draft-ietf-pce-disco-proto-ospf-08.txt   rfc5088.txt 
Network Working Group J.L. Le Roux (Editor) Network Working Group JL. Le Roux, Ed.
Internet Draft France Telecom Request for Comments: 5088 France Telecom
Intended Status: Standard Track Category: Standards Track JP. Vasseur, Ed.
Expires: April 2008 J.P. Vasseur (Editor)
Cisco System Inc. Cisco System Inc.
Y. Ikejiri
Yuichi Ikejiri
NTT Communications NTT Communications
R. Zhang
Raymond Zhang BT
BT Infonet January 2008
October 2007
OSPF Protocol Extensions for Path Computation Element (PCE) Discovery OSPF Protocol Extensions for Path Computation Element (PCE) Discovery
draft-ietf-pce-disco-proto-ospf-08.txt Status of This Memo
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Copyright (C) The IETF Trust (2007). All rights reserved. This document specifies an Internet standards track protocol for the
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Abstract Abstract
There are various circumstances where it is highly desirable for a There are various circumstances where it is highly desirable for a
Path Computation Client (PCC) to be able to dynamically and Path Computation Client (PCC) to be able to dynamically and
automatically discover a set of Path Computation Elements (PCEs), automatically discover a set of Path Computation Elements (PCEs),
along with information that can be used by the PCC for PCE selection. along with information that can be used by the PCC for PCE selection.
When the PCE is a Label Switching Router (LSR) participating in the When the PCE is a Label Switching Router (LSR) participating in the
Interior Gateway Protocol (IGP), or even a server participating Interior Gateway Protocol (IGP), or even a server participating
passively in the IGP, a simple and efficient way to announce PCEs passively in the IGP, a simple and efficient way to announce PCEs
consists of using IGP flooding. For that purpose, this document consists of using IGP flooding. For that purpose, this document
defines extensions to the Open Shortest Path First (OSPF) routing defines extensions to the Open Shortest Path First (OSPF) routing
protocol for the advertisement of PCE Discovery information within an protocol for the advertisement of PCE Discovery information within an
OSPF area or within the entire OSPF routing domain. OSPF area or within the entire OSPF routing domain.
Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
Table of Contents Table of Contents
1. Terminology.................................................3 1. Introduction ....................................................2
2. Introduction................................................4 2. Terminology .....................................................4
3. Overview....................................................5 3. Overview ........................................................5
3.1. PCE Discovery Information...................................5 3.1. PCE Discovery Information ..................................5
3.2. Flooding Scope..............................................5 3.2. Flooding Scope .............................................5
4. The OSPF PCED TLV...........................................6 4. The OSPF PCED TLV ...............................................6
4.1. PCE-ADDRESS Sub-TLV.........................................7 4.1. PCE-ADDRESS Sub-TLV ........................................7
4.2. PATH-SCOPE Sub-TLV..........................................8 4.2. PATH-SCOPE Sub-TLV .........................................8
4.3. PCE-DOMAIN Sub-TLV.........................................10 4.3. PCE-DOMAIN Sub-TLV ........................................10
4.4. NEIG-PCE-DOMAIN Sub-TLV....................................11 4.4. NEIG-PCE-DOMAIN Sub-TLV ...................................11
4.5. PCE-CAP-FLAGS Sub-TLV......................................11 4.5. PCE-CAP-FLAGS Sub-TLV .....................................12
5. Elements of Procedure......................................13 5. Elements of Procedure ..........................................13
6. Backward Compatibility.....................................13 6. Backward Compatibility .........................................14
7. IANA Considerations........................................14 7. IANA Considerations ............................................14
7.1. OSPF TLV...................................................14 7.1. OSPF TLV ..................................................14
7.2. PCE Capability Flags registry..............................14 7.2. PCE Capability Flags Registry .............................14
8. Security Considerations....................................15 8. Security Considerations ........................................15
9. Manageability Considerations...............................15 9. Manageability Considerations ...................................16
9.1. Control of Policy and Functions............................15 9.1. Control of Policy and Functions ...........................16
9.2. Information and Data Model.................................15 9.2. Information and Data Model ................................16
9.3. Liveness Detection and Monitoring..........................15 9.3. Liveness Detection and Monitoring .........................16
9.4. Verify Correct Operations..................................16 9.4. Verify Correct Operations .................................16
9.5. Requirements on Other Protocols and Functional 9.5. Requirements on Other Protocols and Functional
Components...............................................16 Components ................................................16
9.6. Impact on Network Operations...............................16 9.6. Impact on Network Operations ..............................17
10. Acknowledgments............................................16 10. Acknowledgments ...............................................17
11. References.................................................16 11. References ....................................................17
11.1. Normative References.......................................16 11.1. Normative References .....................................17
11.2. Informative References.....................................17 11.2. Informative References ...................................18
12. Editor's Addresses.........................................17
13. Contributors' Addresses....................................18
14. Intellectual Property Statement............................18
1. Terminology
ABR: OSPF Area Border Router.
AS: Autonomous System.
IGP: Interior Gateway Protocol. Either of the two routing
protocols Open Shortest Path First (OSPF) or Intermediate System
to Intermediate System (ISIS).
Intra-area TE LSP: A TE LSP whose path does not cross an IGP area
boundary.
Intra-AS TE LSP: A TE LSP whose path does not cross an AS
boundary.
Inter-area TE LSP: A TE LSP whose path transits two or more IGP
areas. That is a TE LSP that crosses at least one IGP area
boundary.
Inter-AS TE LSP: A TE LSP whose path transits two or more
ASes or sub-ASes (BGP confederations). That is a TE LSP that
crosses at least one AS boundary.
LSA: Link State Advertisement.
LSR: Label Switching Router.
PCC: Path Computation Client. Any client application requesting a
path computation to be performed by a Path Computation Element.
PCE: Path Computation Element. An entity (component, application,
or network node) that is capable of computing a network path or
route based on a network graph, and applying computational
constraints.
PCE-Domain: In a PCE context this refers to any collection of
network elements within a common sphere of address management or
path computational responsibility (referred to as a "domain" in
[RFC4655]). Examples of PCE-Domains include IGP areas and ASes.
This should be distinguished from an OSPF routing domain.
PCEP: Path Computation Element Protocol.
TE LSP: Traffic Engineered Label Switched Path.
