TLV(s) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: RP object body format Figure 10: RP object body format
The RP object body has a variable length and may contain additional The RP object body has a variable length and may contain additional
TLVs. No TLVs are currently defined. TLVs. No TLVs are currently defined.
Reserved (8 bits): Reserved: This field MUST be set to zero on
transmission and MUST be ignored on receipt.
Flags (24 bits) Flags (24 bits)
The following flags are currently defined: The following flags are currently defined:
o Pri (Priority - 3 bits): the Priority field may be used by the o Pri (Priority - 3 bits): the Priority field may be used by the
requesting PCC to specify to the PCE the request's priority from 1 requesting PCC to specify to the PCE the request's priority from 1
to 7. The decision of which priority should be used for a to 7. The decision of which priority should be used for a
specific request is of a local matter and MUST be set to 0 when specific request is of a local matter and MUST be set to 0 when
unused. Furthermore, the use of the path computation request unused. Furthermore, the use of the path computation request
priority by the PCE's scheduler is implementation specific and out priority by the PCE's scheduler is implementation specific and out
of the scope of this document. Note that it is not required for a of the scope of this document. Note that it is not required for a
PCE to support the priority field: in this case, it is RECOMMENDED PCE to support the priority field: in this case, it is RECOMMENDED
to set the priority field to 0 by the PCC in the RP object. If that the PCC set the priority field to 0 in the RP object. If the
the PCE does not take into account the request priority, it is PCE does not take into account the request priority, it is
RECOMMENDED to set the priority field to 0 in the RP object RECOMMENDED to set the priority field to 0 in the RP object
carried within the corresponding PCRep message, regardless of the carried within the corresponding PCRep message, regardless of the
priority value contained in the RP object carried within the priority value contained in the RP object carried within the
corresponding PCReq message. A higher numerical value of the corresponding PCReq message. A higher numerical value of the
priority field reflects a higher priority. Note that it is the priority field reflects a higher priority. Note that it is the
responsibility of the network administrator to make use of the responsibility of the network administrator to make use of the
priority values in a consistent manner across the various PCC(s). priority values in a consistent manner across the various PCCs.
The ability of a PCE to support requests prioritization may be The ability of a PCE to support request prioritization MAY be
dynamically discovered by the PCC(s) by means of PCE capability dynamically discovered by the PCCs by means of PCE capability
discovery. If not advertised by the PCE, a PCC may decide to set discovery. If not advertised by the PCE, a PCC may decide to set
the request priority and will learn the ability of the PCE to the request priority and will learn the ability of the PCE to
support request prioritization by observing the Priority field of support request prioritization by observing the Priority field of
the RP object received in the PCRep message. If the value of the the RP object received in the PCRep message. If the value of the
Pri field is set to 0, this means that the PCE does not support Pri field is set to 0, this means that the PCE does not support
the handling of request priorities: in other words, the path the handling of request priorities: in other words, the path
computation request has been honoured but without taking the computation request has been honoured but without taking the
request priority into account. request priority into account.
o R (Reoptimization - 1 bit): when set, the requesting PCC specifies o R (Reoptimization - 1 bit): when set, the requesting PCC specifies
that the PCReq message relates to the reoptimization of an that the PCReq message relates to the reoptimization of an
existing TE LSP in which case, in addition to the TE LSP existing TE LSP in which case, in addition to the TE LSP
attributes, the current path of the existing TE LSP to be attributes, the current path of the existing TE LSP to be
reoptimized MUST be provided in the PCReq (except for 0-bandwidth reoptimized MUST be provided in the PCReq (except for 0-bandwidth
TE LSP) message by means of an RRO object defined in Section 7.10. TE LSPs) message by means of an RRO object defined in Section 7.10
and (again except in the case of 0-bandwidth TE LSPs) the existing
bandwidth of the LSP to be reoptimized MUST be supplied in an
additional BANDWIDTH object as described in Section 7.7.
o B (Bi-directional - 1 bit): when set, the PCC specifies that the o B (Bi-directional - 1 bit): when set, the PCC specifies that the
path computation request relates to a bidirectional TE LSP that path computation request relates to a bidirectional TE LSP that
has the same traffic engineering requirements including fate has the same traffic engineering requirements including fate
sharing, protection and restoration, LSRs, and resource sharing, protection and restoration, LSRs, TE Links, and resource
requirements (e.g. latency and jitter) in each direction. When requirements (e.g., latency and jitter) in each direction. When
cleared, the TE LSP is unidirectional. cleared, the TE LSP is unidirectional.
o O (strict/lOose - 1 bit): when set, in a PCReq message, this o O (strict/loose - 1 bit): when set, in a PCReq message, this
indicates that a loose path is acceptable. Otherwise, when indicates that a loose path is acceptable. Otherwise, when
cleared, this indicates to the PCE that a path exclusively made of cleared, this indicates to the PCE that a path exclusively made of
strict hops is required. In a PCRep message, when the O bit is strict hops is required. In a PCRep message, when the O bit is
set this indicates that the returned path is a loose path, set this indicates that the returned path is a loose path,
otherwise (the O bit is cleared), the returned path is made of otherwise (the O bit is cleared), the returned path is made of
strict hops. strict hops.
Unassigned bits are considered as reserved and MUST be set to zero on Unassigned bits are considered as reserved and MUST be set to zero on
transmission. transmission.
Request-ID-number (32 bits). The Request-ID-number value combined Request-ID-number (32 bits). The Request-ID-number value combined
with the source IP address of the PCC and the PCE address uniquely with the source IP address of the PCC and the PCE address uniquely
identify the path computation request context. The Request-ID-number identify the path computation request context. The Request-ID-number
MUST be incremented each time a new request is sent to the PCE. The MUST be incremented each time a new request is sent to the PCE. The
value 0x0000000 is considered as invalid. If no path computation value 0x0000000 is considered as invalid. If no path computation
reply is received from the PCE, and the PCC wishes to resend its reply is received from the PCE, and the PCC wishes to resend its
request, the same Request-ID-number MUST be used. Conversely, request, the same Request-ID-number MUST be used. Conversely,
different Request-ID-number MUST be used for different requests sent different Request-ID-number MUST be used for different requests sent
to a PCE. The same Request-ID-number may be used for path to a PCE. The same Request-ID-number MAY be used for path
computation requests sent to different PCEs. The path computation computation requests sent to different PCEs. The path computation
reply is unambiguously identified by the IP source address of the reply is unambiguously identified by the IP source address of the
replying PCE. replying PCE.
7.4.2. Handling of the RP object 7.4.2. Handling of the RP Object
If a PCReq message is received without containing an RP object, the If a PCReq message is received that does not contain an RP object,
PCE MUST send a PCErr message to the requesting PCC with Error- the PCE MUST send a PCErr message to the requesting PCC with Error-
type="Required Object missing" and Error-value="RP Object missing". type="Required Object missing" and Error-value="RP Object missing".
If the O bit of the RP message carried within a PCReq message is If the O bit of the RP message carried within a PCReq message is
cleared and local policy has been configured on the PCE to not cleared and local policy has been configured on the PCE to not
provide explicit path(s) (for instance, for confidentiality reasons), provide explicit paths (for instance, for confidentiality reasons), a
a PCErr message MUST be sent by the PCE to the requesting PCC and the PCErr message MUST be sent by the PCE to the requesting PCC and the
pending path computation request MUST be discarded. The Error-type pending path computation request MUST be discarded. The Error-type
is "Policy Violation" and Error-value is "O bit cleared". is "Policy Violation" and Error-value is "O bit cleared".
R bit: when the R bit of the RP object is set in a PCReq message, R bit: when the R bit of the RP object is set in a PCReq message,
this indicates that the path computation request relates to the this indicates that the path computation request relates to the
reoptimization of an existing TE LSP. In this case, the PCC MUST reoptimization of an existing TE LSP. In this case, the PCC MUST
also provide the strict/loose path by including an RRO object in the also provide the strict/loose path by including an RRO object in the
PCReq message so as to avoid/limit double bandwidth counting if and PCReq message so as to avoid/limit double bandwidth counting if and
only if the TE LSP is a non 0-bandwidth TE LSP. If the PCC has not only if the TE LSP is a non-0-bandwidth TE LSP. If the PCC has not
requested a strict path (O bit set), a reoptimization can still be requested a strict path (O bit set), a reoptimization can still be
requested by the PCC but this implies for the PCE to be either requested by the PCC but this requires that the PCE either be
stateful (keep track of the previously computed path with the stateful (keep track of the previously computed path with the
associated list of strict hops) or to have the ability to retrieve associated list of strict hops), or have the ability to retrieve the
the complete required path segment. Alternatively the PCC MUST be complete required path segment. Alternatively the PCC MUST inform
able to inform PCE of the working path with associated list of strict the PCE of the working path with the associated list of strict hops
hops in PCReq. The absence of an RRO in the PCReq message for a non in PCReq. The absence of an RRO in the PCReq message for a non-0-
0-bandwidth TE LSP when the R bit of the RP object is set MUST bandwidth TE LSP when the R bit of the RP object is set MUST trigger
trigger the sending of a PCErr message with Error-type="Required the sending of a PCErr message with Error-type="Required Object
Object Missing" and Error-value="RRO Object missing for Missing" and Error-value="RRO Object missing for reoptimization".
reoptimization".
If the PCC receives a PCRep message that contains a RP object If the PCC receives a PCRep message that contains a RP object
referring to an unknown Request-ID-Number, the PCC MUST send a PCErr referring to an unknown Request-ID-Number, the PCC MUST send a PCErr
message with Error-Type="Unknown request reference". message with Error-Type="Unknown request reference".
7.5. NO-PATH Object 7.5. NO-PATH Object
The NO-PATH object is used in PCRep messages in response to an The NO-PATH object is used in PCRep messages in response to an
unsuccessful path computation request (the PCE could not find a path unsuccessful path computation request (the PCE could not find a path
satisfying the set of constraints). When a PCE cannot find a path satisfying the set of constraints). When a PCE cannot find a path
satisfying a set of constraints, it MUST include a NO-PATH object in satisfying a set of constraints, it MUST include a NO-PATH object in
the PCRep message. The NO-PATH object is used to report the the PCRep message.
impossibility to find a path that satisfies the set of constraints.
There are potentially several categories of issues that can lead to a There are several categories of issue that can lead to a negative
negative reply. For example, the PCE chain might be broken (should reply. For example, the PCE chain might be broken (should there be
there be more than one PCE involved in the path computation) or no more than one PCE involved in the path computation) or no path
path obeying the set constraints could be found. The "NI (Nature of obeying the set constraints could be found. The "NI (Nature of
Issue)" field in the NO-PATH object is used to report the error Issue)" field in the NO-PATH object is used to report the error
category. category.
Optionally, if the PCE supports such capability, the NO-PATH object Optionally, if the PCE supports such capability, the NO-PATH object
MAY contain an optional NO-PATH-VECTOR TLV defined below used to MAY contain an optional NO-PATH-VECTOR TLV defined below and used to
provide more information on the reasons that led to a negative reply provide more information on the reasons that led to a negative reply.
and the PCRep message MAY also contain a list of objects that specify The PCRep message MAY also contain a list of objects that specify the
the set of constraints that could not be satisfied. The PCE MAY just set of constraints that could not be satisfied. The PCE MAY just
replicate the set of object(s) that was received that was the cause replicate the set of objects that was received that was the cause of
of the unsuccessful computation or MAY optionally report a suggested the unsuccessful computation or MAY optionally report a suggested
value for which a path could have been found. value for which a path could have been found (in which case the value
differs from the value in the original request).
NO-PATH Object-Class is to be assigned by IANA (recommended value=3) NO-PATH Object-Class is to be assigned by IANA (recommended value=3)
NO-PATH Object-Type is to be assigned by IANA (recommended value=1) NO-PATH Object-Type is to be assigned by IANA (recommended value=1)
The format of the NO-PATH object body is as follows: The format of the NO-PATH object body is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Nature Of Issue|C| Flags | Reserved | |Nature Of Issue|C| Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Optional TLV(s) // // Optional TLV(s) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 29, line 31 skipping to change at page 29, line 39
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Nature Of Issue|C| Flags | Reserved | |Nature Of Issue|C| Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Optional TLV(s) // // Optional TLV(s) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: NO-PATH object format Figure 11: NO-PATH Object Format
NI - Nature Of Issue (8 bits): the NI field is used to report the NI - Nature Of Issue (8 bits): the NI field is used to report the
nature of the issue that led to a negative reply. Two values are nature of the issue that led to a negative reply. Two values are
currently defined: currently defined:
0x00: No path satisfying the set of constraints could be found 0x00: No path satisfying the set of constraints could be found
0x01: PCE chain broken 0x01: PCE chain broken
IANA management of the NI field codespace is described in Section 9.
Flags (16 bits). Flags (16 bits).
The following flag is currently defined: The following flag is currently defined:
C flag (1 bit): when set, the PCE indicates the set of unsatisfied C flag (1 bit): when set, the PCE indicates the set of unsatisfied
constraints (reasons why a path could not be found) in the PCRep constraints (reasons why a path could not be found) in the PCRep
message by including the relevant PCEP objects. When cleared, no message by including the relevant PCEP objects. When cleared, no
reason is specified. When the C bit is set, the NI field value MUST failing constraints are specified. The C flag has no meaning and is
be 0x00. ignored unless the NI field is set to 0x00.
Reserved (8 bits): This field MUST be set to zero on transmission and Reserved (8 bits): This field MUST be set to zero on transmission and
MUST be ignored on receipt. MUST be ignored on receipt.
The NO-PATH object body has a variable length and may contain The NO-PATH object body has a variable length and may contain
additional TLVs. The only TLV currently defined is the NO-PATH- additional TLVs. The only TLV currently defined is the NO-PATH-
VECTOR TLV defined below. VECTOR TLV defined below.
Example: consider the case of a PCC that sends a path computation Example: consider the case of a PCC that sends a path computation
request to a PCE for a TE LSP of X MBits/s. Suppose that PCE cannot request to a PCE for a TE LSP of X MBits/s. Suppose that PCE cannot
skipping to change at page 30, line 25 skipping to change at page 30, line 35
the unsuccessful computation is the bandwidth constraint (in this the unsuccessful computation is the bandwidth constraint (in this
case, the NI field value is 0x00 and C flag is set). If the PCE case, the NI field value is 0x00 and C flag is set). If the PCE
supports such capability it may alternatively include the BANDWIDTH supports such capability it may alternatively include the BANDWIDTH
Object and report a value of Y in the bandwidth field of the Object and report a value of Y in the bandwidth field of the
BANDWIDTH object (in this case, the C flag is set) where Y refers to BANDWIDTH object (in this case, the C flag is set) where Y refers to
the bandwidth for which a TE LSP with the same other characteristics the bandwidth for which a TE LSP with the same other characteristics
could have been computed. could have been computed.
