| RFC 9862 | PCEP SR Policy | September 2025 |
| Koldychev, et al. | Standards Track | [Page] |
A Segment Routing (SR) Policy is an ordered list of instructions called "segments" that represent a source-routed policy. Packet 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.¶
This document specifies the Path Computation Element Communication Protocol (PCEP) extension to signal candidate paths of an SR Policy. Additionally, this document updates RFC 8231 to allow delegation and setup 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).¶
This is an Internet Standards Track document.¶
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.¶
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc9862.¶
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.¶
"Segment Routing Policy Architecture" [RFC9256] details the concepts of Segment Routing (SR) Policy [RFC8402] and approaches to steering traffic into an SR Policy.¶
"Path Computation Element Communication Protocol (PCEP) Extensions for Segment Routing" [RFC8664] specifies extensions to the PCEP that allow a stateful Path Computation Element (PCE) to compute and initiate Traffic Engineering (TE) paths, as well as a Path Computation Client (PCC) to request a path subject to certain constraints and optimization criteria in an SR domain. Although PCEP extensions introduced in [RFC8664] enable the creation of SR-TE paths, these do not constitute SR Policies as defined in [RFC9256]. Therefore, they lack support for:¶
Association of SR Policy Candidate Paths signaled via PCEP with Candidate Paths of the same SR Policy signaled via other sources (e.g., local configuration or BGP).¶
Association of an SR Policy with an intent via color, enabling headend-based steering of BGP service routes over SR Policies provisioned via PCEP.¶
"Path Computation Element Communication Protocol (PCEP) Extensions for Establishing Relationships between Sets of Label Switched Paths (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 candidate path is the unit for signaling an SR Policy to a headend as described in Section 2.2 of [RFC9256]. This document extends [RFC8664] to support signaling SR Policy Candidate Paths as LSPs and to signal Candidate Path membership in an SR Policy by means of the Association mechanism. A PCEP Association corresponds to an SR Policy and an LSP corresponds to a Candidate Path. The unit of signaling in PCEP is the LSP, thus, all the information related to an SR Policy is carried at the Candidate Path level.¶
Also, this document updates Section 5.8.2 of [RFC8231], making the use of Path Computation Request (PCReq) and Path Computation Reply (PCRep) messages optional for LSPs that are set up using Path Setup Type 1 (for Segment Routing) [RFC8664] and Path Setup Type 3 (for SRv6) [RFC9603] with the aim of reducing the PCEP message exchanges and simplifying implementation.¶
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.¶
This document uses the following terms defined in [RFC5440]:¶
This document uses the following term defined in [RFC3031]:¶
This document uses the following term defined in [RFC9552]:¶
The following other terms are used in this document:¶
The base PCEP specification [RFC4655] originally defined the use of the PCE architecture for MPLS and GMPLS networks with LSPs instantiated using the RSVP-TE signaling protocol. Over time, support for additional path setup types such as SRv6 has been introduced [RFC9603]. The term "LSP" is used extensively in PCEP specifications, and in the context of this document, refers to a Candidate Path within an SR Policy, which may be an SRv6 path (still represented using the LSP object as specified in [RFC8231]).¶
The SR Policy is represented by a new type of PCEP Association, called the SR Policy Association (SRPA) (see Section 4). The SR Policy Candidate Paths of a specific SR Policy are the LSPs within the same SRPA. The extensions in this document specify the encoding of a single segment list within an SR Policy Candidate Path. Encoding of multiple segment lists is outside the scope of this document and is specified in [PCEP-MULTIPATH].¶
An 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 an SRPA: computation priority of the LSP, Explicit Null Label Policy for the unlabeled IP packets and Drop-Upon-Invalid behavior for traffic steering when the LSP is operationally down (see Section 5).¶
Per [RFC8697], LSPs are associated with other LSPs with which they interact by adding them to a common association group. An association group is uniquely identified by the combination of the following fields in the ASSOCIATION object (Section 6.1 of [RFC8697]): Association Type, Association ID, Association Source, and (if present) Global Association Source, or Extended Association ID. These fields are referred to as "association parameters" (Section 4.4).¶
[RFC8697] specifies the ASSOCIATION object with two Object-Types for IPv4 and IPv6 that includes the field Association Type. This document defines a new Association Type (6) "SR Policy Association" for an 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 SRPA Type MUST be done before using the SRPA. To that aim, a 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 the SRPA (Section 6.1).¶
An SRPA MUST be assigned for all SR Policy LSPs by the PCEP speaker originating the LSP if the capability was advertised by both PCEP speakers. If the above condition is not satisfied, then the receiving PCEP speaker MUST send a PCErr message with:¶
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 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:¶
The existing behavior for the use of Binding SID (BSID) with an SR 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:¶
