rfc9862.original   rfc9862.txt 
PCE Working Group M. Koldychev Internet Engineering Task Force (IETF) M. Koldychev
Internet-Draft S. Sivabalan Request for Comments: 9862 S. Sivabalan
Updates: 8231 (if approved) Ciena Corporation Updates: 8231 Ciena Corporation
Intended status: Standards Track S. Sidor Category: Standards Track S. Sidor
Expires: 6 October 2025 Cisco Systems, Inc. ISSN: 2070-1721 Cisco Systems, Inc.
C. Barth C. Barth
Juniper Networks, Inc. Juniper Networks, Inc.
S. Peng S. Peng
Huawei Technologies Huawei Technologies
H. Bidgoli H. Bidgoli
Nokia Nokia
4 April 2025 October 2025
Path Computation Element Communication Protocol (PCEP) Extensions for Path Computation Element Communication Protocol (PCEP) Extensions for
Segment Routing (SR) Policy Candidate Paths Segment Routing (SR) Policy Candidate Paths
draft-ietf-pce-segment-routing-policy-cp-27
Abstract Abstract
A Segment Routing (SR) Policy is an ordered list of instructions, A Segment Routing (SR) Policy is an ordered list of instructions
called "segments" that represent a source-routed policy. Packet called "segments" that represent a source-routed policy. Packet
flows are steered into an SR Policy on a node where it is flows are steered into an SR Policy on a node where it is
instantiated. An SR Policy is made of one or more candidate paths. instantiated. An SR Policy is made of one or more Candidate Paths.
This document specifies the Path Computation Element Communication This document specifies the Path Computation Element Communication
Protocol (PCEP) extension to signal candidate paths of an SR Policy. Protocol (PCEP) extension to signal Candidate Paths of an SR Policy.
Additionally, this document updates RFC 8231 to allow delegation and Additionally, this document updates RFC 8231 to allow delegation and
setup of an SR Label Switched Path (LSP), without using the path setup of an SR Label Switched Path (LSP) without using the path
computation request and reply messages. This document is applicable computation request and reply messages. This document is applicable
to both Segment Routing over MPLS (SR-MPLS) and Segment Routing over to both Segment Routing over MPLS (SR-MPLS) and Segment Routing over
IPv6 (SRv6). IPv6 (SRv6).
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering This document is a product of the Internet Engineering Task Force
Task Force (IETF). Note that other groups may also distribute (IETF). It represents the consensus of the IETF community. It has
working documents as Internet-Drafts. The list of current Internet- received public review and has been approved for publication by the
Drafts is at https://datatracker.ietf.org/drafts/current/. Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Internet-Drafts are draft documents valid for a maximum of six months Information about the current status of this document, any errata,
and may be updated, replaced, or obsoleted by other documents at any and how to provide feedback on it may be obtained at
time. It is inappropriate to use Internet-Drafts as reference https://www.rfc-editor.org/info/rfc9862.
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 6 October 2025.
Copyright Notice Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 1.1. Requirements Language
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Overview
4. SR Policy Association (SRPA) . . . . . . . . . . . . . . . . 6 4. SR Policy Association (SRPA)
4.1. SR Policy Identifier . . . . . . . . . . . . . . . . . . 7 4.1. SR Policy Identifier
4.2. SR Policy Candidate Path Identifier . . . . . . . . . . . 7 4.2. SR Policy Candidate Path Identifier
4.3. SR Policy Candidate Path Attributes . . . . . . . . . . . 7 4.3. SR Policy Candidate Path Attributes
4.4. Association Parameters . . . . . . . . . . . . . . . . . 8 4.4. Association Parameters
4.5. Association Information . . . . . . . . . . . . . . . . . 9 4.5. Association Information
4.5.1. SR Policy Name TLV . . . . . . . . . . . . . . . . . 10 4.5.1. SRPOLICY-POL-NAME TLV
4.5.2. SR Policy Candidate Path Identifier TLV . . . . . . . 10 4.5.2. SRPOLICY-CPATH-ID TLV
4.5.3. SR Policy Candidate Path Name TLV . . . . . . . . . . 12 4.5.3. SRPOLICY-CPATH-NAME TLV
4.5.4. SR Policy Candidate Path Preference TLV . . . . . . . 12 4.5.4. SRPOLICY-CPATH-PREFERENCE TLV
5. SR Policy Signaling Extensions . . . . . . . . . . . . . . . 13 5. SR Policy Signaling Extensions
5.1. SR Policy Capability TLV . . . . . . . . . . . . . . . . 13 5.1. SRPOLICY-CAPABILITY TLV
5.2. LSP Object TLVs . . . . . . . . . . . . . . . . . . . . . 15 5.2. LSP Object TLVs
5.2.1. Computation Priority TLV . . . . . . . . . . . . . . 15 5.2.1. COMPUTATION-PRIORITY TLV
5.2.2. Explicit Null Label Policy (ENLP) TLV . . . . . . . . 15 5.2.2. EXPLICIT-NULL-LABEL-POLICY TLV
5.2.3. Invalidation TLV . . . . . . . . . . . . . . . . . . 16 5.2.3. INVALIDATION TLV
5.2.3.1. Drop-upon-invalid applies to SR Policy . . . . . 18 5.2.3.1. Drop-Upon-Invalid Applies to SR Policy
5.3. Update to RFC 8231 . . . . . . . . . . . . . . . . . . . 18 5.3. Updates to RFC 8231
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 6. IANA Considerations
6.1. Association Type . . . . . . . . . . . . . . . . . . . . 19 6.1. Association Type
6.2. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 19 6.2. PCEP TLV Type Indicators
6.3. PCEP Errors . . . . . . . . . . . . . . . . . . . . . . . 20 6.3. PCEP Errors
6.4. TE-PATH-BINDING TLV Flag field . . . . . . . . . . . . . 21 6.4. TE-PATH-BINDING TLV Flag Field
6.5. SR Policy Invalidation Operational State . . . . . . . . 21 6.5. SR Policy Invalidation Operational State
6.6. SR Policy Invalidation Configuration State . . . . . . . 22 6.6. SR Policy Invalidation Configuration State
6.7. SR Policy Capability TLV Flag field . . . . . . . . . . . 22 6.7. SR Policy Capability TLV Flag Field
7. Security Considerations
7. Implementation Status . . . . . . . . . . . . . . . . . . . . 23 8. Manageability Considerations
7.1. Cisco . . . . . . . . . . . . . . . . . . . . . . . . . . 23 8.1. Control of Function and Policy
7.2. Juniper . . . . . . . . . . . . . . . . . . . . . . . . . 24 8.2. Information and Data Models
8. Security Considerations . . . . . . . . . . . . . . . . . . . 24 8.3. Liveness Detection and Monitoring
9. Manageability Considerations . . . . . . . . . . . . . . . . 24 8.4. Verify Correct Operations
9.1. Control of Function and Policy . . . . . . . . . . . . . 25 8.5. Requirements on Other Protocols
9.2. Information and Data Models . . . . . . . . . . . . . . . 25 8.6. Impact on Network Operations
9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 25 9. References
9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 25 9.1. Normative References
9.5. Requirements On Other Protocols . . . . . . . . . . . . . 25 9.2. Informative References
9.6. Impact On Network Operations . . . . . . . . . . . . . . 25 Acknowledgements
10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 26 Contributors
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 26 Authors' Addresses
11.1. Normative References . . . . . . . . . . . . . . . . . . 26
11.2. Informative References . . . . . . . . . . . . . . . . . 28
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 29
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30
1. Introduction 1. Introduction
Segment Routing (SR) Policy Architecture [RFC9256] details the "Segment Routing Policy Architecture" [RFC9256] details the concepts
concepts of Segment Routing (SR) Policy [RFC8402] and approaches to of Segment Routing (SR) Policy [RFC8402] and approaches to steering
steering traffic into an SR Policy. traffic into an SR Policy.
Path Computation Element Communication Protocol (PCEP) Extensions for "Path Computation Element Communication Protocol (PCEP) Extensions
Segment Routing [RFC8664] specifies extensions to the PCEP that allow for Segment Routing" [RFC8664] specifies extensions to the PCEP that
a stateful Path Computation Element (PCE) to compute and initiate allow a stateful Path Computation Element (PCE) to compute and
Traffic Engineering (TE) paths, as well as a Path Computation Client initiate Traffic Engineering (TE) paths, as well as a Path
(PCC) to request a path subject to certain constraints and Computation Client (PCC) to request a path subject to certain
optimization criteria in SR domain. Although PCEP extensions constraints and optimization criteria in an SR domain. Although PCEP
introduced in [RFC8664] enables the creation of SR-TE paths, these do extensions introduced in [RFC8664] enable the creation of SR-TE
not constitute SR Policies as defined in [RFC9256] and therefore lack paths, these do not constitute SR Policies as defined in [RFC9256].
support for: Therefore, they lack support for:
* Association of SR Policy Candidate Paths signaled via PCEP with * Association of SR Policy Candidate Paths signaled via PCEP with
Candidate Paths of the same SR Policy signaled via other sources Candidate Paths of the same SR Policy signaled via other sources
(e.g., local configuration or BGP). (e.g., local configuration or BGP).
* Association of SR Policy with an intent via color, enabling * Association of an SR Policy with an intent via color, enabling
headend-based steering of BGP service routes over SR Policies headend-based steering of BGP service routes over SR Policies
provisioned via PCEP. provisioned via PCEP.
PCEP Extensions for establishing relationships between sets of Label "Path Computation Element Communication Protocol (PCEP) Extensions
Switched Paths (LSPs) [RFC8697] introduces a generic mechanism to for Establishing Relationships between Sets of Label Switched Paths
create a grouping of LSPs which is called an Association. (LSPs)" [RFC8697] introduces a generic mechanism to create a grouping
of LSPs that is called an "Association".
An SR Policy is associated with one or more candidate paths. A An SR Policy is associated with one or more Candidate Paths. A
candidate path is the unit for signaling of an SR Policy to a headend Candidate Path is the unit for signaling an SR Policy to a headend as
as described in Section 2.2 of [RFC9256]. This document extends described in Section 2.2 of [RFC9256]. This document extends
[RFC8664] to support signaling SR Policy Candidate Paths as LSPs and [RFC8664] to support signaling SR Policy Candidate Paths as LSPs and
to signal Candidate Path membership in an SR Policy by means of the to signal Candidate Path membership in an SR Policy by means of the
Association mechanism. A PCEP Association corresponds to a SR Policy Association mechanism. A PCEP Association corresponds to an SR
and a LSP corresponds to a Candidate Path. The unit of signaling in Policy and an LSP corresponds to a Candidate Path. The unit of
PCEP is the LSP, thus all the information related to SR Policy is signaling in PCEP is the LSP, thus, all the information related to an
carried at the Candidate Path level. SR Policy is carried at the Candidate Path level.
