draft-ietf-pce-stateful-path-protection-10.txt   draft-ietf-pce-stateful-path-protection-11.txt 
PCE Working Group H. Ananthakrishnan PCE Working Group H. Ananthakrishnan
Internet-Draft Netflix Internet-Draft Netflix
Intended status: Standards Track S. Sivabalan Intended status: Standards Track S. Sivabalan
Expires: March 3, 2020 Cisco Expires: March 28, 2020 Cisco
C. Barth C. Barth
Juniper Networks Juniper Networks
I. Minei I. Minei
Google, Inc Google, Inc
M. Negi M. Negi
Huawei Technologies Huawei Technologies
August 31, 2019 September 25, 2019
PCEP Extensions for Associating Working and Protection LSPs with PCEP Extensions for Associating Working and Protection LSPs with
Stateful PCE Stateful PCE
draft-ietf-pce-stateful-path-protection-10 draft-ietf-pce-stateful-path-protection-11
Abstract Abstract
An active stateful Path Computation Element (PCE) is capable of An active stateful Path Computation Element (PCE) is capable of
computing as well as controlling via Path Computation Element computing as well as controlling via Path Computation Element
Communication Protocol (PCEP) Multiprotocol Label Switching Traffic Communication Protocol (PCEP) Multiprotocol Label Switching Traffic
Engineering Label Switched Paths (MPLS LSP). Furthermore, it is also Engineering (MPLS-TE) Label Switched Paths (LSPs). Furthermore, it
possible for an active stateful PCE to create, maintain, and delete is also possible for an active stateful PCE to create, maintain, and
LSPs. This document defines the PCEP extension to associate two or delete LSPs. This document defines the PCEP extension to associate
more LSPs to provide end-to-end path protection. two or more LSPs to provide end-to-end path protection.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 3, 2020. This Internet-Draft will expire on March 28, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 27 skipping to change at page 2, line 27
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . . 5 3. PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Path Protection Association Type . . . . . . . . . . . . 5 3.1. Path Protection Association Type . . . . . . . . . . . . 5
3.2. Path Protection Association TLV . . . . . . . . . . . . . 5 3.2. Path Protection Association TLV . . . . . . . . . . . . . 6
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. State Synchronization . . . . . . . . . . . . . . . . . . 7 4.1. State Synchronization . . . . . . . . . . . . . . . . . . 7
4.2. PCC-Initiated LSPs . . . . . . . . . . . . . . . . . . . 7 4.2. PCC-Initiated LSPs . . . . . . . . . . . . . . . . . . . 7
4.3. PCE-Initiated LSPs . . . . . . . . . . . . . . . . . . . 7 4.3. PCE-Initiated LSPs . . . . . . . . . . . . . . . . . . . 7
4.4. Session Termination . . . . . . . . . . . . . . . . . . . 7 4.4. Session Termination . . . . . . . . . . . . . . . . . . . 8
4.5. Error Handling . . . . . . . . . . . . . . . . . . . . . 8 4.5. Error Handling . . . . . . . . . . . . . . . . . . . . . 8
5. Other Considerations . . . . . . . . . . . . . . . . . . . . 9 5. Other Considerations . . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
6.1. Association Type . . . . . . . . . . . . . . . . . . . . 9 6.1. Association Type . . . . . . . . . . . . . . . . . . . . 10
6.2. PPAG TLV . . . . . . . . . . . . . . . . . . . . . . . . 10 6.2. Path Protection Association TLV . . . . . . . . . . . . . 10
6.3. PCEP Errors . . . . . . . . . . . . . . . . . . . . . . . 10 6.3. PCEP Errors . . . . . . . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. Manageability Considerations . . . . . . . . . . . . . . . . 11 8. Manageability Considerations . . . . . . . . . . . . . . . . 12
8.1. Control of Function and Policy . . . . . . . . . . . . . 11 8.1. Control of Function and Policy . . . . . . . . . . . . . 12
8.2. Information and Data Models . . . . . . . . . . . . . . . 11 8.2. Information and Data Models . . . . . . . . . . . . . . . 12
8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 11 8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 12
8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 12 8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 12
8.5. Requirements On Other Protocols . . . . . . . . . . . . . 12 8.5. Requirements On Other Protocols . . . . . . . . . . . . . 12
8.6. Impact On Network Operations . . . . . . . . . . . . . . 12 8.6. Impact On Network Operations . . . . . . . . . . . . . . 13
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
10.1. Normative References . . . . . . . . . . . . . . . . . . 12 10.1. Normative References . . . . . . . . . . . . . . . . . . 13
10.2. Informative References . . . . . . . . . . . . . . . . . 13 10.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 15 Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction 1. Introduction
[RFC5440] describes PCEP for communication between a Path Computation [RFC5440] describes Path Computation Element Communication Protocol
Client (PCC) and a PCE or between a pair of PCEs as per [RFC4655]. A for communication between a Path Computation Client (PCC) and a PCE
PCE computes paths for MPLS-TE LSPs based on various constraints and or between a pair of PCEs as per [RFC4655]. A PCE computes paths for
MPLS-TE Label Switched Paths (LSPs) based on various constraints and
optimization criteria. optimization criteria.