2. Introduction 1. Introduction
[RFC4655] describes the motivations and architecture for a Path [RFC4655] describes the motivations and architecture for a Path
Computation Element (PCE)-based Computation Element (PCE)-based path computation model for
path computation model for Multi-Protocol Label Switching (MPLS) and Multi-Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS)
Generalized MPLS (GMPLS) Traffic Engineered Label Switched Paths (TE Traffic Engineered Label Switched Paths (TE LSPs). The model allows
LSPs). The model allows for the separation of the PCE from a Path for the separation of the PCE from a Path Computation Client (PCC)
Computation Client (PCC) (also referred to as a non co-located PCE) (also referred to as a non co-located PCE) and allows for cooperation
and allows for cooperation between PCEs (where one PCE acts as a PCC between PCEs (where one PCE acts as a PCC to make requests of the
to make requests of the other PCE). This relies on a communication other PCE). This relies on a communication protocol between a PCC
protocol between PCC and PCE, and also between PCEs. The requirements and PCE, and also between PCEs. The requirements for such a
for such a communication protocol can be found in [RFC4657], and the communication protocol can be found in [RFC4657], and the
communication protocol is defined in [PCEP]. communication protocol is defined in [PCEP].
The PCE architecture requires that a PCC be aware of the location of The PCE architecture requires that a PCC be aware of the location of
one or more PCEs in its domain, and also, potentially, of PCEs in one or more PCEs in its domain, and, potentially, of PCEs in other
other domains, e.g., in the case of inter-domain TE LSP computation. domains, e.g., in the case of inter-domain TE LSP computation.
A network may contain a large number of PCEs, each with potentially A network may contain a large number of PCEs, each with potentially
distinct capabilities. In such a context it is highly desirable to distinct capabilities. In such a context, it is highly desirable to
have a mechanism for automatic and dynamic PCE discovery that allows have a mechanism for automatic and dynamic PCE discovery that allows
PCCs to automatically discover a set of PCEs along with additional PCCs to automatically discover a set of PCEs, along with additional
information about each PCE that may be used by a PCC to perform PCE information about each PCE that may be used by a PCC to perform PCE
selection. Additionally, it is valuable for a PCC to dynamically selection. Additionally, it is valuable for a PCC to dynamically
detect new PCEs, failed PCEs, or any modification to the PCE detect new PCEs, failed PCEs, or any modification to the PCE
information. Detailed requirements for such a PCE discovery mechanism information. Detailed requirements for such a PCE discovery
are provided in [RFC4674]. mechanism are provided in [RFC4674].
Note that the PCE selection algorithm applied by a PCC is out of the Note that the PCE selection algorithm applied by a PCC is out of the
scope of this document. scope of this document.
When PCCs are LSRs participating in the IGP (OSPF or IS-IS), and PCEs When PCCs are LSRs participating in the IGP (OSPF or IS-IS), and PCEs
are either LSRs or servers also participating in the IGP, an are either LSRs or servers also participating in the IGP, an
effective mechanism for PCE discovery within an IGP routing domain effective mechanism for PCE discovery within an IGP routing domain
consists of utilizing IGP advertisements. consists of utilizing IGP advertisements.
This document defines extensions to OSPFv2 [RFC2328] and OSPFv3 This document defines extensions to OSPFv2 [RFC2328] and OSPFv3
[RFC2740] to allow a PCE in an OSPF routing domain to advertise its [RFC2740] to allow a PCE in an OSPF routing domain to advertise its
location along with some information useful to a PCC for PCE location, along with some information useful to a PCC for PCE
selection so as to satisfy dynamic PCE discovery requirements set selection, so as to satisfy dynamic PCE discovery requirements set
forth in [RFC4674]. forth in [RFC4674].
Generic capability advertisement mechanisms for OSPF are defined in Generic capability advertisement mechanisms for OSPF are defined in
[OSPF-CAP]. These allow a router to advertise its capabilities within [RFC4970]. These allow a router to advertise its capabilities within
an OSPF area or an entire OSPF routing domain. This document an OSPF area or an entire OSPF routing domain. This document
leverages this generic capability advertisement mechanism to fully leverages this generic capability advertisement mechanism to fully
satisfy the dynamic PCE discovery requirements. satisfy the dynamic PCE discovery requirements.
This document defines a new TLV (named the PCE Discovery (PCED) TLV) This document defines a new TLV (named the PCE Discovery TLV (PCED
to be carried within the OSPF Router Information LSA ([OSPF-CAP]). TLV)) to be carried within the OSPF Router Information LSA
([RFC4970]).
The PCE information advertised is detailed in Section 3. Protocol The PCE information advertised is detailed in Section 3. Protocol
extensions and procedures are defined in Sections 4 and 5. extensions and procedures are defined in Sections 4 and 5.
The OSPF extensions defined in this document allow for PCE discovery The OSPF extensions defined in this document allow for PCE discovery
within an OSPF routing domain. Solutions for PCE discovery across AS within an OSPF routing domain. Solutions for PCE discovery across
boundaries are beyond the scope of this document, and for further Autonomous System boundaries are beyond the scope of this document,
study. and are for further study.
2. Terminology
ABR: OSPF Area Border Router.
AS: Autonomous System.
IGP: Interior Gateway Protocol. Either of the two routing protocols,
Open Shortest Path First (OSPF) or Intermediate System to
Intermediate System (IS-IS).
Intra-area TE LSP: A TE LSP whose path does not cross an IGP area
boundary.
Intra-AS TE LSP: A TE LSP whose path does not cross an AS boundary.
Inter-area TE LSP: A TE LSP whose path transits two or more IGP
areas. That is, a TE LSP that crosses at least one IGP area
boundary.
Inter-AS TE LSP: A TE LSP whose path transits two or more ASes or
sub-ASes (BGP confederations). That is, a TE LSP that crosses at
least one AS boundary.
LSA: Link State Advertisement.
LSR: Label Switching Router.
PCC: Path Computation Client. Any client application requesting a
path computation to be performed by a Path Computation Element.
PCE: Path Computation Element. An entity (component, application, or
network node) that is capable of computing a network path or route
based on a network graph and applying computational constraints.
PCED: PCE Discovery.
PCE-Domain: In a PCE context, this refers to any collection of
network elements within a common sphere of address management or path
computational responsibility (referred to as a "domain" in
[RFC4655]). Examples of PCE-Domains include IGP areas and ASes.
This should be distinguished from an OSPF routing domain.
PCEP: Path Computation Element communication Protocol.
TE LSP: Traffic Engineered Label Switched Path.
TLV: Type-Length-Variable data encoding.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
IS-IS extensions for PCE discovery are defined in [RFC5089].
