PCE Working Group M. Koldychev
Internet-Draft S. Sivabalan
Updates: 8231 (if approved) Ciena Corporation
Intended status: Standards Track S. Sidor
Expires: 29 August 2025 Cisco Systems, Inc.
C. Barth
Juniper Networks, Inc.
S. Peng
Huawei Technologies
H. Bidgoli
Nokia
25 February 2025
Path Computation Element Communication Protocol (PCEP) Extensions for
Segment Routing (SR) Policy Candidate Paths
draft-ietf-pce-segment-routing-policy-cp-22
Abstract
Segment Routing (SR) allows a node to steer a packet flow along any
path. SR Policy is an ordered list of segments (i.e., instructions)
that represent a source-routed policy. Packet flows are steered into
an SR Policy on a node where it is instantiated called a headend
node. An SR Policy is made of one or more candidate paths.
This document specifies the Path Computation Element Communication
Protocol (PCEP) extension to signal candidate paths of the SR Policy.
Additionally, this document updates RFC 8231 to allow stateful bring
up of an SR Label Switched Path (LSP), without using the path
computation request and reply messages. This document is applicable
to both Segment Routing over MPLS (SR-MPLS) and Segment Routing over
IPv6 (SRv6).
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on 29 August 2025.
Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. SR Policy Identifier . . . . . . . . . . . . . . . . . . 6
3.2. SR Policy Candidate Path Identifier . . . . . . . . . . . 6
3.3. SR Policy Candidate Path Attributes . . . . . . . . . . . 6
4. SR Policy Association . . . . . . . . . . . . . . . . . . . . 7
4.1. Association Parameters . . . . . . . . . . . . . . . . . 7
4.2. Association Information . . . . . . . . . . . . . . . . . 9
4.2.1. SR Policy Name TLV . . . . . . . . . . . . . . . . . 9
4.2.2. SR Policy Candidate Path Identifier TLV . . . . . . . 10
4.2.3. SR Policy Candidate Path Name TLV . . . . . . . . . . 11
4.2.4. SR Policy Candidate Path Preference TLV . . . . . . . 12
5. Other Mechanisms . . . . . . . . . . . . . . . . . . . . . . 12
5.1. SR Policy Capability TLV . . . . . . . . . . . . . . . . 13
5.2. Computation Priority TLV . . . . . . . . . . . . . . . . 14
5.3. Explicit Null Label Policy (ENLP) TLV . . . . . . . . . . 14
5.4. Invalidation TLV . . . . . . . . . . . . . . . . . . . . 15
5.4.1. Drop-upon-invalid applies to SR Policy . . . . . . . 17
5.5. Update to RFC 8231 . . . . . . . . . . . . . . . . . . . 17
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
6.1. Association Type . . . . . . . . . . . . . . . . . . . . 18
6.2. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 18
6.3. PCEP Errors . . . . . . . . . . . . . . . . . . . . . . . 19
6.4. TE-PATH-BINDING TLV Flag field . . . . . . . . . . . . . 20
6.5. SR Policy Candidate Path Protocol Origin field . . . . . 21
6.6. SR Policy Invalidation Operational State . . . . . . . . 22
6.7. SR Policy Invalidation Configuration State . . . . . . . 22
6.8. SR Policy Capability TLV Flag field . . . . . . . . . . . 23
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7. Implementation Status . . . . . . . . . . . . . . . . . . . . 23
7.1. Cisco . . . . . . . . . . . . . . . . . . . . . . . . . . 24
7.2. Juniper . . . . . . . . . . . . . . . . . . . . . . . . . 24
8. Security Considerations . . . . . . . . . . . . . . . . . . . 24
9. Manageability Considerations . . . . . . . . . . . . . . . . 25
9.1. Control of Function and Policy . . . . . . . . . . . . . 25
9.2. Information and Data Models . . . . . . . . . . . . . . . 25
9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 25
9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 25
9.5. Requirements On Other Protocols . . . . . . . . . . . . . 26
9.6. Impact On Network Operations . . . . . . . . . . . . . . 26
10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 26
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 26
11.1. Normative References . . . . . . . . . . . . . . . . . . 26
11.2. Informative References . . . . . . . . . . . . . . . . . 28
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29
1. Introduction
Segment Routing Policy Architecture [RFC9256] details the concepts of
SR Policy and approaches to steering traffic into an SR Policy.
PCEP Extensions for Segment Routing [RFC8664] specifies extensions to
the Path Computation Element Protocol (PCEP) that allow a stateful
PCE to compute and initiate Traffic Engineering (TE) paths, as well
as a PCC to request a path subject to certain constraint(s) and
optimization criteria in SR networks. Although PCEP extensions
introduced in [RFC8664] were originally used to create SR-TE tunnels,
these are not SR Policies and lack many important features and
details.
PCEP Extensions for Establishing Relationships Between Sets of PCEP
LSPs [RFC8697] introduces a generic mechanism to create a grouping of
LSPs which is called an Association.
This document extends [RFC8664] to support signaling SR Policy
Candidate Paths as PCEP LSPs and to signal Candidate Path membership
in an SR Policy by means of the Association mechanism. The PCEP
Association corresponds to the SR Policy and the PCEP LSP corresponds
to the Candidate Path. The unit of signaling in PCEP is the LSP,
thus all the information is carried at the Candidate Path level.