Stateful PCE [RFC8231] specifies a set of extensions to PCEP to Stateful PCE [RFC8231] specifies a set of extensions to PCEP to
enable stateful control of paths such as MPLS TE LSPs between and enable stateful control of paths such as MPLS-TE LSPs between and
across PCEP sessions in compliance with [RFC4657]. It includes across PCEP sessions in compliance with [RFC4657]. It includes
mechanisms to effect LSP state synchronization between PCCs and PCEs, mechanisms to affect LSP state synchronization between PCCs and PCEs,
delegation of control of LSPs to PCEs, and PCE control of timing and delegation of control of LSPs to PCEs, and PCE control of timing and
sequence of path computations within and across PCEP sessions and sequence of path computations within and across PCEP sessions. The
focuses on a model where LSPs are configured on the PCC and control focus is on a model where LSPs are configured on the PCC and control
over them is delegated to the PCE. Furthermore, a mechanism to over them is delegated to the Stateful PCE. Furthermore, [RFC8281]
dynamically instantiate LSPs on a PCC based on the requests from a specifies a mechanism to dynamically instantiate LSPs on a PCC based
stateful PCE or a controller using stateful PCE, is specified in on the requests from a stateful PCE or a controller using stateful
[RFC8281]. PCE.
Path protection [RFC4427] refers to a paradigm in which the working Path protection [RFC4427] refers to a paradigm in which the working
LSP is protected by one or more protection LSP(s). When the working LSP is protected by one or more protection LSP(s). When the working
LSP fails, protection LSP(s) is/are activated. When the working LSPs LSP fails, protection LSP(s) is/are activated. When the working LSPs
are computed and controlled by the PCE, there is benefit in a mode of are computed and controlled by the PCE, there is benefit in a mode of
operation where protection LSPs are as well. [RFC8051] describes operation where protection LSPs are also computed and controlled by
applicability of path protection in PCE deployments. the same PCE. [RFC8051] describes applicability of path protection
in PCE deployments.
This document specifies a stateful PCEP extension to associate two or This document specifies a stateful PCEP extension to associate two or
more LSPs for the purpose of setting up path protection. The more LSPs for the purpose of setting up path protection. The
proposed extension covers the following scenarios: extension defined in this document covers the following scenarios:
o A PCC initiates a protection LSP and retains the control of the o A PCC initiates a protection LSP and retains the control of the
LSP. The PCC computes the path itself or makes a request for path LSP. The PCC computes the path itself or makes a request for path
computation to a PCE. After the path setup, it reports the computation to a PCE. After the path setup, it reports the
information and state of the path to the PCE. This includes the information and state of the path to the PCE. This includes the
association group identifying the working and protection LSPs. association group identifying the working and protection LSPs.
This is the passive stateful mode [RFC8051]. This is the passive stateful mode [RFC8051].
o A PCC initiates a protection LSP and delegates the control of the o A PCC initiates a protection LSP and delegates the control of the
LSP to a stateful PCE. During delegation the association group LSP to a stateful PCE. During delegation the association group
identifying the working and protection LSPs is included. The PCE identifying the working and protection LSPs is included. The PCE
computes the path for the protection LSP and update the PCC with computes the path for the protection LSP and updates the PCC with
the information about the path as long as it controls the LSP. the information about the path as long as it controls the LSP.
This is the active stateful mode [RFC8051]. This is the active stateful mode [RFC8051].
o A protection LSP could be initiated by a stateful PCE, which o A protection LSP could be initiated by a stateful PCE, which
retains the control of the LSP. The PCE is responsible for retains the control of the LSP. The PCE is responsible for
computing the path of the LSP and updating to the PCC with the computing the path of the LSP and updating to the PCC with the
information about the path. This is the PCE-Initiated mode information about the path. This is the PCE-Initiated mode
[RFC8281]. [RFC8281].
Note that protection LSP can be established (signaled) prior to the Note that a protection LSP can be established (signaled) before the
failure (in which case the LSP is said to be in standby mode failure (in which case the LSP is said to be in standby mode
[RFC4427] or a Primary LSP [RFC4872]) or post failure of the [RFC4427] or a Primary LSP [RFC4872]) or after failure of the
corresponding working LSP according to the operator choice/policy corresponding working LSP (known as a secondary LSP [RFC4872]).
(known as secondary LSP [RFC4872]). Whether to establish it before or after failure is according to
operator choice or policy.
[I-D.ietf-pce-association-group] introduces a generic mechanism to [I-D.ietf-pce-association-group] introduces a generic mechanism to
create a grouping of LSPs which can then be used to define create a grouping of LSPs, which can then be used to define
associations between a set of LSPs that is equally applicable to associations between a set of LSPs. The mechanism is equally
stateful PCE (active and passive modes) and stateless PCE. applicable to stateful PCE (active and passive modes) and stateless
PCE.
This document specifies a PCEP extension to associate one working LSP This document specifies a PCEP extension to associate one working LSP
with one or more protection LSPs using the generic association with one or more protection LSPs using the generic association
mechanism. mechanism.
This document describes a PCEP extension to associate protection LSPs This document describes a PCEP extension to associate protection LSPs
by creating Path Protection Association Group (PPAG) and encoding by creating Path Protection Association Group (PPAG) and encoding
this association in PCEP messages for stateful PCEP sessions. this association in PCEP messages for stateful PCEP sessions.