Also, this document updates Section 5.8.2 of [RFC8231], making the Also, this document updates Section 5.8.2 of [RFC8231], making the
use of Path Computation Request (PCReq) and Path Computation Reply use of Path Computation Request (PCReq) and Path Computation Reply
(PCRep) messages optional for LSPs setup using Path Setup Type 1 (PCRep) messages optional for LSPs that are set up using Path Setup
(Segment Routing) [RFC8664] and Path Setup Type 3 (SRv6) [RFC9603] Type 1 (for Segment Routing) [RFC8664] and Path Setup Type 3 (for
with the aim of reducing the PCEP message exchanges and simplifying SRv6) [RFC9603] with the aim of reducing the PCEP message exchanges
implementation. and simplifying implementation.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. Terminology 2. Terminology
This document uses the following terms defined in [RFC5440]: ERO, This document uses the following terms defined in [RFC5440]:
PCC, PCE, PCEP Peer, and PCEP speaker.
This document uses the following term defined in [RFC3031]: LSP. * Explicit Route Object (ERO)
This document uses the following term defined in [RFC9552]: BGP-LS. * Path Computation Client (PCC)
The following terms are used in this document: * Path Computation Element (PCE)
* PCEP Peer
* PCEP speaker
This document uses the following term defined in [RFC3031]:
* Label Switched Path (LSP)
This document uses the following term defined in [RFC9552]:
* Border Gateway Protocol - Link State (BGP-LS)
The following other terms are used in this document:
Endpoint: The IPv4 or IPv6 endpoint address of an SR Policy, as Endpoint: The IPv4 or IPv6 endpoint address of an SR Policy, as
described in Section 2.1 of [RFC9256]. described in Section 2.1 of [RFC9256].
Color: The 32-bit color of an SR Policy, as described in Section 2.1 Color: The 32-bit color of an SR Policy, as described in Section 2.1
of [RFC9256]. of [RFC9256].
Protocol-Origin: The protocol that was used to create a Candidate Protocol-Origin: The protocol that was used to create a Candidate
Path, as described in Section 2.3 of [RFC9256]. Path, as described in Section 2.3 of [RFC9256].
Originator: A device that created a Candidate Path, as described in Originator: A device that created a Candidate Path, as described in
Section 2.4 of [RFC9256]. Section 2.4 of [RFC9256].
Discriminator: Distinguishes Candidate Paths created by the same Discriminator: Distinguishes Candidate Paths created by the same
device, as described in Section 2.5 of [RFC9256]. device, as described in Section 2.5 of [RFC9256].
Association Parameters: As described in [RFC8697], refers to the key Association parameters: Refers to the key data that uniquely
data that uniquely identifies an Association. identifies an Association, as described in [RFC8697].
Association Information: As described in Section 6.1.4 of [RFC8697], Association information: Refers to information related to
refers to information related to Association Type. Association Type, as described in Section 6.1.4 of [RFC8697].
SR Policy LSP: An LSP setup using Path Setup Type [RFC8408] 1 SR Policy LSP: An LSP setup using Path Setup Type [RFC8408] 1 (for
(Segment Routing) or 3 (SRv6). Segment Routing) or 3 (for SRv6).
SR Policy Association: A new association type used to group SR Policy Association (SRPA): A new Association Type used to group
candidate paths belonging to same SR Policy. Depending on the Candidate Paths belonging to the same SR Policy. Depending on the
discussion context, it can refer to the PCEP ASSOCIATION object of discussion context, it can refer to the PCEP ASSOCIATION object of
SR Policy type or to a group of LSPs that belong to the an SR Policy type or to a group of LSPs that belong to the
association. association.
The base PCEP specification [RFC4655] originally defined the use of The base PCEP specification [RFC4655] originally defined the use of
the PCE architecture for MPLS and GMPLS networks with LSPs the PCE architecture for MPLS and GMPLS networks with LSPs
instantiated using the RSVP-TE signaling protocol. Over time, instantiated using the RSVP-TE signaling protocol. Over time,
support for additional path setup types, such as SRv6, has been support for additional path setup types such as SRv6 has been
introduced [RFC9603]. The term "LSP" is used extensively in PCEP introduced [RFC9603]. The term "LSP" is used extensively in PCEP
specifications and, in the context of this document, refers to a specifications, and in the context of this document, refers to a
Candidate Path within an SR Policy, which may be an SRv6 path (still Candidate Path within an SR Policy, which may be an SRv6 path (still
represented using the LSP Object as specified in [RFC8231]. represented using the LSP object as specified in [RFC8231]).
3. Overview 3. Overview
The SR Policy is represented by a new type of PCEP Association, The SR Policy is represented by a new type of PCEP Association,
called the SR Policy Association (SRPA) (see Section 4). The SR called the SR Policy Association (SRPA) (see Section 4). The SR
Policy Candidate Paths of specific SR Policy are the LSPs within the Policy Candidate Paths of a specific SR Policy are the LSPs within
same SRPA. The extensions in this document specify the encoding of a the same SRPA. The extensions in this document specify the encoding
single segment list within an SR Policy Candidate Path. Encoding of of a single segment list within an SR Policy Candidate Path.
multiple segment lists is outside the scope of this document and Encoding of multiple segment lists is outside the scope of this
specified in [I-D.ietf-pce-multipath]. document and is specified in [PCEP-MULTIPATH].
An SRPA carries three pieces of information: SR Policy Identifier, SR An SRPA carries three pieces of information: SR Policy Identifier, SR
Policy Candidate Path Identifier, and SR Policy Candidate Path Policy Candidate Path Identifier, and SR Policy Candidate Path
Attribute(s). Attribute(s).
This document also specifies some additional information that is not This document also specifies some additional information that is not
encoded as part of an SRPA: Computation Priority of the LSP, Explicit encoded as part of an SRPA: computation priority of the LSP, Explicit
Null Label Policy for the unlabeled IP packets and Drop-upon-invalid NULL Label Policy for the unlabeled IP packets and Drop-Upon-Invalid
behavior for traffic steering when the LSP is operationally down (see behavior for traffic steering when the LSP is operationally down (see
Section 5). Section 5).
4. SR Policy Association (SRPA) 4. SR Policy Association (SRPA)
Per [RFC8697], LSPs are associated with other LSPs with which they Per [RFC8697], LSPs are associated with other LSPs with which they
interact by adding them to a common association group. An interact by adding them to a common association group. An
association group is uniquely identified by the combination of the association group is uniquely identified by the combination of the
following fields in the ASSOCIATION object (Section 6.1 of following fields in the ASSOCIATION object (Section 6.1 of
[RFC8697]): Association Type, Association ID, Association Source, and [RFC8697]): Association Type, Association ID, Association Source, and
(if present) Global Association Source, or Extended Association ID. (if present) Global Association Source, or Extended Association ID.
These fields are referred to as Association Parameters (Section 4.4). These fields are referred to as "association parameters"
(Section 4.4).
[RFC8697] specifies the ASSOCIATION Object with two Object-Types for [RFC8697] specifies the ASSOCIATION object with two Object-Types for
IPv4 and IPv6 which includes the field "Association Type". This IPv4 and IPv6 that includes the field Association Type. This
document defines a new Association type (6) "SR Policy Association" document defines a new Association Type (6) "SR Policy Association"
for SRPA. for an SRPA.
[RFC8697] specifies the mechanism for the capability advertisement of [RFC8697] specifies the mechanism for the capability advertisement of
the Association Types supported by a PCEP speaker by defining an the Association Types supported by a PCEP speaker by defining an
ASSOC-Type-List TLV to be carried within an OPEN object. This ASSOC-Type-List TLV to be carried within an OPEN object. This
capability exchange for the SR Policy Association Type MUST be done capability exchange for the SRPA Type MUST be done before using the
before using the SRPA. To that aim, a PCEP speaker MUST include the SRPA. To that aim, a PCEP speaker MUST include the SRPA Type (6) in
SRPA Type (6) in the ASSOC-Type-List TLV and MUST receive the same the ASSOC-Type-List TLV and MUST receive the same from the PCEP peer
from the PCEP peer before using the SRPA (Section 6.1). before using the SRPA (Section 6.1).
SRPA MUST be assigned for all SR Policy LSPs by PCEP speaker An SRPA MUST be assigned for all SR Policy LSPs by the PCEP speaker
originating the LSP if capability was advertised by both PCEP originating the LSP if the capability was advertised by both PCEP
speakers. If the above condition is not satisfied, then the speakers. If the above condition is not satisfied, then the
receiving PCEP speaker MUST send a PCErr message with Error-Type = 6 receiving PCEP speaker MUST send a PCErr message with:
"Mandatory Object Missing", Error-Value = TBD1 "Missing SR Policy
Association".
A given LSP MUST belong to at most one SRPA, since an SR Policy * Error-Type = 6 "Mandatory Object Missing"
* Error-value = 22 "Missing SR Policy Association"
A given LSP MUST belong to one SRPA at most, since an SR Policy
Candidate Path cannot belong to multiple SR Policies. If a PCEP Candidate Path cannot belong to multiple SR Policies. If a PCEP
speaker receives a PCEP message requesting to join more than one SRPA speaker receives a PCEP message requesting to join more than one SRPA
for the same LSP, then the PCEP speaker MUST send a PCErr message for the same LSP, then the PCEP speaker MUST send a PCErr message
with Error-Type = 26 "Association Error", Error-Value = 7 "Cannot with:
join the association group".
The existing behavior for the use of Binding SID with SR Policy is * Error-Type = 26 "Association Error"
already documented in [RFC9604]. If BSID value allocation failed,
because of conflict with BSID used by another policy, then PCEP peer * Error-value = 7 "Cannot join the association group"
MUST send a PCErr message with Error-Type = 32 "Binding label/SID
failure" and Error-value = 2 "Unable to allocate the specified The existing behavior for the use of Binding SID (BSID) with an SR
binding value". Policy is already documented in [RFC9604]. If BSID value allocation
failed because of conflict with the BSID used by another policy, then
the PCEP peer MUST send a PCErr message with:
* Error-Type = 32 "Binding label/SID failure"
* Error-value = 2 "Unable to allocate the specified binding value"
4.1. SR Policy Identifier 4.1. SR Policy Identifier
SR Policy Identifier uniquely identifies an SR Policy [RFC9256] The SR Policy Identifier uniquely identifies an SR Policy [RFC9256]
within the SR domain. SR Policy Identifier is assigned by PCEP peer within the SR domain. The SR Policy Identifier is assigned by the
originating the LSP and MUST be uniform across all the PCEP sessions. PCEP peer originating the LSP and MUST be uniform across all the PCEP
Candidate Paths within an SR Policy MUST carry the same SR Policy sessions. Candidate Paths within an SR Policy MUST carry the same SR
Identifiers in their SRPAs. Candidate Paths within an SR Policy MUST Policy Identifiers in their SRPAs. Candidate Paths within an SR
NOT change their SR Policy Identifiers for the lifetime of the PCEP Policy MUST NOT change their SR Policy Identifiers for the lifetime
session. If the above conditions are not satisfied, the receiving of the PCEP session. If the above conditions are not satisfied, the
PCEP speaker MUST send a PCEP Error (PCErr) message with Error-Type = receiving PCEP speaker MUST send a PCEP Error (PCErr) message with:
26 "Association Error" and Error Value = 20 "SR Policy Identifier
Mismatch". SR Policy Identifier consists of: * Error-Type = 26 "Association Error"
* Error-value = 20 "SR Policy Identifier Mismatch"
The SR Policy Identifier consists of:
* Headend router where the SR Policy originates. * Headend router where the SR Policy originates.