3. Overview 3. Overview
3.1. PCE Discovery Information 3.1. PCE Discovery Information
The PCE discovery information is composed of: The PCE discovery information is composed of:
- The PCE location: an IPv4 and/or IPv6 address that is used to reach - The PCE location: an IPv4 and/or IPv6 address that is used to
the PCE. It is RECOMMENDED to use an address that is always reach the PCE. It is RECOMMENDED to use an address that is always
reachable if there is any connectivity to the PCE; reachable if there is any connectivity to the PCE;
- The PCE path computation scope (i.e., intra-area, inter-area, - The PCE path computation scope (i.e., intra-area, inter-area,
inter-AS, or inter-layer); inter-AS, or inter-layer);
- The set of one or more PCE-Domain(s) into which the PCE has - The set of one or more PCE-Domain(s) into which the PCE has
visibility and for which the PCE can compute paths; visibility and for which the PCE can compute paths;
- The set of zero, one or more neighbor PCE-Domain(s) toward which - The set of zero, one, or more neighbor PCE-Domain(s) toward which
the PCE can compute paths; the PCE can compute paths;
- A set of communication capabilities (e.g., support for request - A set of communication capabilities (e.g., support for request
prioritization) and path computation-specific capabilities prioritization) and path computation-specific capabilities (e.g.,
(e.g., supported constraints). supported constraints).
PCE discovery information is by nature fairly static and does not PCE discovery information is, by nature, fairly static and does not
change with PCE activity. Changes in PCE discovery information may change with PCE activity. Changes in PCE discovery information may
occur as a result of PCE configuration updates, PCE occur as a result of PCE configuration updates, PCE
deployment/activation, PCE deactivation/suppression, or PCE failure. deployment/activation, PCE deactivation/suppression, or PCE failure.
Hence, this information is not expected to change frequently. Hence, this information is not expected to change frequently.
3.2. Flooding Scope 3.2. Flooding Scope
The flooding scope for PCE information advertised through OSPF can be The flooding scope for PCE information advertised through OSPF can be
limited to one or more OSPF areas the PCE belongs to, or can be limited to one or more OSPF areas the PCE belongs to, or can be
extended across the entire OSPF routing domain. extended across the entire OSPF routing domain.
Note that some PCEs may belong to multiple areas, in which case the Note that some PCEs may belong to multiple areas, in which case the
flooding scope may comprise these areas. This could be the case for flooding scope may comprise these areas. This could be the case for
an ABR, for instance, advertising its PCE information within the an ABR, for instance, advertising its PCE information within the
backbone area and/or a subset of its attached IGP area(s). backbone area and/or a subset of its attached IGP area(s).
4. The OSPF PCED TLV 4. The OSPF PCED TLV
The OSPF PCE Discovery TLV (PCED TLV) contains non-ordered set of The OSPF PCE Discovery TLV (PCED TLV) contains a non-ordered set of
sub-TLVs. sub-TLVs.
The format of the OSPF PCED TLV and its sub-TLVs is identical to the The format of the OSPF PCED TLV and its sub-TLVs is identical to the
TLV format used by the Traffic Engineering Extensions to OSPF TLV format used by the Traffic Engineering Extensions to OSPF
[RFC3630]. That is, the TLV is composed of 2 octets for the type, 2 [RFC3630]. That is, the TLV is composed of 2 octets for the type, 2
octets specifying the TLV length, and a value field. The Length field octets specifying the TLV length, and a value field. The Length
defines the length of the value portion in octets. field defines the length of the value portion in octets.
The TLV is padded to four-octet alignment; padding is not included in The TLV is padded to 4-octet alignment; padding is not included in
the Length field (so a three octet value would have a length of the Length field (so a 3-octet value would have a length of 3, but
three, but the total size of the TLV would be eight octets). Nested the total size of the TLV would be 8 octets). Nested TLVs are also
TLVs are also four-octet aligned. Unrecognized types are ignored. 4-octet aligned. Unrecognized types are ignored.
The OSPF PCED TLV has the following format: The OSPF PCED TLV has the following format:
1 2 3 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// sub-TLVs // // sub-TLVs //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type To be defined by IANA (suggested value=5) Type: 6
Length Variable Length: Variable
Value This comprises one or more sub-TLVs Value: This comprises one or more sub-TLVs
Five sub-TLVs are defined: Five sub-TLVs are defined:
Sub-TLV type Length Name Sub-TLV type Length Name
1 variable PCE-ADDRESS sub-TLV 1 variable PCE-ADDRESS sub-TLV
2 4 PATH-SCOPE sub-TLV 2 4 PATH-SCOPE sub-TLV
3 4 PCE-DOMAIN sub-TLV 3 4 PCE-DOMAIN sub-TLV
4 4 NEIG-PCE-DOMAIN sub-TLV 4 4 NEIG-PCE-DOMAIN sub-TLV
5 variable PCE-CAP-FLAGS sub-TLV 5 variable PCE-CAP-FLAGS sub-TLV
The PCE-ADDRESS and PATH-SCOPE sub-TLVs MUST always be present within The PCE-ADDRESS and PATH-SCOPE sub-TLVs MUST always be present within
the PCED TLV. the PCED TLV.
The PCE-DOMAIN and NEIG-PCE-DOMAIN sub-TLVs are optional. They MAY be The PCE-DOMAIN and NEIG-PCE-DOMAIN sub-TLVs are optional. They MAY
present in the PCED TLV to facilitate selection of inter-domain PCEs. be present in the PCED TLV to facilitate selection of inter-domain
PCEs.
The PCE-CAP-FLAGS sub-TLV is optional and MAY be present in the PCED The PCE-CAP-FLAGS sub-TLV is optional and MAY be present in the PCED
TLV to facilitate the PCE selection process. TLV to facilitate the PCE selection process.
Malformed PCED TLVs or sub-TLVs not explicitly described in this Malformed PCED TLVs or sub-TLVs not explicitly described in this
document MUST cause the LSA to be treated as malformed according to document MUST cause the LSA to be treated as malformed according to
the normal procedures of OSPF. the normal procedures of OSPF.
Any unrecognized sub-TLV MUST be silently ignored. Any unrecognized sub-TLV MUST be silently ignored.
The PCED TLV is carried within an OSPF Router Information LSA The PCED TLV is carried within an OSPF Router Information LSA defined
defined in [OSPF-CAP]. in [RFC4970].
No additional sub-TLVs will be added to the PCED TLV in the future. No additional sub-TLVs will be added to the PCED TLV in the future.
If a future application requires the advertisement of additional PCE If a future application requires the advertisement of additional PCE
information in OSPF, this will not be carried in the Router information in OSPF, this will not be carried in the Router
Information LSA. Information LSA.
The following sub-sections describe the sub-TLVs which may be carried The following sub-sections describe the sub-TLVs that may be carried
within the PCED sub-TLV. within the PCED TLV.
4.1. PCE-ADDRESS Sub-TLV 4.1. PCE-ADDRESS Sub-TLV
The PCE-ADDRESS sub-TLV specifies an IP address that can be The PCE-ADDRESS sub-TLV specifies an IP address that can be used to
used to reach the PCE. It is RECOMMENDED to make use of an address reach the PCE. It is RECOMMENDED to make use of an address that is
that is always reachable, provided that the PCE is alive and always reachable, provided that the PCE is alive and reachable.
reachable.