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This document updates Section 5.8.2 of [RFC8231], making the PCReq
message optional for LSPs set up using Path Setup Type 1 (Segment
Routing) described in [RFC8664] and 3 (SRv6) described in [RFC9603],
allowing a PCC to delegate such LSP by sending a PCRpt without the
preliminary PCReq and PCRep messages, with the aim of reducing the
PCEP message exchanges and simplifying implementation.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Terminology
The following terminologies are used in this document:
Endpoint: The IPv4 or IPv6 endpoint address of an SR Policy, as
described in [RFC9256] Section 2.1.
Color: The 32-bit color of an SR Policy, as described in [RFC9256]
Section 2.1.
Protocol-Origin: The protocol that was used to create the Candidate
Path, as described in [RFC9256] Section 2.3.
Originator: Device that created the Candidate Path, as described in
[RFC9256] Section 2.4.
Discriminator: Distinguishes Candidate Paths created by the same
device, as described in [RFC9256] Section 2.5.
Association Parameters: As described in [RFC8697], refers to the key
data, that uniquely identifies the Association.
Association Information: As described in [RFC8697], refers to the
non-key information about the Association.
SR Policy LSP: An LSP set up using Path Setup Type 1 (Segment
Routing) or 3 (SRv6).
ASN: Autonomous System Number.
BSID: Binding Segment Identifier.
ENLP: Explicit Null Label Policy.
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IGP: Interior Gateway Protocol.
LSP: Label Switched Path.
MPLS: Multiprotocol Label Switching.
PCC: Path Computation Client.
PCE: Path Computation Element.
PCEP: Path Computation Element Protocol.
SID: Segment Identifier.
SR: Segment Routing.
SRPA: SR Policy Association. A new association type 'SR Policy
Association' is used to group candidate paths belonging to the SR
Policy. Depending on the discussion context, it can refer to the
PCEP ASSOCIATION object of SR Policy type or to a group of LSPs
that belong to the association.
SRPM: SR Policy Manager.
SR-TE: Segment Routing Traffic Engineering.
TE: Traffic Engineering.
TLV: Type-Length-Value.
3. Overview
The SR Policy is represented by a new type of PCEP Association,
called the SR Policy Association. The SR Candidate Paths of an SR
Policy are the PCEP LSPs within the same SRPA. The subject of
encoding multiple Segment Lists within an SR Policy Candidate Path is
described in [I-D.ietf-pce-multipath].
The SRPA carries three pieces of information: SR Policy Identifier,
SR Policy Candidate Path Identifier, and SR Policy Candidate Path
Attribute(s).
This document also specifies some additional information that is not
encoded as part of SRPA: Computation Priority, Explicit Null Label
Policy and Drop-upon-invalid behavior.
This document does not propose any extension for the use of BSID with
SR Policy; the existing behavior is documented in [RFC9604].
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3.1. SR Policy Identifier
SR Policy Identifier uniquely identifies the SR Policy [RFC9256]
within the network. SR Policy Identifier MUST be the same for all SR
Policy Candidate Paths in the same SRPA. SR Policy Identifier MUST
be constant for a given SR Policy Candidate Path for the lifetime of
the PCEP session. SR Policy Identifier MUST be different for
different SRPAs. If the identifier is inconsistent among Candidate
Paths, changes during the lifetime of the PCEP session, or is not
unique across different SRPAs, the PCEP speaker MUST send a PCErr
message with Error-Type = 26 "Association Error" and Error Value = 20
"SR Policy Identifier Mismatch". SR Policy Identifier consist of:
* Headend router where the SR Policy originates.
* Color of SR Policy ([RFC9256] Section 2.1).
* Endpoint of SR Policy ([RFC9256] Section 2.1).
3.2. SR Policy Candidate Path Identifier
SR Policy Candidate Path Identifier uniquely identifies the SR Policy
Candidate Path within the context of an SR Policy. SR Policy
Candidate Path Identifier MUST be constant for the lifetime of the
PCEP session. SR Policy Candidate Path Identifier MUST be different
for distinct Candidate Paths within the same SRPA. If an identifier
changes during the lifetime of the PCEP session or is not unique
among distinct Candidate Paths, the PCEP speaker MUST send a PCErr
message with Error-Type = 26 "Association Error" and Error Value = 21
"SR Policy Candidate Path Identifier Mismatch". SR Policy Candidate
Path Identifier consist of:
* Protocol Origin ([RFC9256] Section 2.3).
* Originator ([RFC9256] Section 2.4).
* Discriminator ([RFC9256] Section 2.5).
3.3. SR Policy Candidate Path Attributes
SR Policy Candidate Path Attributes carry optional, non-key
information about the Candidate Path and MAY change during the
lifetime of the LSP. SR Policy Candidate Path Attributes consist of:
* Candidate Path preference.
* Candidate Path name.
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* SR Policy name.
4. SR Policy Association
As per [RFC8697], LSPs are associated with other LSPs with which they
interact by adding them to a common association group. As described
in [RFC8697], the association group is uniquely identified by the
combination of the following fields in the ASSOCIATION object:
Association Type, Association ID, Association Source, and (if
present) Global Association Source or Extended Association ID,
referred to as Association Parameters.
[RFC8697] specifies the ASSOCIATION Object with two Object-Types for
IPv4 and IPv6 which includes the field "Association Type". This
document defines a new Association type (6) "SR Policy Association"
for SRPA.