* Color of the SR Policy ([RFC9256], Section 2.1). * Color of the SR Policy ([RFC9256], Section 2.1).
* Endpoint of the SR Policy ([RFC9256], Section 2.1). * Endpoint of the SR Policy ([RFC9256], Section 2.1).
4.2. SR Policy Candidate Path Identifier 4.2. SR Policy Candidate Path Identifier
SR Policy Candidate Path Identifier uniquely identifies the SR Policy The SR Policy Candidate Path Identifier uniquely identifies the SR
Candidate Path within the context of an SR Policy. SR Policy Policy Candidate Path within the context of an SR Policy. The SR
Candidate Path Identifier is assigned by PCEP peer originating the Policy Candidate Path Identifier is assigned by the PCEP peer
LSP. Candidate Paths within an SR Policy MUST NOT change their SR originating the LSP. Candidate Paths within an SR Policy MUST NOT
Policy Candidate Path Identifiers for the lifetime of the PCEP change their SR Policy Candidate Path Identifiers for the lifetime of
session. Two or more Candidate Paths within an SR Policy MUST NOT the PCEP session. Two or more Candidate Paths within an SR Policy
carry same SR Policy Candidate Path Identifiers in their SRPAs. If MUST NOT carry the same SR Policy Candidate Path Identifiers in their
the above conditions are not satisfied, the PCEP speaker MUST send a SRPAs. If the above conditions are not satisfied, the PCEP speaker
PCErr message with Error-Type = 26 "Association Error" and Error MUST send a PCErr message with:
Value = 21 "SR Policy Candidate Path Identifier Mismatch". SR Policy
Candidate Path Identifier consists of:
* Protocol Origin ([RFC9256], Section 2.3). * Error-Type = 26 "Association Error"
* Originator ([RFC9256], Section 2.4). * Error-value = 21 "SR Policy Candidate Path Identifier Mismatch"
* Discriminator ([RFC9256], Section 2.5). The SR Policy Candidate Path Identifier consists of:
* Protocol-Origin ([RFC9256], Section 2.3)
* Originator ([RFC9256], Section 2.4)
* Discriminator ([RFC9256], Section 2.5)
4.3. SR Policy Candidate Path Attributes 4.3. SR Policy Candidate Path Attributes
SR Policy Candidate Path Attributes carry optional, non-key SR Policy Candidate Path Attributes carry optional, non-key
information about a Candidate Path and MAY change during the lifetime information about a Candidate Path and MAY change during the lifetime
of an LSP. SR Policy Candidate Path Attributes consists of: of an LSP. SR Policy Candidate Path Attributes consist of:
* Candidate Path preference ([RFC9256], Section 2.7). * Candidate Path Preference ([RFC9256], Section 2.7)
* Candidate Path name ([RFC9256], Section 2.6). * Candidate Path name ([RFC9256], Section 2.6)
* SR Policy name ([RFC9256], Section 2.1). * SR Policy name ([RFC9256], Section 2.1)
4.4. Association Parameters 4.4. Association Parameters
Per Section 2.1 of [RFC9256], an SR Policy is identified through the Per Section 2.1 of [RFC9256], an SR Policy is identified through the
<headend, color, endpoint> tuple. <Headend, Color, Endpoint> tuple.
The Association Parameters consists of: The association parameters consist of:
* Association Type: Set to 6 "SR Policy Association". Association Type: Set to 6 "SR Policy Association".
* Association Source (IPv4/IPv6): Set to the headend value of the SR Association Source (IPv4/IPv6): Set to the headend value of the SR
Policy, as defined in [RFC9256] Section 2.1. Policy, as defined in [RFC9256], Section 2.1.
* Association ID (16-bit): Always set to the numeric value "1". Association ID (16 bit): Always set to the numeric value 1.
* Extended Association ID TLV: Mandatory TLV for SR Policy Extended Association ID TLV: Mandatory TLV for an SRPA. Encodes the
Association. Encodes the Color and Endpoint of the SR Policy Color and Endpoint of the SR Policy (Figure 1).
(Figure 1).
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 31 | Length = 8 or 20 | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Color | | Color |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Endpoint ~ ~ Endpoint ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Extended Association ID TLV Format Figure 1: Extended Association ID TLV Format
Type: Extended Association ID TLV, type = 31 [RFC8697]. Type: 31 for the Extended Association ID TLV [RFC8697].
Length: 8 octets if IPv4 address or 20 octets if IPv6 address is Length: 8 octets if IPv4 address or 20 octets if IPv6 address is
encoded in the Endpoint field. encoded in the Endpoint field.
Color: unsigned non-zero 32-bit integer value, SR Policy color per Color: Unsigned non-zero 32-bit integer value, SR Policy color
Section 2.1 of [RFC9256]. per Section 2.1 of [RFC9256].
Endpoint: can be either IPv4 (4 octets) or IPv6 address (16 octets). Endpoint: Can be either IPv4 (4 octets) or IPv6 address (16
This value MAY be different from the one contained in the Destination octets). This value MAY be different from the one contained in
address field in the END-POINTS object, or in the Tunnel Endpoint the destination address field in the END-POINTS object, or in
Address field in the LSP-IDENTIFIERS TLV (Section 2.1 of [RFC9256]). the Tunnel Endpoint Address field in the LSP-IDENTIFIERS TLV
(Section 2.1 of [RFC9256]).
If a PCEP speaker receives an SRPA object whose Association If a PCEP speaker receives an SRPA object whose association
Parameters do not follow the above specification, then the PCEP parameters do not follow the above specification, then the PCEP
speaker MUST send a PCErr message with Error-Type = 26 "Association speaker MUST send a PCErr message with:
Error", Error-Value = 20 "SR Policy Identifier Mismatch".
The encoding choice of the Association Parameters in this way is * Error-Type = 26 "Association Error"
* Error-value = 20 "SR Policy Identifier Mismatch"
The encoding choice of the association parameters in this way is
meant to guarantee that there is no possibility of a race condition meant to guarantee that there is no possibility of a race condition
when multiple PCEP speakers want to associate the same SR Policy at when multiple PCEP speakers want to associate the same SR Policy at
the same time. By adhering to this format, all PCEP speakers come up the same time. By adhering to this format, all PCEP speakers come up
with the same Association Parameters independently of each other with the same association parameters independently of each other
based on the SR Policy parameters [RFC9256]. based on the SR Policy parameters [RFC9256].
The last hop of a computed SR Policy Candidate Path MAY differ from The last hop of a computed SR Policy Candidate Path MAY differ from
the Endpoint contained in the <headend, color, endpoint> tuple. An the Endpoint contained in the <Headend, Color, Endpoint> tuple. An
example use case is to terminate the SR Policy before reaching the example use case is to terminate the SR Policy before reaching the
Endpoint and have decapsulated traffic be forwarded the rest of the Endpoint and have decapsulated traffic be forwarded the rest of the
path to the Endpoint node using the native Interior Gateway Protocol path to the Endpoint node using the Interior Gateway Protocol (IGP)
(IGP) path(s). In this example, the destination of the SR Policy shortest path(s). In this example, the destination of the SR Policy
Candidate Paths will be some node before the Endpoint, but the Candidate Paths will be some node before the Endpoint, but the
Endpoint value is still used at the headend to steer traffic with Endpoint value is still used at the headend to steer traffic with
that Endpoint IP address into the SR Policy. The Destination of the that Endpoint IP address into the SR Policy. The destination of the
SR Policy Candidate Path is signaled using the END-POINTS object and/ SR Policy Candidate Path is signaled using the END-POINTS object and/
or LSP-IDENTIFIERS TLV, per the usual PCEP procedure. When neither or the LSP-IDENTIFIERS TLV, per the usual PCEP procedure. When
the END-POINTS object nor LSP-IDENTIFIERS TLV is present, the PCEP neither the END-POINTS object nor the LSP-IDENTIFIERS TLV is present,
speaker MUST extract the destination from the Endpoint field in the the PCEP speaker MUST extract the destination from the Endpoint field
SRPA Extended Association ID TLV. in the SRPA Extended Association ID TLV.
SR Policy with Color-Only steering is signaled with the Endpoint SR Policy with Color-Only steering is signaled with the Endpoint
value set to unspecified, i.e., 0.0.0.0 for IPv4 or :: for IPv6, per value set to unspecified, i.e., 0.0.0.0 for IPv4 or :: for IPv6, per
Section 8.8. of [RFC9256]. Section 8.8 of [RFC9256].
4.5. Association Information 4.5. Association Information
The SRPA object may carry the following TLVs: The SRPA object may carry the following TLVs:
* SRPOLICY-POL-NAME TLV (Section 4.5.1): (optional) encodes the SR SRPOLICY-POL-NAME TLV (Section 4.5.1): (optional) encodes the SR
Policy Name string. Policy Name string.
* SRPOLICY-CPATH-ID TLV (Section 4.5.2): (mandatory) encodes the SR SRPOLICY-CPATH-ID TLV (Section 4.5.2): (mandatory) encodes the SR
Policy Candidate Path Identifier. Policy Candidate Path Identifier.
* SRPOLICY-CPATH-NAME TLV (Section 4.5.3): (optional) encodes the SR SRPOLICY-CPATH-NAME TLV (Section 4.5.3): (optional) encodes the SR
Policy Candidate Path string name. Policy Candidate Path string name.
* SRPOLICY-CPATH-PREFERENCE TLV (Section 4.5.4): (optional) encodes SRPOLICY-CPATH-PREFERENCE TLV (Section 4.5.4): (optional) encodes
the SR Policy Candidate Path preference value. the SR Policy Candidate Path Preference value.
When a mandatory TLV is missing from an SRPA object, the PCEP speaker When a mandatory TLV is missing from an SRPA object, the PCEP speaker
MUST send a PCErr message with Error-Type = 6 "Mandatory Object MUST send a PCErr message with:
Missing", Error-Value = 21 "Missing SR Policy Mandatory TLV".
* Error-Type = 6 "Mandatory Object Missing"
* Error-value = 21 "Missing SR Policy Mandatory TLV"
Only one TLV instance of each TLV type can be carried in an SRPA Only one TLV instance of each TLV type can be carried in an SRPA
object, and only the first occurrence is processed. Any others MUST object, and only the first occurrence is processed. Any others MUST
be silently ignored. be silently ignored.
4.5.1. SR Policy Name TLV 4.5.1. SRPOLICY-POL-NAME TLV
The SRPOLICY-POL-NAME TLV (Figure 2) is an optional TLV for the SRPA The SRPOLICY-POL-NAME TLV (Figure 2) is an optional TLV for the SRPA
object. It is RECOMMENDED that the size of the name for the SR object. It is RECOMMENDED that the size of the name for the SR
Policy is limited to 255 bytes. Implementations MAY choose to Policy is limited to 255 bytes. Implementations MAY choose to
truncate long names to 255 bytes to simplify interoperability with truncate long names to 255 bytes to simplify interoperability with
other protocols. other protocols.