When the NO-PATH object is absent from a PCRep message, the path When the NO-PATH object is absent from a PCRep message, the path
computation request has been fully satisfied and the corresponding computation request has been fully satisfied and the corresponding
path(s) is/are provided in the PCRep message. paths are provided in the PCRep message.
An optional TLV named NO-PATH-VECTOR MAY be included in the NO-PATH An optional TLV named NO-PATH-VECTOR MAY be included in the NO-PATH
object in order to provide more information on the reasons that led object in order to provide more information on the reasons that led
to a negative reply. to a negative reply.
The NO-PATH-VECTOR TLV is compliant with the PCEP TLV format defined in section 7.1 The NO-PATH-VECTOR TLV is compliant with the PCEP TLV format defined in
and is comprised of 2 bytes for the type, 2 bytes specifying the TLV length (length of section 7.1 and is comprised of 2 bytes for the type, 2 bytes specifying
the value portion in bytes) followed by a fix length value field of 32-bits flags field. the TLV length (length of the value portion in bytes) followed by a fixed
length value field of 32-bit flags field.
TYPE: To be assigned by IANA (suggested value=1) TYPE: To be assigned by IANA (suggested value=1)
LENGTH: 1 LENGTH: 1
VALUE: 32-bits flags field VALUE: 32-bit flags field
IANA is requested to manage the space of flags carried in the NO- IANA is requested to manage the space of flags carried in the NO-
PATH-VECTOR TLV (see Section 9). PATH-VECTOR TLV (see Section 9).
The following flags are currently defined: The following flags are currently defined:
o 0x01: PCE currently unavailable o Bit number: 1 - PCE currently unavailable
o 0x02: Unknown destination o Bit number: 2 - Unknown destination
o 0x03: Unknown source o Bit number: 3 - Unknown source
7.6. END-POINT Object 7.6. END-POINT Object
The END-POINTS object is used in a PCReq message to specify the The END-POINTS object is used in a PCReq message to specify the
source IP address and the destination IP address of the path for source IP address and the destination IP address of the path for
which a path computation is requested. The P flag of the END-POINT which a path computation is requested. The P flag of the END-POINT
object MUST be set. If the END-POINT objet is received with the P object MUST be set. If the END-POINT objet is received with the P
flag cleared, the receiving peer MUST send a PCErr message with flag cleared, the receiving peer MUST send a PCErr message with
Error-type=10 and Error-value=1. The corresponding path computation Error-type=10 and Error-value=1. The corresponding path computation
request MUST be cancelled by the PCE without further notification. request MUST be cancelled by the PCE without further notification.
skipping to change at page 32, line 15 skipping to change at page 32, line 15
as follows: as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source IPv4 address | | Source IPv4 address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination IPv4 address | | Destination IPv4 address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: END-POINTS object body format for IPv4 Figure 12: END-POINTS Object Body Format for IPv4
The format of the END-POINTS object for IPv6 (Object-Type=2) is as follows: The format of the END-POINTS object for IPv6 (Object-Type=2) is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Source IPv6 address (16 bytes) | | Source IPv6 address (16 bytes) |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Destination IPv6 address (16 bytes) | | Destination IPv6 address (16 bytes) |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: END-POINTS object body format for IPv6 Figure 13: END-POINTS Object Body Format for IPv6
The END-POINTS object body has a fixed length of 8 bytes for IPv4 and The END-POINTS object body has a fixed length of 8 bytes for IPv4 and
32 bytes for IPv6. 32 bytes for IPv6.
If more than one END-POINTS object is present, the first MUST be
processed and subsequent objects ignored.
7.7. BANDWIDTH Object 7.7. BANDWIDTH Object
The BANDWIDTH object is used to specify the requested bandwidth for a The BANDWIDTH object is used to specify the requested bandwidth for a
TE LSP. TE LSP.
If the requested bandwidth is equal to 0, the BANDWIDTH object is If the requested bandwidth is equal to 0, the BANDWIDTH object is
optional. Conversely, if the requested bandwidth is non equal to 0, optional. Conversely, if the requested bandwidth is non equal to 0,
the PCReq message MUST contain a BANDWIDTH object. the PCReq message MUST contain a BANDWIDTH object.
In the case of the reoptimization of a TE LSP, the bandwidth of the In the case of the reoptimization of a TE LSP, the bandwidth of the
existing TE LSP MUST also be included in addition to the requested existing TE LSP MUST also be included in addition to the requested
bandwidth if and only if the two values differ. Consequently, two bandwidth if and only if the two values differ. Consequently, two
Object-Type are defined that refer to the requested bandwidth and the Object-Type values are defined that refer to the requested bandwidth
bandwidth of the TE LSP for which a reoptimization is being and the bandwidth of the TE LSP for which a reoptimization is being
performed. performed.
The BANDWIDTH object may be carried within PCReq and PCRep messages. The BANDWIDTH object may be carried within PCReq and PCRep messages.
BANDWIDTH Object-Class is to be assigned by IANA (recommended BANDWIDTH Object-Class is to be assigned by IANA (recommended
value=5) value=5)
Two Object-Type are defined for the BANDWIDTH object: Two Object-Type values are defined for the BANDWIDTH object:
o Requested bandwidth: BANDWIDTH Object-Type is to be assigned by o Requested bandwidth: BANDWIDTH Object-Type is to be assigned by
IANA (recommended value=1) IANA (recommended value=1)
o Bandwidth of an existing TE LSP for which a reoptimization is o Bandwidth of an existing TE LSP for which a reoptimization is
requested. BANDWIDTH Object-Type is to be assigned by IANA requested. BANDWIDTH Object-Type is to be assigned by IANA
(recommended value=2) (recommended value=2)
The format of the BANDWIDTH object body is as follows: The format of the BANDWIDTH object body is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bandwidth | | Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 14: BANDWIDTH object body format Figure 14: BANDWIDTH Object Body Format
Bandwidth: 32 bits. The requested bandwidth is encoded in 32 bits in Bandwidth: 32 bits. The requested bandwidth is encoded in 32 bits in
IEEE floating point format, expressed in bytes per second. IEEE floating point format, expressed in bytes per second. Refer to
Section 3.1.2 of [RFC3471] for a table of commonly used values.
The BANDWIDTH object body has a fixed length of 4 bytes. The BANDWIDTH object body has a fixed length of 4 bytes.
7.8. METRIC Object 7.8. METRIC Object
The METRIC object is optional and can be used for several purposes. The METRIC object is optional and can be used for several purposes.
In a PCReq message, a PCC MAY insert a METRIC object: In a PCReq message, a PCC MAY insert one of more METRIC objects:
o To indicate the metric that MUST be optimized by the path o To indicate the metric that MUST be optimized by the path
computation algorithm (IGP metric, TE metric, Hop counts). computation algorithm (IGP metric, TE metric, Hop counts).
Currently, three metrics are defined: the IGP cost, the TE metric Currently, three metrics are defined: the IGP cost, the TE metric
(see [RFC3785]) and the number of hops traversed by a TE LSP. (see [RFC3785]) and the number of hops traversed by a TE LSP.
o To indicate a bound on the path cost that MUST NOT be exceeded for o To indicate a bound on the path cost that MUST NOT be exceeded for
the path to be considered as acceptable by the PCC. the path to be considered as acceptable by the PCC.
In a PCRep message, the METRIC object MAY be inserted so as to In a PCRep message, the METRIC object MAY be inserted so as to
provide the cost for the computed path. It MAY also be inserted provide the cost for the computed path. It MAY also be inserted
within a PCRep with the NO-PATH object to indicate that the metric within a PCRep with the NO-PATH object to indicate that the metric
constraint could not be satisfied. constraint could not be satisfied.
The path computation algorithmic aspects used by the PCE to optimize The path computation algorithmic aspects used by the PCE to optimize
a path with respect to a specific metric are outside the scope of a path with respect to a specific metric are outside the scope of
this document. this document.
It must be understood that such path metric is only meaningful if It must be understood that such path metrics are only meaningful if
used consistently: for instance, if the delay of a path computation used consistently: for instance, if the delay of a computed path
segment is exchanged between two PCEs residing in different domains, segment is exchanged between two PCEs residing in different domains,
consistent ways of defining the delay must be used. consistent ways of defining the delay must be used.
The absence of the METRIC object MUST be interpreted by the PCE as a The absence of the METRIC object MUST be interpreted by the PCE as a
path computation request for which the PCE may choose the metric to path computation request for which no constraints need be applied to
be used. any of the metrics.
METRIC Object-Class is to be assigned by IANA (recommended value=6) METRIC Object-Class is to be assigned by IANA (recommended value=6)
METRIC Object-Type is to be assigned by IANA (recommended value=1) METRIC Object-Type is to be assigned by IANA (recommended value=1)
The format of the METRIC object body is as follows: The format of the METRIC object body is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags |C|B| T | | Reserved | Flags |C|B| T |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| metric-value | | metric-value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 15: METRIC object body format Figure 15: METRIC Object Body Format
The METRIC object body has a fixed length of 8 bytes. The METRIC object body has a fixed length of 8 bytes.
Reserved (16 bits): This field MUST be set to zero on transmission Reserved (16 bits): This field MUST be set to zero on transmission
and MUST be ignored on receipt. and MUST be ignored on receipt.
T (Type - 8 bits): Specifies the metric type. T (Type - 8 bits): Specifies the metric type.
Three values are currently defined: Three values are currently defined:
skipping to change at page 34, line 45 skipping to change at page 35, line 4
Reserved (16 bits): This field MUST be set to zero on transmission Reserved (16 bits): This field MUST be set to zero on transmission
and MUST be ignored on receipt. and MUST be ignored on receipt.
T (Type - 8 bits): Specifies the metric type. T (Type - 8 bits): Specifies the metric type.
Three values are currently defined: Three values are currently defined:
o T=1: IGP metric o T=1: IGP metric
o T=2: TE metric o T=2: TE metric
o T=3: Hop Counts o T=3: Hop Counts
Flags (8 bits): Two flags are currently defined: Flags (8 bits): Two flags are currently defined:
o B (Bound - 1 bit): When set in a PCReq message, the metric-value o B (Bound - 1 bit): When set in a PCReq message, the metric-value
indicates a bound (a maximum) for the path cost that must not be indicates a bound (a maximum) for the path metric that must not be
exceeded for the PCC to consider the computed path as acceptable. exceeded for the PCC to consider the computed path as acceptable.
The path metric must be less than or equal to the value specified
in the Metric-value field. When the B flag is cleared, the
metric-value field is not used to reflect a bound constraint.
When the B flag is cleared, the metric-value field is not used to o C (Computed Metric - 1 bit): When set in a PCReq message, this
reflect a bound constraint. indicates that the PCE MUST provide the computed path metric value
(should a path satisfying the constraints be found) in the PCRep
o C (Cost - 1 bit): When set in a PCReq message, this indicates that message for the corresponding metric.
the PCE MUST provide the computed path cost (should a path
satisfying the constraints be found) in the PCRep message for the
corresponding metric.
Unassigned flags MUST be set to zero on transmission and MUST be Unassigned flags MUST be set to zero on transmission and MUST be
ignored on receipt. ignored on receipt.
Metric-value (32 bits): metric value encoded in 32 bits in IEEE Metric-value (32 bits): metric value encoded in 32 bits in IEEE
floating point format. floating point format.
Multiple METRIC Objects MAY be inserted in a PCRep or the PCReq Multiple METRIC Objects MAY be inserted in a PCRep or the PCReq
message. There MUST be at most one instance of the METRIC object for message. There MUST be at most one instance of the METRIC object for
each metric type with the same B flag value. If two or more each metric type with the same B flag value. If two or more
instances of a METRIC object with the same B flag value are present instances of a METRIC object with the same B flag value are present
for a metric type, only the first instance MUST be considered and for a metric type, only the first instance MUST be considered and
other instances MUST be ignored. other instances MUST be ignored.
In a PCReq message the presence of multiple METRIC objects can be The presence of two METRIC objects of the same type with a different
used to specify a multi-parameters (e.g. a metric may be a constraint value of the B-Flag in a PCEReq message is allowed. Furthermore, it
or a parameter to minimize/maximize) objective function or multiple is also allowed to insert in a PCReq message two METRIC objects with
bounds for different constraints where at most one METRIC object must the same type that have both their B-Flag cleared: in this case, an
be used to indicate the metric to optimize (B-flag is cleared): the objective function must be used by the PCE to solve a multi-parameter
other METRIC object MUST be used to reflect bound constraints (B-Flag constraint problem.
is set). If a PCReq message is received that contains two METRIC
objects with the B flag set, the receiving peer MUST send a PCErr
message with Error-type=10 and Error-value=2.
A METRIC object used to indicate the metric to optimize during the A METRIC object used to indicate the metric to optimize during the
path computation MUST have the B-Flag cleared and the T-Flag set to path computation MUST have the B-Flag cleared and the C-Flag set to
the appropriate value. When the path computation relates to the the appropriate value. When the path computation relates to the
reoptimization of an exiting TE LSP (in which case R-Flag of the RP reoptimization of an exiting TE LSP (in which case R-Flag of the RP
object is set) an implementation MAY decide to set the metric-value object is set) an implementation MAY decide to set the metric-value
field to the cost of the TE LSP to be reoptimized with regards to a field to the computed value of the metric of the TE LSP to be
specific metric type. reoptimized with regards to a specific metric type.
A METRIC object used to reflect a bound MUST have the B-Flag set, the A METRIC object used to reflect a bound MUST have the B-Flag set, the
T-Flag and metric-value field set to the appropriate values. C-Flag and metric-value field set to the appropriate values.
In a PCRep message, unless not allowed by PCE policy, at least one In a PCRep message, unless not allowed by PCE policy, at least one
METRIC object MUST be present that reports the computed path cost in METRIC object MUST be present that reports the computed path metric
particular if the C bit of the METRIC object was set in the if the C bit of the METRIC object was set in the corresponding path
corresponding path computation request (the B-flag MUST be cleared); computation request (the B-flag MUST be cleared). The C-flag has no
optionally the PCRep message MAY contain additional METRIC objects meaning in a PCRep message. Optionally the PCRep message MAY contain
that correspond to bound constraints, in which case the metric-value additional METRIC objects that correspond to bound constraints, in
MUST be equal to the corresponding path metric cost (the B-flag MUST which case the metric-value MUST be equal to the corresponding
be set). If no path satisfying the constraints could be found by the computed path metric (the B-flag MUST be set). If no path satisfying
PCE, the METRIC objects MAY also be present in the PCRep message with the constraints could be found by the PCE, the METRIC objects MAY
the NO-PATH object to indicate the constraint metric that could be also be present in the PCRep message with the NO-PATH object to
satisfied. indicate the constraint metric that could be satisfied.