1.1. Requirements Language 1.1. Requirements Language
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PCEP: Path Computation Element Communication Protocol. PCEP: Path Computation Element Communication Protocol.
PPAG: Path Protection Association Group. PPAG: Path Protection Association Group.
TLV: Type, Length, and Value. TLV: Type, Length, and Value.
3. PCEP Extensions 3. PCEP Extensions
3.1. Path Protection Association Type 3.1. Path Protection Association Type
LSPs are not associated by listing the other LSPs with which they As per [I-D.ietf-pce-association-group], LSPs are not associated by
interact, but rather by making them belong to an association group listing the other LSPs with which they interact, but rather by making
referred to as "Path Protection Association Group" (PPAG) in this them belong to an association groups. All LSPs join an association
document. All LSPs join a PPAG individually. PPAG is based on the group individually. The generic ASSOCIATION object is used to
generic Association object used to associate two or more LSPs associate two or more LSPs as specified in
specified in [I-D.ietf-pce-association-group]. A member of a PPAG [I-D.ietf-pce-association-group]. This document defines a new
can take the role of working or protection LSP. This document Association type called "Path Protection Association Type" of value
defines a new Association type called "Path Protection Association TBD1 and a "Path Protection Association Group" (PPAG). A member LSP
Type" of value TBD1. A PPAG can have one working LSP and/or one or of a PPAG can take the role of working or protection LSP. A PPAG can
more protection LSPs. The source, destination and Tunnel ID (as have one working LSP and/or one or more protection LSPs. The source,
carried in LSP-IDENTIFIERS TLV [RFC8231], with description as per destination, Tunnel ID (as carried in LSP-IDENTIFIERS TLV [RFC8231],
[RFC3209]) of all LSPs within a PPAG MUST be the same. As per with description as per [RFC3209]), and Protection Type (PT) (in Path
[RFC3209], TE tunnel is used to associate a set of LSPs during Protection Association TLV) of all LSPs within a PPAG MUST be the
reroute or to spread a traffic trunk over multiple paths. same. As per [RFC3209], TE tunnel is used to associate a set of LSPs
during reroute or to spread a traffic trunk over multiple paths.
The format of the Association object used for PPAG is specified in The format of the Association object used for PPAG is specified in
[I-D.ietf-pce-association-group]. [I-D.ietf-pce-association-group].
[I-D.ietf-pce-association-group] specifies the mechanism for the [I-D.ietf-pce-association-group] specifies the mechanism for the
capability advertisement of the Association types supported by a PCEP capability advertisement of the Association types supported by a PCEP
speaker by defining a ASSOC-Type-List TLV to be carried within an speaker by defining a ASSOC-Type-List TLV to be carried within an
OPEN object. This capability exchange for the Association type OPEN object. This capability exchange for the Association type
described in this document (i.e. Path Protection Association Type) described in this document (i.e. Path Protection Association Type)
MAY be done before using the policy association, i.e., the PCEP MAY be done before using this association, i.e., the PCEP speaker MAY
speaker MAY include the Path Protection Association Type (TBD1) in include the Path Protection Association Type (TBD1) in the ASSOC-
the ASSOC-Type-List TLV before using the PPAG in the PCEP messages. Type-List TLV before using the PPAG in the PCEP messages.
This Association type is dynamic in nature and created by the PCC or This Association type is dynamic in nature and created by the PCC or
PCE for the LSPs belonging to the same TE tunnel (as described in PCE for the LSPs belonging to the same TE tunnel (as described in
[RFC3209]) originating at the same head node and terminating at the [RFC3209]) originating at the same head node and terminating at the
same destination. These associations are conveyed via PCEP messages same destination. These associations are conveyed via PCEP messages
to the PCEP peer. As per [I-D.ietf-pce-association-group], the to the PCEP peer. As per [I-D.ietf-pce-association-group], the
association source is set to the local PCEP speaker address that association source is set to the local PCEP speaker address that
created the association, unless local policy dictates otherwise. created the association, unless local policy dictates otherwise.
Operator-configured Association Range MUST NOT be set for this Operator-configured Association Range MUST NOT be set for this
Association type and MUST be ignored. Association type and MUST be ignored.
3.2. Path Protection Association TLV 3.2. Path Protection Association TLV
The Path Protection Association TLV is an optional TLV for use with The Path Protection Association TLV is an optional TLV for use in the
the Path Protection Association Type. The Path Protection ASSOCIATION Object with the Path Protection Association Type. The
Association TLV MUST NOT be present more than once. If it appears Path Protection Association TLV MUST NOT be present more than once.
more than once, only the first occurrence is processed and any others If it appears more than once, only the first occurrence is processed
MUST be ignored. and any others MUST be ignored.
The Path Protection Association TLV follows the PCEP TLV format of The Path Protection Association TLV follows the PCEP TLV format of
[RFC5440]. [RFC5440].
The type (16 bits) of the TLV is TBD2. The length field (16 bit) has The type (16 bits) of the TLV is TBD2. The length field (16 bit) has
a fixed value of 4. a fixed value of 4.
The value comprises of a single field, the Path Protection The value comprises of a single field, the Path Protection
Association Flags (32 bits), where each bit represents a flag option. Association Flags (32 bits), where each bit represents a flag option.