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 | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
~ SR Policy Name ~ ~ SR Policy Name ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: SRPOLICY-POL-NAME TLV Format Figure 2: SRPOLICY-POL-NAME TLV Format
Type: 56 for "SRPOLICY-POL-NAME" TLV. Type: 56 for the SRPOLICY-POL-NAME TLV.
Length: indicates the length of the value portion of the TLV in Length: Indicates the length of the value portion of the TLV in
octets and MUST be greater than 0. The TLV MUST be zero-padded so octets and MUST be greater than 0. The TLV MUST be zero-padded so
that the TLV is 4-octet aligned. Padding is not included in the that the TLV is 4-octet aligned. Padding is not included in the
Length field. Length field.
SR Policy Name: SR Policy name, as defined in Section 2.1 of SR Policy Name: SR Policy name, as defined in Section 2.1 of
[RFC9256]. It MUST be a string of printable ASCII [RFC0020] [RFC9256]. It MUST be a string of printable ASCII [RFC0020]
characters, without a NULL terminator. characters, without a NULL terminator.
4.5.2. SR Policy Candidate Path Identifier TLV 4.5.2. SRPOLICY-CPATH-ID TLV
The SRPOLICY-CPATH-ID TLV (Figure 3) is a mandatory TLV for the SRPA The SRPOLICY-CPATH-ID TLV (Figure 3) is a mandatory TLV for the SRPA
object. object.
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 | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Proto. Origin | Reserved | | Proto-Origin | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Originator ASN | | Originator ASN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Originator Address | | Originator Address |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discriminator | | Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: SRPOLICY-CPATH-ID TLV Format Figure 3: SRPOLICY-CPATH-ID TLV Format
Type: 57 for "SRPOLICY-CPATH-ID" TLV. Type: 57 for the SRPOLICY-CPATH-ID TLV.
Length: 28. Length: 28.
Protocol Origin: 8-bit unsigned integer value that encodes the Protocol-Origin: 8-bit unsigned integer value that encodes the
protocol origin. The values of this field are specified in IANA Protocol-Origin. The values of this field are specified in the
registry "SR Policy Protocol Origin" under "Segment Routing" registry IANA registry "SR Policy Protocol Origin" under the "Segment
group, which was introduced in Section 8.4 of Routing" registry group, which is introduced in Section 8.4 of
[I-D.ietf-idr-bgp-ls-sr-policy]. Note that in the PCInitiate message [ADV-SR-POLICY]. Note that in the PCInitiate message [RFC8281],
[RFC8281], the Protocol Origin is always set to 10 - "PCEP (In PCEP the Protocol-Origin is always set to 10 - "PCEP (In PCEP or when
or when BGP-LS Producer is PCE)". The "SR Policy Protocol Origin" BGP-LS Producer is PCE)". The "SR Policy Protocol Origin" IANA
IANA registry includes a combination of values intended for use in registry includes a combination of values intended for use in PCEP
PCEP and BGP-LS. When the registry contains two variants of values and BGP-LS. When the registry contains two variants of values
associated with the mechanism or protocol used for provisioning of associated with the mechanism or protocol used for provisioning of
the Candidate Path, for example 1 - "PCEP" and 10 - "PCEP (In PCEP or the Candidate Path, for example 1 - "PCEP" and 10 - "PCEP (In PCEP
when BGP-LS Producer is PCE)", the "(In PCEP or when BGP-LS Producer or when BGP-LS Producer is PCE)", the "(In PCEP or when BGP-LS
is PCE)" variants MUST be used in PCEP. Producer is PCE)", then variants MUST be used in PCEP.
Reserved: This field MUST be set to zero on transmission and MUST be Reserved: This field MUST be set to zero on transmission and MUST be
ignored on receipt. ignored on receipt.
Originator Autonomous System Number (ASN): Represented as a 32-bit Originator Autonomous System Number (ASN): Represented as a 32-bit
unsigned integer value, part of the originator identifier, as unsigned integer value, part of the originator identifier, as
specified in Section 2.4 of [RFC9256]. When sending a PCInitiate specified in Section 2.4 of [RFC9256]. When sending a PCInitiate
message [RFC8281], the PCE is the originator of the Candidate Path. message [RFC8281], the PCE is the originator of the Candidate
If the PCE is configured with an ASN, then it MUST set it, otherwise Path. If the PCE is configured with an ASN, then it MUST set it;
the ASN is set to 0. otherwise, the ASN is set to 0.
Originator Address: Represented as a 128-bit value as specified in Originator Address: Represented as a 128-bit value as specified in
Section 2.4 of [RFC9256]. When sending a PCInitiate message, the PCE Section 2.4 of [RFC9256]. When sending a PCInitiate message, the
is acting as the originator and therefore MAY set this to an address PCE is acting as the originator and therefore MAY set this to an
that it owns. address that it owns.
Discriminator: 32-bit unsigned integer value that encodes the Discriminator: 32-bit unsigned integer value that encodes the
Discriminator of the Candidate Path, as specified in Section 2.5 of Discriminator of the Candidate Path, as specified in Section 2.5
[RFC9256]. This is the field that mainly distinguishes different SR of [RFC9256]. This is the field that mainly distinguishes
Policy Candidate Paths, coming from the same originator. It is different SR Policy Candidate Paths, coming from the same
allowed to be any number in the 32-bit range. originator. It is allowed to be any number in the 32-bit range.
4.5.3. SR Policy Candidate Path Name TLV 4.5.3. SRPOLICY-CPATH-NAME TLV
The SRPOLICY-CPATH-NAME TLV (Figure 4) is an optional TLV for the The SRPOLICY-CPATH-NAME TLV (Figure 4) is an optional TLV for the
SRPA object. It is RECOMMENDED that the size of the name for the SR SRPA object. It is RECOMMENDED that the size of the name for the SR
Policy is limited to 255 bytes. Implementations MAY choose to Policy is limited to 255 bytes. Implementations MAY choose to
truncate long names to 255 bytes to simplify interoperability with truncate long names to 255 bytes to simplify interoperability with
other protocols. other protocols.
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 | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
~ SR Policy Candidate Path Name ~ ~ SR Policy Candidate Path Name ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: SRPOLICY-CPATH-NAME TLV Format Figure 4: SRPOLICY-CPATH-NAME TLV Format
Type: 58 for "SRPOLICY-CPATH-NAME" TLV. Type: 58 for the SRPOLICY-CPATH-NAME TLV.
Length: indicates the length of the value portion of the TLV in Length: Indicates the length of the value portion of the TLV in
octets and MUST be greater than 0. The TLV MUST be zero-padded so octets and MUST be greater than 0. The TLV MUST be zero-padded so
that the TLV is 4-octet aligned. Padding is not included in the that the TLV is 4-octet aligned. Padding is not included in the
Length field. Length field.
SR Policy Candidate Path Name: SR Policy Candidate Path Name, as SR Policy Candidate Path Name: SR Policy Candidate Path Name, as
defined in Section 2.6 of [RFC9256]. It MUST be a string of defined in Section 2.6 of [RFC9256]. It MUST be a string of
printable ASCII characters, without a NULL terminator. printable ASCII characters, without a NULL terminator.
4.5.4. SR Policy Candidate Path Preference TLV 4.5.4. SRPOLICY-CPATH-PREFERENCE TLV
The SRPOLICY-CPATH-PREFERENCE TLV (Figure 5) is an optional TLV for The SRPOLICY-CPATH-PREFERENCE TLV (Figure 5) is an optional TLV for
the SRPA object. If the TLV is absent, then default Preference value the SRPA object. If the TLV is absent, then the default Preference
is 100, per Section 2.7 of [RFC9256]. value is 100, per Section 2.7 of [RFC9256].
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 | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preference | | Preference |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: SRPOLICY-CPATH-PREFERENCE TLV Format Figure 5: SRPOLICY-CPATH-PREFERENCE TLV Format
Type: 59 for "SRPOLICY-CPATH-PREFERENCE" TLV. Type: 59 for the SRPOLICY-CPATH-PREFERENCE TLV.
Length: 4. Length: 4.
Preference: 32-bit unsigned integer value that encodes preference of Preference: 32-bit unsigned integer value that encodes the
the Candidate Path as defined in Section 2.7 of [RFC9256]. Preference of the Candidate Path as defined in Section 2.7 of
[RFC9256].
5. SR Policy Signaling Extensions 5. SR Policy Signaling Extensions
This section introduces mechanisms described for SR Policies in This section introduces mechanisms described for SR Policies in
[RFC9256] to PCEP. These extensions do not make use of the SRPA for [RFC9256] to PCEP. These extensions do not make use of the SRPA for
signaling in PCEP therefore cannot rely on the Association capability signaling in PCEP; therefore, they cannot rely on the Association
negotiation in ASSOC-Type-List TLV and separate capability capability negotiation in the ASSOC-Type-List TLV. Instead, separate
negotiation is required. capability negotiation is required.
This document specifies four new TLVs to be carried in the OPEN or This document specifies four new TLVs to be carried in the OPEN or
LSP object. Only one TLV instance of each type can be carried, and LSP object. Only one TLV instance of each type can be carried, and
only the first occurrence is processed. Any others MUST be ignored. only the first occurrence is processed. Any others MUST be ignored.
5.1. SR Policy Capability TLV 5.1. SRPOLICY-CAPABILITY TLV
The SRPOLICY-CAPABILITY TLV (Figure 6) is a TLV for the OPEN object. The SRPOLICY-CAPABILITY TLV (Figure 6) is a TLV for the OPEN object.
It is used at session establishment to learn the peer's capabilities It is used at session establishment to learn the peer's capabilities
with respect to SR Policy. Implementations that support SR Policy with respect to SR Policy. Implementations that support SR Policy
MUST include SRPOLICY-CAPABILITY TLV in the OPEN object if the MUST include the SRPOLICY-CAPABILITY TLV in the OPEN object if the
extension is enabled. In addition, the ASSOC-Type-List TLV extension is enabled. In addition, the ASSOC-Type-List TLV
containing SRPA Type (6) MUST be present in the OPEN object, as containing SRPA Type (6) MUST be present in the OPEN object, as
specified in Section 4. specified in Section 4.
If a PCEP speaker receives SRPA but the SRPOLICY-CAPABILITY TLV is If a PCEP speaker receives an SRPA but the SRPOLICY-CAPABILITY TLV is
not exchanged, then the PCEP speaker MUST send a PCErr message with not exchanged, then the PCEP speaker MUST send a PCErr message with
Error- Type = 10 ("Reception of an invalid object") and Error-Value = Error-Type = 10 "Reception of an invalid object" and Error-value = 44
TBD2 ("Missing SRPOLICY-CAPABILITY TLV") and MUST then close the PCEP "Missing SRPOLICY-CAPABILITY TLV" and MUST then close the PCEP
session. session.
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 | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |L| |I|E|P| | Flags |L| |I|E|P|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: SRPOLICY-CAPABILITY TLV Format Figure 6: SRPOLICY-CAPABILITY TLV Format
Type: 71 for "SRPOLICY-CAPABILITY" TLV. Type: 71 for the SRPOLICY-CAPABILITY TLV.
Length: 4.
Flags (32 bits): Length: 4.