The PCE-ADDRESS sub-TLV is mandatory; it MUST be present within the The PCE-ADDRESS sub-TLV is mandatory; it MUST be present within the
PCED TLV. It MAY appear twice, when the PCE has both an IPv4 and IPv6 PCED TLV. It MAY appear twice, when the PCE has both an IPv4 and
address. It MUST NOT appear more than once for the same address type. IPv6 address. It MUST NOT appear more than once for the same address
If it appears more than once, only the first occurrence is processed type. If it appears more than once for the same address type, only
and any others MUST be ignored. the first occurrence is processed and any others MUST be ignored.
The format of the PCE-ADDRESS sub-TLV is as follows: The format of the PCE-ADDRESS sub-TLV is as follows:
1 2 3 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 1 | Length | | Type = 1 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| address-type | Reserved | | address-type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// PCE IP Address // // PCE IP Address //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
PCE-ADDRESS sub-TLV format PCE-ADDRESS sub-TLV format
Type: 1
Type 1 Length: 8 (IPv4) or 20 (IPv6)
Length 8 (IPv4) or 20 (IPv6)
Address-type: Address-type:
1 IPv4 1 IPv4
2 IPv6 2 IPv6
Reserved: SHOULD be set to zero on transmission and MUST be Reserved: SHOULD be set to zero on transmission and MUST be ignored
ignored on receipt. on receipt.
PCE IP Address: The IP address to be used to reach the PCE. PCE IP Address: The IP address to be used to reach the PCE.
4.2. PATH-SCOPE Sub-TLV 4.2. PATH-SCOPE Sub-TLV
The PATH-SCOPE sub-TLV indicates the PCE path computation scope, The PATH-SCOPE sub-TLV indicates the PCE path computation scope,
which refers to the PCE's ability to compute or take part in the which refers to the PCE's ability to compute or take part in the
computation of paths for intra-area, inter-area, inter-AS, or inter- computation of paths for intra-area, inter-area, inter-AS, or inter-
layer_TE LSPs. layer TE LSPs.
The PATH-SCOPE sub-TLV is mandatory; it MUST be present within the The PATH-SCOPE sub-TLV is mandatory; it MUST be present within the
PCED TLV. There MUST be exactly one instance of the PATH-SCOPE sub- PCED TLV. There MUST be exactly one instance of the PATH-SCOPE
TLV within each PCED TLV. If it appears more than once, only the sub-TLV within each PCED TLV. If it appears more than once, only the
first occurrence is processed and any others MUST be ignored. first occurrence is processed and any others MUST be ignored.
The PATH-SCOPE sub-TLV contains a set of bit-flags indicating the The PATH-SCOPE sub-TLV contains a set of bit-flags indicating the
supported path scopes, and four fields indicating PCE preferences. supported path scopes, and four fields indicating PCE preferences.
The PATH-SCOPE sub-TLV has the following format: The PATH-SCOPE sub-TLV has the following format:
1 2 3 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 2 | Length | | Type = 2 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|1|2|3|4|5| Reserved |PrefL|PrefR|PrefS|PrefY| Res | |0|1|2|3|4|5| Reserved |PrefL|PrefR|PrefS|PrefY| Res |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type 2 Type: 2
Length 4 Length: 4
Value This comprises a 2-octet flag field where each bit Value: This comprises a 2-octet flags field where each bit
represents a supported path scope, as well as four represents a supported path scope, as well as four
preference fields used to specify PCE preferences. preference fields used to specify PCE preferences.
The following bits are defined: The following bits are defined:
Bit Path Scope Bit Path Scope
0 L bit: Can compute intra-area paths 0 L bit: Can compute intra-area paths.
1 R bit: Can act as PCE for inter-area TE LSP 1 R bit: Can act as PCE for inter-area TE LSP
computation computation.
2 Rd bit: Can act as a default PCE for inter-area TE LSP 2 Rd bit: Can act as a default PCE for inter-area TE LSP
computation computation.
3 S bit: Can act as PCE for inter-AS TE LSP computation 3 S bit: Can act as PCE for inter-AS TE LSP computation.
4 Sd bit: Can act as a default PCE for inter-AS TE LSP 4 Sd bit: Can act as a default PCE for inter-AS TE LSP
computation
5 Y bit: Can compute or take part into the computation
of paths across layers.
PrefL field: PCE's preference for intra-area TE LSPs
computation. computation.
5 Y bit: Can act as PCE for inter-layer TE LSP
PrefR field: PCE's preference for inter-area TE LSPs
computation. computation.
PrefS field: PCE's preference for inter-AS TE LSPs PrefL field: PCE's preference for intra-area TE LSP computation.
computation.
PrefY field: PCE's preference for inter-layer TE LSPs PrefR field: PCE's preference for inter-area TE LSP computation.
computation.
PrefS field: PCE's preference for inter-AS TE LSP computation.
PrefY field: PCE's preference for inter-layer TE LSP computation.
Res: Reserved for future use. Res: Reserved for future use.
The L, R, S, and Y bits are set when the PCE can act as a PCE for The L, R, S, and Y bits are set when the PCE can act as a PCE for
intra-area, inter-area, inter-AS, or inter-layer TE LSPs computation intra-area, inter-area, inter-AS, or inter-layer TE LSP computation,
respectively. These bits are non-exclusive. respectively. These bits are non-exclusive.
When set, the Rd bit indicates that the PCE can act as a default PCE When set, the Rd bit indicates that the PCE can act as a default PCE
for inter-area TE LSPs computation (that is, the PCE can compute a for inter-area TE LSP computation (that is, the PCE can compute a
path toward any neighbor area). Similarly, when set, the Sd bit path toward any neighbor area). Similarly, when set, the Sd bit
indicates that the PCE can act as a default PCE for inter-AS TE LSP indicates that the PCE can act as a default PCE for inter-AS TE LSP
computation (the PCE can compute a path toward any neighbor AS). computation (the PCE can compute a path toward any neighbor AS).
When the Rd and Sd bit are set the PCED TLV MUST NOT contain a NEIG- When the Rd and Sd bit are set, the PCED TLV MUST NOT contain a
PCE-DOMAIN sub-TLV (see Section 4.1.4). NEIG-PCE-DOMAIN sub-TLV (see Section 4.4).
When the R bit is clear, the Rd bit SHOULD be clear on transmission When the R bit is clear, the Rd bit SHOULD be clear on transmission
and MUST be ignore on receipt. When the S bit is clear, the Sd bit and MUST be ignored on receipt. When the S bit is clear, the Sd bit
SHOULD be clear on transmission and MUST be ignored on receipt. SHOULD be clear on transmission and MUST be ignored on receipt.