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PT | Unassigned Flags |S|P| | PT | Unassigned Flags |S|P|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Path Protection Association TLV format Figure 1: Path Protection Association TLV format
Path Protection Association Flags (32 bits) - The following flags are Path Protection Association Flags (32 bits) - The following flags are
currently defined - currently defined -
Protecting (P): 1 bit - This bit is as defined in Section 14.1 of Protecting (P): 1 bit - This bit is as defined in Section 14.1 of
[RFC4872] to indicate if the LSP is working or protection LSP. [RFC4872] to indicate if the LSP is a working (0) or protection
(1) LSP.
Secondary (S): 1 bit - This bit is as defined in Section 14.1 of Secondary (S): 1 bit - This bit is as defined in Section 14.1 of
[RFC4872] to indicate if the LSP is primary or secondary LSP. The [RFC4872] to indicate if the LSP is a primary (0) or secondary (1)
S flag is ignored if the P flag is not set. LSP. The S flag is ignored if the P flag is not set.
Protection Type (PT): 6 bits - This field is as defined in Protection Type (PT): 6 bits - This field is as defined in
Section 14.1 of [RFC4872] to indicate the LSP protection type in Section 14.1 of [RFC4872] to indicate the LSP protection type in
use. use. Any type already defined or that could be defined in the
future for use in the RSVP-TE PROTECTION object is acceptable in
this TLV unless explicitly stated otherwise.
Unassigned bits are considered reserved. They MUST be set to 0 on Unassigned bits are considered reserved. They MUST be set to 0 on
transmission and MUST be ignored on receipt. transmission and MUST be ignored on receipt.
If the TLV is missing, it is considered that the LSP is the working If the TLV is missing in PPAG ASSOCIATION object, it is considered
LSP (i.e. as if P bit is unset). that the LSP is a working LSP (i.e. as if the P bit is unset).
4. Operation 4. Operation
An LSP is associated with other LSPs with which they interact by An LSP is associated with other LSPs with which it interacts by
adding them to a common association group via the ASSOCIATION object. adding them to a common association group via the ASSOCIATION object.
All procedures and error-handling for the ASSOCIATION object is as All procedures and error-handling for the ASSOCIATION object is as
per [I-D.ietf-pce-association-group]. per [I-D.ietf-pce-association-group].
4.1. State Synchronization 4.1. State Synchronization
During state synchronization, a PCC reports all the existing LSP During state synchronization, a PCC reports all the existing LSP
states as described in [RFC8231]. The association group membership states as described in [RFC8231]. The association group membership
pertaining to an LSP is also reported as per pertaining to an LSP is also reported as per
[I-D.ietf-pce-association-group]. This includes PPAGs. [I-D.ietf-pce-association-group]. This includes PPAGs.
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4.1. State Synchronization 4.1. State Synchronization
During state synchronization, a PCC reports all the existing LSP During state synchronization, a PCC reports all the existing LSP
states as described in [RFC8231]. The association group membership states as described in [RFC8231]. The association group membership
pertaining to an LSP is also reported as per pertaining to an LSP is also reported as per
[I-D.ietf-pce-association-group]. This includes PPAGs. [I-D.ietf-pce-association-group]. This includes PPAGs.
4.2. PCC-Initiated LSPs 4.2. PCC-Initiated LSPs
A PCC can associate a set of LSPs under its control for path A PCC can associate a set of LSPs under its control for path
protection purpose. Similarly, the PCC can remove one or more LSPs protection purposes. Similarly, the PCC can remove one or more LSPs
under its control from the corresponding PPAG. In both cases, the under its control from the corresponding PPAG. In both cases, the
PCC reports the change in association to PCE(s) via Path Computation PCC reports the change in association to PCE(s) via Path Computation
Report (PCRpt) message. A PCC can also delegate the working and Report (PCRpt) messages. A PCC can also delegate the working and
protection LSPs to an active stateful PCE, where the PCE would protection LSPs to an active stateful PCE, where the PCE would
control the LSPs. The stateful PCE could update the paths and control the LSPs. The stateful PCE could update the paths and
attributes of the LSPs in the association group via Path Computation attributes of the LSPs in the association group via Path Computation
Update (PCUpd) message. A PCE could also update the association to Update (PCUpd) message. A PCE could also update the association to
the PCC via PCUpd message. These procedures are described in the PCC via PCUpd message. These procedures are described in
[I-D.ietf-pce-association-group]. [I-D.ietf-pce-association-group].
It is expected that both working and protection LSP are delegated It is expected that both working and protection LSPs are delegated
together (and to the same PCE) to avoid any race conditions. Refer together (and to the same PCE) to avoid any race conditions. Refer
to [I-D.litkowski-pce-state-sync] for the problem description. to [I-D.litkowski-pce-state-sync] for the problem description.
4.3. PCE-Initiated LSPs 4.3. PCE-Initiated LSPs
A PCE can create/update working and protection LSPs independently. A PCE can create/update working and protection LSPs independently.