The SR Policy Identifier uniquely identifies an SR Policy [RFC9256] within the SR domain. The SR Policy Identifier is assigned by the PCEP peer originating the LSP and MUST be uniform across all the PCEP sessions. Candidate Paths within an SR Policy MUST carry the same SR Policy Identifiers in their SRPAs. Candidate Paths within an SR Policy MUST NOT change their SR Policy Identifiers for the lifetime of the PCEP session. If the above conditions are not satisfied, the receiving PCEP speaker MUST send a PCEP Error (PCErr) message with:¶
The SR Policy Identifier consists of:¶
Headend router where the SR Policy originates.¶
Color of the SR Policy ([RFC9256], Section 2.1).¶
Endpoint of the SR Policy ([RFC9256], Section 2.1).¶
The SR Policy Candidate Path Identifier uniquely identifies the SR Policy Candidate Path within the context of an SR Policy. The SR Policy Candidate Path Identifier is assigned by the PCEP peer originating the LSP. Candidate Paths within an SR Policy MUST NOT change their SR Policy Candidate Path Identifiers for the lifetime of the PCEP session. Two or more Candidate Paths within an SR Policy MUST NOT carry the same SR Policy Candidate Path Identifiers in their SRPAs. If the above conditions are not satisfied, the PCEP speaker MUST send a PCErr message with:¶
The SR Policy Candidate Path Identifier consists of:¶
Protocol-Origin ([RFC9256], Section 2.3)¶
Originator ([RFC9256], Section 2.4)¶
Discriminator ([RFC9256], Section 2.5)¶
SR Policy Candidate Path Attributes carry optional, non-key information about a Candidate Path and MAY change during the lifetime of an LSP. SR Policy Candidate Path Attributes consist of:¶
Candidate Path preference ([RFC9256], Section 2.7)¶
Candidate Path name ([RFC9256], Section 2.6)¶
SR Policy name ([RFC9256], Section 2.1)¶
Per Section 2.1 of [RFC9256], an SR Policy is identified through the <Headend, Color, Endpoint> tuple.¶
The association parameters consist of:¶
Mandatory TLV for an SRPA. Encodes the Color and Endpoint of the SR Policy (Figure 1).¶
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 ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
If a 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:¶
The encoding choice of the association parameters in this way is meant 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 parameters [RFC9256].¶
The last hop of a 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 be forwarded the rest of the path to the Endpoint node using the native Interior Gateway Protocol (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 headend to steer traffic with that Endpoint IP address into the SR Policy. The Destination of the SR Policy Candidate Path is signaled using the END-POINTS object and/or the LSP-IDENTIFIERS TLV, per the usual PCEP procedure. When neither the END-POINTS object nor the 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 Endpoint value set to unspecified, i.e., 0.0.0.0 for IPv4 or :: for IPv6, per Section 8.8 of [RFC9256].¶
The SRPA object may carry the following TLVs:¶
When a mandatory TLV is missing from an SRPA object, the PCEP speaker MUST send a PCErr message with:¶
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 be silently ignored.¶
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 Policy is limited to 255 bytes. Implementations MAY choose to truncate long names to 255 bytes to simplify interoperability with other protocols.¶
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 ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The SRPOLICY-CPATH-ID TLV (Figure 3) 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 Policy is limited to 255 bytes. Implementations MAY choose to truncate long names to 255 bytes to simplify interoperability with other protocols.¶
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 ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The SRPOLICY-CPATH-PREFERENCE TLV (Figure 5) is an optional TLV for the SRPA object. If the TLV is absent, then the default Preference value is 100, 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This section introduces mechanisms described for SR Policies in [RFC9256] to PCEP. These extensions do not make use of the SRPA for signaling in PCEP, and therefore cannot rely on the Association capability negotiation in the ASSOC-Type-List TLV and separate capability negotiation is required.¶
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.¶
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 with respect to SR Policy. Implementations that support SR Policy MUST include the SRPOLICY-CAPABILITY TLV in the OPEN object if the extension is enabled. 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 an 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 = 44 "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| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
32 bits. The following flags are currently defined:¶
Unassigned bits MUST be set to 0 on transmission and MUST be ignored on receipt. More flags can be assigned in the future per (Section 6.7).¶
This section is introducing three new TLVs to be carried in the LSP object introduced in Section 7.3 of [RFC8231].¶
The COMPUTATION-PRIORITY TLV (Figure 7) is an optional TLV. 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 that packet. 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 SR Policy manager as described in Section 4.1 of [RFC9256]. If an ENLP TLV is not 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 receiving 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The ENLP unassigned values may be used for future extensions, and implementations MUST ignore the ENLP TLV with unrecognized values. The behavior signaled in this TLV MAY be overridden by local configuration by the network operator based on their deployment requirements. Section 4.1 of [RFC9256] describes the behavior on the headend for the handling of the explicit null label.¶