The PrefL, PrefR, PrefS, and PrefY fields are each three bits long The PrefL, PrefR, PrefS, and PrefY fields are each three bits long
and allow the PCE to specify a preference for each computation scope, and allow the PCE to specify a preference for each computation scope,
where 7 reflects the highest preference. Such preferences can be used where 7 reflects the highest preference. Such preferences can be
for weighted load balancing of path computation requests. An operator used for weighted load balancing of path computation requests. An
may decide to configure a preference for each computation scope at operator may decide to configure a preference for each computation
each PCE so as to balance the path computation load among them. The scope at each PCE so as to balance the path computation load among
algorithms used by a PCC to load balance its path computation them. The algorithms used by a PCC to load balance its path
requests according to such PCE preferences is out of the scope of computation requests according to such PCE preferences is out of the
this document and is a matter for local or network-wide policy. The scope of this document and is a matter for local or network-wide
same or different preferences may be used for each scope. For policy. The same or different preferences may be used for each
instance, an operator that wants a PCE capable of both inter-area and scope. For instance, an operator that wants a PCE capable of both
inter-AS computation to be prefered for use for inter-AS computations inter-area and inter-AS computation to be preferred for use for
may configure PrefS higher than PrefR. inter-AS computations may configure PrefS higher than PrefR.
When the L, R, S, or Y bits are cleared, the PrefL, PrefR, PrefS, and When the L, R, S, or Y bits are cleared, the PrefL, PrefR, PrefS, and
PrefY fields SHOULD respectively be set to 0 on transmission and MUST PrefY fields SHOULD respectively be set to 0 on transmission and MUST
be ignored on receipt. be ignored on receipt.
Both reserved fields SHOULD be set to zero on transmission and MUST Both reserved fields SHOULD be set to zero on transmission and MUST
be ignored on receipt. be ignored on receipt.
4.3. PCE-DOMAIN Sub-TLV 4.3. PCE-DOMAIN Sub-TLV
The PCE-DOMAIN sub-TLV specifies a PCE-Domain (area or AS) where the The PCE-DOMAIN sub-TLV specifies a PCE-Domain (area or AS) where the
PCE has topology visibility and through which the PCE can compute PCE has topology visibility and through which the PCE can compute
paths. paths.
The PCE-DOMAIN sub-TLV SHOULD be present when PCE-Domains for which The PCE-DOMAIN sub-TLV SHOULD be present when PCE-Domains for which
the PCE can operate cannot be inferred by other IGP information, for the PCE can operate cannot be inferred by other IGP information: for
instance when the PCE is inter-domain capable (i.e., when the R bit instance, when the PCE is inter-domain capable (i.e., when the R bit
or S bit is set) and the flooding scope is the entire routing domain or S bit is set) and the flooding scope is the entire routing domain
(see Section 5 for a discussion of how the flooding scope is set and (see Section 5 for a discussion of how the flooding scope is set and
interpreted). interpreted).
A PCED TLV may include multiple PCE-DOMAIN sub-TLVs when the PCE has A PCED TLV may include multiple PCE-DOMAIN sub-TLVs when the PCE has
visibility into multiple PCE-Domains. visibility into multiple PCE-Domains.
The PCE-DOMAIN sub-TLV has the following format: The PCE-DOMAIN sub-TLV has the following format:
1 2 3 1 2 3
skipping to change at page 10, line 38 skipping to change at page 10, line 49
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=3 | Length | | Type=3 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain-type | Reserved | | Domain-type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain ID | | Domain ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
PCE-DOMAIN sub-TLV format PCE-DOMAIN sub-TLV format
Type 3 Type: 3
Length 8 Length: 8
Two domain-type values are defined: Two domain-type values are defined:
1 OSPF Area ID 1 OSPF Area ID
2 AS Number 2 AS Number
Domain ID: With the domain-type set to 1, this indicates the 32 Domain ID: With the domain-type set to 1, this indicates the
bit Area ID of an area where the PCE has visibility and can 32-bit Area ID of an area where the PCE has visibility and can
compute paths. With domain-type set to 2, this indicates an AS compute paths. With domain-type set to 2, this indicates an AS
number of an AS where the PCE has visibility and can compute number of an AS where the PCE has visibility and can compute
paths. When the AS number is coded in two octets, the AS Number paths. When the AS number is coded in two octets, the AS Number
field MUST have its first two octets set to 0. field MUST have its first two octets set to 0.
.
4.4. NEIG-PCE-DOMAIN Sub-TLV 4.4. NEIG-PCE-DOMAIN Sub-TLV
The NEIG-PCE-DOMAIN sub-TLV specifies a neighbor PCE-domain (area or The NEIG-PCE-DOMAIN sub-TLV specifies a neighbor PCE-Domain (area or
AS) toward which a PCE can compute paths. It means that the PCE can AS) toward which a PCE can compute paths. It means that the PCE can
take part in the computation of inter-domain TE LSPs with paths that take part in the computation of inter-domain TE LSPs with paths that
transit this neighbor PCE-domain. transit this neighbor PCE-Domain.
A PCED sub-TLV may include several NEIG-PCE-DOMAIN sub-TLVs when the A PCED sub-TLV may include several NEIG-PCE-DOMAIN sub-TLVs when the
PCE can compute paths towards several neighbour PCE-domains. PCE can compute paths towards several neighbor PCE-Domains.
The NEIG-PCE-DOMAIN sub-TLV has the same format as the PCE-DOMAIN The NEIG-PCE-DOMAIN sub-TLV has the same format as the PCE-DOMAIN
sub-TLV: sub-TLV:
1 2 3 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 4 | Length | | Type = 4 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain-type | Reserved | | Domain-type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain ID | | Domain ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
NEIG-PCE-DOMAIN sub-TLV format NEIG-PCE-DOMAIN sub-TLV format
Type 4 Type: 4
Length 8 Length: 8
Two domain-type values are defined: Two domain-type values are defined:
1 OSPF Area ID 1 OSPF Area ID
2 AS Number 2 AS Number
Domain ID: With the domain-type set to 1, this indicates the 32 Domain ID: With the domain-type set to 1, this indicates the
bit Area ID of a neighbour area toward which the PCE can 32-bit Area ID of a neighbor area toward which the PCE can compute
compute paths. With domain-type set to 2, this indicates the AS paths. With domain-type set to 2, this indicates the AS number of
number of a neighbor AS toward which the PCE can compute paths. a neighbor AS toward which the PCE can compute paths. When the AS
When the AS number is coded in two octets, the AS Number field number is coded in two octets, the AS Number field MUST have its
MUST have its first two octets set to 0. first two octets set to 0.