As specified in [I-D.ietf-pce-association-group], Association Groups As specified in [I-D.ietf-pce-association-group], Association Groups
can be created by both the PCE and the PCC. Further, a PCE can can be created by both the PCE and the PCC. Further, a PCE can
remove a protection LSP from a PPAG as specified in remove a protection LSP from a PPAG as specified in
[I-D.ietf-pce-association-group]. The PCE uses PCUpd or Path [I-D.ietf-pce-association-group]. The PCE uses PCUpd or Path
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4.4. Session Termination 4.4. Session Termination
As per [I-D.ietf-pce-association-group] the association information As per [I-D.ietf-pce-association-group] the association information
is cleared along with the LSP state information. When a PCEP session is cleared along with the LSP state information. When a PCEP session
is terminated, after expiry of State Timeout Interval at the PCC, the is terminated, after expiry of State Timeout Interval at the PCC, the
LSP state associated with that PCEP session is reverted to operator- LSP state associated with that PCEP session is reverted to operator-
defined default parameters or behaviors as per [RFC8231]. The same defined default parameters or behaviors as per [RFC8231]. The same
procedure is also followed for the association information. On procedure is also followed for the association information. On
session termination at the PCE, when the LSP state reported by PCC is session termination at the PCE, when the LSP state reported by PCC is
cleared, the association information is also cleared as per cleared, the association information is also cleared as per
[I-D.ietf-pce-association-group]. Where there are no LSPs in a [I-D.ietf-pce-association-group]. Where there are no LSPs in a
association group, the association is considered to be deleted. association group, the association is considered to be deleted.
4.5. Error Handling 4.5. Error Handling
As per the processing rules specified in section 5.4 of As per the processing rules specified in section 6.4 of
[I-D.ietf-pce-association-group], if a PCEP speaker does not support [I-D.ietf-pce-association-group], if a PCEP speaker does not support
this Path Protection Association Type, it would return a PCErr this Path Protection Association Type, it would return a PCErr
message with Error-Type 26 "Association Error" and Error-Value 1 message with Error-Type 26 "Association Error" and Error-Value 1
"Association type is not supported". "Association type is not supported".
All LSPs (working or protection) within a PPAG MUST belong to the All LSPs (working or protection) within a PPAG MUST belong to the
same TE Tunnel (as described in [RFC3209]) and have the same source same TE Tunnel (as described in [RFC3209]) and have the same source
and destination. If a PCEP speaker attempts to add an LSP to a PPAG and destination. If a PCEP speaker attempts to add or update an LSP
and the Tunnel ID (as carried in LSP-IDENTIFIERS TLV [RFC8231], with to a PPAG and the Tunnel ID (as carried in LSP-IDENTIFIERS TLV
description as per [RFC3209]) or source or destination of the LSP is [RFC8231], with description as per [RFC3209]) or source or
different from the LSP(s) in the PPAG, the PCC MUST send PCErr with destination of the LSP is different from the LSP(s) in the PPAG, the
Error-Type 26 (Association Error) [I-D.ietf-pce-association-group] PCEP speaker MUST send PCErr with Error-Type 26 (Association Error)
and Error-Value TBD3 (Tunnel ID or End points mismatch for Path [I-D.ietf-pce-association-group] and Error-Value TBD3 (Tunnel ID or
Protection Association). In case of Path Protection, LSP-IDENTIFIERS End points mismatch for Path Protection Association). In case of
TLV SHOULD be included for all LSPs (including Segment Routing (SR) Path Protection, LSP-IDENTIFIERS TLV SHOULD be included for all LSPs
[I-D.ietf-pce-segment-routing]). (including Segment Routing (SR) [I-D.ietf-pce-segment-routing]). If
the Protection Type (PT) (in Path Protection Association TLV) is
different from the LSPs in the PPAG, the PCEP speaker MUST send PCErr
with Error-Type 26 (Association Error)
[I-D.ietf-pce-association-group] and Error-Value 6 (Association
information mismatch) as per [I-D.ietf-pce-association-group].
When the PCEP peer does not support the protection type set in PPAG, When the PCEP peer does not support the protection type set in PPAG,
the PCEP peer MUST send PCErr with Error-Type 26 (Association Error) the PCEP peer MUST send PCErr with Error-Type 26 (Association Error)
[I-D.ietf-pce-association-group] and Error-Value TBD5 (Protection [I-D.ietf-pce-association-group] and Error-Value TBD5 (Protection
type is not supported). type is not supported).
A given LSP MAY belong to more than one PPAG. If there is a conflict A given LSP MAY belong to more than one PPAG. If there is a conflict
between any of the two PPAGs, the PCEP peer MUST send PCErr with between any of the two PPAGs, the PCEP peer MUST send PCErr with
Error-Type 26 (Association Error) [I-D.ietf-pce-association-group] Error-Type 26 (Association Error) [I-D.ietf-pce-association-group]
and Error-Value 6 (Association information mismatch) as per and Error-Value 6 (Association information mismatch) as per
[I-D.ietf-pce-association-group]. [I-D.ietf-pce-association-group].
When the protection type is set to 1+1 or 1:N with N=1, there MUST be When the protection type is set to 1+1 (i.e., protection type=0x08 or
only one working LSP and one protection LSP within a PPAG. If a PCEP 0x10), there MUST be at maximum, only one working LSP and one
protection LSP within a PPAG. If a PCEP speaker attempts to add
another working/protection LSP, the PCEP peer MUST send PCErr with
Error-Type 26 (Association Error) [I-D.ietf-pce-association-group]
and Error-Value TBD4 (Attempt to add another working/protection LSP
for Path Protection Association).