[RFC8697] specifies the mechanism for the capability advertisement of
the Association Types supported by a PCEP speaker by defining an
ASSOC-Type-List TLV to be carried within an OPEN object. This
capability exchange for the SR Policy Association Types MUST be done
before using the SRPA. Thus, the PCEP speaker MUST include the SRPA
Type (6) in the ASSOC-Type-List TLV and MUST receive the same from
the PCEP peer before using SRPA.
A given LSP MUST belong to at most one SRPA, since an SR Policy
Candidate Path cannot belong to multiple SR Policies. If a PCEP
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
with Error-Type = 26 "Association Error", Error-Value = 7 "Cannot
join the association group".
4.1. Association Parameters
As per [RFC9256], an SR Policy is identified through the tuple
<headend, color, endpoint>. The headend is encoded in the
'Association Source' field in the ASSOCIATION object. The color and
endpoint are encoded as part of the Extended Association ID TLV.
The Association Parameters (see Section 2) consist of:
* Association Type: Part of the base ASSOCIATION object. Set to 6
"SR Policy Association".
* Association Source (IPv4/IPv6): Part of the base ASSOCIATION
object. Set to the headend value of the SR Policy, as defined in
[RFC9256] Section 2.1.
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* Association ID (16-bit): Part of the base ASSOCIATION object.
Always set to the numeric value "1". This 16-bit field does not
store meaningful data, because neither the Color nor the Endpoint
can fit in it.
* Extended Association ID TLV: Mandatory TLV of the ASSOCIATION
object. Encodes the Color and Endpoint of the SR Policy.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 31 | Length = 8 or 20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Color |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Endpoint ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Extended Association ID TLV format
Type: Extended Association ID TLV, type = 31 [RFC8697].
Length: Either 8 or 20, depending on whether IPv4 or IPv6 address is
encoded in the Endpoint field.
Color: SR Policy color value, non-zero as per [RFC9256] Section 2.1.
Endpoint: can be either IPv4 or IPv6. This value MAY be different
from the one contained in the Destination address field in the END-
POINTS object, or in the Tunnel Endpoint Address field in the LSP-
IDENTIFIERS TLV.
If the PCEP speaker receives an SRPA object whose Association
Parameters do not follow the above specification, then the PCEP
speaker MUST send a PCErr message with Error-Type = 26 "Association
Error", Error-Value = 20 "SR Policy Identifier Mismatch".
The purpose of choosing the Association Parameters in this way is to
guarantee that there is no possibility of a race condition 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
with the same Association Parameters independently of each other
based on the SR Policy [RFC9256] parameters. Thus, there is no
chance that different PCEP speakers will come up with different
Association Parameters for the same SR Policy.
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The last hop of the computed SR Policy Candidate Path MAY differ from
the Endpoint contained in the <headend, color, endpoint> tuple. An
example use case is to terminate the SR Policy before reaching the
Endpoint and have decapsulated traffic go the rest of the way to the
Endpoint node using the native IGP path(s). In this example, the
destination of the SR Policy Candidate Paths will be some node before
the Endpoint, but the Endpoint value is still used at the head-end to
steer traffic with that Endpoint IP into the SR Policy. The
Destination of the SR Policy Candidate Path is signaled using the
END-POINTS object and/or LSP-IDENTIFIERS TLV, as per the usual PCEP
procedures. When neither the END-POINTS object nor LSP-IDENTIFIERS
TLV is present, the PCEP speaker MUST extract the destination from
the Endpoint field in the SRPA Extended Association ID TLV.
SR Policy with Color-Only steering is signaled with the End-Point
value set to null, i.e., 0.0.0.0 for IPv4 or :: for IPv6, see
[RFC9256] Section 8.8.1.
4.2. Association Information
The SRPA object may carry the following TLVs:
* SRPOLICY-POL-NAME TLV: (optional) encodes SR Policy Name string.
* SRPOLICY-CPATH-ID TLV: (mandatory) encodes SR Policy Candidate
Path Identifier.
* SRPOLICY-CPATH-NAME TLV: (optional) encodes SR Policy Candidate
Path string name.
* SRPOLICY-CPATH-PREFERENCE TLV: (optional) encodes SR Policy
Candidate Path preference value.
Out of these TLVs, the SRPOLICY-CPATH-ID TLV is mandatory, all others
are optional. When a mandatory TLV is missing from the SRPA object,
the PCEP speaker MUST send a PCErr message with Error-Type = 6
"Mandatory Object Missing", Error-Value = 21 "Missing SR Policy
Mandatory TLV".
This document specifies four new TLVs to be carried in the SRPA
object. Only one TLV instance of each type can be carried, and only
the first occurrence is processed. Any others MUST be ignored.
4.2.1. SR Policy Name TLV
The SRPOLICY-POL-NAME TLV is an optional TLV for the SRPA object.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ SR Policy Name ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: The SRPOLICY-POL-NAME TLV format
Type: 56 for "SRPOLICY-POL-NAME" TLV.
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
that the TLV is 4-octet aligned.
SR Policy Name: SR Policy name, as defined in [RFC9256]. It MUST be
a string of printable ASCII characters, without a NULL terminator.
4.2.2. SR Policy Candidate Path Identifier TLV
The SRPOLICY-CPATH-ID TLV is a mandatory TLV for the SRPA object.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Proto. Origin | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Originator ASN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Originator Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: The SRPOLICY-CPATH-ID TLV format
Type: 57 for "SRPOLICY-CPATH-ID" TLV.