Example: if a PCC sends a path computation request to a PCE where the Example: if a PCC sends a path computation request to a PCE where the
metric to optimize is the IGP metric and the TE metric must not metric to optimize is the IGP metric and the TE metric must not
exceed the value of M, two METRIC object are inserted in the PCReq exceed the value of M, two METRIC object are inserted in the PCReq
message: message:
o First METRIC Object with B=0, T=1, C=1, metric-value=0x0000 o First METRIC Object with B=0, T=1, C=1, metric-value=0x0000
o Second METRIC Object with B=1, T=2, metric-value=M o Second METRIC Object with B=1, T=2, metric-value=M
If a path satisfying the set of constraints can be found by the PCE If a path satisfying the set of constraints can be found by the PCE
and no policy preventing to provide the path cost is in place, the and there is no policy that prevents the return of the computed
PCE inserts one METRIC object with B=0, T=1, metric-value= computed metric, the PCE inserts one METRIC object with B=0, T=1, metric-
IGP path cost. Additionally, the PCE may insert a second METRIC value= computed IGP path cost. Additionally, the PCE may insert a
object with B=1, T=2, metric-value= computed TE path cost. second METRIC object with B=1, T=2, metric-value= computed TE path
cost.
7.9. Explicit Route Object 7.9. Explicit Route Object
The ERO is used to encode a TE LSP. The ERO is carried within a The ERO is used to encode the path of a TE LSP through the network.
PCRep message to provide the computed TE LSP should have the path The ERO is carried within a PCRep message to provide the computed TE
computation been successful. LSP should the path computation have been successful.
The contents of this object are identical in encoding to the contents The contents of this object are identical in encoding to the contents
of the Explicit Route Object defined in [RFC3209], [RFC3473] and of the Resource Reservation Protocol Traffic Engineering Extensions
[RFC3477]. That is, the object is constructed from a series of sub- (RSVP-TE) Explicit Route Object (ERO) defined in [RFC3209], [RFC3473]
objects. Any RSVP ERO sub-object already defined or that could be and [RFC3477]. That is, the object is constructed from a series of
defined in the future for use in the ERO is acceptable in this sub-objects. Any RSVP-TE ERO sub-object already defined or that
object. could be defined in the future for use in the RSVP-TE ERO is
acceptable in this object.
PCEP ERO sub-object types correspond to RSVP ERO sub-object types. PCEP ERO sub-object types correspond to RSVP-TE ERO sub-object types.
Since the explicit path is available for immediate signaling by the Since the explicit path is available for immediate signaling by the
MPLS or GMPLS control plane, the meanings of all of the sub-objects MPLS or GMPLS control plane, the meanings of all of the sub-objects
and fields in this object are identical to those defined for the ERO. and fields in this object are identical to those defined for the ERO.
ERO Object-Class is to be assigned by IANA (recommended value=7) ERO Object-Class is to be assigned by IANA (recommended value=7)
ERO Object-Type is to be assigned by IANA (recommended value=1) ERO Object-Type is to be assigned by IANA (recommended value=1)
7.10. Route Record Object 7.10. Reported Route Object
The RRO is used to record the route followed by a TE LSP. The PCEP The RRO is exclusively carried within a PCReq message so as to report
RRO is exclusively carried within a PCReq message so as to specify
the route followed by a TE LSP for which a reoptimization is desired. the route followed by a TE LSP for which a reoptimization is desired.
The contents of this object are identical in encoding to the contents The contents of this object are identical in encoding to the contents
of the Route Record Object defined in [RFC3209], [RFC3473] and of the Route Record Object defined in [RFC3209], [RFC3473] and
[RFC3477]. That is, the object is constructed from a series of sub- [RFC3477]. That is, the object is constructed from a series of sub-
objects. Any RSVP RRO sub-object already defined or that could be objects. Any RSVP-TE RRO sub-object already defined or that could be
defined in the future for use in the RRO is acceptable in this defined in the future for use in the RSVP-TE RRO is acceptable in
object. this object.
The meanings of all of the sub-objects and fields in this object are The meanings of all of the sub-objects and fields in this object are
identical to those defined for the RRO. identical to those defined for the RSVP-TE RRO.
PCEP RRO sub-object types correspond to RSVP RRO sub-object types. PCEP RRO sub-object types correspond to RSVP-TE RRO sub-object types.
RRO Object-Class is to be assigned by IANA (recommended value=8) RRO Object-Class is to be assigned by IANA (recommended value=8)
RRO Object-Type is to be assigned by IANA (recommended value=1) RRO Object-Type is to be assigned by IANA (recommended value=1)
7.11. LSPA Object 7.11. LSPA Object
The LSPA object is optional and specifies various TE LSP attributes The LSPA object is optional and specifies various TE LSP attributes
to be taken into account by the PCE during path computation. The to be taken into account by the PCE during path computation. The
LSPA (LSP Attributes) object can either be carried within a PCReq LSPA (LSP Attributes) object can be carried within a PCReq message,
message or a PCRep message in case of unsuccessful path computation or a PCRep message in case of unsuccessful path computation (in this
(in this case, the PCRep message also contains a NO-PATH object and case, the PCRep message also contains a NO-PATH object and the LSPA
the LSPA object is used to indicate the set of constraint(s) that object is used to indicate the set of constraints that could not be
could not be satisfied). Most of the fields of the LSPA object are satisfied). Most of the fields of the LSPA object are identical to
identical to the fields of the SESSION-ATTRIBUTE object defined in the fields of the SESSION-ATTRIBUTE (C-Type = 7) object defined in
[RFC3209] and [RFC4090]. When absent from the PCReq message, this [RFC3209] and [RFC4090]. When absent from the PCReq message, this
means that the Setup and Holding priorities are equal to 0, and there means that the Setup and Holding priorities are equal to 0, and there
are no affinity constraints. are no affinity constraints.
LSPA Object-Class is to be assigned by IANA (recommended value=9) LSPA Object-Class is to be assigned by IANA (recommended value=9)
LSPA Object-Types is to be assigned by IANA (recommended value=1) LSPA Object-Types is to be assigned by IANA (recommended value=1)
The format of the LSPA object body is: The format of the LSPA object body is:
0 1 2 3 0 1 2 3
skipping to change at page 38, line 22 skipping to change at page 38, line 22
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Include-all | | Include-all |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Setup Prio | Holding Prio | Flags |L| Reserved | | Setup Prio | Holding Prio | Flags |L| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Optional TLV(s) // // Optional TLV(s) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 16: LSPA object body format Figure 16: LSPA Object Body Format
Setup Prio (Setup Priority - 8 bits). The priority of the session Setup Prio (Setup Priority - 8 bits). The priority of the TE LSP
with respect to taking resources, in the range of 0 to 7. The value with respect to taking resources, in the range of 0 to 7. The value
0 is the highest priority. The Setup Priority is used in deciding 0 is the highest priority. The Setup Priority is used in deciding
whether this session can preempt another session. whether this session can preempt another session.
Holding Prio (Holding Priority - 8 bits). The priority of the Holding Prio (Holding Priority - 8 bits). The priority of the TE LSP
session with respect to holding resources, in the range of 0 to 7. with respect to holding resources, in the range of 0 to 7. The value
The value 0 is the highest priority. Holding Priority is used in 0 is the highest priority. Holding Priority is used in deciding
deciding whether this session can be preempted by another session. whether this session can be preempted by another session.
Flags (8 bits) Flags (8 bits)
The flag L corresponds to the "Local protection desired" bit The flag L corresponds to the "Local protection desired" bit
([RFC3209]) of the SESSION-ATTRIBUTE Object. ([RFC3209]) of the SESSION-ATTRIBUTE Object.
L Flag (Local protection desired). When set, this means that the L Flag (Local protection desired). When set, this means that the
computed path must include links protected with Fast Reroute as computed path must include links protected with Fast Reroute as
defined in [RFC4090]. defined in [RFC4090].
skipping to change at page 39, line 11 skipping to change at page 39, line 11
Note that Optional TLVs may be defined in the future to carry Note that Optional TLVs may be defined in the future to carry
additional TE LSP attributes such as those defined in [RFC4420]. additional TE LSP attributes such as those defined in [RFC4420].
7.12. Include Route Object Object 7.12. Include Route Object Object
The IRO (Include Route Object) is optional and can be used to specify The IRO (Include Route Object) is optional and can be used to specify
that the computed path MUST traverse a set of specified network that the computed path MUST traverse a set of specified network
elements. The IRO MAY be carried within PCReq and PCRep messages. elements. The IRO MAY be carried within PCReq and PCRep messages.
When carried within a PCRep message with the NO-PATH object, the IRO When carried within a PCRep message with the NO-PATH object, the IRO
indicates the set of elements that fail the PCE to find a path. indicates the set of elements that cause de PCE to fail to find a
path.
IRO Object-Class is to be assigned by IANA (recommended value=10) IRO Object-Class is to be assigned by IANA (recommended value=10)
IRO Object-Type is to be assigned by IANA (recommended value=1) IRO Object-Type is to be assigned by IANA (recommended value=1)
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// (Subobjects) // // (Subobjects) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 17: IRO body format Figure 17: IRO Body Format
Subobjects The IRO is made of sub-object(s) identical to the ones
defined in [RFC3209], [RFC3473] and [RFC3477] for use in EROs. Subobjects: The IRO is made of subobjects identical to the ones
defined in [RFC3209], [RFC3473] and [RFC3477] where the IRO subobject
type is identical to the subobject type defined in the related
documents.
The following subobject types are supported. The following subobject types are supported.
Type Subobject Type Subobject
1 IPv4 prefix 1 IPv4 prefix
2 IPv6 prefix 2 IPv6 prefix
4 Unnumbered Interface ID 4 Unnumbered Interface ID
32 Autonomous system number 32 Autonomous system number
The L bit of such sub-object has no meaning within an IRO. The L bit of such sub-object has no meaning within an IRO.
7.13. SVEC Object 7.13. SVEC Object
7.13.1. Notion of Dependent and Synchronized path computation requests 7.13.1. Notion of Dependent and Synchronized Path Computation Requests
Independent versus dependent path computation requests: path Independent versus dependent path computation requests: path
computation requests are said to be independent if they are not computation requests are said to be independent if they are not
related to each other. Conversely a set of dependent path related to each other. Conversely a set of dependent path
computation requests is such that their computations cannot be computation requests is such that their computations cannot be
performed independently of each other (a typical example of dependent performed independently of each other (a typical example of dependent
requests is the computation of a set of diverse paths). requests is the computation of a set of diverse paths).
Synchronized versus non-synchronized path computation requests: a set Synchronized versus non-synchronized path computation requests: a set
of path computation requests is said to be non-synchronized if their of path computation requests is said to be non-synchronized if their
respective treatment (path computations) can be performed by a PCE in respective treatment (path computations) can be performed by a PCE in
a serialized and independent fashion. a serialized and independent fashion.
There are various circumstances where the synchronization of a set of There are various circumstances where the synchronization of a set of
path computations may be beneficial or required. path computations may be beneficial or required.
Consider the case of a set of N TE LSPs for which a PCC needs to send Consider the case of a set of N TE LSPs for which a PCC needs to send
path computation requests to a PCE. The first solution consists of path computation requests to a PCE. The first solution consists of
sending N separate PCReq messages to the selected PCE. In this case, sending N separate PCReq messages to the selected PCE. In this case,
the path computation requests are non synchronized. Note that the the path computation requests are non-synchronized. Note that the
PCC may chose to distribute the set of N requests across K PCEs for PCC may chose to distribute the set of N requests across K PCEs for
load balancing purpose. Considering that M (with M<N) requests are load balancing purposes. Considering that M (with M<N) requests are
sent to a particular PCEi, as described above, such M requests can be sent to a particular PCEi, as described above, such M requests can be
sent in the form of successive PCReq messages destined to PCEi or sent in the form of successive PCReq messages destined to PCEi or
bundled within a single PCReq message (since PCEP allows for the bundled within a single PCReq message (since PCEP allows for the
bundling of multiple path computation requests within a single PCReq bundling of multiple path computation requests within a single PCReq
message). That said, even in the case of independent requests, it message). That said, even in the case of independent requests, it
can be desirable to request from the PCE the computation of their can be desirable to request from the PCE the computation of their
paths in a synchronized fashion that is likely to lead to more paths in a synchronized fashion that is likely to lead to more
optimal path computations and/or reduced blocking probability if the optimal path computations and/or reduced blocking probability if the
PCE is a stateless PCE. In other words, the PCE should not compute PCE is a stateless PCE. In other words, the PCE should not compute
the corresponding paths in a serialized and independent manner but it the corresponding paths in a serialized and independent manner but it
skipping to change at page 40, line 27 skipping to change at page 40, line 32
bundling of multiple path computation requests within a single PCReq bundling of multiple path computation requests within a single PCReq
message). That said, even in the case of independent requests, it message). That said, even in the case of independent requests, it
can be desirable to request from the PCE the computation of their can be desirable to request from the PCE the computation of their
paths in a synchronized fashion that is likely to lead to more paths in a synchronized fashion that is likely to lead to more
optimal path computations and/or reduced blocking probability if the optimal path computations and/or reduced blocking probability if the
PCE is a stateless PCE. In other words, the PCE should not compute PCE is a stateless PCE. In other words, the PCE should not compute
the corresponding paths in a serialized and independent manner but it the corresponding paths in a serialized and independent manner but it
should rather "simultaneously" compute their paths. For example, should rather "simultaneously" compute their paths. For example,
trying to "simultaneously" compute the paths of M TE LSPs may allow trying to "simultaneously" compute the paths of M TE LSPs may allow
the PCE to improve the likelihood to meet multiple constraints. the PCE to improve the likelihood to meet multiple constraints.
Consider the case of two TE LSPs requesting N1 MBits/s and N2 MBits/s Consider the case of two TE LSPs requesting N1 MBits/s and N2 MBits/s
respectively and a maximum tolerable end-to-end delay for each TE LSP respectively and a maximum tolerable end-to-end delay for each TE LSP
of X ms. There may be circumstances where the computation of the of X ms. There may be circumstances where the computation of the
first TE LSP irrespectively of the second TE LSP may lead to the first TE LSP irrespectively of the second TE LSP may lead to the
impossibility to meet the delay constraint for the second TE LSP. A impossibility to meet the delay constraint for the second TE LSP.
second example is related to the bandwidth constraint. It is quite
A second example is related to the bandwidth constraint. It is quite
straightforward to provide examples where a serialized independent straightforward to provide examples where a serialized independent
path computation approach would lead to the impossibility to satisfy path computation approach would lead to the impossibility to satisfy
both requests (due to bandwidth fragmentation) while a synchronized both requests (due to bandwidth fragmentation) while a synchronized
path computation would successfully satisfy both requests. A last path computation would successfully satisfy both requests.
example relates to the ability to avoid the allocation of the same
resource to multiple requests thus helping to reduce the call set up A last example relates to the ability to avoid the allocation of the
failure probability compared to the serialized computation of same resource to multiple requests thus helping to reduce the call
set up failure probability compared to the serialized computation of
independent requests. independent requests.