When the protection type is set to 1:N (i.e., protection type=0x04),
there MUST be at maximum, only one working LSP and number of
protection LSPs MUST NOT be more than N within a PPAG. If a PCEP
speaker attempts to add another working/protection LSP, the PCEP peer speaker attempts to add another working/protection LSP, the PCEP peer
MUST send PCErr with Error-Type 26 (Association Error) MUST send PCErr with Error-Type 26 (Association Error)
[I-D.ietf-pce-association-group] and Error-Value TBD4 (Attempt to add [I-D.ietf-pce-association-group] and Error-Value TBD4 (Attempt to add
another working/protection LSP for Path Protection Association). another working/protection LSP for Path Protection Association).
When the protection type is set to 1:N with N>1, there MUST be only During the make-before-break (MBB) procedure, two paths will briefly
one working LSP and number of protection LSPs MUST NOT be more than N coexist. The error handling related to number of LSPs allowed in a
within a PPAG. If a PCEP speaker attempts to add another working/ PPAG MUST NOT be applied during MBB.
protection LSP, the PCEP peer MUST send PCErr with Error-Type 26
(Association Error) [I-D.ietf-pce-association-group] and Error-Value
TBD4 (Attempt to add another working/protection LSP for Path
Protection Association).
All processing as per [I-D.ietf-pce-association-group] continues to All processing as per [I-D.ietf-pce-association-group] continues to
apply. apply.
5. Other Considerations 5. Other Considerations
The working and protection LSPs are typically resource disjoint The working and protection LSPs are typically resource disjoint
(e.g., node, SRLG disjoint). This ensures that a single failure will (e.g., node, SRLG disjoint). This ensures that a single failure will
not affect both the working and protection LSPs. The disjoint not affect both the working and protection LSPs. The disjoint
requirement for a group of LSPs is handled via another Association requirement for a group of LSPs is handled via another Association
type called "Disjointness Association", as described in type called "Disjointness Association", as described in
[I-D.ietf-pce-association-diversity]. The diversity requirements for [I-D.ietf-pce-association-diversity]. The diversity requirements for
the protection LSP are also handled by including both ASSOCIATION the protection LSP are also handled by including both ASSOCIATION
objects identifying both the protection association group and the objects identifying both the protection association group and the
disjoint association group for the group of LSPs. disjoint association group for the group of LSPs. The relationship
between the Synchronization VECtor (SVEC) object and the Disjointness
Association is described in section 5.3 of
[I-D.ietf-pce-association-diversity].
[RFC4872] introduces the concept and mechanisms to support the [RFC4872] introduces the concept and mechanisms to support the
association of one LSP to another LSP across different RSVP - Traffic association of one LSP to another LSP across different RSVP Traffic
Engineering (RSVP-TE) sessions using ASSOCIATION and PROTECTION Engineering (RSVP-TE) sessions using ASSOCIATION and PROTECTION
object. The information in the PPAG TLV in PCEP as received from the object. The information in the Path Protection Association TLV in
PCE, is used to trigger the signalling of working LSP and protection PCEP as received from the PCE is used to trigger the signaling of
LSP, with the Path Protection Association Flags mapped to the working LSP and protection LSP, with the Path Protection Association
corresponding fields in the PROTECTION Object in RSVP-TE. Flags mapped to the corresponding fields in the PROTECTION Object in
RSVP-TE.
6. IANA Considerations 6. IANA Considerations
[Note to RFC Editor and IANA: Sections 3.1, 3.2, and 4.5 contain [Note to RFC Editor and IANA: Sections 3.1, 3.2, and 4.5 contain
"TBD1" through "TBD5" those should be replaced by the values that "TBD1" through "TBD5" those should be replaced by the values that
IANA assigns.] IANA assigns.]