The following flags are currently defined: Flags: 32 bits. The following flags are currently defined:
* P-flag (Computation Priority): If set to '1' by a PCEP speaker, P-flag (Computation Priority): If set to 1 by a PCEP speaker, the
the P flag indicates that the PCEP speaker supports the handling P-flag indicates that the PCEP speaker supports the handling of
of COMPUTATION-PRIORITY TLV for the SR Policy (Section 5.2.1). If the COMPUTATION-PRIORITY TLV for the SR Policy (Section 5.2.1).
this flag is set to 0, then the receiving PCEP speaker MUST NOT If this flag is set to 0, then the receiving PCEP speaker MUST
send the COMPUTATION-PRIORITY TLV and MUST ignore it on receipt. NOT send the COMPUTATION-PRIORITY TLV and MUST ignore it on
receipt.
* E-Flag (Explicit NULL Label Policy): If set to '1' by a PCEP E-flag (Explicit NULL Label Policy): If set to 1 by a PCEP
speaker, the E flag indicates that the PCEP speaker supports the speaker, the E-flag indicates that the PCEP speaker supports
handling of Explicit Null Label Policy (ENLP) TLV for the SR the handling of the EXPLICIT-NULL-LABEL-POLICY TLV for the SR
Policy (Section 5.2.2). If this flag is set to 0, then the Policy (Section 5.2.2). If this flag is set to 0, then the
receiving PCEP speaker MUST NOT send the ENLP TLV and MUST ignore receiving PCEP speaker MUST NOT send the EXPLICIT-NULL-LABEL-
it on receipt. POLICY TLV and MUST ignore it on receipt.
* I-Flag (Invalidation): If set to '1' by a PCEP speaker, the I flag I-flag (Invalidation): If set to 1 by a PCEP speaker, the I-flag
indicates that the PCEP speaker supports the handling of indicates that the PCEP speaker supports the handling of the
INVALIDATION TLV for the SR Policy (Section 5.2.3). If this flag INVALIDATION TLV for the SR Policy (Section 5.2.3). If this
is set to 0, then the receiving PCEP speaker MUST NOT send the flag is set to 0, then the receiving PCEP speaker MUST NOT send
INVALIDATION TLV and MUST ignore it on receipt. the INVALIDATION TLV and MUST ignore it on receipt.
* L-Flag (Stateless Operation): If set to '1' by a PCEP speaker, the L-flag (Stateless Operation): If set to 1 by a PCEP speaker, the
L flag indicates that the PCEP speaker supports the stateless L-flag indicates that the PCEP speaker supports the stateless
(PCReq/PCRep) operations for the SR Policy (Section 5.3). If the (PCReq/PCRep) operations for the SR Policy (Section 5.3). If
PCE set this flag to 0, then the PCC MUST NOT send PCReq messages the PCE set this flag to 0, then the PCC MUST NOT send PCReq
to this PCE for the SR Policy. messages to this PCE for the SR Policy.
Unassigned bits MUST be set to '0' on transmission and MUST be Unassigned bits MUST be set to 0 on transmission and MUST be ignored
ignored on receipt. More flags can be assigned in the future per on receipt. More flags can be assigned in the future per
(Section 6.7). (Section 6.7).
5.2. LSP Object TLVs 5.2. LSP Object TLVs
This section is introducing three new TLVs to be carried in LSP This section is introducing three new TLVs to be carried in the LSP
object introduced in Section 7.3 of [RFC8231]. object introduced in Section 7.3 of [RFC8231].
5.2.1. Computation Priority TLV 5.2.1. COMPUTATION-PRIORITY TLV
The COMPUTATION-PRIORITY TLV (Figure 7) is an optional TLV. It is The COMPUTATION-PRIORITY TLV (Figure 7) is an optional TLV. It is
used to signal the numerical computation priority, as specified in used to signal the numerical computation priority, as specified in
Section 2.12 of [RFC9256]. If the TLV is absent from the LSP object Section 2.12 of [RFC9256]. If the TLV is absent from the LSP object,
and the P-flag in the SRPOLICY-CAPABILITY TLV is set to 1, a default and the P-flag in the SRPOLICY-CAPABILITY TLV is set to 1, a default
Priority value of 128 is used. Priority value of 128 is used.
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 | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Priority | Reserved | | Priority | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: COMPUTATION-PRIORITY TLV Format Figure 7: COMPUTATION-PRIORITY TLV Format
Type: 68 for "COMPUTATION-PRIORITY" TLV. Type: 68 for the COMPUTATION-PRIORITY TLV.
Length: 4. Length: 4.
Priority: 8-bit unsigned integer value that encodes numerical Priority: 8-bit unsigned integer value that encodes numerical
priority with which this LSP is to be recomputed by the PCE upon priority with which this LSP is to be recomputed by the PCE upon
topology change. Lowest value is the highest priority. topology change. The lowest value is the highest priority.
Reserved: This field MUST be set to zero on transmission and MUST be Reserved: This field MUST be set to zero on transmission and MUST be
ignored on receipt. ignored on receipt.
5.2.2. Explicit Null Label Policy (ENLP) TLV 5.2.2. EXPLICIT-NULL-LABEL-POLICY TLV
To steer an unlabeled IP packet into an SR policy for the MPLS data To steer an unlabeled IP packet into an SR Policy for the MPLS data
plane, it is necessary to push a label stack of one or more labels on plane, it is necessary to push a label stack of one or more labels on
that packet. The Explicit NULL Label Policy (ENLP) TLV is an that packet. The EXPLICIT-NULL-LABEL-POLICY TLV is an optional TLV
optional TLV for the LSP object used to indicate whether an Explicit for the LSP object used to indicate whether an Explicit NULL label
NULL Label [RFC3032] must be pushed on an unlabeled IP packet before [RFC3032] must be pushed on an unlabeled IP packet before any other
any other labels. The contents of this TLV are used by the SR Policy labels. The contents of this TLV are used by the SR Policy manager
Manager as described in Section 4.1 of [RFC9256]. If an ENLP TLV is as described in Section 4.1 of [RFC9256]. If an EXPLICIT-NULL-LABEL-
not present, the decision of whether to push an Explicit NULL label POLICY TLV is not present, the decision of whether to push an
on a given packet is a matter of local configuration. Note that Explicit NULL label on a given packet is a matter of local
Explicit Null is currently only defined for SR-MPLS and not for SRv6. configuration. Note that Explicit NULL is currently only defined for
Therefore, the receiving PCEP speaker MUST ignore the presence of SR-MPLS and not for SRv6. Therefore, the receiving PCEP speaker MUST
this TLV for SRv6 Policies. ignore the presence of this TLV for SRv6 Policies.
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 | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ENLP | Reserved | | ENLP | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: Explicit Null Label Policy (ENLP) TLV Format Figure 8: EXPLICIT-NULL-LABEL-POLICY TLV Format
Type: 69 for "ENLP" TLV. Type: 69 for the EXPLICIT-NULL-LABEL-POLICY TLV.
Length: 4. Length: 4.
ENLP (Explicit NULL Label Policy): 8-bit unsigned integer value that ENLP: Explicit NULL Label Policy. 8-bit unsigned integer value that
indicates whether Explicit NULL labels are to be pushed on unlabeled indicates whether Explicit NULL labels are to be pushed on
IP packets that are being steered into a given SR policy. The values unlabeled IP packets that are being steered into a given SR
of this field are specified in IANA registry "SR Policy ENLP Values" Policy. The values of this field are specified in the IANA
under "Segment Routing" registry group, which was introduced in registry "SR Policy ENLP Values" under the "Segment Routing"
Section 6.10 of [I-D.ietf-idr-sr-policy-safi]. registry group, which was introduced in Section 6.10 of [RFC9830].
Reserved: This field MUST be set to zero on transmission and MUST be Reserved: This field MUST be set to zero on transmission and MUST be
ignored on receipt. ignored on receipt.
The ENLP unassigned values may be used for future extensions and The ENLP unassigned values may be used for future extensions, and
implementations MUST ignore the ENLP TLV with unrecognized values. implementations MUST ignore the EXPLICIT-NULL-LABEL-POLICY TLV with
The behavior signaled in this TLV MAY be overridden by local unrecognized values. The behavior signaled in this TLV MAY be
configuration by the network operator based on their deployment overridden by local configuration by the network operator based on
requirements. The Section 4.1 of [RFC9256] describes the behavior on their deployment requirements. Section 4.1 of [RFC9256] describes
the headend for the handling of the explicit null label. the behavior on the headend for the handling of the Explicit NULL
label.
5.2.3. Invalidation TLV 5.2.3. INVALIDATION TLV
The INVALIDATION TLV (Figure 9) is an optional TLV. This TLV is used The INVALIDATION TLV (Figure 9) is an optional TLV. This TLV is used
to control traffic steering into an LSP when the LSP is operationally to control traffic steering into an LSP when the LSP is operationally
down/invalid. In the context of SR Policy, this TLV facilitates the down/invalid. In the context of SR Policy, this TLV facilitates the
Drop-upon-invalid behavior, specified in Section 8.2 of [RFC9256]. Drop-Upon-Invalid behavior, specified in Section 8.2 of [RFC9256].
Normally, if the LSP is down/invalid then it stops attracting Normally, if the LSP is down/invalid then it stops attracting
traffic; traffic that would have been destined for that LSP is traffic; traffic that would have been destined for that LSP is
redirected somewhere else, such as via IGP or another LSP. The Drop- redirected somewhere else, such as via IGP or another LSP. The Drop-
upon-invalid behavior specifies that the LSP keeps attracting traffic Upon-Invalid behavior specifies that the LSP keeps attracting traffic
and the traffic has to be dropped at the headend. Such an LSP is and the traffic has to be dropped at the headend. Such an LSP is
said to be "in drop state". While in the drop state, the LSP said to be "in drop state". While in the drop state, the LSP
operational state is "UP", as indicated by the O-flag in the LSP operational state is "UP", as indicated by the O-flag in the LSP
object. However, the ERO object MAY be empty, if no valid path has object. However, the ERO object MAY be empty if no valid path has
been computed. been computed.
The INVALIDATION TLV is used in both directions between PCEP peers: The INVALIDATION TLV is used in both directions between PCEP peers:
* PCE -> PCC: PCE specifies to the PCC whether to enable or disable * PCE -> PCC: The PCE specifies to the PCC whether to enable or
Drop-upon-invalid (Config). disable Drop-Upon-Invalid (Config).
* PCC -> PCE: PCC reports the current setting of the Drop-upon- * PCC -> PCE: The PCC reports the current setting of the Drop-Upon-
invalid (Config) and also whether the LSP is currently in the drop Invalid (Config) and also whether the LSP is currently in the drop
state (Oper). state (Oper).
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 | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Oper | Config | Reserved | | Oper | Config | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: INVALIDATION TLV Format Figure 9: INVALIDATION TLV Format
Type: 70 for "INVALIDATION" TLV. Type: 70 for the INVALIDATION TLV.
Length: 4. Length: 4.