The NEIG-PCE-DOMAIN sub-TLV MUST be present at least once with The NEIG-PCE-DOMAIN sub-TLV MUST be present at least once with
domain-type set to 1 if the R bit is set and the Rd bit is cleared, domain-type set to 1 if the R bit is set and the Rd bit is cleared,
and MUST be present at least once with domain-type set to 2 if the S and MUST be present at least once with domain-type set to 2 if the S
bit is set and the Sd bit is cleared. bit is set and the Sd bit is cleared.
4.5. PCE-CAP-FLAGS Sub-TLV 4.5. PCE-CAP-FLAGS Sub-TLV
The PCE-CAP-FLAGS sub-TLV is an optional sub-TLV used to indicate PCE The PCE-CAP-FLAGS sub-TLV is an optional sub-TLV used to indicate PCE
capabilities. It MAY be present within the PCED TLV. It MUST NOT be capabilities. It MAY be present within the PCED TLV. It MUST NOT be
present more than once. If it appears more than once, only the first present more than once. If it appears more than once, only the first
occurrence is processed and any others MUST be ignored. occurrence is processed and any others MUST be ignored.
The value field of the PCE-CAP-FLAGS sub-TLV is made up of an array The value field of the PCE-CAP-FLAGS sub-TLV is made up of an array
of units of 32 bit-flags numbered from the most significant bit as of units of 32-bit flags numbered from the most significant bit as
bit zero, where each bit represents one PCE capability. bit zero, where each bit represents one PCE capability.
The format of the PCE-CAP-FLAGS sub-TLV is as follows: The format of the PCE-CAP-FLAGS sub-TLV 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 5 | Length | | Type = 5 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// PCE Capability Flags // // PCE Capability Flags //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type 5 Type: 5
Length Multiple of 4 octets Length: Multiple of 4 octets
Value This contains an array of units of 32 bit flags Value: This contains an array of units of 32-bit flags
numbered from the most significant as bit zero, where numbered from the most significant as bit zero, where
each bit represents one PCE capability. each bit represents one PCE capability.
IANA is requested to manage the space of the PCE Capability Flags IANA will manage the space of the PCE Capability Flags.
The following bits are to be assigned by IANA: The following bits have been assigned by IANA:
Bit Capabilities Bit Capabilities
0 Path computation with GMPLS link constraints 0 Path computation with GMPLS link constraints
1 Bidirectional path computation 1 Bidirectional path computation
2 Diverse path computation 2 Diverse path computation
3 Load-balanced path computation 3 Load-balanced path computation
4 Synchronized path computation 4 Synchronized path computation
5 Support for multiple objective functions 5 Support for multiple objective functions
6 Support for additive path constraints 6 Support for additive path constraints
skipping to change at page 13, line 9 skipping to change at page 13, line 33
These capabilities are defined in [RFC4657]. These capabilities are defined in [RFC4657].
Reserved bits SHOULD be set to zero on transmission and MUST be Reserved bits SHOULD be set to zero on transmission and MUST be
ignored on receipt. ignored on receipt.
5. Elements of Procedure 5. Elements of Procedure
The PCED TLV is advertised within OSPFv2 Router Information LSAs The PCED TLV is advertised within OSPFv2 Router Information LSAs
(Opaque type of 4 and Opaque ID of 0) or OSPFv3 Router Information (Opaque type of 4 and Opaque ID of 0) or OSPFv3 Router Information
LSAs (function code of 12) which are defined in [OSPF-CAP]. As such, LSAs (function code of 12), which are defined in [RFC4970]. As such,
elements of procedure are inherited from those defined in [OSPF-CAP]. elements of procedure are inherited from those defined in [RFC4970].
In OSPFv2 the flooding scope is controlled by the opaque LSA type (as In OSPFv2, the flooding scope is controlled by the opaque LSA type
defined in [RFC2370]) and in OSPFv3 by the S1/S2 bits (as defined in (as defined in [RFC2370]) and in OSPFv3, by the S1/S2 bits (as
[RFC2740]). If the flooding scope is local to an area then the PCED defined in [RFC2740]). If the flooding scope is area local, then the
TLV MUST be carried within an OSPFv2 type 10 router information LSA PCED TLV MUST be carried within an OSPFv2 type 10 router information
or an OSPFV3 Router Information LSA with the S1 bit set and the S2 LSA or an OSPFV3 Router Information LSA with the S1 bit set and the
bit clear. If the flooding scope is the entire IGP domain then the S2 bit clear. If the flooding scope is the entire IGP domain, then
PCED TLV MUST be carried within an OSPFv2 type 11 Router Information the PCED TLV MUST be carried within an OSPFv2 type 11 Router
LSA or OSPFv3 Router Information LSA with the S1 bit clear and the S2 Information LSA or OSPFv3 Router Information LSA with the S1 bit
bit set. When only the L bit of the PATH-SCOPE sub-TLV is set, the clear and the S2 bit set. When only the L bit of the PATH-SCOPE
flooding scope MUST be area local. sub-TLV is set, the flooding scope MUST be area local.
When the PCE function is deactivated, the OSPF speaker advertising When the PCE function is deactivated, the OSPF speaker advertising
this PCE MUST originate a new Router Information LSA that no longer this PCE MUST originate a new Router Information LSA that no longer
includes the corresponding PCED TLV, provided there are other TLVs in includes the corresponding PCED TLV, provided there are other TLVs in
the LSA. If there are no other TLVs in the LSA, it MUST either send the LSA. If there are no other TLVs in the LSA, it MUST either send
an empty Router Information LSA or purge it by prematurely aging it. an empty Router Information LSA or purge it by prematurely aging it.
The PCE address (i.e., the address indicated within the PCE ADDRESS The PCE address (i.e., the address indicated within the PCE-ADDRESS
TLV) SHOULD be reachable via some prefixes advertised by OSPF. This sub-TLV) SHOULD be reachable via some prefixes advertised by OSPF.
allows the detection of a PCE failure to be sped up. When the PCE
address is no longer reachable, the PCE node has failed, has been
torn down, or there is no longer IP connectivity to the PCE.
A change in information in the PCED TLV MUST NOT trigger any SPF The PCED TLV information regarding a specific PCE is only considered
computation at a receiving router. current and useable when the router advertising this information is
itself reachable via OSPF calculated paths in the same area of the
LSA in which the PCED TLV appears.
The way PCEs determine the information they advertise is out of the A change in the state of a PCE (activate, deactivate, parameter
scope of this document. Some information may be configured on the PCE change) MUST result in a corresponding change in the PCED TLV
(e.g., address, preferences, scope) and other information may be information advertised by an OSPF router (inserted, removed, updated)
in its LSA. The way PCEs determine the information they advertise,
and how that information is made available to OSPF, is out of the
scope of this document. Some information may be configured (e.g.,
address, preferences, scope) and other information may be
automatically determined by the PCE (e.g., areas of visibility). automatically determined by the PCE (e.g., areas of visibility).