6.1. Association Type 6.1. Association Type
This document defines a new Association type, originally defined in This document defines a new Association type, originally defined in
skipping to change at page 10, line 5 skipping to change at page 10, line 27
[I-D.ietf-pce-association-group]), as follows: [I-D.ietf-pce-association-group]), as follows:
+----------------------+-------------------------+------------------+ +----------------------+-------------------------+------------------+
| Association type | Association Name | Reference | | Association type | Association Name | Reference |
| Value | | | | Value | | |
+----------------------+-------------------------+------------------+ +----------------------+-------------------------+------------------+
| TBD1 | Path Protection | This | | TBD1 | Path Protection | This |
| | Association | document | | | Association | document |
+----------------------+-------------------------+------------------+ +----------------------+-------------------------+------------------+
6.2. PPAG TLV 6.2. Path Protection Association TLV
This document defines a new TLV for carrying additional information This document defines a new TLV for carrying additional information
of LSPs within a path protection association group. IANA is of LSPs within a path protection association group. IANA is
requested to make the assignment of a new value for the existing requested to make the assignment of a new value for the existing
"PCEP TLV Type Indicators" registry as follows: "PCEP TLV Type Indicators" registry as follows:
+---------------+-----------------------------------+---------------+ +---------------+-----------------------------------+---------------+
| TLV Type | TLV Name | Reference | | TLV Type | TLV Name | Reference |
| Value | | | | Value | | |
+---------------+-----------------------------------+---------------+ +---------------+-----------------------------------+---------------+
skipping to change at page 10, line 30 skipping to change at page 11, line 4
This document requests that a new sub-registry, named "Path This document requests that a new sub-registry, named "Path
protection Association Group TLV Flag Field", is created within the protection Association Group TLV Flag Field", is created within the
"Path Computation Element Protocol (PCEP) Numbers" registry to manage "Path Computation Element Protocol (PCEP) Numbers" registry to manage
the Flag field in the Path Protection Association Group TLV. New the Flag field in the Path Protection Association Group TLV. New
values are to be assigned by Standards Action [RFC8126]. Each bit values are to be assigned by Standards Action [RFC8126]. Each bit
should be tracked with the following qualities: should be tracked with the following qualities:
o Bit number (count from 0 as the most significant bit) o Bit number (count from 0 as the most significant bit)
o Name flag o Name flag
o Reference o Reference
+------------+-----------------------+----------------+ +------------+-----------------------+----------------+
| Bit Number | Name | Reference | | Bit Number | Name | Reference |
+------------+-----------------------+----------------+ +------------+-----------------------+----------------+
| 31 | P - PROTECTION-LSP | This document | | 31 | P - PROTECTION-LSP | This document |
| 30 | S - SECONDARY-LSP | This document | | 30 | S - SECONDARY-LSP | This document |
| 6-29 | Unassigned | This document |
| 0-5 | Protection Type Flags | This document | | 0-5 | Protection Type Flags | This document |
+------------+-----------------------+----------------+ +------------+-----------------------+----------------+
Table 1: PPAG TLV Table 1: Path Protection Association TLV Flag Field
6.3. PCEP Errors 6.3. PCEP Errors
This document defines new Error-Values related to path protection This document defines new Error-Values related to path protection
association for Error-type 26 "Association Error" defined in association for Error-type 26 "Association Error" defined in
[I-D.ietf-pce-association-group]. IANA is requested to allocate new [I-D.ietf-pce-association-group]. IANA is requested to allocate new
error values within the "PCEP-ERROR Object Error Types and Values" error values within the "PCEP-ERROR Object Error Types and Values"
sub-registry of the PCEP Numbers registry, as follows: sub-registry of the PCEP Numbers registry, as follows:
+-------------+-----------------------------------------+-----------+ +---------+----------+-----------------+----------------------------+
| Error-value | Meaning | Reference | | Error- | Error- | Meaning | Reference |
+-------------+-----------------------------------------+-----------+ | type | value | | |
| TBD3 | Tunnel ID or End points mismatch for | This | +---------+----------+-----------------+----------------------------+
| | Path Protection Association | document | | 26 | | Association | [I-D.ietf-pce-association- |
| TBD4 | Attempt to add another | This | | | | Error | group] |
| | working/protection LSP for Path | document | | | | | |
| | Protection Association | | | | TBD3 | Tunnel ID or | This document |
| TBD5 | Protection type is not supported | This | | | | End points | |
| | | document | | | | mismatch for | |
+-------------+-----------------------------------------+-----------+ | | | Path Protection | |
| | | Association | |
| | TBD4 | Attempt to add | This document |
| | | another working | |
| | | /protection LSP | |
| | | for Path | |
| | | Protection | |
| | | Association | |
| | TBD5 | Protection type | This document |
| | | is not | |
| | | supported | |
+---------+----------+-----------------+----------------------------+
7. Security Considerations 7. Security Considerations
The security considerations described in [RFC8231], [RFC8281], and The security considerations described in [RFC8231], [RFC8281], and
[RFC5440] apply to the extensions described in this document as well. [RFC5440] apply to the extensions described in this document as well.
Additional considerations related to associations where a malicious Additional considerations related to associations where a malicious
PCEP speaker could be spoofed and could be used as an attack vector PCEP speaker could be spoofed and could be used as an attack vector
by creating associations as described in by creating associations as described in
[I-D.ietf-pce-association-group]. Adding a spurious protection LSP [I-D.ietf-pce-association-group]. Adding a spurious protection LSP
to the Path Protection Association group could give false sense of to the Path Protection Association group could give false sense of
network reliability, which leads to issues when the working LSP is network reliability, which leads to issues when the working LSP is
down and the protection LSP fails as well. Thus securing the PCEP down and the protection LSP fails as well. Thus securing the PCEP
session using Transport Layer Security (TLS) [RFC8253], as per the session using Transport Layer Security (TLS) [RFC8253], as per the
recommendations and best current practices in [RFC7525], is recommendations and best current practices in BCP 195 [RFC7525], is
RECOMMENDED. RECOMMENDED.
8. Manageability Considerations 8. Manageability Considerations
8.1. Control of Function and Policy 8.1. Control of Function and Policy
Mechanisms defined in this document do not imply any control or Mechanisms defined in this document do not imply any control or
policy requirements in addition to those already listed in [RFC5440], policy requirements in addition to those already listed in [RFC5440],
[RFC8231], and [RFC8281]. [RFC8231], and [RFC8281].
skipping to change at page 12, line 33 skipping to change at page 13, line 22
We would like to thank Jeff Tantsura, Xian Zhang and Greg Mirsky for We would like to thank Jeff Tantsura, Xian Zhang and Greg Mirsky for
their contributions to this document. their contributions to this document.