Oper: An 8-bit flag field that encodes the operational state of the Oper: An 8-bit flag field that encodes the operational state of the
LSP. It MUST be set to 0 by the PCE when sending and MUST be ignored LSP. It MUST be set to 0 by the PCE when sending and MUST be
by the PCC upon receipt. See Section 6.5 for IANA information. ignored by the PCC upon receipt. See Section 6.5 for IANA
information.
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| |D| | |D|
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 10: Oper state of Drop-upon-invalid feature Figure 10: Oper State of Drop-Upon-Invalid Feature
* D: dropping - the LSP is actively dropping traffic as a result of * D: Dropping - the LSP is actively dropping traffic as a
Drop-upon-invalid behavior being activated. result of Drop-Upon-Invalid behavior being activated.
* The unassigned bits in the Flag octet MUST be set to zero upon * The unassigned bits in the Flag octet MUST be set to zero
transmission and MUST be ignored upon receipt. upon transmission and MUST be ignored upon receipt.
Config: An 8-bit flag field that encodes the configuration of the Config: An 8-bit flag field that encodes the configuration of the
LSP. See Section 6.6 for IANA information. LSP. See Section 6.6 for IANA information.
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| |D| | |D|
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 11: Config state of Drop-upon-invalid feature Figure 11: Config State of Drop-Upon-Invalid Feature
* D: drop enabled - the Candidate Path has Drop-upon-invalid feature * D: Drop enabled - the Candidate Path has Drop-Upon-Invalid
enabled. feature enabled.
* The unassigned bits in the Flag octet MUST be set to zero upon * The unassigned bits in the Flag octet MUST be set to zero
transmission and MUST be ignored upon receipt. upon transmission and MUST be ignored upon receipt.
Reserved: This field MUST be set to zero on transmission and MUST be Reserved: This field MUST be set to zero on transmission and MUST be
ignored on receipt. ignored on receipt.
5.2.3.1. Drop-upon-invalid applies to SR Policy 5.2.3.1. Drop-Upon-Invalid Applies to SR Policy
The Drop-upon-invalid feature is somewhat special among the other SR The Drop-Upon-Invalid feature is somewhat special among the other SR
Policy features in the way that it is enabled/disabled. This feature Policy features in the way that it is enabled/disabled. This feature
is enabled only on the whole SR Policy, not on a particular Candidate is enabled only on the whole SR Policy, not on a particular Candidate
Path of that SR Policy, i.e., when any Candidate Path has Drop-upon- Path of that SR Policy, i.e., when any Candidate Path has Drop-Upon-
invalid enabled, it means that the whole SR Policy has the feature Invalid enabled, it means that the whole SR Policy has the feature
enabled. As stated in Section 8.1 of [RFC9256], an SR Policy is enabled. As stated in Section 8.1 of [RFC9256], an SR Policy is
invalid when all its Candidate Paths are invalid. invalid when all its Candidate Paths are invalid.
Once all the Candidate Paths of an SR Policy have become invalid, Once all the Candidate Paths of an SR Policy have become invalid,
then the SR Policy checks whether any of the Candidate Paths have then the SR Policy checks whether any of the Candidate Paths have
Drop-upon-invalid enabled. If so, the SR Policy enters the drop Drop-Upon-Invalid enabled. If so, the SR Policy enters the drop
state and "activates" the highest preference Candidate Path which has state and "activates" the highest preference Candidate Path that has
the Drop-upon-invalid enabled. Note that only one Candidate Path the Drop-Upon-Invalid enabled. Note that only one Candidate Path
needs to be reported to the PCE with the D (dropping) flag set. needs to be reported to the PCE with the Dropping (D) flag set.
5.3. Update to RFC 8231 5.3. Updates to RFC 8231
Section 5.8.2 of [RFC8231], allows delegation of an LSP in Section 5.8.2 of [RFC8231] allows delegation of an LSP in
operationally down state, but at the same time mandates the use of operationally down state, but at the same time mandates the use of
PCReq before sending PCRpt. This document updates Section 5.8.2 of PCReq before sending PCRpt. This document updates Section 5.8.2 of
[RFC8231], by making that section of [RFC8231] not applicable to SR [RFC8231], by making that section of [RFC8231] not applicable to SR
Policy LSPs. Thus, when a PCC wants to delegate an SR Policy LSP, it Policy LSPs. Thus, when a PCC wants to delegate an SR Policy LSP, it
MAY proceed directly to sending PCRpt, without first sending PCReq MAY proceed directly to sending PCRpt, without first sending PCReq
and waiting for PCRep. This has the advantage of reducing the number and waiting for PCRep. This has the advantage of reducing the number
of PCEP messages and simplifying the implementation. of PCEP messages and simplifying the implementation.
Furthermore, a PCEP speaker is not required to support PCReq/PCRep at Furthermore, a PCEP speaker is not required to support PCReq/PCRep at
all for SR Policies. The PCEP speaker can indicate support for all for SR Policies. The PCEP speaker can indicate support for
PCReq/PCRep via the "L-Flag" in the SRPOLICY-CAPABILITY TLV (See PCReq/PCRep via the L-flag in the SRPOLICY-CAPABILITY TLV (see
Section 5.1). When this flag is cleared, or when the SRPOLICY- Section 5.1). When this flag is cleared, or when the SRPOLICY-
CAPABILITY TLV is absent, the given peer MUST NOT be sent PCReq/PCRep CAPABILITY TLV is absent, the given peer MUST NOT be sent PCReq/PCRep
messages for SR Policy LSPs. Conversely, when this flag is set, the messages for SR Policy LSPs. Conversely, when this flag is set, the
peer can receive and process PCReq/PCRep messages for SR Policy LSPs. peer can receive and process PCReq/PCRep messages for SR Policy LSPs.
The above applies only to SR Policy LSPs and does not affect other The above applies only to SR Policy LSPs and does not affect other
LSP types, such as RSVP-TE LSPs. For other LSP types, Section 5.8.2 LSP types, such as RSVP-TE LSPs. For other LSP types, Section 5.8.2
of [RFC8231] continues to apply. of [RFC8231] continues to apply.
6. IANA Considerations 6. IANA Considerations
IANA maintains the "Path Computation Element Protocol (PCEP) Numbers" IANA maintains the "Path Computation Element Protocol (PCEP) Numbers"
registry at <https://www.iana.org/assignments/pcep>. registry at <https://www.iana.org/assignments/pcep>.
6.1. Association Type 6.1. Association Type
This document defines a new association type: SR Policy Association. This document defines a new Association Type: SR Policy Association.
IANA is requested to confirm the following allocation in the IANA has made the following assignment in the "ASSOCIATION Type
"ASSOCIATION Type Field" registry within the "Path Computation Field" registry within the "Path Computation Element Protocol (PCEP)
Element Protocol (PCEP) Numbers" registry group: Numbers" registry group:
+-----------+-------------------------------------------+-----------+ +======+=======================+===========+
| Type | Name | Reference | | Type | Name | Reference |
+-----------+-------------------------------------------+-----------+ +======+=======================+===========+
| 6 | SR Policy Association | This.I-D | | 6 | SR Policy Association | RFC 9862 |
+-----------+-------------------------------------------+-----------+ +------+-----------------------+-----------+
Table 1
6.2. PCEP TLV Type Indicators 6.2. PCEP TLV Type Indicators
This document defines eight new TLVs for carrying additional This document defines eight new TLVs for carrying additional
information about SR Policy and SR Policy Candidate Paths. IANA is information about SR Policy and SR Policy Candidate Paths. IANA has
requested to confirm the following allocations in the existing "PCEP made the following assignments in the existing "PCEP TLV Type
TLV Type Indicators" registry as follows: Indicators" registry:
+-----------+-------------------------------------------+-----------+ +=======+============================+===========+
| Value | Description | Reference | | Value | Description | Reference |
+-----------+-------------------------------------------+-----------+ +=======+============================+===========+
| 56 | SRPOLICY-POL-NAME | This.I-D | | 56 | SRPOLICY-POL-NAME | RFC 9862 |
+-----------+-------------------------------------------+-----------+ +-------+----------------------------+-----------+
| 57 | SRPOLICY-CPATH-ID | This.I-D | | 57 | SRPOLICY-CPATH-ID | RFC 9862 |
+-----------+-------------------------------------------+-----------+ +-------+----------------------------+-----------+
| 58 | SRPOLICY-CPATH-NAME | This.I-D | | 58 | SRPOLICY-CPATH-NAME | RFC 9862 |
+-----------+-------------------------------------------+-----------+ +-------+----------------------------+-----------+
| 59 | SRPOLICY-CPATH-PREFERENCE | This.I-D | | 59 | SRPOLICY-CPATH-PREFERENCE | RFC 9862 |
+-----------+-------------------------------------------+-----------+ +-------+----------------------------+-----------+
| 68 | COMPUTATION-PRIORITY | This.I-D | | 68 | COMPUTATION-PRIORITY | RFC 9862 |
+-----------+-------------------------------------------+-----------+ +-------+----------------------------+-----------+
| 69 | EXPLICIT-NULL-LABEL-POLICY | This.I-D | | 69 | EXPLICIT-NULL-LABEL-POLICY | RFC 9862 |
+-----------+-------------------------------------------+-----------+ +-------+----------------------------+-----------+
| 70 | INVALIDATION | This.I-D | | 70 | INVALIDATION | RFC 9862 |
+-----------+-------------------------------------------+-----------+ +-------+----------------------------+-----------+
| 71 | SRPOLICY-CAPABILITY | This.I-D | | 71 | SRPOLICY-CAPABILITY | RFC 9862 |
+-----------+-------------------------------------------+-----------+ +-------+----------------------------+-----------+
Table 2
6.3. PCEP Errors 6.3. PCEP Errors
This document defines one new Error-Value within the "Mandatory This document defines the following:
Object Missing" Error-Type, two new Error-Values within the
"Association Error" Error-Type and one new Error-Value within the
"Reception of an invalid object".
IANA is requested to confirm the following allocations within the * one new Error-value within the "Mandatory Object Missing" Error-
"PCEP-ERROR Object Error Types and Values" registry of the "Path Type,
Computation Element Protocol (PCEP) Numbers" registry group.
+------------+------------------+-----------------------+-----------+ * one new Error-value within the "Reception of an invalid object",
| Error-Type | Meaning | Error-value | Reference | and
+------------+------------------+-----------------------+-----------+
| 6 | Mandatory Object | | [RFC5440] |
| | Missing | | |
+------------+------------------+-----------------------+-----------+
| | | 21: Missing SR | This.I-D |
| | | Policy Mandatory TLV | |
+------------+------------------+-----------------------+-----------+
| 26 | Association | | [RFC8697] |
| | Error | | |
+------------+------------------+-----------------------+-----------+
| | | 20: SR Policy | This.I-D |
| | | Identifers Mismatch | |
+------------+------------------+-----------------------+-----------+
| | | 21: SR Policy | This.I-D |
| | | Candidate Path | |
| | | Identifier Mismatch | |
+------------+------------------+-----------------------+-----------+
IANA is requested to make new allocations within the "PCEP-ERROR * two new Error-values within the "Association Error" Error-Type.
Object Error Types and Values" registry of the "Path Computation
Element Protocol (PCEP) Numbers" registry group.