Dependent path computation are usually synchronized. For example, in Dependent path computation are usually synchronized. For example, in
the case of the computation of M diverse paths, if such paths are the case of the computation of M diverse paths, if such paths are
computed in a non-synchronized fashion this seriously increases the computed in a non-synchronized fashion this seriously increases the
probability of not being able to satisfy all requests (sometimes also probability of not being able to satisfy all requests (sometimes also
referred to as the well-know "trapping problem"). Furthermore, this referred to as the well-know "trapping problem").
would not allow a PCE to implement objective functions such as trying
to minimize the sum of the TE LSP costs. In such a case, the path Furthermore, this would not allow a PCE to implement objective
computation requests must be synchronized: they cannot be computed functions such as trying to minimize the sum of the TE LSP costs. In
independently of each other. Conversely a set of independent path such a case, the path computation requests must be synchronized: they
computation requests may or may not be synchronized. cannot be computed independently of each other.
Conversely a set of independent path computation requests may or may
not be synchronized.
The synchronization of a set of path computation requests is achieved The synchronization of a set of path computation requests is achieved
by using the SVEC object that specifies the list of synchronized by using the SVEC object that specifies the list of synchronized
requests that can either be dependent or independent. requests that can either be dependent or independent.
PCEP supports the following three modes: PCEP supports the following three modes:
o Bundle of a set of independent and non-synchronized path o Bundle of a set of independent and non-synchronized path
computation requests, computation requests,
skipping to change at page 41, line 40 skipping to change at page 42, line 4
request the synchronization of M path computation requests. The SVEC request the synchronization of M path computation requests. The SVEC
object is a variable length object that lists the set of M path object is a variable length object that lists the set of M path
computation requests that must be synchronized. Each path computation requests that must be synchronized. Each path
computation request is uniquely identified by the Request-ID-number computation request is uniquely identified by the Request-ID-number
carried within the respective RP object. The SVEC object also carried within the respective RP object. The SVEC object also
contains a set of flags that specify the synchronization type. contains a set of flags that specify the synchronization type.
SVEC Object-Class is to be assigned by IANA (recommended value=11) SVEC Object-Class is to be assigned by IANA (recommended value=11)
SVEC Object-Type is to be assigned by IANA (recommended value=1) SVEC Object-Type is to be assigned by IANA (recommended value=1)
One Object-Type is defined for this object to be assigned by IANA
with a recommended value of 1.
The format of the SVEC object body is as follows: The format of the SVEC object body is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags |S|N|L| | Reserved | Flags |S|N|L|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Request-ID-number #1 | | | Request-ID-number #1 | |
// // // //
| Request-ID-number #M | | Request-ID-number #M |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 42, line 16 skipping to change at page 42, line 16
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags |S|N|L| | Reserved | Flags |S|N|L|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Request-ID-number #1 | | | Request-ID-number #1 | |
// // // //
| Request-ID-number #M | | Request-ID-number #M |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 18: SVEC body object format Figure 18: SVEC Body Object Format
Reserved (8 bits): This field MUST be set to zero on transmission and Reserved (8 bits): This field MUST be set to zero on transmission and
MUST be ignored on receipt. MUST be ignored on receipt.
Flags (24 bits): Defines the potential dependency between the set of Flags (24 bits): Defines the potential dependency between the set of
path computation requests. path computation requests.
o L (Link diverse) bit: when set, this indicates that the computed o L (Link diverse) bit: when set, this indicates that the computed
paths corresponding to the requests specified by the following RP paths corresponding to the requests specified by the following RP
objects MUST NOT have any link in common. objects MUST NOT have any link in common.
skipping to change at page 42, line 49 skipping to change at page 42, line 49
Unassigned flags MUST be set to zero on transmission and MUST be Unassigned flags MUST be set to zero on transmission and MUST be
ignored on receipt. ignored on receipt.
The flags defined above are not exclusive. The flags defined above are not exclusive.
7.13.3. Handling of the SVEC Object 7.13.3. Handling of the SVEC Object
The SVEC object allows a PCC to specify a list of M path computation The SVEC object allows a PCC to specify a list of M path computation
requests that MUST be synchronized along with a potential dependency. requests that MUST be synchronized along with a potential dependency.
The set of M path computation requests may be sent within a single The set of M path computation requests may be sent within a single
PCReq message or multiple PCReq message. In the later case, it is PCReq message or multiple PCReq messages. In the later case, it is
RECOMMENDED for the PCE to implement a local timer activated upon the RECOMMENDED for the PCE to implement a local timer activated upon the
receipt of the first PCReq message that contains the SVEC object receipt of the first PCReq message that contains the SVEC object
after the expiration of which, if all the M path computation requests after the expiration of which, if all the M path computation requests
have not been received, a protocol error is triggered (this timer is have not been received, a protocol error is triggered (this timer is
called the SyncTimer). When a PCE receives a path computation called the SyncTimer). When a PCE receives a path computation
request that cannot be satisfied (for example because the PCReq request that cannot be satisfied (for example, because the PCReq
message contains an object with the P bit set that is not supported), message contains an object with the P bit set that is not supported),
the PCE sends a PCErr message for this request (see Section 7.2, the the PCE sends a PCErr message for this request (see Section 7.2, the
PCE MUST cancel the whole set of related path computation requests PCE MUST cancel the whole set of related path computation requests
and MUST send a PCErr message with Error-Type="Synchronized path and MUST send a PCErr message with Error-Type="Synchronized path
computation request missing". computation request missing".
Note that such PCReq message may also contain non-synchronized path Note that such PCReq message may also contain non-synchronized path
computation requests. For example, the PCReq message may comprise N computation requests. For example, the PCReq message may comprise N
synchronized path computation requests related to RP 1, ... , RP N synchronized path computation requests related to RP 1, ... , RP N
listed in the SVEC object along with any other path computation listed in the SVEC object along with any other path computation
requests. requests that are processed as normal.
7.14. NOTIFICATION Object 7.14. NOTIFICATION Object
The NOTIFICATION object is exclusively carried within a PCNtf message The NOTIFICATION object is exclusively carried within a PCNtf message
and can either be used in a message sent by a PCC to a PCE or by a and can either be used in a message sent by a PCC to a PCE or by a
PCE to a PCC so as to notify of an event. PCE to a PCC so as to notify of an event.
NOTIFICATION Object-Class is to be assigned by IANA (recommended NOTIFICATION Object-Class is to be assigned by IANA (recommended
value=12) value=12)
NOTIFICATION Object-Type is to be assigned by IANA (recommended NOTIFICATION Object-Type is to be assigned by IANA (recommended
value=1) value=1)
One Object-Type is defined for this object to be assigned by IANA
with a recommended value of 1.
The format of the NOTIFICATION body object is as follows: The format of the NOTIFICATION body object is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags | NT | NV | | Reserved | Flags | NT | NV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Optional TLV(s) // // Optional TLV(s) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 43, line 45 skipping to change at page 43, line 44
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags | NT | NV | | Reserved | Flags | NT | NV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Optional TLV(s) // // Optional TLV(s) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 19: NOTIFICATION body object format Figure 19: NOTIFICATION Body Object Format
Reserved (8 bits): This field MUST be set to zero on transmission and Reserved (8 bits): This field MUST be set to zero on transmission and
MUST be ignored on receipt. MUST be ignored on receipt.
Flags (8 bits): no flags are currently defined. Unassigned flags Flags (8 bits): no flags are currently defined. Unassigned flags
MUST be set to zero on transmission and MUST be ignored on receipt. MUST be set to zero on transmission and MUST be ignored on receipt.
NT (Notification Type - 8 bits): the Notification-type specifies the NT (Notification Type - 8 bits): the Notification-type specifies the
class of notification class of notification
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addition information related to the nature of the notification. addition information related to the nature of the notification.
Both the Notification-type and Notification-value should be managed Both the Notification-type and Notification-value should be managed
by IANA. by IANA.
The following Notification-type and Notification-value values are The following Notification-type and Notification-value values are
currently defined: currently defined:
o Notification-type=1: Pending Request cancelled o Notification-type=1: Pending Request cancelled
* Notification-value=1: PCC cancels a set of pending request(s). * Notification-value=1: PCC cancels a set of pending requests. A
A Notification-type=1, Notification-value=1 indicates that the Notification-type=1, Notification-value=1 indicates that the
PCC wants to inform a PCE of the cancellation of a set of PCC wants to inform a PCE of the cancellation of a set of
pending request(s). Such event could be triggered because of pending requests. Such an event could be triggered because of
external conditions such as the receipt of a positive reply external conditions such as the receipt of a positive reply
from another PCE (should the PCC have sent multiple requests to from another PCE (should the PCC have sent multiple requests to
a set of PCEs for the same path computation request), a network a set of PCEs for the same path computation request), a network
event such as a network failure rendering the request obsolete event such as a network failure rendering the request obsolete,
or any other event(s) local to the PCC. A NOTIFICATION object or any other events local to the PCC. A NOTIFICATION object
with Notification-type=1, Notification-value=1 is carried with Notification-type=1, Notification-value=1 is carried
within a PCNtf message sent by the PCC to the PCE. The RP within a PCNtf message sent by the PCC to the PCE. The RP
object corresponding to the cancelled request MUST also be object corresponding to the cancelled request MUST also be
present in the PCNtf message. Multiple RP objects may be present in the PCNtf message. Multiple RP objects may be
carried within the PCNtf message in which case the notification carried within the PCNtf message in which case the notification
applies to all of them. If such notification is received by a applies to all of them. If such a notification is received by
PCC from a PCE, the PCC MUST silently ignore the notification a PCC from a PCE, the PCC MUST silently ignore the notification
and no errors should be generated. and no errors should be generated.
* Notification-value=2: PCE cancels a set of pending request(s). * Notification-value=2: PCE cancels a set of pending requests. A
A Notification-type=1, Notification-value=2 indicates that the Notification-type=1, Notification-value=2 indicates that the
PCE wants to inform a PCC of the cancellation of a set of PCE wants to inform a PCC of the cancellation of a set of
pending request(s). Such event could be triggered because of pending requests. A NOTIFICATION object with Notification-
PCE overloaded state or because of missing path computation type=1, Notification-value=2 is carried within a PCNtf message
requests that are part the set of synchronized path computation sent by a PCE to a PCC. The RP object corresponding to the
requests. A NOTIFICATION object with Notification-type=1, cancelled request MUST also be present in the PCNtf message.
Notification-value=2 is carried within a PCNtf message sent by Multiple RP objects may be carried within the PCNtf message in
a PCE to a PCC. The RP object corresponding to the cancelled which case the notification applies to all of them. If such
request MUST also be present in the PCNtf message. Multiple RP notification is received by a PCE from a PCC, the PCE MUST
objects may be carried within the PCNtf message in which case silently ignore the notification and no errors should be
the notification applies to all of them. If such notification generated.
is received by a PCE from a PCC, the PCE MUST silently ignore
the notification and no errors should be generated.
o Notification-type=2: Overloaded PCE o Notification-type=2: Overloaded PCE
* Notification-value=1: A Notification-type=2, Notification- * Notification-value=1: A Notification-type=2, Notification-
value=1 indicates to the PCC(s) that the PCE is currently in an value=1 indicates to the PCC(s) that the PCE is currently in an
overloaded state. If no RP objects are comprised in the PCNtf overloaded state. If no RP objects are included in the PCNtf
message, this indicates that no other requests SHOULD be sent message, this indicates that no other requests SHOULD be sent
to that PCE until the overloaded state is cleared: the pending to that PCE until the overloaded state is cleared: the pending
requests are not affected and will be served. If some pending requests are not affected and will be served. If some pending
requests cannot be served due to the overloaded state, the PCE requests cannot be served due to the overloaded state, the PCE
MUST also include a set of RP object(s) that identifies the set MUST also include a set of RP objects that identifies the set
of pending requests that are cancelled by the PCE and will not of pending requests that are cancelled by the PCE and will not
be honored. In this case, the PCE does not have to send an be honored. In this case, the PCE does not have to send an
additional PCNtf message with Notification-type=1 and additional PCNtf message with Notification-type=1 and
Notification-value=2 since the list of cancelled requests is Notification-value=2 since the list of cancelled requests is
specified by including the corresponding set of RP object(s). specified by including the corresponding set of RP object(s).
If such notification is received by a PCE from a PCC, the PCE If such notification is received by a PCE from a PCC, the PCE
MUST silently ignore the notification and no errors should be MUST silently ignore the notification and no errors should be
generated. generated.
Optionally, a TLV named OVERLOADED-DURATION may be included in the Optionally, a TLV named OVERLOADED-DURATION may be included in the
NOTIFICATION object that specifies the period of time during which no further NOTIFICATION object that specifies the period of time during which
request should be sent to the PCE. Once this period of time has elapsed, the PCE no further request should be sent to the PCE. Once this period of
should no longer be considered in congested state. time has elapsed, the PCE should no longer be considered in congested
state.
The OVERLOADED-DURATION TLV is compliant with the PCEP TLV format defined in section 7.1 The OVERLOADED-DURATION TLV is compliant with the PCEP TLV format
and is comprised of 2 bytes for the type, 2 bytes specifying the TLV length (length of defined in section 7.1 and is comprised of 2 bytes for the type,
the value portion in bytes) followed by a fix length value field of 32-bits flags field. 2 bytes specifying the TLV length (length of the value portion in bytes)
followed by a fix length value field of 32-bits flags field.
TYPE: To be assigned by IANA (suggested value=2) TYPE: To be assigned by IANA (suggested value=2)
LENGTH: 4 LENGTH: 4
VALUE: 32-bits flags field indicates the estimated PCE congestion duration in seconds. VALUE: 32-bits flags field indicates the estimated PCE congestion
duration in seconds.
* Notification-value=2: A Notification-type=2, Notification- * Notification-value=2: A Notification-type=2, Notification-
value=2 indicates that the PCE is no longer in congested state value=2 indicates that the PCE is no longer in congested state
and is available to process new path computation requests. An and is available to process new path computation requests. An
implementation MUST make sure that a PCE sends such implementation SHOULD make sure that a PCE sends such
notification to every PCC to which a Notification message (with notification to every PCC to which a Notification message (with
Notification-type=2, Notification-value=1) has been sent unless Notification-type=2, Notification-value=1) has been sent unless
an OVERLOADED-DURATION TLV has been included in the an OVERLOADED-DURATION TLV has been included in the
corresponding message and the PCE wishes to wait for the corresponding message and the PCE wishes to wait for the
expiration of that period of time before receiving new expiration of that period of time before receiving new
requests. If such notification is received by a PCE from a requests. If such notification is received by a PCE from a
PCC, the PCE MUST silently ignore the notification and no PCC, the PCE MUST silently ignore the notification and no
errors should be generated. It is RECOMMENDED to support some errors should be generated. It is RECOMMENDED to support some
dampening notification procedure on the PCE so as to avoid too dampening notification procedure on the PCE so as to avoid too
frequent congestion state and congestion state release frequent congestion state and congestion state release
notifications. For example, an implementation could make use notifications. For example, an implementation could make use
of an hysteresis approach using a dual-thresholds mechanism of an hysteresis approach using a dual-thresholds mechanism
triggering the sending of congestion state notifications. triggering the sending of congestion state notifications.