Length: 28.
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Protocol Origin: 8-bit value that encodes the protocol origin, as
specified in Section 6.5. Note that in the PCInitiate message
[RFC8281], the Protocol Origin is always set to 10 - "PCEP (In PCEP
or when BGP-LS Producer is PCE)". The "SR Policy Protocol Origin"
IANA registry includes a combination of values intended for use in
PCEP and BGP-LS. When the registry contains two variants of values
associated with the mechanism or protocol used for provisioning of
the Candidate Path, for example 1 - "PCEP" and 10 - "PCEP (In PCEP or
when BGP-LS Producer is PCE)", the "(In PCEP or when BGP-LS Producer
is PCE)" variants MUST be used in PCEP.
Reserved: This field MUST be set to zero on transmission and MUST be
ignored on receipt.
Originator ASN: Represented as a 4-byte number, part of the
originator identifier, as specified in Section 2.4 of [RFC9256].
When sending a PCInitiate message [RFC8281], the PCE is the
originator of the Candidate Path. AS number is not a PCE concept and
PCE is not required to have one for itself. If the PCE has its AS
number, then it MUST set it, otherwise the AS number can be set to 0.
Originator Address: Represented as a 128-bit value as specified in
Section 2.4 of [RFC9256]. When sending a PCInitiate message, the PCE
is acting as the originator and therefore MUST set this to an address
that it owns.
Discriminator: 32-bit value that encodes the Discriminator of the
Candidate Path, as specified in [RFC9256] Section 2.5. This is the
field that mainly distinguishes different SR Candidate Paths, coming
from the same originator. It is allowed to be any number in the
32-bit range.
4.2.3. SR Policy Candidate Path Name TLV
The SRPOLICY-CPATH-NAME TLV is an optional TLV for the SRPA object.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ SR Policy Candidate Path Name ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: The SRPOLICY-CPATH-NAME TLV format
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Type: 58 for "SRPOLICY-CPATH-NAME" TLV.
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
that the TLV is 4-octet aligned.
SR Policy Candidate Path Name: SR Policy Candidate Path Name, as
defined in [RFC9256]. It MUST be a string of printable ASCII
characters, without a NULL terminator.
4.2.4. SR Policy Candidate Path Preference TLV
The SRPOLICY-CPATH-PREFERENCE TLV is an optional TLV for the SRPA
object. If the TLV is absent, then default Preference value is 100,
as per Section 2.7 of [RFC9256].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preference |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: The SRPOLICY-CPATH-PREFERENCE TLV format
Type: 59 for "SRPOLICY-CPATH-PREFERENCE" TLV.
Length: 4.
Preference: Numerical preference of the Candidate Path as defined in
Section 2.7 of [RFC9256].
5. Other Mechanisms
This section describes mechanisms that are standardized for SR
Policies in [RFC9256], but do not make use of the SRPA for signaling
in PCEP. Since SRPA is not used, there needs to be a separate
capability negotiation.
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
only the first occurrence is processed. Any others MUST be ignored.
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5.1. SR Policy Capability TLV
The SRPOLICY-CAPABILITY TLV is a TLV for the OPEN object. It is used
at session establishment to learn the peer's capabilities with
respect to SR Policy. Implementations that support SR Policy MUST
include SRPOLICY-CAPABILITY TLV in the OPEN object. In addition, the
ASSOC-Type-List TLV containing SRPA Type (6) MUST be present in the
OPEN object, as specified in Section 4.
If a PCEP speaker receives SRPA but the SRPOLICY-CAPABILITY TLV is
not exchanged, then the PCEP speaker MUST send a PCErr message with
Error- Type = 10 ("Reception of an invalid object") and Error-Value =
TBD ("Missing SRPOLICY-CAPABILITY TLV") and MUST then close the PCEP
session.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |L| |I|E|P|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: The SRPOLICY-CAPABILITY TLV format
Type: 71 for "SRPOLICY-CAPABILITY TLV.
Length: 4.
P-flag (Computation Priority): If set to '1' by a PCEP speaker, the P
flag indicates that the PCEP speaker supports the handling of
COMPUTATION-PRIORITY TLV for the SR Policy, see Section 5.2. If this
flag is not set, then the PCEP speaker MUST 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 speaker,
the E flag indicates that the PCEP speaker supports the handling of
ENLP TLV for the SR Policy, see Section 5.3. If this flag is not
set, then the PCEP speaker MUST NOT send the ENLP TLV and MUST ignore
it on receipt.
I-Flag (Invalidation): If set to '1' by a PCEP speaker, the I flag
indicates that the PCEP speaker supports the handling of INVALIDATION
TLV for the SR Policy, see Section 5.4. If this flag is not set,
then the PCEP speaker MUST NOT send the INVALIDATION TLV and MUST
ignore it on receipt.
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L-Flag (Stateless Operation): If set to '1' by a PCEP speaker, the L
flag indicates that the PCEP speaker supports the stateless (PCReq/
PCRep) operations for the SR Policy, see Section 5.5. If the PCE did
not set this flag then the PCC MUST NOT send PCReq messages to this
PCE for the SR Policy.
Unassigned bits MUST be set to '0' on transmission and MUST be
ignored on receipt.
5.2. Computation Priority TLV
The COMPUTATION-PRIORITY TLV is an optional TLV for the LSP object.