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 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; 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 headend. Such an LSP is 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 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:¶
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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 by the PCC upon receipt. See Section 6.5 for IANA information.¶
0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ | |D| +-+-+-+-+-+-+-+-+
An 8-bit flag field that encodes the configuration of the LSP. See Section 6.6 for IANA information.¶
0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ | |D| +-+-+-+-+-+-+-+-+
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 Section 8.1 of [RFC9256], an SR Policy is invalid when all its Candidate Paths are 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 Drop-Upon-Invalid enabled. If so, the SR Policy enters the drop state and "activates" the highest preference Candidate Path that 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.¶
Section 5.8.2 of [RFC8231] 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 Section 5.8.2 of [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 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-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, Section 5.8.2 of [RFC8231] continues to apply.¶
IANA maintains the "Path Computation Element Protocol (PCEP) Numbers" registry at <https://www.iana.org/assignments/pcep>.¶
This document defines a new Association Type: SR Policy Association. IANA has made the following assignment in the "ASSOCIATION Type Field" registry within the "Path Computation Element Protocol (PCEP) Numbers" registry group:¶
| Type | Name | Reference |
|---|---|---|
| 6 | SR Policy Association | RFC 9862 |
This document defines eight new TLVs for carrying additional information about SR Policy and SR Policy Candidate Paths. IANA has made the following assignments in the existing "PCEP TLV Type Indicators" registry:¶
| Value | Description | Reference |
|---|---|---|
| 56 | SRPOLICY-POL-NAME | RFC 9862 |
| 57 | SRPOLICY-CPATH-ID | RFC 9862 |
| 58 | SRPOLICY-CPATH-NAME | RFC 9862 |
| 59 | SRPOLICY-CPATH-PREFERENCE | RFC 9862 |
| 68 | COMPUTATION-PRIORITY | RFC 9862 |
| 69 | EXPLICIT-NULL-LABEL-POLICY | RFC 9862 |
| 70 | INVALIDATION | RFC 9862 |
| 71 | SRPOLICY-CAPABILITY | RFC 9862 |
This document defines the following:¶
IANA has made the following assignments in 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 |
|---|---|---|---|
| 6 | Mandatory Object Missing | [RFC5440] | |
| 21: Missing SR Policy Mandatory TLV | RFC 9862 | ||
| 26 | Association Error | [RFC8697] | |
| 20: SR Policy Identifers Mismatch | RFC 9862 | ||
| 21: SR Policy Candidate Path Identifier Mismatch | RFC 9862 |
IANA has made the following assigments in 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 |
|---|---|---|---|
| 6 | Mandatory Object Missing | [RFC5440] | |
| 22: Missing SR Policy Association | RFC 9862 | ||
| 10 | Reception of an invalid object | [RFC5440] | |
| 44: Missing SRPOLICY-CAPABILITY TLV | RFC 9862 |
A draft version of this document added a new bit in the "TE-PATH-BINDING TLV Flag Field" registry of the "Path Computation Element Protocol (PCEP) Numbers" registry group, which was early allocated by IANA.¶
IANA has marked the bit position as deprecated.¶
| Bit | Description | Reference |
|---|---|---|
| 1 | Deprecated (Specified-BSID-only) | RFC 9862 |
IANA has created and will maintain a new registry under the "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 will be tracked with the following qualities:¶
| Bit | Description | Reference |
|---|---|---|
| 0 - 6 | Unassigned | |
| 7 | D: Dropping - the LSP is currently attracting traffic and actively dropping it. | RFC 9862 |
IANA has created and will maintain a new registry under the "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 will be tracked with the following qualities:¶
| Bit | Description | Reference |
|---|---|---|
| 0 - 6 | Unassigned. | |
| 7 | D: Drop enabled - the Drop-Upon-Invalid is enabled on the LSP. | RFC 9862 |
IANA has created and will maintain a new registry under the "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 will be tracked with the following qualities:¶
| 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 |
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.¶
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].¶
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.¶
A PCE or PCC implementation MAY allow the capabilities specified in Section 5.1 and the capability for support of an SRPA advertised in the ASSOC-Type-List TLV to be enabled and disabled.¶
[PCEP-SRv6-YANG] defines a YANG module with common building blocks for PCEP extensions described in Section 4.¶
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].¶
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 an SRPA object.¶
An implementation SHOULD allow the operator to view the capabilities defined in this document advertised by each PCEP peer.¶
An implementation SHOULD allow the operator to view LSPs associated with a specific SR Policy Identifier.¶
The PCEP extensions defined in this document do not imply any new requirements on other protocols.¶
The mechanisms defined in [RFC5440], [RFC8231], [RFC9256], and [RFC9603] also apply to the PCEP extensions defined in this document.¶
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.¶