+------------+------------------+-----------------------+-----------+ IANA has made the following assignments in the "PCEP-ERROR Object
| Error-Type | Meaning | Error-value | Reference | Error Types and Values" registry of the "Path Computation Element
+------------+------------------+-----------------------+-----------+ Protocol (PCEP) Numbers" registry group.
| 6 | Mandatory Object | | [RFC5440] |
| | Missing | | |
+------------+------------------+-----------------------+-----------+
| | | TBD1: Missing SR | This.I-D |
| | | Policy Association | |
+------------+------------------+-----------------------+-----------+
| 10 | Reception of an | | [RFC5440] |
| | invalid object | | |
+------------+------------------+-----------------------+-----------+
| | | TBD2: Missing | This.I-D |
| | | SRPOLICY-CAPABILITY | |
| | | TLV | |
+------------+------------------+-----------------------+-----------+
6.4. TE-PATH-BINDING TLV Flag field +============+=================+=======================+===========+
| Error-Type | Meaning | Error-value | Reference |
+============+=================+=======================+===========+
| 6 | Mandatory | | [RFC5440] |
| | Object Missing | | |
| +-----------------+-----------------------+-----------+
| | | 21: Missing SR Policy | RFC 9862 |
| | | Mandatory TLV | |
| +-----------------+-----------------------+-----------+
| | | 22: Missing SR Policy | RFC 9862 |
| | | Association | |
+------------+-----------------+-----------------------+-----------+
| 10 | Reception of an | | [RFC5440] |
| | invalid object | | |
| +-----------------+-----------------------+-----------+
| | | 44: Missing SRPOLICY- | RFC 9862 |
| | | CAPABILITY TLV | |
+------------+-----------------+-----------------------+-----------+
| 26 | Association | | [RFC8697] |
| | Error | | |
| +-----------------+-----------------------+-----------+
| | | 20: SR Policy | RFC 9862 |
| | | Identifiers Mismatch | |
| +-----------------+-----------------------+-----------+
| | | 21: SR Policy | RFC 9862 |
| | | Candidate Path | |
| | | Identifier Mismatch | |
+------------+-----------------+-----------------------+-----------+
An earlier version of this document added new bit within the "TE- Table 3
PATH-BINDING TLV Flag field" registry of the "Path Computation
Element Protocol (PCEP) Numbers" registry group, which was also early
allocated by the IANA.
IANA is requested to mark the bit position as deprecated. 6.4. TE-PATH-BINDING TLV Flag Field
+------------+------------------------------------------+-----------+ A draft version of this document added a new bit in the "TE-PATH-
| Bit position | Description | Reference | BINDING TLV Flag Field" registry of the "Path Computation Element
+--------------+----------------------------------------+-----------+ Protocol (PCEP) Numbers" registry group, which was early allocated by
| 1 | Deprecated (Specified-BSID-only) | This.I-D | IANA.
+--------------+----------------------------------------+-----------+
IANA has marked the bit position as deprecated.
+=====+==================================+===========+
| Bit | Description | Reference |
+=====+==================================+===========+
| 1 | Deprecated (Specified-BSID-only) | RFC 9862 |
+-----+----------------------------------+-----------+
Table 4
6.5. SR Policy Invalidation Operational State 6.5. SR Policy Invalidation Operational State
This document requests IANA to maintain a new registry under "Path IANA has created and will maintain a new registry under the "Path
Computation Element Protocol (PCEP) Numbers" registry group. The new Computation Element Protocol (PCEP) Numbers" registry group. The new
registry is called "SR Policy Invalidation Operational Flags". New registry is called "SR Policy Invalidation Operational Flags". New
values are to be assigned by "IETF review" [RFC8126]. Each bit values are to be assigned by "IETF Review" [RFC8126]. Each bit will
should be tracked with the following qualities: be tracked with the following qualities:
* Bit (counting from bit 0 as the most significant bit). * Bit (counting from bit 0 as the most significant bit)
* Description. * Description
* Reference. * Reference
+-------+-----------------------------------------------+-----------+ +=====+========================================+===========+
| Bit | Description | Reference | | Bit | Description | Reference |
+-------+-----------------------------------------------+-----------+ +=====+========================================+===========+
| 0 - 6 | Unassigned | This.I-D | | 0 - | Unassigned | |
+-------+-----------------------------------------------+-----------+ | 6 | | |
| 7 | D: dropping - the LSP is currently attracting | This.I-D | +-----+----------------------------------------+-----------+
| | traffic and actively dropping it. | | | 7 | D: Dropping - the LSP is actively | RFC 9862 |
+-------+-----------------------------------------------+-----------+ | | dropping traffic as a result of Drop- | |
| | Upon-Invalid behavior being activated. | |
+-----+----------------------------------------+-----------+
Table 5
6.6. SR Policy Invalidation Configuration State 6.6. SR Policy Invalidation Configuration State
This document requests IANA to maintain a new registry under "Path IANA has created and will maintain a new registry under the "Path
Computation Element Protocol (PCEP) Numbers" registry group. The new Computation Element Protocol (PCEP) Numbers" registry group. The new
registry is called "SR Policy Invalidation Configuration Flags". New registry is called "SR Policy Invalidation Configuration Flags". New
values are to be assigned by "IETF review" [RFC8126]. Each bit values are to be assigned by "IETF Review" [RFC8126]. Each bit will
should be tracked with the following qualities: be tracked with the following qualities:
* Bit (counting from bit 0 as the most significant bit). * Bit (counting from bit 0 as the most significant bit)
* Description. * Description
* Reference. * Reference
+-------+-----------------------------------------------+-----------+ +=======+========================================+===========+
| Bit | Description | Reference | | Bit | Description | Reference |
+-------+-----------------------------------------------+-----------+ +=======+========================================+===========+
| 0 - 6 | Unassigned. | This.I-D | | 0 - 6 | Unassigned. | |
+-------+-----------------------------------------------+-----------+ +-------+----------------------------------------+-----------+
| 7 | D: drop enabled - the Drop-upon-invalid is | This.I-D | | 7 | D: Drop enabled - the Candidate Path | RFC 9862 |
| | enabled on the LSP. | | | | has Drop-Upon-Invalid feature enabled. | |
+-------+-----------------------------------------------+-----------+ +-------+----------------------------------------+-----------+
6.7. SR Policy Capability TLV Flag field Table 6
This document requests IANA to maintain a new registry under "Path 6.7. SR Policy Capability TLV Flag Field
IANA has created and will maintain a new registry under the "Path
Computation Element Protocol (PCEP) Numbers" registry group. The new Computation Element Protocol (PCEP) Numbers" registry group. The new
registry is called "SR Policy Capability TLV Flag Field". New values registry is called "SR Policy Capability TLV Flag Field". New values
are to be assigned by "IETF review" [RFC8126]. Each bit should be are to be assigned by "IETF Review" [RFC8126]. Each bit will be
tracked with the following qualities: tracked with the following qualities:
* Bit (counting from bit 0 as the most significant bit). * Bit (counting from bit 0 as the most significant bit)
* Description.
* Reference.
+--------+-----------------------------------------------+-----------+
| Bit | Description | Reference |
+--------+-----------------------------------------------+-----------+
| 0 - 26 | Unassigned | This.I-D |
+--------+-----------------------------------------------+-----------+
| 27 | Stateless Operation (L-Flag) | This.I-D |
+--------+-----------------------------------------------+-----------+
| 28 | Unassigned | This.I-D |
+--------+-----------------------------------------------+-----------+
| 29 | Invalidation (I-Flag) | This.I-D |
+--------+-----------------------------------------------+-----------+
| 30 | Explicit NULL Label Policy (E-Flag) | This.I-D |
+--------+-----------------------------------------------+-----------+
| 31 | Computation Priority (P-flag) | This.I-D |
+--------+-----------------------------------------------+-----------+
7. Implementation Status
[Note to the RFC Editor - remove this section before publication, as
well as remove the reference to RFC 7942.]
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
7.1. Cisco
* Organization: Cisco Systems
* Implementation: IOS-XR PCC and PCE.
* Description: All features supported except Computation Priority,
Explicit NULL and Invalidation Drop.
* Maturity Level: Production.
* Coverage: Full.
* Contact: ssidor@cisco.com
7.2. Juniper
* Organization: Juniper Networks
* Implementation: PCC and PCE.
* Description: Everything in -05 except SR Policy Name TLV and SR * Description
Policy Candidate Path Name TLV.
* Maturity Level: Production. * Reference
* Coverage: Partial. +========+=====================================+===========+
| Bit | Description | Reference |
+========+=====================================+===========+
| 0 - 26 | Unassigned | RFC 9862 |
+--------+-------------------------------------+-----------+
| 27 | Stateless Operation (L-flag) | RFC 9862 |
+--------+-------------------------------------+-----------+
| 28 | Unassigned | RFC 9862 |
+--------+-------------------------------------+-----------+
| 29 | Invalidation (I-flag) | RFC 9862 |
+--------+-------------------------------------+-----------+
| 30 | Explicit NULL Label Policy (E-flag) | RFC 9862 |
+--------+-------------------------------------+-----------+
| 31 | Computation Priority (P-flag) | RFC 9862 |
+--------+-------------------------------------+-----------+
* Contact: cbarth@juniper.net Table 7
8. Security Considerations 7. Security Considerations
The information carried in the newly defined SRPA object and TLVs The information carried in the newly defined SRPA object and TLVs
could provide an eavesdropper with additional information about the could provide an eavesdropper with additional information about the
SR Policy. SR Policy.
The security considerations described in [RFC5440], [RFC8231], The security considerations described in [RFC5440], [RFC8231],
[RFC8281], [RFC8664], [RFC8697], [RFC9256] and [RFC9603] are [RFC8281], [RFC8664], [RFC8697], [RFC9256], and [RFC9603] are
applicable to this specification. applicable to this specification.
As per [RFC8231], it is RECOMMENDED that these PCEP extensions can As per [RFC8231], it is RECOMMENDED that these PCEP extensions can
only be activated on authenticated and encrypted sessions across PCEs only be activated on authenticated and encrypted sessions across PCEs
and PCCs belonging to the same administrative authority, using and PCCs belonging to the same administrative authority, using
Transport Layer Security (TLS) [RFC8253] as per the recommendations Transport Layer Security (TLS) [RFC8253] as per the recommendations
and best current practices in [RFC9325]. and best current practices in [RFC9325].
9. Manageability Considerations 8. Manageability Considerations
All manageability requirements and considerations listed in All manageability requirements and considerations listed in
[RFC5440], [RFC8231], [RFC8664], [RFC9256], and [RFC9603] apply to [RFC5440], [RFC8231], [RFC8664], [RFC9256], and [RFC9603] apply to
PCEP protocol extensions defined in this document. In addition, PCEP protocol extensions defined in this document. In addition,
requirements and considerations listed in this section apply. requirements and considerations listed in this section apply.
9.1. Control of Function and Policy 8.1. Control of Function and Policy
A PCE or PCC implementation MAY allow the capabilities specified in A PCE or PCC implementation MAY allow the capabilities specified in
Section 5.1 and the capability for support of SRPA advertised in Section 5.1 and the capability for support of an SRPA advertised in
ASSOC-Type-List TLV to be enabled and disabled. the ASSOC-Type-List TLV to be enabled and disabled.