Furthermore, in case of high instabilities of the PCE Furthermore, in case of high instabilities of the PCE
resources, an additional dampening mechanism SHOULD be used resources, an additional dampening mechanism SHOULD be used
(linear or exponential) to pace the notification frequency and (linear or exponential) to pace the notification frequency and
avoid path computation requests oscillation. avoid path computation requests oscillation.
* Alternatively, PCE may decide to signal its (non) overloaded
state using a IGP-based notification mechanism as defined in
[I-D.ietf-pce-disco-proto-isis]and
[I-D.ietf-pce-disco-proto-ospf]. A PCE may also decide to
signal its overloaded state using PCEP and its no longer
overloaded state using an IGP-based notification and vice-
versa.
7.15. PCEP-ERROR Object 7.15. PCEP-ERROR Object
The PCEP-ERROR object is exclusively carried within a PCErr message The PCEP-ERROR object is exclusively carried within a PCErr message
to notify of a PCEP error. to notify of a PCEP error.
PCEP-ERROR Object-Class is to be assigned by IANA (recommended PCEP-ERROR Object-Class is to be assigned by IANA (recommended
value=13) value=13)
PCEP-ERROR Object-Type is to be assigned by IANA (recommended PCEP-ERROR Object-Type is to be assigned by IANA (recommended
value=1) value=1)
One Object-Type is defined for this object to be assigned by IANA
with a recommended value of 1.
The format of the PCEP-ERROR object body is as follows: The format of the PCEP-ERROR object body is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags | Error-Type | Error-Value | | Reserved | Flags | Error-Type | Error-Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Optional TLV(s) // // Optional TLV(s) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 46, line 43 skipping to change at page 46, line 34
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags | Error-Type | Error-Value | | Reserved | Flags | Error-Type | Error-Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Optional TLV(s) // // Optional TLV(s) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 20: PCEP-ERROR object body format Figure 20: PCEP-ERROR Object Body Format
A PCEP-ERROR object is used to report a PCEP error and is A PCEP-ERROR object is used to report a PCEP error and is
characterized by an Error-Type that specifies the type of error and characterized by an Error-Type that specifies the type of error and
an Error-value that provides additional information about the error an Error-value that provides additional information about the error
type. Both the Error-Type and the Error-Value should be managed by type. Both the Error-Type and the Error-Value should be managed by
IANA (see the IANA section). IANA (see the IANA section).
Reserved (8 bits): This field MUST be set to zero on transmission and Reserved (8 bits): This field MUST be set to zero on transmission and
MUST be ignored on receipt. MUST be ignored on receipt.
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Error-value (8 bits): provides additional details about the error. Error-value (8 bits): provides additional details about the error.
Optionally the PCEP-ERROR object may contain additional TLV so as to Optionally the PCEP-ERROR object may contain additional TLV so as to
provide further information about the encountered error. provide further information about the encountered error.
A single PCErr message may contain multiple PCEP-ERROR objects. A single PCErr message may contain multiple PCEP-ERROR objects.
For each PCEP error, an Error-type and an Error-value are defined. For each PCEP error, an Error-type and an Error-value are defined.
Error-Type Meaning Error-Type Meaning
1 PCEP session establishment failure 1 PCEP session establishment failure
Error-value=1: reception of a malformed message Error-value=1: reception of an invalid Open message or
a non Open message.
Error-value=2: no Open message received before the expiration Error-value=2: no Open message received before the expiration
of the OpenWait timer of the OpenWait timer
Error-value=3: unacceptable and non negotiable session Error-value=3: unacceptable and non negotiable session
characteristics characteristics
Error-value=4: unacceptable but negotiable session Error-value=4: unacceptable but negotiable session
characteristics characteristics
Error-value=5: reception of a second Open message Error-value=5: reception of a second Open message
with still unacceptable session characteristics with still unacceptable session characteristics
Error-value=6: reception of a PCErr message proposing Error-value=6: reception of a PCErr message proposing
unacceptable session characteristics unacceptable session characteristics
skipping to change at page 48, line 34 skipping to change at page 48, line 35
Error-value=2: Unrecognized object Type Error-value=2: Unrecognized object Type
4 Not supported object 4 Not supported object
Error-value=1: Not supported object class Error-value=1: Not supported object class
Error-value=2: Not supported object Type Error-value=2: Not supported object Type
5 Policy violation 5 Policy violation
Error-value=1: C bit of the METRIC object set (request rejected) Error-value=1: C bit of the METRIC object set (request rejected)
Error-value=2: O bit of the RP object set (request rejected) Error-value=2: O bit of the RP object set (request rejected)
6 Mandatory Object missing 6 Mandatory Object missing
Error-value=1: RP object missing Error-value=1: RP object missing
Error-value=2: RRO object missing for a reoptimization Error-value=2: RRO object missing for a reoptimization
request (R bit of the RP object set) when bandwidth request (R bit of the RP object set) when
is not equal to 0. bandwidth is not equal to 0.
Error-value=3: END-POINTS object missing Error-value=3: END-POINTS object missing
7 Synchronized path computation request missing 7 Synchronized path computation request missing
8 Unknown request reference 8 Unknown request reference
9 Attempt to establish a second PCEP session 9 Attempt to establish a second PCEP session
10 Reception of a malformed object 10 Reception of an invalid object
Error-value=1: reception of an object with P flag not set although Error-value=1: reception of an object with P flag not set
the P-flag must be set according to this specification. although the P-flag must be set according to this
Error-value=2: reception of a PCReq message with two METRIC objects specification.
with B-flag set.
Error-Type=1: PCEP session establishment failure. Error-Type=1: PCEP session establishment failure.
If a malformed message is received, the receiving PCEP peer MUST send If a malformed message is received, the receiving PCEP peer MUST send
a PCErr message with Error-type=1, Error-value=1. a PCErr message with Error-type=1, Error-value=1.
If no Open message is received before the expiration of the OpenWait If no Open message is received before the expiration of the OpenWait
timer, the receiving PCEP peer MUST send a PCErr message with Error- timer, the receiving PCEP peer MUST send a PCErr message with Error-
type=1, Error-value=2 (see Section 10 for details). type=1, Error-value=2 (see Appendix A for details).
If one or more PCEP session characteristic(s) are unacceptable by the If one or more PCEP session characteristics are unacceptable by the
receiving peer and are not negotiable, it MUST send a PCErr message receiving peer and are not negotiable, it MUST send a PCErr message
with Error-type=1, Error-value=3. with Error-type=1, Error-value=3.
If an Open message is received with unacceptable session If an Open message is received with unacceptable session
characteristics but these characteristics are negotiable, the characteristics but these characteristics are negotiable, the
receiving PCEP peer MUST send a PCErr message with Error-type-1, receiving PCEP peer MUST send a PCErr message with Error-type-1,
Error-value=4 (see Section 6.2 for details). Error-value=4 (see Section 6.2 for details).
If a second Open message is received during the PCEP session If a second Open message is received during the PCEP session
establishment phase and the session characteristics are still establishment phase and the session characteristics are still
skipping to change at page 49, line 47 skipping to change at page 49, line 48
or recognized but not supported, then the PCE MUST send a PCErr or recognized but not supported, then the PCE MUST send a PCErr
message with a PCEP-ERROR object (Error-Type=3 and 4 respectively). message with a PCEP-ERROR object (Error-Type=3 and 4 respectively).
In addition, the PCE MAY include in the PCErr message the unknown or In addition, the PCE MAY include in the PCErr message the unknown or
not supported object. The corresponding path computation request not supported object. The corresponding path computation request
MUST be cancelled by the PCE without further notification. MUST be cancelled by the PCE without further notification.
Error-Type=5: if a path computation request is received that is not Error-Type=5: if a path computation request is received that is not
compliant with an agreed policy between the PCC and the PCE, the PCE compliant with an agreed policy between the PCC and the PCE, the PCE
MUST send a PCErr message with a PCEP-ERROR object (Error-Type=5). MUST send a PCErr message with a PCEP-ERROR object (Error-Type=5).
The corresponding path computation MUST be cancelled. Policy- The corresponding path computation MUST be cancelled. Policy-
specific TLV(s) carried within the PCEP-ERROR object may be defined specific TLVs carried within the PCEP-ERROR object may be defined in
in other documents to specify the nature of the policy violation. other documents to specify the nature of the policy violation.
Error-Type=6: if a path computation request is received that does not Error-Type=6: if a path computation request is received that does not
contain a mandatory object, the PCE MUST send a PCErr message with a contain a mandatory object, the PCE MUST send a PCErr message with a
PCEP-ERROR object (Error-Type=6). If there are multiple mandatory PCEP-ERROR object (Error-Type=6). If there are multiple mandatory
objects missing, the PCErr message MUST contain one PCEP-ERROR object objects missing, the PCErr message MUST contain one PCEP-ERROR object
per missing object. The corresponding path computation MUST be per missing object. The corresponding path computation MUST be
cancelled. cancelled.
Error-Type=7: if a PCC sends a synchronized path computation request Error-Type=7: if a PCC sends a synchronized path computation request
to a PCE and the PCE does not receive all the synchronized path to a PCE and the PCE does not receive all the synchronized path
computation requests listed within the corresponding SVEC object computation requests listed within the corresponding SVEC object
after the expiration of the timer SyncTimer defined in after the expiration of the timer SyncTimer defined in
Section 7.13.3, the PCE MUST send a PCErr message with a PCEP-ERROR Section 7.13.3, the PCE MUST send a PCErr message with a PCEP-ERROR
object (Error-Type=7). The corresponding synchronized path object (Error-Type=7). The corresponding synchronized path
computation MUST be cancelled. It is RECOMMENDED for the PCE to computation MUST be cancelled. It is RECOMMENDED for the PCE to
include the REQ-MISSING TLV(s) (defined below) that identifies the include the REQ-MISSING TLVs (defined below) that identifies the
missing request(s). missing request(s).
The REQ-MISSING TLV is compliant with the PCEP TLV format defined in section 7.1 The REQ-MISSING TLV is compliant with the PCEP TLV format defined
and is comprised of 2 bytes for the type, 2 bytes specifying the TLV length (length of in section 7.1 and is comprised of 2 bytes for the type, 2 bytes
the value portion in bytes) followed by a fix length value field of 4 bytes. specifying the TLV length (length of the value portion in bytes)
followed by a fix length value field of 4 bytes.
TYPE: To be assigned by IANA (suggested value=3) TYPE: To be assigned by IANA (suggested value=3)
LENGTH: 4 LENGTH: 4
VALUE: 4 bytes that indicates the request-id-number that corresponds to the missing VALUE: 4 bytes that indicates the request-id-number that corresponds
request. to the missing request.
Error-Type=8: if a PCC receives a PCRep message related to an unknown Error-Type=8: if a PCC receives a PCRep message related to an unknown
path computation request, the PCC MUST send a PCErr message with a path computation request, the PCC MUST send a PCErr message with a
PCEP-ERROR object (Error-Type=8). In addition, the PCC MUST include PCEP-ERROR object (Error-Type=8). In addition, the PCC MUST include
in the PCErr message the unknown RP object. in the PCErr message the unknown RP object.
Error-Type=9: if a PCEP peer detects an attempt from another PCEP Error-Type=9: if a PCEP peer detects an attempt from another PCEP
peer to establish a second PCEP session, it MUST send a PCErr message peer to establish a second PCEP session, it MUST send a PCErr message
with Error-type=9, Error-value=1. The existing PCEP session MUST be with Error-type=9, Error-value=1. The existing PCEP session MUST be
preserved and all subsequent messages related to the tentative preserved and all subsequent messages related to the tentative
establishment of the second PCEP session MUST be silently ignored. establishment of the second PCEP session MUST be silently ignored.
7.16. LOAD-BALANCING Object 7.16. LOAD-BALANCING Object
There are situations where no TE LSP with a bandwidth of X could be There are situations where no TE LSP with a bandwidth of X could be
found by a PCE although such bandwidth requirement could be satisfied found by a PCE although such bandwidth requirement could be satisfied
by a set of TE LSPs such that the sum of their bandwidths is equal to by a set of TE LSPs such that the sum of their bandwidths is equal to
X. Thus it might be useful for a PCC to request a set of TE LSPs so X. Thus, it might be useful for a PCC to request a set of TE LSPs so
that the sum of their bandwidth is equal to X MBits/s, with that the sum of their bandwidth is equal to X MBits/s, with
potentially some constraints on the number of TE LSPs and the minimum potentially some constraints on the number of TE LSPs and the minimum
bandwidth of each of these TE LSPs. Such request is made by bandwidth of each of these TE LSPs. Such request is made by
inserting a LOAD-BALANCING object in a PCReq message sent to a PCE. inserting a LOAD-BALANCING object in a PCReq message sent to a PCE.
The LOAD-BALANCING object is optional. The LOAD-BALANCING object is optional.
LOAD-BALANCING Object-Class is to be assigned by IANA (recommended LOAD-BALANCING Object-Class is to be assigned by IANA (recommended
value=14) value=14)
skipping to change at page 51, line 12 skipping to change at page 51, line 14
The LOAD-BALANCING object is optional. The LOAD-BALANCING object is optional.
LOAD-BALANCING Object-Class is to be assigned by IANA (recommended LOAD-BALANCING Object-Class is to be assigned by IANA (recommended
value=14) value=14)
LOAD-BALANCING Object-Type is to be assigned by IANA (recommended LOAD-BALANCING Object-Type is to be assigned by IANA (recommended
value=1) value=1)
The format of the LOAD-BALANCING object body is as follows: The format of the LOAD-BALANCING object body is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | flags | Max-LSP | | Reserved | flags | Max-LSP |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Min-Bandwidth | | Min-Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 21: LOAD-BALANCING object body format Figure 21: LOAD-BALANCING Object Body Format
Reserved (16 bits): This field MUST be set to zero on transmission Reserved (16 bits): This field MUST be set to zero on transmission
and MUST be ignored on receipt. and MUST be ignored on receipt.
Flags (8 bits): No Flag is currently defined. The Flag field MUST be Flags (8 bits): No Flag is currently defined. The Flag field MUST be
set to zero on transmission and MUST be ignored on receipt). set to zero on transmission and MUST be ignored on receipt.