Thanks to Ines Robles for the RTGDIR review. Thanks to Ines Robles for the RTGDIR review.
Thanks to Pete Resnick for the GENART review. Thanks to Pete Resnick for the GENART review.
Thanks to Donald Eastlake for the SECDIR review. Thanks to Donald Eastlake for the SECDIR review.
Thanks to Barry Leiba, Benjamin Kaduk, Eric Vyncke, and Roman Danyliw
for the IESG review.
10. References 10. References
10.1. Normative References 10.1. 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, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
skipping to change at page 13, line 10 skipping to change at page 14, line 5
Ed., "RSVP-TE Extensions in Support of End-to-End Ed., "RSVP-TE Extensions in Support of End-to-End
Generalized Multi-Protocol Label Switching (GMPLS) Generalized Multi-Protocol Label Switching (GMPLS)
Recovery", RFC 4872, DOI 10.17487/RFC4872, May 2007, Recovery", RFC 4872, DOI 10.17487/RFC4872, May 2007,
<https://www.rfc-editor.org/info/rfc4872>. <https://www.rfc-editor.org/info/rfc4872>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440, Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009, DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>. <https://www.rfc-editor.org/info/rfc5440>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <https://www.rfc-editor.org/info/rfc7525>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP) Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC 8231, Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017, DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>. <https://www.rfc-editor.org/info/rfc8231>.
[RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
"PCEPS: Usage of TLS to Provide a Secure Transport for the
Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>.
[RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path
Computation Element Communication Protocol (PCEP) Computation Element Communication Protocol (PCEP)
Extensions for PCE-Initiated LSP Setup in a Stateful PCE Extensions for PCE-Initiated LSP Setup in a Stateful PCE
Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, Model", RFC 8281, DOI 10.17487/RFC8281, December 2017,
<https://www.rfc-editor.org/info/rfc8281>. <https://www.rfc-editor.org/info/rfc8281>.
[I-D.ietf-pce-association-group] [I-D.ietf-pce-association-group]
Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H., Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H.,
Dhody, D., and Y. Tanaka, "Path Computation Element Dhody, D., and Y. Tanaka, "Path Computation Element
Communication Protocol (PCEP) Extensions for Establishing Communication Protocol (PCEP) Extensions for Establishing
skipping to change at page 14, line 16 skipping to change at page 15, line 21
Element (PCE) Communication Protocol Generic Element (PCE) Communication Protocol Generic
Requirements", RFC 4657, DOI 10.17487/RFC4657, September Requirements", RFC 4657, DOI 10.17487/RFC4657, September
2006, <https://www.rfc-editor.org/info/rfc4657>. 2006, <https://www.rfc-editor.org/info/rfc4657>.
[RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J. [RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J.
Hardwick, "Path Computation Element Communication Protocol Hardwick, "Path Computation Element Communication Protocol
(PCEP) Management Information Base (MIB) Module", (PCEP) Management Information Base (MIB) Module",
RFC 7420, DOI 10.17487/RFC7420, December 2014, RFC 7420, DOI 10.17487/RFC7420, December 2014,
<https://www.rfc-editor.org/info/rfc7420>. <https://www.rfc-editor.org/info/rfc7420>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <https://www.rfc-editor.org/info/rfc7525>.
[RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a [RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a
Stateful Path Computation Element (PCE)", RFC 8051, Stateful Path Computation Element (PCE)", RFC 8051,
DOI 10.17487/RFC8051, January 2017, DOI 10.17487/RFC8051, January 2017,
<https://www.rfc-editor.org/info/rfc8051>. <https://www.rfc-editor.org/info/rfc8051>.
[RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
"PCEPS: Usage of TLS to Provide a Secure Transport for the
Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>.
[I-D.ietf-pce-pcep-yang] [I-D.ietf-pce-pcep-yang]
Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A
YANG Data Model for Path Computation Element YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", draft-ietf-pce-pcep- Communications Protocol (PCEP)", draft-ietf-pce-pcep-
yang-12 (work in progress), July 2019. yang-12 (work in progress), July 2019.
[I-D.ietf-pce-association-diversity] [I-D.ietf-pce-association-diversity]
Litkowski, S., Sivabalan, S., Barth, C., and M. Negi, Litkowski, S., Sivabalan, S., Barth, C., and M. Negi,
"Path Computation Element Communication Protocol (PCEP) "Path Computation Element Communication Protocol (PCEP)
Extension for LSP Diversity Constraint Signaling", draft- Extension for LSP Diversity Constraint Signaling", draft-
ietf-pce-association-diversity-09 (work in progress), ietf-pce-association-diversity-10 (work in progress),
August 2019. August 2019.
[I-D.ietf-pce-segment-routing] [I-D.ietf-pce-segment-routing]
Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
and J. Hardwick, "PCEP Extensions for Segment Routing", and J. Hardwick, "PCEP Extensions for Segment Routing",
draft-ietf-pce-segment-routing-16 (work in progress), draft-ietf-pce-segment-routing-16 (work in progress),
March 2019. March 2019.
[I-D.litkowski-pce-state-sync] [I-D.litkowski-pce-state-sync]
Litkowski, S., Sivabalan, S., Li, C., and H. Zheng, "Inter Litkowski, S., Sivabalan, S., Li, C., and H. Zheng, "Inter
 End of changes. 51 change blocks. 
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