9.2. Information and Data Models 8.2. Information and Data Models
[I-D.ietf-pce-pcep-srv6-yang] defines YANG module with common [PCEP-SRv6-YANG] defines a YANG module with common building blocks
building blocks for PCEP Extensions described in Section 4. for PCEP extensions described in Section 4 of this document.
9.3. Liveness Detection and Monitoring 8.3. Liveness Detection and Monitoring
Mechanisms defined in this document do not imply any new liveness Mechanisms defined in this document do not imply any new liveness
detection and monitoring requirements in addition to those already detection and monitoring requirements in addition to those already
listed in [RFC5440], [RFC8664], and [RFC9256]. listed in [RFC5440], [RFC8664], and [RFC9256].
9.4. Verify Correct Operations 8.4. Verify Correct Operations
Operation verification requirements already listed in [RFC5440], Operation verification requirements already listed in [RFC5440],
[RFC8231], [RFC8664], [RFC9256], and [RFC9603] are applicable to [RFC8231], [RFC8664], [RFC9256], and [RFC9603] are applicable to
mechanisms defined in this document. mechanisms defined in this document.
An implementation MUST allow the operator to view SR Policy An implementation MUST allow the operator to view SR Policy
Identifier and SR Policy Candidate Path Identifier advertised in SRPA Identifier and SR Policy Candidate Path Identifier advertised in an
object. SRPA object.
An implementation SHOULD allow the operator to view the capabilities An implementation SHOULD allow the operator to view the capabilities
defined in this document advertised by each PCEP peer. defined in this document advertised by each PCEP peer.
An implementation SHOULD allow the operator to view LSPs associated An implementation SHOULD allow the operator to view LSPs associated
with specific SR Policy Identifier. with a specific SR Policy Identifier.
9.5. Requirements On Other Protocols 8.5. Requirements on Other Protocols
The PCEP extensions defined in this document do not imply any new The PCEP extensions defined in this document do not imply any new
requirements on other protocols. requirements on other protocols.
9.6. Impact On Network Operations 8.6. Impact on Network Operations
The mechanisms defined in [RFC5440], [RFC8231], [RFC9256] and The mechanisms defined in [RFC5440], [RFC8231], [RFC9256], and
[RFC9603] also apply to the PCEP extensions defined in this document. [RFC9603] also apply to the PCEP extensions defined in this document.
10. Acknowledgement 9. References
We would like to thank Abdul Rehman, Andrew Stone, Boris Khasanov,
Cheng Li, Dhruv Dhody, Gorry Fairhurst, Gyan Mishra, Huaimo Chen,
Ines Robles, Joseph Salowey, Ketan Talaulikar, Marina Fizgeer, Mike
Bishopm, Praveen Kumar, Robert Sparks, Roman Danyliw, Stephane
Litkowski, Tom Petch, Zoey Rose, Xiao Min, Xiong Quan for review and
suggestions.
11. References
11.1. Normative References 9.1. Normative References
[RFC0020] Cerf, V., "ASCII format for network interchange", STD 80, [RFC0020] Cerf, V., "ASCII format for network interchange", STD 80,
RFC 20, DOI 10.17487/RFC0020, October 1969, RFC 20, DOI 10.17487/RFC0020, October 1969,
<https://www.rfc-editor.org/info/rfc20>. <https://www.rfc-editor.org/info/rfc20>.
[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>.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001, Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
<https://www.rfc-editor.org/info/rfc3032>. <https://www.rfc-editor.org/info/rfc3032>.
[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>.
[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>.
[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
skipping to change at page 28, line 17 skipping to change at line 1234
Security (TLS) and Datagram Transport Layer Security Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November (DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November
2022, <https://www.rfc-editor.org/info/rfc9325>. 2022, <https://www.rfc-editor.org/info/rfc9325>.
[RFC9603] Li, C., Ed., Kaladharan, P., Sivabalan, S., Koldychev, M., [RFC9603] Li, C., Ed., Kaladharan, P., Sivabalan, S., Koldychev, M.,
and Y. Zhu, "Path Computation Element Communication and Y. Zhu, "Path Computation Element Communication
Protocol (PCEP) Extensions for IPv6 Segment Routing", Protocol (PCEP) Extensions for IPv6 Segment Routing",
RFC 9603, DOI 10.17487/RFC9603, July 2024, RFC 9603, DOI 10.17487/RFC9603, July 2024,
<https://www.rfc-editor.org/info/rfc9603>. <https://www.rfc-editor.org/info/rfc9603>.
11.2. Informative References 9.2. Informative References
[I-D.ietf-idr-sr-policy-safi]
Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P., and
D. Jain, "Advertising Segment Routing Policies in BGP",
Work in Progress, Internet-Draft, draft-ietf-idr-sr-
policy-safi-13, 6 February 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-sr-
policy-safi-13>.
[I-D.ietf-idr-bgp-ls-sr-policy] [ADV-SR-POLICY]
Previdi, S., Talaulikar, K., Dong, J., Gredler, H., and J. Previdi, S., Talaulikar, K., Ed., Dong, J., Gredler, H.,
Tantsura, "Advertisement of Segment Routing Policies using and J. Tantsura, "Advertisement of Segment Routing
BGP Link-State", Work in Progress, Internet-Draft, draft- Policies using BGP Link-State", Work in Progress,
ietf-idr-bgp-ls-sr-policy-17, 6 March 2025, Internet-Draft, draft-ietf-idr-bgp-ls-sr-policy-17, 6
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-bgp- March 2025, <https://datatracker.ietf.org/doc/html/draft-
ls-sr-policy-17>. ietf-idr-bgp-ls-sr-policy-17>.
[I-D.ietf-pce-multipath] [PCEP-MULTIPATH]
Koldychev, M., Sivabalan, S., Saad, T., Beeram, V. P., Koldychev, M., Sivabalan, S., Saad, T., Beeram, V. P.,
Bidgoli, H., Yadav, B., Peng, S., and G. S. Mishra, "PCEP Bidgoli, H., Yadav, B., Peng, S., Mishra, G. S., and S.
Extensions for Signaling Multipath Information", Work in Sidor, "Path Computation Element Communication Protocol
Progress, Internet-Draft, draft-ietf-pce-multipath-12, 8 (PCEP) Extensions for Signaling Multipath Information",
October 2024, <https://datatracker.ietf.org/doc/html/ Work in Progress, Internet-Draft, draft-ietf-pce-
draft-ietf-pce-multipath-12>. multipath-16, 17 October 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-pce-
multipath-16>.
[I-D.ietf-pce-pcep-srv6-yang] [PCEP-SRv6-YANG]
Li, C., Sivabalan, S., Peng, S., Koldychev, M., and L. Li, C., Sivabalan, S., Peng, S., Koldychev, M., and L.
Ndifor, "A YANG Data Model for Segment Routing (SR) Policy Ndifor, "A YANG Data Model for Segment Routing (SR) Policy
and SR in IPv6 (SRv6) support in Path Computation Element and SR in IPv6 (SRv6) support in Path Computation Element
Communications Protocol (PCEP)", Work in Progress, Communications Protocol (PCEP)", Work in Progress,
Internet-Draft, draft-ietf-pce-pcep-srv6-yang-06, 19 Internet-Draft, draft-ietf-pce-pcep-srv6-yang-08, 14
October 2024, <https://datatracker.ietf.org/doc/html/ October 2025, <https://datatracker.ietf.org/doc/html/
draft-ietf-pce-pcep-srv6-yang-06>. draft-ietf-pce-pcep-srv6-yang-08>.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, Label Switching Architecture", RFC 3031,
DOI 10.17487/RFC3031, January 2001, DOI 10.17487/RFC3031, January 2001,
<https://www.rfc-editor.org/info/rfc3031>. <https://www.rfc-editor.org/info/rfc3031>.
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path [RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655, Computation Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006, DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>. <https://www.rfc-editor.org/info/rfc4655>.
skipping to change at page 29, line 25 skipping to change at line 1283
[RFC9552] Talaulikar, K., Ed., "Distribution of Link-State and [RFC9552] Talaulikar, K., Ed., "Distribution of Link-State and
Traffic Engineering Information Using BGP", RFC 9552, Traffic Engineering Information Using BGP", RFC 9552,
DOI 10.17487/RFC9552, December 2023, DOI 10.17487/RFC9552, December 2023,
<https://www.rfc-editor.org/info/rfc9552>. <https://www.rfc-editor.org/info/rfc9552>.
[RFC9604] Sivabalan, S., Filsfils, C., Tantsura, J., Previdi, S., [RFC9604] Sivabalan, S., Filsfils, C., Tantsura, J., Previdi, S.,
and C. Li, Ed., "Carrying Binding Label/SID in PCE-Based and C. Li, Ed., "Carrying Binding Label/SID in PCE-Based
Networks", RFC 9604, DOI 10.17487/RFC9604, August 2024, Networks", RFC 9604, DOI 10.17487/RFC9604, August 2024,
<https://www.rfc-editor.org/info/rfc9604>. <https://www.rfc-editor.org/info/rfc9604>.
Appendix A. Contributors [RFC9830] Previdi, S., Filsfils, C., Talaulikar, K., Ed., Mattes,
P., and D. Jain, "Advertising Segment Routing Policies in
BGP", RFC 9830, DOI 10.17487/RFC9830, September 2025,
<https://www.rfc-editor.org/info/rfc9830>.
Acknowledgements
We would like to thank Abdul Rehman, Andrew Stone, Boris Khasanov,
Cheng Li, Dhruv Dhody, Gorry Fairhurst, Gyan Mishra, Huaimo Chen,
Ines Robles, Joseph Salowey, Ketan Talaulikar, Marina Fizgeer, Mike
Bishopm, Praveen Kumar, Robert Sparks, Roman Danyliw, Stephane
Litkowski, Tom Petch, Zoey Rose, Xiao Min, and Xiong Quan for their
reviews and suggestions.
Contributors
Dhruv Dhody Dhruv Dhody
Huawei Huawei
India India
Email: dhruv.ietf@gmail.com Email: dhruv.ietf@gmail.com
Cheng Li Cheng Li
Huawei Technologies Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd. Huawei Campus, No. 156 Beiqing Rd.
Beijing, 10095 Beijing
10095
China China
Email: chengli13@huawei.com Email: chengli13@huawei.com
Zafar Ali Zafar Ali
Cisco Systems, Inc. Cisco Systems, Inc
Email: zali@cisco.com Email: zali@cisco.com
Rajesh Melarcode Rajesh Melarcode
Cisco Systems, Inc. Cisco Systems, Inc.
2000 Innovation Dr. 2000 Innovation Dr.
Kanata, Ontario Kanata Ontario
Canada Canada
Email: rmelarco@cisco.com Email: rmelarco@cisco.com
Authors' Addresses Authors' Addresses
Mike Koldychev Mike Koldychev
Ciena Corporation Ciena Corporation
385 Terry Fox Dr. 385 Terry Fox Dr.
Kanata Ontario K2K 0L1 Kanata Ontario K2K 0L1
Canada Canada
Email: mkoldych@proton.me Email: mkoldych@proton.me
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