It is used to signal the numerical computation priority, as specified
in 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 Priority value of 128 is used.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Priority | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: The COMPUTATION-PRIORITY TLV format
Type: 68 for "COMPUTATION-PRIORITY" TLV.
Length: 4.
Priority: Numerical priority with which this LSP is to be recomputed
by the PCE upon topology change. Lowest value is the highest
priority. The default value of priority is 128 (if this TLV is
absent), see Section 2.12 of [RFC9256].
Reserved: This field MUST be set to zero on transmission and MUST be
ignored on receipt.
5.3. Explicit Null Label Policy (ENLP) TLV
To steer an unlabeled IP packet into an SR policy, it is necessary to
create a label stack for that packet, and push one or more labels
onto that stack. The Explicit NULL Label Policy (ENLP) TLV is an
optional TLV for the LSP object used to indicate whether an Explicit
NULL Label [RFC3032] must be pushed on an unlabeled IP packet before
any other labels. The contents of this TLV are used by the SRPM as
described in section 4.1 of [RFC9256]. If an ENLP TLV is not
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present, the decision of whether to push an Explicit NULL label on a
given packet is a matter of local configuration. Note that Explicit
Null is currently only defined for SR MPLS and not for SRv6.
Therefore the PCEP speaker MUST ignore the presence of this TLV for
SRv6 Policies.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ENLP | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: The Explicit Null Label Policy (ENLP) TLV format
Type: 69 for "ENLP" TLV.
Length: 4.
ENLP (Explicit NULL Label Policy): Indicates whether Explicit NULL
labels are to be pushed on unlabeled IP packets that are being
steered into a given SR policy. The values of this field are
specified in IANA registry "SR Policy ENLP Values" under "Segment
Routing" registry group, which was introduced in Section 6.10 of
[I-D.ietf-idr-sr-policy-safi].
Reserved: This field MUST be set to zero on transmission and MUST be
ignored on receipt.
The ENLP reserved values may be used for future extensions and
implementations MUST ignore the ENLP TLV with these values. The
behavior signaled in this TLV MAY be overridden by local
configuration. Section 4.1 of [RFC9256] describes the behavior on
the headend for the handling of the explicit null label.
5.4. Invalidation TLV
The INVALIDATION TLV is an optional TLV for the LSP object. It is
used to control traffic steering into the LSP when the LSP is
operationally down/invalid. In the context of SR Policy, this TLV
facilitates the Drop-upon-invalid behavior, specified in Section 8.2
of [RFC9256]. Normally, if the LSP is down/invalid then it stops
attracting traffic and traffic that would have been destined for that
LSP is redirected somewhere else, such as via IGP or another LSP.
The Drop-upon-invalid behavior specifies that the LSP keeps
attracting traffic and the traffic has to be dropped at the head-end.
Such an LSP is said to be "in drop state". While in the drop state,
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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 been computed.
The INVALIDATION TLV is used in both directions between PCEP peers:
* PCE -> PCC: PCE specifies to the PCC whether to enable or disable
Drop-upon-invalid (Config).
* PCC -> PCE: PCC reports the current setting of the Drop-upon-
invalid (Config) and also whether the LSP is currently in the drop
state (Oper).
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Oper | Config | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: The INVALIDATION TLV format
Type: 70 for "INVALIDATION" TLV.
Length: 4.
Oper: encodes the current state of the LSP, i.e., whether it is
actively dropping traffic right now. This field can be set to non-
zero values only by the PCC, it MUST be set to 0 by the PCE and MUST
be ignored by the PCC. See Section Section 6.6 for IANA information.
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
| |D|
+-+-+-+-+-+-+-+-+
Figure 10: Oper state of Drop-upon-invalid feature
* D: dropping - the LSP is currently attracting traffic and actively
dropping it.
* The unassigned bits in the Flag octet MUST be set to zero upon
transmission and MUST be ignored upon receipt.
Config: encodes the current setting of the Drop-upon-invalid feature.
See Section Section 6.7 for IANA information.
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0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
| |D|
+-+-+-+-+-+-+-+-+
Figure 11: Config state of Drop-upon-invalid feature
* D: drop enabled - the Candidate Path has Drop-upon-invalid feature
enabled.
* The unassigned bits in the Flag octet MUST be set to zero upon
transmission and MUST be ignored upon receipt.
Reserved: This field MUST be set to zero on transmission and MUST be
ignored on receipt.
5.4.1. Drop-upon-invalid applies to SR Policy
The Drop-upon-invalid feature is somewhat special among the other SR
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
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
enabled. As stated in [RFC9256] Section 8.1, the SR Policy is
invalid when all its Candidate Paths are invalid.
Once all the Candidate Paths of the SR Policy have become invalid,
then the SR Policy checks whether any of the Candidate Paths have
Drop-upon-invalid enabled. If so, SR Policy enters the drop state
and "activates" the highest preference Candidate Path which has the
Drop-upon-invalid enabled. Note that only one Candidate Path needs
to be reported to the PCE with the D (dropping) flag set.
5.5. Update to RFC 8231
[RFC8231] Section 5.8.2, allows delegation of an LSP in operationally
down state, but at the same time mandates the use of PCReq before
sending PCRpt. This document updates [RFC8231] Section 5.8.2, by
making this section not applicable to SR Policy LSPs. Thus, when a
PCC wants to delegate an SR Policy LSP, it MAY proceed directly to
sending PCRpt, without first sending PCReq and waiting for PCRep.