A change in information in the PCED TLV MUST NOT trigger any SPF
computation at a receiving router.
6. Backward Compatibility 6. Backward Compatibility
The PCED TLV defined in this document does not introduce any The PCED TLV defined in this document does not introduce any
interoperability issues. interoperability issues.
A router not supporting the PCED TLV will just silently ignore the A router not supporting the PCED TLV will just silently ignore the
TLV as specified in [OSPF-CAP]. TLV as specified in [RFC4970].
7. IANA Considerations 7. IANA Considerations
7.1. OSPF TLV 7.1. OSPF TLV
IANA has defined a registry for TLVs carried in the Router IANA has defined a registry for TLVs carried in the Router
Information LSA defined in [OSPF-CAP]. IANA is requested to assign a Information LSA defined in [RFC4970]. IANA has assigned a new TLV
new TLV code-point for the PCED TLV carried within the Router codepoint for the PCED TLV carried within the Router Information LSA.
Information LSA.
Value TLV Name Reference Value TLV Name Reference
----- -------- ---------- ----- -------- ----------
5 PCED (this document) 6 PCED (this document)
7.2. PCE Capability Flags registry 7.2. PCE Capability Flags Registry
This document provides new capability bit flags, which are present This document provides new capability bit flags, which are present in
in the PCE-CAP-FLAGS TLV referenced in section 4.1.5. the PCE-CAP-FLAGS TLV referenced in Section 4.1.5.
The IANA is requested to create a new top-level OSPF registry, the The IANA has created a new top-level OSPF registry, the "PCE
"PCE Capability Flags" registry, and to manage the space of PCE Capability Flags" registry, and will manage the space of PCE
capability bit flags numbering them in the usual IETF notation capability bit flags numbering them in the usual IETF notation
starting at zero and continuing at least through 31, with the most starting at zero and continuing at least through 31, with the most
significant bit as bit zero. significant bit as bit zero.
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: Each bit should be tracked with the following qualities:
- Bit number - Bit number
- Capability Description - Capability Description
- Defining RFC - Defining RFC
Several bits are defined in this document. Here are the suggested Several bits are defined in this document. The following values have
values: been assigned:
Bit Capability Description Bit Capability Description
0 Path computation with GMPLS link constraints 0 Path computation with GMPLS link constraints
1 Bidirectional path computation 1 Bidirectional path computation
2 Diverse path computation 2 Diverse path computation
3 Load-balanced path computation 3 Load-balanced path computation
4 Synchronized paths computation 4 Synchronized paths computation
5 Support for multiple objective functions 5 Support for multiple objective functions
6 Support for additive path constraints 6 Support for additive path constraints
(max hop count, etc.) (max hop count, etc.)
7 Support for request prioritization 7 Support for request prioritization
8 Support for multiple requests per message 8 Support for multiple requests per message
8. Security Considerations 8. Security Considerations
This document defines OSPF extensions for PCE discovery within an This document defines OSPF extensions for PCE discovery within an
administrative domain. Hence the security of the PCE discovery relies administrative domain. Hence the security of the PCE discovery
on the security of OSPF. relies on the security of OSPF.
Mechanisms defined to ensure authenticity and integrity of OSPF LSAs Mechanisms defined to ensure authenticity and integrity of OSPF LSAs
[RFC2154], and their TLVs, can be used to secure the PCE Discovery [RFC2154], and their TLVs, can be used to secure the PCE Discovery
information as well. information as well.
OSPF provides no encryption mechanism for protecting the privacy of OSPF provides no encryption mechanism for protecting the privacy of
LSAs, and in particular the privacy of the PCE discovery information. LSAs and, in particular, the privacy of the PCE discovery
information.
9. Manageability Considerations 9. Manageability Considerations
Manageability considerations for PCE Discovery are addressed in Manageability considerations for PCE Discovery are addressed in
Section 4.10 of [RFC4674]. Section 4.10 of [RFC4674].
9.1. Control of Policy and Functions 9.1. Control of Policy and Functions
Requirements for the configuration of PCE discovery parameters on Requirements for the configuration of PCE discovery parameters on
PCCs and PCEs are discussed in Section 4.10.1 of [RFC4674]. PCCs and PCEs are discussed in Section 4.10.1 of [RFC4674].
In particular, a PCE implementation SHOULD allow the following In particular, a PCE implementation SHOULD allow the following
parameters to be configured on the PCE: parameters to be configured on the PCE:
- The PCE IPv4/IPv6 address(es) (see Section 4.1)
- The PCE Scope, including the inter-domain functions (inter- - The PCE IPv4/IPv6 address(es) (see Section 4.1).
area, inter-AS, inter-layer), the preferences, and whether the
PCE can act as default PCE (see Section 4.2) - The PCE Scope, including the inter-domain functions
- The PCE domains (see Section 4.3) (inter-area, inter-AS, inter-layer), the preferences,
- The neighbour PCE domains (see Section 4.4) and whether the PCE can act as default PCE (see Section 4.2).
- The PCE capabilities (see Section 4.5)
- The PCE-Domains (see Section 4.3).
- The neighbor PCE-Domains (see Section 4.4).
- The PCE capabilities (see Section 4.5).
9.2. Information and Data Model 9.2. Information and Data Model
A MIB module for PCE Discovery is defined in [PCED-MIB]. A MIB module for PCE Discovery is defined in [PCED-MIB].
9.3. Liveness Detection and Monitoring 9.3. Liveness Detection and Monitoring
PCE Discovery Protocol liveness detection relies upon OSPF liveness This document specifies the use of OSPF as a PCE Discovery Protocol.
detection. OSPF already includes a liveness detection mechanism The requirements specified in [RFC4674] include the ability to
(Hello protocol), and PCE discovery does not require additional determine liveness of the PCE Discovery protocol. Normal operation
capabilities. of the OSPF protocol meets these requirements.
Procedures defined in Section 5 allow a PCC to detect when a PCE has
been deactivated, or is no longer reachable.
9.4. Verify Correct Operations 9.4. Verify Correct Operations
The correlation of information advertised against information The correlation of information advertised against information
received can be achieved by comparing the information in the PCED TLV received can be achieved by comparing the information in the PCED TLV
received by the PCC with that stored at the PCE using the PCED MIB received by the PCC with that stored at the PCE using the PCED MIB
[PCED-MIB]. The number of dropped, corrupt, and rejected information [PCED-MIB]. The number of dropped, corrupt, and rejected information
elements are available through the PCED MIB. elements are available through the PCED MIB.