Max-LSP (8 bits): maximum number of TE LSPs in the set Max-LSP (8 bits): maximum number of TE LSPs in the set
Min-Bandwidth (32 bits). Specifies the minimum bandwidth of each Min-Bandwidth (32 bits). Specifies the minimum bandwidth of each
element of the set of TE LSPs. The bandwidth is encoded in 32 bits element of the set of TE LSPs. The bandwidth is encoded in 32 bits
in IEEE floating point format, expressed in bytes per second. in IEEE floating point format, expressed in bytes per second.
The LOAD-BALANCING object body has a fixed length of 8 bytes. The LOAD-BALANCING object body has a fixed length of 8 bytes.
If a PCC requests the computation of a set of TE LSP(s) so that the If a PCC requests the computation of a set of TE LSPs so that the sum
sum of their bandwidth is X, the maximum number of TE LSP is N and of their bandwidth is X, the maximum number of TE LSP is N and each
each TE LSP must at least have a bandwidth of B, it inserts a TE LSP must at least have a bandwidth of B, it inserts a BANDWIDTH
BANDWIDTH object specifying X as the required bandwidth and a LOAD- object specifying X as the required bandwidth and a LOAD-BALANCING
BALANCING object with the Max-LSP and Min-Bandwidth fields set to N object with the Max-LSP and Min-Bandwidth fields set to N and B
and B respectively. respectively.
7.17. CLOSE Object 7.17. CLOSE Object
The CLOSE object MUST be present in each Close message. There MUST The CLOSE object MUST be present in each Close message. There MUST
be only one CLOSE object per Close message. If a Close message is be only one CLOSE object per Close message. If a Close message is
received that contains more than one CLOSE object, the first CLOSE received that contains more than one CLOSE object, the first CLOSE
object is the one that must be processed. Other CLOSE object(s) MUST object is the one that must be processed. Other CLOSE object(s) MUST
be silently ignored. be silently ignored.
CLOSE Object-Class is to be assigned by IANA (recommended value=15) CLOSE Object-Class is to be assigned by IANA (recommended value=15)
skipping to change at page 52, line 17 skipping to change at page 52, line 21
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags | Reason | | Reserved | Flags | Reason |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// Optional TLV(s) // // Optional TLV(s) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 22: CLOSE Object format Figure 22: CLOSE Object Format
Reason (4 bits): specifies the reason for closing the PCEP session.
The setting of this field is optional. The following values are Reserved (16 bits): This field MUST be set to zero on transmission
currently defined. and MUST be ignored on receipt.
Flags (8 bits): No Flags are currently defined. The Flag field MUST
be set to zero on transmission and MUST be ignored on receipt.
Reason (8 bits): specifies the reason for closing the PCEP session.
The setting of this field is optional. IANA is requested to manage
the codespace of the Reason field. The following values are
currently defined (To be confirmed by IANA).
Reasons Reasons
Value Meaning Value Meaning
1 No explanation provided 1 No explanation provided
2 DeadTimer expired 2 DeadTimer expired
3 Reception of a malformed PCEP message 3 Reception of a malformed PCEP message
Reserved (16 bits): This field MUST be set to zero on transmission
and MUST be ignored on receipt.
Flags (4 bits): No Flags are currently defined. The Flag field MUST
be set to zero on transmission and MUST be ignored on receipt.
Optional TLVs may be included within the CLOSE object body. The Optional TLVs may be included within the CLOSE object body. The
specification of such TLVs is outside the scope of this document. specification of such TLVs is outside the scope of this document.
8. Manageability Considerations 8. Manageability Considerations
This section follows the guidance of This section follows the guidance of
[I-D.ietf-pce-manageability-requirements]. [I-D.ietf-pce-manageability-requirements].
8.1. Control of Function and Policy 8.1. Control of Function and Policy
A PCEP implementation SHOULD allow configuring the following PCEP A PCEP implementation SHOULD allow configuring the following PCEP
session parameters on a PCEP peer: session parameters on the implementation:
o The local keepalive and Deadtimer (i.e. parameters send by the o The local Keepalive and DeadTimer (i.e., parameters sent by the
PCEP speaker in an Open message), PCEP peer in an Open message),
o The maximum acceptable remote keepalive and dead timers
(i.e.parameters sent by a peer in an Open message), o The maximum acceptable remote Keepalive and DeadTimer (i.e.,
parameters received from a peer in an Open message),
o Negotiation enabled or disabled, o Negotiation enabled or disabled,
o If negotiation is allowed, the minimum acceptable Keepalive and o If negotiation is allowed, the minimum acceptable Keepalive and
Deadtimer timers sent by a PCEP peer, Deadtimer timers received from a PCEP peer,
o The SyncTimer, o The SyncTimer,
o The maximum number of sessions that can be setup, o The maximum number of sessions that can be setup,
o Request timer: amount of time a PCC waits for a reply before o Request timer: amount of time a PCC waits for a reply before
resending its path computation requests (potentially to an resending its path computation requests (potentially to an
alternate PCE). alternate PCE).
These parameters may be configured as default parameters for any PCEP These parameters may be configured as default parameters for any PCEP
skipping to change at page 53, line 45 skipping to change at page 53, line 49
for initiation by the peer, for initiation by the peer,
o The PCEP session parameters, as listed above, if they differ from o The PCEP session parameters, as listed above, if they differ from
the default parameters, the default parameters,
o A set of PCEP policies including the type of operations allowed o A set of PCEP policies including the type of operations allowed
for the PCEP peer (e.g. diverse path computation, synchronization, for the PCEP peer (e.g. diverse path computation, synchronization,
etc.) etc.)
A PCEP implementation MUST allow restricting the set of PCEP peers A PCEP implementation MUST allow restricting the set of PCEP peers
that can initiate a PCEP session with the PCEP speaker (e.g. list of that can initiate a PCEP session with the PCEP speaker (e.g., list of
authorized PCEP peers, all PCEP peers in the area, all PCEP peers in authorized PCEP peers, all PCEP peers in the area, all PCEP peers in
the AS). the AS).
8.2. Information and Data Models 8.2. Information and Data Models
A PCEP MIB module is defined in [I-D.kkoushik-pce-pcep-mib] that A PCEP MIB module is defined in [I-D.kkoushik-pce-pcep-mib] that
describes managed objects for modeling of PCEP communication describes managed objects for modeling of PCEP communication
including: including:
o PCEP client configuration and status, o PCEP client configuration and status,
o PCEP peer configuration and information, o PCEP peer configuration and information,
o PCEP session configuration and information, o PCEP session configuration and information,
o Notifications to indicate PCEP session changes. o Notifications to indicate PCEP session changes.
8.3. Liveness Detection and Monitoring 8.3. Liveness Detection and Monitoring
PCEP includes a keepalive mechanism, allowing checking the liveliness PCEP includes a keepalive mechanism to check the liveliness of a PCEP
of a PCEP peer and a notification procedure allowing a PCE to peer and a notification procedure allowing a PCE to advertise its
advertise its congestion state to a PCC. Also, procedures in order congestion state to a PCC. Also, procedures in order to monitor the
to monitor the liveliness and performances of a given PCE chain (in liveliness and performances of a given PCE chain (in case of
case of Multiple-PCE path computation) are defined in Multiple-PCE path computation) are defined in
[I-D.vasseur-pce-monitoring]. [I-D.ietf-pce-monitoring].
8.4. Verifying Correct Operation 8.4. Verifying Correct Operation
Verifying the correct operation of a PCEP communication can be Verifying the correct operation of a PCEP communication can be
performed by monitoring various parameters. A PCEP implementation performed by monitoring various parameters. A PCEP implementation
SHOULD provide the following parameters: SHOULD provide the following parameters:
o Response time (minimum, average and maximum), on a per PCE Peer o Response time (minimum, average and maximum), on a per PCE Peer
basis, basis,
skipping to change at page 55, line 5 skipping to change at page 55, line 5
o Number of failed computations, o Number of failed computations,
o Number of requests for which no reply has been received after the o Number of requests for which no reply has been received after the
expiration of a configurable timer and by verifying that a expiration of a configurable timer and by verifying that a
returned path fit in with the requested TE parameters. returned path fit in with the requested TE parameters.
A PCEP implementation SHOULD log error events (e.g. corrupted A PCEP implementation SHOULD log error events (e.g. corrupted
messages, unrecognized objects, etc.). messages, unrecognized objects, etc.).
8.5. Requirements on Other Protocols and Functional Componentssection 8.5. Requirements on Other Protocols and Functional Components
PCEP does not put any new requirements on other protocols. As PCEP PCEP does not put any new requirements on other protocols. As PCEP
relies on the TCP transport protocol, PCEP management can make use of relies on the TCP transport protocol, PCEP management can make use of
TCP management mechanisms (such as the TCP MIB defined in [RFC4022]). TCP management mechanisms (such as the TCP MIB defined in [RFC4022]).
The PCE Discovery mechanisms ([I-D.ietf-pce-disco-proto-isis],
[I-D.ietf-pce-disco-proto-ospf]) may have an impact on PCEP. To The PCE Discovery mechanisms ([RFC5088], [RFC5089]) may have an
avoid that a high frequency of PCE Discovery/Disappearance trigger impact on PCEP. To avoid that a high frequency of PCE Discovery/
high frequency of PCEP session setup/deletion, it is RECOMMENDED to Disappearance trigger high frequency of PCEP session setup/deletion,
introduce some dampening for establishment of PCEP sessions. it is RECOMMENDED to introduce some dampening for establishment of
PCEP sessions.
8.6. Impact on Network Operation 8.6. Impact on Network Operation
In order to avoid any unacceptable impact on network operations, an In order to avoid any unacceptable impact on network operations, an
implementation SHOULD allow limiting the number of session that can implementation SHOULD allow a limit to be placed on the number of
be setup on a PCEP speaker, and MAY allow limiting the rate of session that can be set up on a PCEP speaker, and MAY allow a limit
messages sent by a PCEP speaker and received from a peer. It MAY to be placed on the rate of messages sent by a PCEP speaker and
also allow sending a notification when a rate threshold is reached. received from a peer. It MAY also allow sending a notification when
a rate threshold is reached.
9. IANA Considerations 9. IANA Considerations
IANA assigns values to the PCEP protocol parameters (messages, IANA assigns values to the PCEP protocol parameters (messages,
objects, TLVs). objects, TLVs).
IANA is requested to establish a new top-level registry to contain
all PCEP codepoints and sub-registries.
The allocation policy for each new registry is by IETF Consensus: new
values are assigned through the IETF consensus process (see
[RFC2434]). Specifically, new assignments are made via RFCs approved
by the IESG. Typically, the IESG will seek input on prospective
assignments from appropriate persons (e.g., a relevant Working Group
if one exists).
9.1. TCP Port 9.1. TCP Port
PCEP will use a well-known TCP port to be assigned by IANA. PCEP will use a well-known TCP port to be assigned by IANA.
9.2. PCEP Messages 9.2. PCEP Messages
IANA is requested to create a registry for PCEP messages. Each PCEP IANA is requested to create a registry for PCEP messages. Each PCEP
message has a message type value. message has a message type value.
Value Meaning Reference Value Meaning Reference
skipping to change at page 57, line 20 skipping to change at page 57, line 35
1 1
14 LOAD-BALANCING This document 14 LOAD-BALANCING This document
Object-Type Object-Type
1 1
15 CLOSE This document 15 CLOSE This document
Object-Type Object-Type
1 1
9.4. Notification Object 9.4. RP Object
A NOTIFICATION object is characterized by a Notification-type that New bit numbers may be allocated only by an IETF Consensus action.
specifies the class of notification and a Notification-value that Each bit should be tracked with the following qualities:
provides additional information related to the nature of the
notification. Both the Notification-type and Notification-value are o Bit number
managed by IANA (see IANA section).
o Capability Description
o Defining RFC
Several bits are defined in this document. The following values have
been assigned:
Codespace of the Flag field (Metric Object)
Bit Description Reference
1-3 Priority This document
4 Reoptimization This document
5 Bi-directional This document
6 Strict/Loose This document
9.5. Notification Object
IANA is requested to create a registry for the Notification-type and
Notification-value of the Notification Object and manage the code
space.
Notification-type Name Reference Notification-type Name Reference
1 Pending Request cancelled This document 1 Pending Request cancelled This document
Notification-value Notification-value
1: PCC cancels a set of pending request(s) 1: PCC cancels a set of pending request(s)
2: PCE cancels a set of pending request(s) 2: PCE cancels a set of pending request(s)
2 PCE Congestion This document 2 PCE Congestion This document
Notification-value Notification-value
1: PCE in congested state 1: PCE in congested state
2: PCE no longer in congested state 2: PCE no longer in congested state
9.5. PCEP Error Object 9.6. PCEP-ERROR Object
PCEP-ERROR objects are used to report a PCEP error and are IANA is requested to create a registry for the Error-type and Error-
characterized by an Error-Type which specifies the type of error and value of the PCEP Error Object and manage the code space.
an Error-value that provides additional information about the error
type. Both the Error-Type and the Error-Value are managed by IANA.
For each PCEP error, an Error-type and an Error-value are defined. For each PCEP error, an Error-type and an Error-value are defined.
Error-Type Meaning Reference Error-Type Meaning Reference
1 PCEP session establishment failure This document 1 PCEP session establishment failure This document
Error-value=1: reception of a malformed message Error-value=1: reception of an invalid Open message or
a non Open message.
Error-value=2: no Open message received before the expiration Error-value=2: no Open message received before the expiration
of the OpenWait timer of the OpenWait timer
Error-value=3: unacceptable and non negotiable session Error-value=3: unacceptable and non negotiable session
characteristics characteristics
Error-value=4: unacceptable but negotiable session Error-value=4: unacceptable but negotiable session
characteristics characteristics
Error-value=5: reception of a second Open message Error-value=5: reception of a second Open message
with still unacceptable session characteristics with still unacceptable session characteristics
Error-value=6: reception of a PCErr message proposing Error-value=6: reception of a PCErr message proposing
unacceptable session characteristics unacceptable session characteristics
skipping to change at page 58, line 40 skipping to change at page 59, line 41
Error-value=1: C bit of the METRIC object set (request rejected) Error-value=1: C bit of the METRIC object set (request rejected)
Error-value=2: O bit of the RP object cleared (request rejected) Error-value=2: O bit of the RP object cleared (request rejected)
6 Mandatory Object missing This document 6 Mandatory Object missing This document
Error-value=1: RP object missing Error-value=1: RP object missing
Error-value=2: RRO missing for a reoptimization Error-value=2: RRO missing for a reoptimization
request (R bit of the RP object set) request (R bit of the RP object set)
Error-value=3: END-POINTS object missing Error-value=3: END-POINTS object missing
7 Synchronized path computation request missing This document 7 Synchronized path computation request missing This document
8 Unknown request reference This document 8 Unknown request reference This document
9 Attempt to establish a second PCEP session This document 9 Attempt to establish a second PCEP session This document
10 Reception of a malformed object 10 Reception of an invalid object This document
Error-value=1: reception of an object with P flag not set although This document Error-value=1: reception of an object with P flag not set although
the P-flag must be set according to this specification. the P-flag must be set according to this specification.