This has the advantage of reducing the number of PCEP messages and
simplifying the implementation.
Furthermore, a PCEP speaker is not required to support PCReq/PCRep at
all for SR Policies. The PCEP speaker can indicate support for
PCReq/PCRep via the "L-Flag" in the SRPOLICY-CAPABILITY TLV (See
Section 5.1). When this flag is cleared, or when the SRPOLICY-
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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
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
LSP types, such as RSVP-TE LSPs. For other LSP types, [RFC8231]
Section 5.8.2 continues to apply.
6. IANA Considerations
6.1. Association Type
This document defines a new association type: SR Policy Association.
IANA is requested to confirm the following allocation in the
"ASSOCIATION Type Field" registry [RFC8697] within the "Path
Computation Element Protocol (PCEP) Numbers" registry group:
+-----------+-------------------------------------------+-----------+
| Type | Name | Reference |
+-----------+-------------------------------------------+-----------+
| 6 | SR Policy Association | This.I-D |
+-----------+-------------------------------------------+-----------+
6.2. PCEP TLV Type Indicators
This document defines eight new TLVs for carrying additional
information about SR Policy and SR Candidate Paths. IANA is
requested to confirm the following allocations in the existing "PCEP
TLV Type Indicators" registry as follows:
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+-----------+-------------------------------------------+-----------+
| Value | Description | Reference |
+-----------+-------------------------------------------+-----------+
| 56 | SRPOLICY-POL-NAME | This.I-D |
+-----------+-------------------------------------------+-----------+
| 57 | SRPOLICY-CPATH-ID | This.I-D |
+-----------+-------------------------------------------+-----------+
| 58 | SRPOLICY-CPATH-NAME | This.I-D |
+-----------+-------------------------------------------+-----------+
| 59 | SRPOLICY-CPATH-PREFERENCE | This.I-D |
+-----------+-------------------------------------------+-----------+
| 68 | COMPUTATION-PRIORITY | This.I-D |
+-----------+-------------------------------------------+-----------+
| 69 | EXPLICIT-NULL-LABEL-POLICY | This.I-D |
+-----------+-------------------------------------------+-----------+
| 70 | INVALIDATION | This.I-D |
+-----------+-------------------------------------------+-----------+
| 71 | SRPOLICY-CAPABILITY | This.I-D |
+-----------+-------------------------------------------+-----------+
6.3. PCEP Errors
This document defines one new Error-Value within the "Mandatory
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
"PCEP-ERROR Object Error Types and Values" registry of the "Path
Computation Element Protocol (PCEP) Numbers" registry group.
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+------------+------------------+-----------------------+-----------+
| Error-Type | Meaning | Error-value | Reference |
+------------+------------------+-----------------------+-----------+
| 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
Object Error Types and Values" registry of the "Path Computation
Element Protocol (PCEP) Numbers" registry group.
+------------+------------------+-----------------------+-----------+
| Error-Type | Meaning | Error-value | Reference |
+------------+------------------+-----------------------+-----------+
| 10 | Reception of an | | [RFC5440] |
| | invalid object | | |
+------------+------------------+-----------------------+-----------+
| | | TBA: Missing | This.I-D |
| | | SRPOLICY-CAPABILITY | |
| | | TLV | |
+------------+------------------+-----------------------+-----------+
6.4. TE-PATH-BINDING TLV Flag field
An earlier version of this document added new bit within the "TE-
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 cancel the early allocation made which is not
needed anymore. As per the instructions from the chairs, please mark
it as deprecated.
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+------------+------------------------------------------+-----------+
| Bit position | Description | Reference |
+--------------+----------------------------------------+-----------+
| 1 | Deprecated (Specified-BSID-only) | This.I-D |
+--------------+----------------------------------------+-----------+
6.5. SR Policy Candidate Path Protocol Origin field
[Note to IANA: The new registry creation request below is also
present in the draft-ietf-idr-bgp-ls-sr-policy. IANA is requested to
process the registry creation via the first of these two documents to
reach the publication stage and the authors of the other document
would update the IANA considerations suitably. Note that draft-ietf-
idr-bgp-ls-sr-policy allocates different values in BGP.] [Note to
RFC-Editor: Please remove the above and this note before
publication.]
This document requests IANA to maintain a new registry under "Segment
Routing" registry group. The new registry is called "SR Policy
Protocol Origin". New values are to be assigned by "Expert Review"
[RFC8126] using the guidelines for Designated Experts as specified in
[RFC9256]. The registry contains the following codepoints:
+---------+--------------------------------------+---------------+
| Code | | |
| Point | Protocol Origin | Reference |
+---------+--------------------------------------+---------------+
| 0 | Reserved (not to be used) | this document |
| 1 | PCEP | this document |
| 2 | BGP SR Policy | this document |
| 3 | Configuration (CLI, YANG model via | this document |
| | NETCONF, etc.) | |
| 4-9 | Unassigned | this document |
| 10 | PCEP (In PCEP or when | this document |
| | BGP-LS Producer is PCE) | |
| 11-19 | Unassigned | this document |
| 20 | BGP SR Policy (In PCEP or when | this document |
| | BGP-LS Producer is PCE) | |
| 21-29 | Unassigned | this document |
| 30 | Configuration (CLI, YANG model via | this document |
| | NETCONF, etc.) (In PCEP or when | |
| | BGP-LS Producer is PCE) | |
| 31-250 | Unassigned | this document |
| 251-255 | Private Use (not to be assigned by | this document |
| | IANA) | |
+---------+--------------------------------------+---------------+
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6.6. SR Policy Invalidation Operational State
This document requests IANA to maintain a new registry under "Path
Computation Element Protocol (PCEP) Numbers" registry group. The new
registry is called "SR Policy Invalidation Operational Flags". New
values are to be assigned by "IETF review" [RFC8126]. Each bit
should be tracked with the following qualities:
* Bit (counting from bit 0 as the most significant bit).