9.5. Requirements on Other Protocols and Functional Components 9.5. Requirements on Other Protocols and Functional Components
skipping to change at page 16, line 29 skipping to change at page 17, line 16
Frequent changes in PCE information advertised in the PCED TLV, may Frequent changes in PCE information advertised in the PCED TLV, may
have a significant impact on OSPF and might destabilize the operation have a significant impact on OSPF and might destabilize the operation
of the network by causing the PCCs to swap between PCEs. of the network by causing the PCCs to swap between PCEs.
As discussed in Section 4.10.4 of [RFC4674], it MUST be possible to As discussed in Section 4.10.4 of [RFC4674], it MUST be possible to
apply at least the following controls: apply at least the following controls:
- Configurable limit on the rate of announcement of changed - Configurable limit on the rate of announcement of changed
parameters at a PCE. parameters at a PCE.
- Control of the impact on PCCs such as through rate-limiting
- Control of the impact on PCCs, such as through rate-limiting
the processing of PCED TLVs. the processing of PCED TLVs.
- Configurable control of triggers that cause a PCC to swap to - Configurable control of triggers that cause a PCC to swap to
another PCE. another PCE.
10. Acknowledgments 10. Acknowledgments
We would like to thank Lucy Wong, Adrian Farrel, Les Ginsberg, Mike We would like to thank Lucy Wong, Adrian Farrel, Les Ginsberg, Mike
Shand, and Lou Berger for their useful comments and suggestions. Shand, and Lou Berger for their useful comments and suggestions.
We would also like to thank Dave Ward, Lars Eggert, Sam Hartman, and We would also like to thank Dave Ward, Lars Eggert, Sam Hartman, Tim
Tim Polk for their comments during the final stages of publication. Polk, and Lisa Dusseault for their comments during the final stages
of publication.
11. References 11. References
11.1. Normative References 11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2328] Moy, J., "OSPF Version 2", RFC 2328, April 1998. [RFC2154] Murphy, S., Badger, M., and B. Wellington, "OSPF with
Digital Signatures", RFC 2154, June 1997.
[RFC2740] Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6", [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
RFC 2740, December 1999.
[RFC2370] Coltun, R., "The OSPF Opaque LSA Option", RFC 2370, July [RFC2370] Coltun, R., "The OSPF Opaque LSA Option", RFC 2370, July
1998. 1998.
[RFC3630] Katz, D., Yeung, D., Kompella, K., "Traffic Engineering [RFC2740] Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6",
Extensions to OSPF Version 2", RFC 3630, September 2003. RFC 2740, December 1999.
[OSPF-CAP] Lindem, A., Shen, N., Aggarwal, R., Shaffer, S., Vasseur, [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic
J.P., "Extensions to OSPF for advertising Optional Router Engineering (TE) Extensions to OSPF Version 2", RFC 3630,
Capabilities", draft-ietf-ospf-cap, work in progress. September 2003.
[RFC2154] Murphy, S., Badger, M., and B. Wellington, "OSPF with [RFC4970] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R.,
Digital Signatures", RFC 2154, June 1997. and S. Shaffer, "Extensions to OSPF for Advertising
Optional Router Capabilities", RFC 4970, July 2007.
11.2. Informative References 11.2. Informative References
[RFC4657] Ash, J., Le Roux, J.L., "PCE Communication Protocol Generic [PCED-MIB] Stephan, E., "Definitions of Managed Objects for Path
Requirements", RFC4657, September 2006. Computation Element Discovery", Work in Progress, March
2007.
[PCEP] Vasseur, Le Roux, et al., "Path Computation Element (PCE) [PCEP] Vasseur, JP., Ed., and JL. Le Roux, Ed., "Path
communication Protocol (PCEP) - Version 1", draft-ietf-pce-pcep, work Computation Element (PCE) communication Protocol (PCEP)
in progress. ", Work in Progress, November 2007.
[PCED-MIB] Stephan, E., "Definitions of Managed Objects for Path [RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element Discovery", draft-ietf-pce-disc-mib, work in Computation Element (PCE)-Based Architecture", RFC 4655,
progress. August 2006.
[PCED-ISIS] Le Roux, Vasseur, et al. "IS-IS protocol extensions for [RFC4657] Ash, J., Ed., and J. Le Roux, Ed., "Path Computation
Path Computation Element (PCE) Discovery", draft-ietf-pce-disco- Element (PCE) Communication Protocol Generic
proto-isis, work in progress. Requirements", RFC 4657, September 2006.
[RFC4655] Farrel, A., Vasseur, J.P., Ash, J., "Path Computation [RFC4674] Le Roux, J., Ed., "Requirements for Path Computation
Element (PCE)-based Architecture", RFC4655, August 2006. Element (PCE) Discovery", RFC 4674, October 2006.
[RFC4674] Le Roux, J.L., et al. "Requirements for PCE discovery", [RFC5089] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
RFC4674, October 2006. Zhang, "IS-IS Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5089, January 2008.
12. Editor's Addresses Authors' Addresses
Jean-Louis Le Roux (Editor) Jean-Louis Le Roux (Editor)
France Telecom France Telecom
2, avenue Pierre-Marzin 2, avenue Pierre-Marzin
22307 Lannion Cedex 22307 Lannion Cedex
FRANCE FRANCE
Email: jeanlouis.leroux@orange-ftgroup.com EMail: jeanlouis.leroux@orange-ftgroup.com
Jean-Philippe Vasseur (Editor) Jean-Philippe Vasseur (Editor)
Cisco Systems, Inc. Cisco Systems, Inc.
1414 Massachusetts avenue 1414 Massachusetts Avenue
Boxborough , MA - 01719 Boxborough, MA 01719
USA USA
Email: jpv@cisco.com EMail: jpv@cisco.com
13. Contributors' Addresses
Yuichi Ikejiri Yuichi Ikejiri
NTT Communications Corporation NTT Communications Corporation
1-1-6, Uchisaiwai-cho, Chiyoda-ku 1-1-6, Uchisaiwai-cho, Chiyoda-ku
Tokyo 100-8019 Tokyo 100-8019
JAPAN JAPAN
Email: y.ikejiri@ntt.com EMail: y.ikejiri@ntt.com
Raymond Zhang Raymond Zhang
BT Infonet BT
2160 E. Grand Ave. 2160 E. Grand Ave.
El Segundo, CA 90025 El Segundo, CA 90025
USA USA
Email: raymond_zhang@bt.infonet.com EMail: raymond.zhang@bt.com
14. Intellectual Property Statement Full Copyright Statement
Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
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attempt made to obtain a general license or permission for the use of attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
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this standard. Please address the information to the IETF at this standard. Please address the information to the IETF at
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Disclaimer of Validity
This document and the information contained herein are provided
on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE
ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The IETF Trust (2007). This document is subject to the
rights, licenses and restrictions contained in BCP 78, and except as
set forth therein, the authors retain all their rights.
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