Error-value=2: reception of a PCReq message with two METRIC objects
with B-flag set.
9.6. CLOSE Object 9.7. CLOSE Object
The CLOSE object MUST be present in each Close message in order to The CLOSE object MUST be present in each Close message in order to
close a PCEP session. The reason field of the CLOSE object specifies close a PCEP session. The reason field of the CLOSE object specifies
the reason for closing the PCEP session. The reason field of the the reason for closing the PCEP session. The reason field of the
CLOSE object is managed by IANA. CLOSE object is managed by IANA.
Reasons Reasons
Value Meaning Value Meaning
1 No explanation provided 1 No explanation provided
2 DeadTimer expired 2 DeadTimer expired
3 Reception of a malformed PCEP message 3 Reception of a malformed PCEP message
9.7. PCEP TLV format 9.8. NO-PATH Object
IANA is requested to create a registry to manage the codespace of NI
field present in the NO-PATH Object.
Value Meaning Reference
0 No path satisfying the set This document
of constraints could be found
1 PCE chain broken This docuement
9.9. METRIC Object
IANA is requested to create a registry to manage the codespace of T
field and the Flag field of the METRIC Object.
Codespace of the T field (Metric Object)
Value Meaning Reference
1 IGP metric This document
2 TE metric This document
3 Hop Counts This document
New bit numbers may be allocated only by an IETF Consensus action.
Each bit should be tracked with the following qualities:
o Bit number
o Capability Description
o Defining RFC
Several bits are defined in this document. The following values have
been assigned:
Codespace of the Flag field (Metric Object)
Bit Description Reference
1 Bound This document
2 Computed metric This document
9.10. PCEP TLV Type Indicators
IANA is requested to create a registry for the PCEP TLVs. IANA is requested to create a registry for the PCEP TLVs.
Value Meaning Reference Value Meaning Reference
1 NO-PATH-VECTOR TLV This document 1 NO-PATH-VECTOR TLV This document
2 OVERLOAD-DURATION TLV This document 2 OVERLOAD-DURATION TLV This document
3 REQ-MISSING TLV This document 3 REQ-MISSING TLV This document
9.8. NO-PATH-VECTOR TLV 9.11. NO-PATH-VECTOR TLV
IANA is requested to manage the space of flags carried in the NO- IANA is requested to manage the space of flags carried in the NO-
PATH-VECTOR TLV defined in this document, numbering them in the usual PATH-VECTOR TLV defined in this document, numbering them in the usual
IETF notation starting at zero and continuing through 31. IETF notation starting at zero and continuing through 31.
New bit numbers may be allocated only by an IETF Consensus action. New bit numbers may be allocated only by an IETF Consensus action.
Each bit should be tracked with the following qualities: - Bit number Each bit should be tracked with the following qualities: - Bit number
- Name flag - Reference - Name flag - Reference
Bits Number Name Flag Reference Bit Number Name Reference
1 PCE currently Unavailable This document 1 PCE currently Unavailable This document
2 Unknown Destination This document 2 Unknown Destination This document
3 Unknown Source This document 3 Unknown Source This document
10. PCEP Finite State Machine (FSM) 10. Security Considerations
PCEP could be the target of the following attacks:
o Spoofing (PCC or PCE impersonation)
o Snooping (message interception)
o Falsification
o Denial of Service
A PCEP attack may have significant impact, particularly in an
inter-AS context as PCEP facilitates inter-AS path establishment.
Several mechanisms are proposed below, so as to ensure
authentication, integrity and privacy of PCEP Communications, and
also to protect against DoS attacks.
10.1. PCEP Authentication and Integrity
It is RECOMMENDED to use TCP-MD5 [RFC1321] signature option to
provide for the authenticity and integrity of PCEP messages. This
will allow protecting against PCE or PCC impersonation and also
against message content falsification.
This requires the maintenance, exchange and configuration of MD-5
keys on PCCs and PCEs. Note that such maintenance may be especially
onerous to the operators as pointed out in
[I-D.ietf-rpsec-bgpsecrec]. Hence it is important to limit the
number of keys while ensuring the required level of security.
MD-5 signature faces some limitations, as explained in [RFC2385].
Note that when a digest technique stronger than MD5 is specified and
implemented, PCEP could be easily upgraded to use it.
10.2. PCEP Privacy
Ensuring PCEP communication privacy is of key importance, especially
in an inter-AS context, where PCEP communication end-points do not
reside in the same AS, as an attacker that intercept a PCE message
could obtain sensitive information related to computed paths and
resources. Privacy can be ensured thanks to encryption. To ensure
privacy of PCEP communication, IPsec [RFC4303] tunnels MAY be used
between PCC and PCEs or between PCEs. Note that this could also be
used to ensure Authentication and Integrity, in which case, TCP MD-5
option would not be required.
10.3. Protection Against Denial of Service Attacks
10.3.1. Protection Against TCP DoS Attacks
PCEP can be the target of TCP DoS attacks, such as for instance SYN
attacks, as all protocols running on top of TCP. PCEP can use the
same mechanisms as defined in [RFC5036] to mitigate the threat of
such attacks:
o A PCE should avoid promiscuous TCP listens for PCEP TCP connection
establishment. It should use only listens that are specific to
authorized PCCs.
o The use of the MD5 option helps somewhat since it prevents a SYN
from being accepted unless the MD5 segment checksum is valid.
However, the receiver must compute the checksum before it can
decide to discard an otherwise acceptable SYN segment.
o The use of access-list on the PCE so as to restrict access to
authorized PCCs.
10.3.2. Request Input Shaping/Policing
A PCEP implementation may be subject to Denial Of Service attacks
consisting of sending a very large number of PCEP messages (e.g.
PCReq messages). Thus, especially in multi-Service Provider
environments, a PCE implementation should implement request input
shaping/policing so as to throttle the amount of received PCEP
messages without compromising the implementation behavior.
11. Authors' Addresses
The content of this document was contributed by the editors and the
co-authors listed below:
Arthi Ayyangar
Juniper Networks
1194 N. Mathilda Ave
Sunnyvale, CA 94089
USA
Email: arthi@juniper.net
Eiji Oki
NTT
Midori 3-9-11
Musashino, Tokyo, 180-8585
JAPAN
Email: oki.eiji@lab.ntt.co.jp
Alia Atlas
British Telecom
Email: akatlas@alum.mit.edu
Andrew Dolganow
Alcatel
600 March Road
Ottawa, ON K2K 2E6
CANADA
Email: andrew.dolganow@alcatel.com
Yuichi Ikejiri
NTT Communications Corporation
1-1-6 Uchisaiwai-cho, Chiyoda-ku
Tokyo, 100-819
JAPAN
Email: y.ikejiri@ntt.com
Kenji Kumaki
KDDI Corporation
Garden Air Tower Iidabashi, Chiyoda-ku,
Tokyo, 102-8460
JAPAN
Email: ke-kumaki@kddi.com
12. Acknowledgements
The authors would like to thank Dave Oran, Dean Cheng, Jerry Ash,
Igor Bryskin, Carol Iturrade, Siva Sivabalan, Rich Bradford, Richard
Douville, Jon Parker, Martin German and Dennis Aristow for their very
valuable input. Special thank to Adrian Farrel for his very valuable
suggestions. The authors would also like to thank Fabien Verhaeghe
for the very fruitful discussions and useful suggestions.
13. References
13.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links
in Resource ReSerVation Protocol - Traffic Engineering
(RSVP-TE)", RFC 3477, January 2003.
[RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute
Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
May 2005.
13.2. Informative References
[I-D.ietf-pce-inter-layer-req]
Oki, E., "PCC-PCE Communication and PCE Discovery
Requirements for Inter-Layer Traffic Engineering",
draft-ietf-pce-inter-layer-req-06 (work in progress),
November 2007.
[I-D.ietf-pce-interas-pcecp-reqs]
Bitar, N., "Inter-AS Requirements for the Path Computation
Element Communication Protocol (PCECP)",
draft-ietf-pce-interas-pcecp-reqs-03 (work in progress),
July 2007.
[I-D.ietf-pce-manageability-requirements]
Farrel, A., "Inclusion of Manageability Sections in PCE
Working Group Drafts",
draft-ietf-pce-manageability-requirements-02 (work in
progress), August 2007.
[I-D.ietf-pce-monitoring]
Vasseur, J., Roux, J., and Y. Ikejiri, "A set of
monitoring tools for Path Computation Element based
Architecture", draft-ietf-pce-monitoring-01 (work in
progress), February 2008.
[I-D.ietf-rpsec-bgpsecrec]
Christian, B. and T. Tauber, "BGP Security Requirements",
draft-ietf-rpsec-bgpsecrec-09 (work in progress),
November 2007.
[I-D.kkoushik-pce-pcep-mib]
Stephan, E. and K. Koushik, "PCE communication
protocol(PCEP) Management Information Base",
draft-kkoushik-pce-pcep-mib-01 (work in progress),
July 2007.
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992.
[RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5
Signature Option", RFC 2385, August 1998.
[RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Functional Description", RFC 3471,
January 2003.
[RFC3785] Le Faucheur, F., Uppili, R., Vedrenne, A., Merckx, P., and
T. Telkamp, "Use of Interior Gateway Protocol (IGP) Metric
as a second MPLS Traffic Engineering (TE) Metric", BCP 87,
RFC 3785, May 2004.
[RFC4022] Raghunarayan, R., "Management Information Base for the
Transmission Control Protocol (TCP)", RFC 4022,
March 2005.
[RFC4101] Rescorla, E. and IAB, "Writing Protocol Models", RFC 4101,
June 2005.
[RFC4234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 4234, October 2005.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, December 2005.
[RFC4420] Farrel, A., Papadimitriou, D., Vasseur, J., and A.
Ayyangar, "Encoding of Attributes for Multiprotocol Label
Switching (MPLS) Label Switched Path (LSP) Establishment
Using Resource ReserVation Protocol-Traffic Engineering
(RSVP-TE)", RFC 4420, February 2006.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006.
[RFC4657] Ash, J. and J. Le Roux, "Path Computation Element (PCE)
Communication Protocol Generic Requirements", RFC 4657,
September 2006.
[RFC4674] Le Roux, J., "Requirements for Path Computation Element
(PCE) Discovery", RFC 4674, October 2006.
[RFC4927] Le Roux, J., "Path Computation Element Communication
Protocol (PCECP) Specific Requirements for Inter-Area MPLS
and GMPLS Traffic Engineering", RFC 4927, June 2007.
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October 2007.
[RFC5088] Le Roux, JL., Vasseur, JP., Ikejiri, Y., and R. Zhang,
"OSPF Protocol Extensions for Path Computation Element
(PCE) Discovery", RFC 5088, January 2008.
[RFC5089] Le Roux, JL., Vasseur, JP., Ikejiri, Y., and R. Zhang,
"IS-IS Protocol Extensions for Path Computation Element
(PCE) Discovery", RFC 5089, January 2008.
Appendix A. PCEP Finite State Machine (FSM)
The section describes the PCEP Finite State Machine (FSM). The section describes the PCEP Finite State Machine (FSM).
PCEP Finite State Machine PCEP Finite State Machine
+-+-+-+-+-+-+<------+ +-+-+-+-+-+-+<------+
+------| SessionUP |<---+ | +------| SessionUP |<---+ |
| +-+-+-+-+-+-+ | | | +-+-+-+-+-+-+ | |
| | | | | |
| +->+-+-+-+-+-+-+ | | | +->+-+-+-+-+-+-+ | |
skipping to change at page 62, line 25 skipping to change at page 70, line 25
o Sends an Open message, o Sends an Open message,
o Starts the OpenWait timer, o Starts the OpenWait timer,
o Moves to the OpenWait state. o Moves to the OpenWait state.
If the connection establishment fails, the system remains in the Idle If the connection establishment fails, the system remains in the Idle
state. Any other event received in the Idle state is ignored. state. Any other event received in the Idle state is ignored.
It is expected that an implementation will use an exponentially It is expected that an implementation will use an exponentially
increase timer between automatically generated Initialization events increasing timer between automatically generated Initialization
and between retrials of TCP connection establishments. events and between retries of TCP connection establishment.
TCPPending State TCPPending State
If the TCP connection establishment succeeds, the system: If the TCP connection establishment succeeds, the system:
o Sends an Open message, o Sends an Open message,
o Starts the OpenWait timer, o Starts the OpenWait timer,
o Moves to the OpenWait state. o Moves to the OpenWait state.
If the TCP connection establishment fails (an error is detected If the TCP connection establishment fails (an error is detected
during the TCP connection establishment) or the Connect timer during the TCP connection establishment) or the Connect timer
expires: expires:
If ConnectRetry =ConnectMaxRetry the system moves to the Idle State o If ConnectRetry =ConnectMaxRetry the system moves to the Idle
State
If ConnectRetry < ConnectMaxRetry the system: o If ConnectRetry < ConnectMaxRetry the system:
o Initiates of a TCP connection with the PCEP peer, 1. Initiates of a TCP connection with the PCEP peer,
o Increments the ConnectRetry variable, 2. Increments the ConnectRetry variable,
3. Restarts the Connect timer,
o Restarts the Connect timer, 4. Stays in the TPCPending state.
o Stays in the TPCPending state.
In response to any other event the system releases the PCEP resources In response to any other event the system releases the PCEP resources
for that peer and moves back to the Idle state. for that peer and moves back to the Idle state.
OpenWait State: OpenWait State:
In the OpenWait state, the system waits for an Open message from its In the OpenWait state, the system waits for an Open message from its
PCEP peer. PCEP peer.
If the system receives an Open message from the PCEP peer before the If the system receives an Open message from the PCEP peer before the
expiration of the OpenWait timer, the system first examines all of expiration of the OpenWait timer, the system first examines all of
its sessions that are in the OpenWait or KeepWait state. If another its sessions that are in the OpenWait or KeepWait state. If another
session with the same PCEP peer already exists (same IP address), session with the same PCEP peer already exists (same IP address),
then the system performs the following collision resolution then the system performs the following collision resolution
procedure: procedure:
o If the system has initiated the current session and has a lower IP o If the system has initiated the current session and it has a lower
address than the PCEP Peer, the system closes the TCP connection, IP address than the PCEP Peer, the system closes the TCP
releases the PCEP resources for the pending session and moves back connection, releases the PCEP resources for the pending session
to the Idle state. and moves back to the Idle state.
o If the session was initiated by the PCEP peer and the system has a o If the session was initiated by the PCEP peer and the system has a
higher IP address that the PCEP Peer, the system closes the TCP higher IP address that the PCEP Peer, the system closes the TCP
connection, releases the PCEP resources for the pending session, connection, releases the PCEP resources for the pending session,
and moves back to the Idle state. and moves back to the Idle state.
o Otherwise, the system checks the PCEP session attributes o Otherwise, the system checks the PCEP session attributes
(Keepalive frequency, DeadTimer, ...). (Keepalive frequency, DeadTimer, ...).