* Description.
* Reference.
+-------+-----------------------------------------------+-----------+
| Bit | Description | Reference |
+-------+-----------------------------------------------+-----------+
| 0 - 6 | Unassigned | This.I-D |
+-------+-----------------------------------------------+-----------+
| 7 | D: dropping - the LSP is currently attracting | This.I-D |
| | traffic and actively dropping it. | |
+-------+-----------------------------------------------+-----------+
6.7. SR Policy Invalidation Configuration State
This document requests IANA to maintain a new registry under "Path
Computation Element Protocol (PCEP) Numbers" registry group. The new
registry is called "SR Policy Invalidation Configuration Flags". New
values are to be assigned by "IETF review" [RFC8126]. Each bit
should be tracked with the following qualities:
* Bit (counting from bit 0 as the most significant bit).
* Description.
* Reference.
+-------+-----------------------------------------------+-----------+
| Bit | Description | Reference |
+-------+-----------------------------------------------+-----------+
| 0 - 6 | Unassigned. | This.I-D |
+-------+-----------------------------------------------+-----------+
| 7 | D: drop enabled - the Drop-upon-invalid is | This.I-D |
| | enabled on the LSP. | |
+-------+-----------------------------------------------+-----------+
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6.8. SR Policy Capability TLV Flag field
This document requests IANA to maintain a new registry under "Path
Computation Element Protocol (PCEP) Numbers" registry group. The new
registry is called "SR Policy Capability TLV Flag Field". New values
are to be assigned by "IETF review" [RFC8126]. Each bit should be
tracked with the following qualities:
* Bit (counting from bit 0 as the most significant bit).
* Description.
* Reference.
+--------+-----------------------------------------------+-----------+
| Bit | Description | Reference |
+--------+-----------------------------------------------+-----------+
| 0 - 26 | Unassigned | This.I-D |
+--------+-----------------------------------------------+-----------+
| 27 | Stateless Operation | This.I-D |
+--------+-----------------------------------------------+-----------+
| 28 | Unassigned | This.I-D |
+--------+-----------------------------------------------+-----------+
| 29 | Invalidation | This.I-D |
+--------+-----------------------------------------------+-----------+
| 30 | Explicit NULL Label Policy | This.I-D |
+--------+-----------------------------------------------+-----------+
| 31 | Computation Priority | 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.
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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
Policy Candidate Path Name TLV.
* Maturity Level: Production.
* Coverage: Partial.
* Contact: cbarth@juniper.net
8. Security Considerations
The information carried in the newly defined SRPA object and TLVs
could provide an eavesdropper with additional information about the
SR Policy.
The security considerations described in [RFC5440], [RFC8231],
[RFC8281], [RFC8664], [RFC8697], [RFC9256] and [RFC9603] are
applicable to this specification.
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As per [RFC8231], it is RECOMMENDED that these PCEP extensions can
only be activated on authenticated and encrypted sessions across PCEs
and PCCs belonging to the same administrative authority, using
Transport Layer Security (TLS) [RFC8253] as per the recommendations
and best current practices in [RFC9325].
9. Manageability Considerations
All manageability requirements and considerations listed in
[RFC5440], [RFC8231], [RFC8664], [RFC9256] and [RFC9603] apply to
PCEP protocol extensions defined in this document. In addition,
requirements and considerations listed in this section apply.
9.1. Control of Function and Policy
A PCE or PCC implementation MAY allow the capabilities specified in
Section 5.1 and the capability for support of SRPA advertised in
ASSOC-Type-List TLV to be enabled and disabled.
9.2. Information and Data Models
The PCEP YANG module [I-D.ietf-pce-pcep-yang] will be extended with
PCEP extensions specified Section 5 of this document.
[I-D.ietf-pce-pcep-srv6-yang] defines YANG module with common
building blocks for PCEP Extensions described in Section 4.
9.3. Liveness Detection and Monitoring
Mechanisms defined in this document do not imply any new liveness
detection and monitoring requirements in addition to those already
listed in [RFC5440], [RFC8664] and [RFC9256].
9.4. Verify Correct Operations
Operation verification requirements already listed in [RFC5440],
[RFC8231], [RFC8664], [RFC9256] and [RFC9603] are applicable to
mechanisms defined in this document.
An implementation MUST allow the operator to view SR Policy
Identifier and SR Policy Candidate Path Identifier advertised in SRPA
object.
An implementation SHOULD allow the operator to view the capabilities
defined in this document.
An implementation SHOULD allow the operator to view LSPs associated
with specific SR Policy Identifier.
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9.5. Requirements On Other Protocols
The PCEP extensions defined in this document do not imply any new
requirements on other protocols.
9.6. Impact On Network Operations
The mechanisms defined in [RFC5440], [RFC8231], [RFC9256] and
[RFC9603] also apply to the PCEP extensions defined in this document.