If an error is detected (e.g. malformed Open message, presence of two If an error is detected (e.g. malformed Open message, reception of a
Open objects, ...), PCEP generates an error notification, the PCEP message that is not an Open message, presence of two Open objects,
peer sends a PCErr message with Error-Type=1 and Error-value=1. The ...), PCEP generates an error notification, the PCEP peer sends a
system releases the PCEP resources for the PCEP peer, closes the TCP PCErr message with Error-Type=1 and Error-value=1. The system
releases the PCEP resources for the PCEP peer, closes the TCP
connection and moves to the Idle state. connection and moves to the Idle state.
If no errors are detected, PCEP increments the OpenRetry variable. If no errors are detected, PCEP increments the OpenRetry variable.
If no errors are detected, OpenRetry=1 and the session If no errors are detected, OpenRetry=1 and the session
characteristics are unacceptable, the PCEP peer sends a PCErr with characteristics are unacceptable, the PCEP peer sends a PCErr with
Error-Type=1 and Error-value=5, the system releases the PCEP Error-Type=1 and Error-value=5, the system releases the PCEP
resources for that peer and moves back to the Idle state. resources for that peer and moves back to the Idle state.
If no errors are detected and the session characteristics are If no errors are detected, and the session characteristics are
acceptable to the local system, the system: acceptable to the local system, the system:
o Sends a Keepalive message to the PCEP peer, o Sends a Keepalive message to the PCEP peer,
o Starts the Keepalive timer, o Starts the Keepalive timer,
o Sets the RemoteOK variable to 1. o Sets the RemoteOK variable to 1.
If LocalOK=1 the system clears the OpenWait timer and moves to the UP If LocalOK=1 the system clears the OpenWait timer and moves to the UP
state. state.
If LocalOK=0 the system clears the OpenWait timer, starts the If LocalOK=0 the system clears the OpenWait timer, starts the
KeepWait timer and moves to the KeepWait state. KeepWait timer and moves to the KeepWait state.
If no errors are detected but the session characteristics are If no errors are detected, but the session characteristics are
unacceptable and non-negotiable, the PCEP peer sends a PCErr with unacceptable and non-negotiable, the PCEP peer sends a PCErr with
Error-Type=1 and Error-value=3, the system releases the PCEP Error-Type=1 and Error-value=3, the system releases the PCEP
resources for that peer, and moves back to the Idle state. resources for that peer, and moves back to the Idle state.
If no errors are detected, OpenRetry=0, the session characteristics If no errors are detected, and OpenRetry is 0, and the session
are unacceptable but negotiable (such as the Keepalive period or the characteristics are unacceptable but negotiable (such as, the
DeadTimer), the system: Keepalive period or the DeadTimer), then the system:
o Increments the OpenRetry variable, o Increments the OpenRetry variable,
o Sends a PCErr message with Error-Type=1 and Error-value=4 that o Sends a PCErr message with Error-Type=1 and Error-value=4 that
contains proposed acceptable session characteristics, contains proposed acceptable session characteristics,
o If LocalOK=1, the system restarts the OpenWait timer and stays in o If LocalOK=1, the system restarts the OpenWait timer and stays in
the OpenWait state the OpenWait state
o If LocalOK=0, the system clears the OpenWait timer, starts the o If LocalOK=0, the system clears the OpenWait timer, starts the
skipping to change at page 66, line 4 skipping to change at page 74, line 4
UP State UP State
In the UP state, the PCEP peer starts exchanging PCEP messages In the UP state, the PCEP peer starts exchanging PCEP messages
according to the session characteristics. according to the session characteristics.
If the Keepalive timer expires, the system restarts the Keepalive If the Keepalive timer expires, the system restarts the Keepalive
timer and sends a Keepalive message. timer and sends a Keepalive message.
If no PCEP message (Keepalive, PCReq, PCRep, PCNtf) is received from If no PCEP message (Keepalive, PCReq, PCRep, PCNtf) is received from
the PCEP peer after the expiration of the DeadTimer, the system the PCEP peer before the expiration of the DeadTimer, the system
terminates PCEP session according to the procedure defined in terminates PCEP session according to the procedure defined in
Section 6.8, releases the PCEP resources for that PCEP peer, closes Section 6.8, releases the PCEP resources for that PCEP peer, closes
the TCP connection and moves to the Idle State. the TCP connection and moves to the Idle State.
If a malformed message is received, the system terminates the PCEP If a malformed message is received, the system terminates the PCEP
session according to the procedure defined in Section 6.8, releases session according to the procedure defined in Section 6.8, releases
the PCEP resources for that PCEP peer, closes the TCP connection and the PCEP resources for that PCEP peer, closes the TCP connection and
moves to the Idle State. moves to the Idle State.
If the system detects that the PCEP peer tries to setup a second TCP If the system detects that the PCEP peer tries to setup a second TCP
connection, it stops the TCP connection establishment and sends a connection, it stops the TCP connection establishment and sends a
PCErr with Error-Type=9. PCErr with Error-Type=9.
If the TCP connection fails, the system releases the PCEP resources If the TCP connection fails, the system releases the PCEP resources
for that PCEP peer, closes the TCP connection and moves to the Idle for that PCEP peer, closes the TCP connection and moves to the Idle
State. State.
11. Security Considerations Appendix B. PCEP Variables
PCEP could be the target of the following attacks:
o Spoofing (PCC or PCE impersonation)
o Snooping (message interception)
o Falsification
o Denial of Service
A PCEP attack may have significant impact, particularly in an
inter-AS context as PCEP facilitates inter-AS path establishment.
Several mechanisms are proposed below, so as to ensure
authentication, integrity and privacy of PCEP Communications, and
also to protect against DoS attacks.
11.1. PCEP Authentication and Integrity
It is RECOMMENDED to use TCP-MD5 [RFC1321] signature option to
provide for the authenticity and integrity of PCEP messages. This
will allow protecting against PCE or PCC impersonation and also
against message content falsification.
This requires the maintenance, exchange and configuration of MD-5
keys on PCCs and PCEs. Note that such maintenance may be especially
onerous to the operators as pointed out in
[I-D.ietf-rpsec-bgpsecrec]. Hence it is important to limit the
number of keys while ensuring the required level of security.
MD-5 signature faces some limitations, as per explained in [RFC2385].
Note that when one digest technique stronger than MD5 is specified
and implemented, PCEP could be easily upgraded to use it.
11.2. PCEP Privacy
Ensuring PCEP communication privacy is of key importance, especially
in an inter-AS context, where PCEP communication end-points do not
reside in the same AS, as an attacker that intercept a PCE message
could obtain sensitive information related to computed paths and
resources. Privacy can be ensured thanks to encryption. To ensure
privacy of PCEP communication, IPSec [RFC4303] tunnels MAY be used
between PCC and PCEs or between PCEs. Note that this could also be
used to ensure Authentication and Integrity, in which case, TCP MD-5
option would not be required.
11.3. Protection against Denial of Service attacks
PCEP can be the target of TCP DoS attacks, such as for instance SYN
attacks, as all protocols running on top of TCP. PCEP can use the
same mechanisms as defined in [RFC3036] to mitigate the threat of
such attacks:
o A PCE should avoid promiscuous TCP listens for PCEP TCP connection
establishment. It should use only listens that are specific to
authorized PCCs.
o The use of the MD5 option helps somewhat since it prevents a SYN
from being accepted unless the MD5 segment checksum is valid.
However, the receiver must compute the checksum before it can
decide to discard an otherwise acceptable SYN segment.
o The use of access-list on the PCE so as to restrict access to
authorized PCCs.
11.4. Request input shaping/policing
A PCEP implementation may be subject to Denial Of Service attacks
consisting of sending a very large number of PCEP messages (e.g.
PCReq messages). Thus, especially in multi-Service Providers
environments, a PCE implementation should implement request input
shaping/policing so as to throttle the amount of received PCEP
messages without compromising the implementation behavior.
12. Authors' addresses
This document was the collective work of several authors. The
content of this document was contributed by the editors and the co-
authors listed below:
Arthi Ayyangar
Nuova Systems
2600 San Tomas Expressway
Santa Clara, CA 95051
USA
Email: arthi@nuovasystems.com
Eiji Oki
NTT
Midori 3-9-11
Musashino, Tokyo, 180-8585
JAPAN
Email: oki.eiji@lab.ntt.co.jp
Alia Atlas
Google
1600 Amphitheatre Parkway
Montain View, CA 94043
USA
Email: akatlas@alum.mit.edu
Andrew Dolganow
Alcatel
600 March Road
Ottawa, ON K2K 2E6
CANADA
Email: andrew.dolganow@alcatel.com
Yuichi Ikejiri
NTT Communications Corporation
1-1-6 Uchisaiwai-cho, Chiyoda-ku
Tokyo, 100-819
JAPAN
Email: y.ikejiri@ntt.com
Kenji Kumaki
KDDI Corporation
Garden Air Tower Iidabashi, Chiyoda-ku,
Tokyo, 102-8460
JAPAN
Email: ke-kumaki@kddi.com
13. Acknowledgements
The authors would like to thank Dave Oran, Dean Cheng, Jerry Ash,
Igor Bryskin, Carol Iturrade, Siva Sivabalan, Rich Bradford, Richard
Douville, Jon Parker, Martin German and Dennis Aristow for their very
valuable input. Special thank to Adrian Farrel for his very valuable
suggestions. The authors would also like to thank Fabien Verhaeghe
for the very fruitfull discussions and useful suggestions.
14. References
14.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links
in Resource ReSerVation Protocol - Traffic Engineering
(RSVP-TE)", RFC 3477, January 2003.
[RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute
Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
May 2005.
14.2. Informative References
[I-D.ietf-pce-disco-proto-isis]
Roux, J., "IS-IS Protocol Extensions for Path Computation
Element (PCE) Discovery",
draft-ietf-pce-disco-proto-isis-08 (work in progress),
September 2007.
[I-D.ietf-pce-disco-proto-ospf]
Roux, J., "OSPF Protocol Extensions for Path Computation
Element (PCE) Discovery",
draft-ietf-pce-disco-proto-ospf-08 (work in progress),
September 2007.
[I-D.ietf-pce-inter-layer-req]
Oki, E., "PCC-PCE Communication and PCE Discovery
Requirements for Inter-Layer Traffic Engineering",
draft-ietf-pce-inter-layer-req-06 (work in progress),
November 2007.
[I-D.ietf-pce-interas-pcecp-reqs]
Bitar, N., "Inter-AS Requirements for the Path Computation
Element Communication Protocol (PCECP)",
draft-ietf-pce-interas-pcecp-reqs-03 (work in progress),
July 2007.
[I-D.ietf-pce-manageability-requirements]
Farrel, A., "Inclusion of Manageability Sections in PCE
Working Group Drafts",
draft-ietf-pce-manageability-requirements-02 (work in
progress), August 2007.
[I-D.ietf-rpsec-bgpsecrec]
Christian, B. and T. Tauber, "BGP Security Requirements",
draft-ietf-rpsec-bgpsecrec-08 (work in progress),
July 2007.
[I-D.kkoushik-pce-pcep-mib]
Stephan, E. and K. Koushik, "PCE communication
protocol(PCEP) Management Information Base",
draft-kkoushik-pce-pcep-mib-01 (work in progress),
July 2007.
[I-D.vasseur-pce-monitoring]
Vasseur, J., "A set of monitoring tools for Path
Computation Element based Architecture",
draft-vasseur-pce-monitoring-03 (work in progress),
May 2007.
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992.
[RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5
Signature Option", RFC 2385, August 1998.
[RFC3036] Andersson, L., Doolan, P., Feldman, N., Fredette, A., and
B. Thomas, "LDP Specification", RFC 3036, January 2001.
[RFC3785] Le Faucheur, F., Uppili, R., Vedrenne, A., Merckx, P., and
T. Telkamp, "Use of Interior Gateway Protocol (IGP) Metric
as a second MPLS Traffic Engineering (TE) Metric", BCP 87,
RFC 3785, May 2004.
[RFC4022] Raghunarayan, R., "Management Information Base for the
Transmission Control Protocol (TCP)", RFC 4022,
March 2005.
[RFC4101] Rescorla, E. and IAB, "Writing Protocol Models", RFC 4101,
June 2005.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, December 2005.
[RFC4420] Farrel, A., Papadimitriou, D., Vasseur, J., and A.
Ayyangar, "Encoding of Attributes for Multiprotocol Label
Switching (MPLS) Label Switched Path (LSP) Establishment
Using Resource ReserVation Protocol-Traffic Engineering
(RSVP-TE)", RFC 4420, February 2006.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006.
[RFC4657] Ash, J. and J. Le Roux, "Path Computation Element (PCE)
Communication Protocol Generic Requirements", RFC 4657,
September 2006.
[RFC4674] Le Roux, J., "Requirements for Path Computation Element
(PCE) Discovery", RFC 4674, October 2006.
[RFC4927] Le Roux, J., "Path Computation Element Communication
Protocol (PCECP) Specific Requirements for Inter-Area MPLS
and GMPLS Traffic Engineering", RFC 4927, June 2007.
Appendix A. PCEP Variables
PCEP defines the following configurable variables: PCEP defines the following configurable variables:
KeepAlive timer: minimum period of time between the sending of PCEP KeepAlive timer: minimum period of time between the sending of PCEP
messages (Keepalive, PCReq, PCRep, PCNtf) to a PCEP peer. A messages (Keepalive, PCReq, PCRep, PCNtf) to a PCEP peer. A
suggested value for the Keepalive timer is 30 seconds. suggested value for the Keepalive timer is 30 seconds.
DeadTimer: period of timer after the expiration of which a PCEP peer DeadTimer: period of timer after the expiration of which a PCEP peer
declared the session down if no PCEP message has been received. declared the session down if no PCEP message has been received.
skipping to change at page 73, line 7 skipping to change at page 76, line 7
JL Le Roux (editor) JL Le Roux (editor)
France Telecom France Telecom
2, Avenue Pierre-Marzin 2, Avenue Pierre-Marzin
Lannion, 22307 Lannion, 22307
FRANCE FRANCE
Email: jeanlouis.leroux@orange-ftgroup.com Email: jeanlouis.leroux@orange-ftgroup.com
Full Copyright Statement Full Copyright Statement
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
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