10. Acknowledgement
Would like to thank Ketan Talaulikar, Dhruv Dhody, Stephane
Litkowski, Boris Khasanov, Abdul Rehman, Zoey Rose, Praveen Kumar and
Tom Petch for review and suggestions.
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
<https://www.rfc-editor.org/info/rfc3032>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<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
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
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[RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for Stateful PCE", RFC 8231,
DOI 10.17487/RFC8231, September 2017,
<https://www.rfc-editor.org/info/rfc8231>.
[RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
"PCEPS: Usage of TLS to Provide a Secure Transport for the
Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>.
[RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path
Computation Element Communication Protocol (PCEP)
Extensions for PCE-Initiated LSP Setup in a Stateful PCE
Model", RFC 8281, DOI 10.17487/RFC8281, December 2017,
<https://www.rfc-editor.org/info/rfc8281>.
[RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
and J. Hardwick, "Path Computation Element Communication
Protocol (PCEP) Extensions for Segment Routing", RFC 8664,
DOI 10.17487/RFC8664, December 2019,
<https://www.rfc-editor.org/info/rfc8664>.
[RFC8697] Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H.,
Dhody, D., and Y. Tanaka, "Path Computation Element
Communication Protocol (PCEP) Extensions for Establishing
Relationships between Sets of Label Switched Paths
(LSPs)", RFC 8697, DOI 10.17487/RFC8697, January 2020,
<https://www.rfc-editor.org/info/rfc8697>.
[RFC9256] Filsfils, C., Talaulikar, K., Ed., Voyer, D., Bogdanov,
A., and P. Mattes, "Segment Routing Policy Architecture",
RFC 9256, DOI 10.17487/RFC9256, July 2022,
<https://www.rfc-editor.org/info/rfc9256>.
[RFC9325] Sheffer, Y., Saint-Andre, P., and T. Fossati,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November
2022, <https://www.rfc-editor.org/info/rfc9325>.
[RFC9603] Li, C., Ed., Kaladharan, P., Sivabalan, S., Koldychev, M.,
and Y. Zhu, "Path Computation Element Communication
Protocol (PCEP) Extensions for IPv6 Segment Routing",
RFC 9603, DOI 10.17487/RFC9603, July 2024,
<https://www.rfc-editor.org/info/rfc9603>.
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[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>.
11.2. Informative References
[I-D.ietf-pce-multipath]
Koldychev, M., Sivabalan, S., Saad, T., Beeram, V. P.,
Bidgoli, H., Yadav, B., Peng, S., and G. S. Mishra, "PCEP
Extensions for Signaling Multipath Information", Work in
Progress, Internet-Draft, draft-ietf-pce-multipath-12, 8
October 2024, <https://datatracker.ietf.org/doc/html/
draft-ietf-pce-multipath-12>.
[RFC9604] Sivabalan, S., Filsfils, C., Tantsura, J., Previdi, S.,
and C. Li, Ed., "Carrying Binding Label/SID in PCE-Based
Networks", RFC 9604, DOI 10.17487/RFC9604, August 2024,
<https://www.rfc-editor.org/info/rfc9604>.
[I-D.ietf-pce-pcep-yang]
Dhody, D., Beeram, V. P., Hardwick, J., and J. Tantsura,
"A YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", Work in Progress,
Internet-Draft, draft-ietf-pce-pcep-yang-30, 26 January
2025, <https://datatracker.ietf.org/doc/html/draft-ietf-
pce-pcep-yang-30>.
[I-D.ietf-pce-pcep-srv6-yang]
Li, C., Sivabalan, S., Peng, S., Koldychev, M., and L.
Ndifor, "A YANG Data Model for Segment Routing (SR) Policy
and SR in IPv6 (SRv6) support in Path Computation Element
Communications Protocol (PCEP)", Work in Progress,
Internet-Draft, draft-ietf-pce-pcep-srv6-yang-06, 19
October 2024, <https://datatracker.ietf.org/doc/html/
draft-ietf-pce-pcep-srv6-yang-06>.
Appendix A. Contributors
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Internet-Draft PCEP SR Policy February 2025
Dhruv Dhody
Huawei
India
Email: dhruv.ietf@gmail.com
Cheng Li
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing, 10095
China
Email: chengli13@huawei.com
Zafar Ali
Cisco Systems, Inc.
Email: zali@cisco.com
Rajesh Melarcode
Cisco Systems, Inc.
2000 Innovation Dr.
Kanata, Ontario
Canada
Email: rmelarco@cisco.com
Authors' Addresses
Mike Koldychev
Ciena Corporation
385 Terry Fox Dr.
Kanata Ontario K2K 0L1
Canada
Email: mkoldych@proton.me
Siva Sivabalan
Ciena Corporation
385 Terry Fox Dr.
Kanata Ontario K2K 0L1
Canada
Email: ssivabal@ciena.com
Koldychev, et al. Expires 29 August 2025 [Page 29]
Internet-Draft PCEP SR Policy February 2025
Samuel Sidor
Cisco Systems, Inc.
Eurovea Central 3.
811 09 Bratislava
Slovakia
Email: ssidor@cisco.com
Colby Barth
Juniper Networks, Inc.
Email: cbarth@juniper.net
Shuping Peng
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing
100095
China
Email: pengshuping@huawei.com
Hooman Bidgoli
Nokia
Email: hooman.bidgoli@nokia.com
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