Path Computation Element Communication Protocol (PCEP) Extensions for Segment Routing leveraging the IPv6 dataplane
draft-ietf-pce-segment-routing-ipv6-15
| Document | Type | Active Internet-Draft (pce WG) | |
|---|---|---|---|
| Authors | Cheng Li , Mahendra Singh Negi , Siva Sivabalan , Mike Koldychev , Prejeeth Kaladharan , Yongqing Zhu | ||
| Last updated | 2022-10-23 | ||
| Replaces | draft-negi-pce-segment-routing-ipv6 | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | WG state | WG Document | |
| Document shepherd | (None) | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-ietf-pce-segment-routing-ipv6-15
PCE Working Group C. Li
Internet-Draft Huawei Technologies
Intended status: Standards Track M. Negi
Expires: 26 April 2023 RtBrick Inc
S. Sivabalan
Ciena Corporation
M. Koldychev
Cisco Systems, Inc.
P. Kaladharan
RtBrick Inc
Y. Zhu
China Telecom
23 October 2022
Path Computation Element Communication Protocol (PCEP) Extensions for
Segment Routing leveraging the IPv6 dataplane
draft-ietf-pce-segment-routing-ipv6-15
Abstract
The Source Packet Routing in Networking (SPRING) architecture
describes how Segment Routing (SR) can be used to steer packets
through an IPv6 or MPLS network using the source routing paradigm.
SR enables any head-end node to select any path without relying on a
hop-by-hop signaling technique (e.g., LDP or RSVP-TE).
It depends only on "segments" that are advertised by Link-State IGPs.
A Segment Routed Path can be derived from a variety of mechanisms,
including an IGP Shortest Path Tree (SPT), explicit configuration, or
a PCE.
Since SR can be applied to both MPLS and IPv6 forwarding plane, a PCE
should be able to compute SR-Path for both MPLS and IPv6 forwarding
plane. This document describes the extensions required for SR
support for IPv6 data plane in Path Computation Element communication
Protocol (PCEP). The PCEP extension and mechanism to support SR-MPLS
is described in RFC 8664. This document extends it to support SRv6
(SR over IPv6).
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Internet-Drafts are working documents of the Internet Engineering
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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."
This Internet-Draft will expire on 26 April 2023.
Copyright Notice
Copyright (c) 2022 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 . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Overview of PCEP Operation in SRv6 Networks . . . . . . . . . 6
3.1. Operation Overview . . . . . . . . . . . . . . . . . . . 6
3.2. SRv6-Specific PCEP Message Extensions . . . . . . . . . . 7
4. Object Formats . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. The OPEN Object . . . . . . . . . . . . . . . . . . . . . 7
4.1.1. The SRv6 PCE Capability sub-TLV . . . . . . . . . . . 7
4.2. The RP/SRP Object . . . . . . . . . . . . . . . . . . . . 9
4.3. ERO . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.3.1. SRv6-ERO Subobject . . . . . . . . . . . . . . . . . 9
4.3.1.1. SID Structure . . . . . . . . . . . . . . . . . . 11
4.3.1.2. Order of the Optional fields . . . . . . . . . . 13
4.4. RRO . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.4.1. SRv6-RRO Subobject . . . . . . . . . . . . . . . . . 13
5. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1. Exchanging the SRv6 Capability . . . . . . . . . . . . . 14
5.2. ERO Processing . . . . . . . . . . . . . . . . . . . . . 15
5.2.1. SRv6 ERO Validation . . . . . . . . . . . . . . . . . 16
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5.2.2. Interpreting the SRv6-ERO . . . . . . . . . . . . . . 17
5.3. RRO Processing . . . . . . . . . . . . . . . . . . . . . 17
6. Security Considerations . . . . . . . . . . . . . . . . . . . 18
7. Manageability Considerations . . . . . . . . . . . . . . . . 18
7.1. Control of Function and Policy . . . . . . . . . . . . . 18
7.2. Information and Data Models . . . . . . . . . . . . . . . 18
7.3. Liveness Detection and Monitoring . . . . . . . . . . . . 19
7.4. Verify Correct Operations . . . . . . . . . . . . . . . . 19
7.5. Requirements On Other Protocols . . . . . . . . . . . . . 19
7.6. Impact On Network Operations . . . . . . . . . . . . . . 19
8. Implementation Status . . . . . . . . . . . . . . . . . . . . 19
8.1. Cisco's Commercial Delivery . . . . . . . . . . . . . . . 20
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
9.1. PCEP ERO and RRO subobjects . . . . . . . . . . . . . . . 20
9.2. New SRv6-ERO Flag Registry . . . . . . . . . . . . . . . 20
9.3. PATH-SETUP-TYPE-CAPABILITY Sub-TLV Type Indicators . . . 21
9.4. SRv6 PCE Capability Flags . . . . . . . . . . . . . . . . 21
9.5. New Path Setup Type . . . . . . . . . . . . . . . . . . . 22
9.6. ERROR Objects . . . . . . . . . . . . . . . . . . . . . . 22
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 23
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
11.1. Normative References . . . . . . . . . . . . . . . . . . 23
11.2. Informative References . . . . . . . . . . . . . . . . . 24
Appendix A. Contributor . . . . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
1. Introduction
As per [RFC8402], with Segment Routing (SR), a node steers a packet
through an ordered list of instructions, called segments. A segment
can represent any instruction, topological or service-based. A
segment can have a semantic local to an SR node or global within an
SR domain. SR allows to enforce a flow through any path and service
chain while maintaining per-flow state only at the ingress node of
the SR domain. Segments can be derived from different components:
IGP, BGP, Services, Contexts, Locater, etc. The list of segment
forming the path is called the Segment List and is encoded in the
packet header. Segment Routing can be applied to the IPv6
architecture with the Segment Routing Header (SRH) [RFC8754]. A
segment is encoded as an IPv6 address. An ordered list of segments
is encoded as an ordered list of IPv6 addresses in the routing
header. The active segment is indicated by the Destination Address
of the packet. Upon completion of a segment, a pointer in the new
routing header is incremented and indicates the next segment.
Segment Routing use cases are described in [RFC7855] and [RFC8354].
Segment Routing protocol extensions are defined in [RFC8667], and
[RFC8666].
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As per [RFC8754], an SRv6 Segment identifier is an 128-bit value.
"SRv6 SID" or simply "SID" are often used as a shorter reference for
"SRv6 Segment". Further details are in an illustration provided in
[RFC8986].
The SR architecture can be applied to the MPLS forwarding plane
without any change, in which case an SR path corresponds to an MPLS
Label Switching Path (LSP). The SR is applied to IPV6 forwarding
plane using Source Routing Header (SRH) [RFC8754]. A SR path can be
derived from an IGP Shortest Path Tree (SPT), but SR-TE paths may not
follow IGP SPT. Such paths may be chosen by a suitable network
planning tool, or a PCE and provisioned on the ingress node.
[RFC5440] describes Path Computation Element communication Protocol
(PCEP) for communication between a Path Computation Client (PCC) and
a Path Computation Element (PCE) or between a pair of PCEs. A PCE or
a PCC operating as a PCE (in hierarchical PCE environment) computes
paths for MPLS Traffic Engineering LSPs (MPLS-TE LSPs) based on
various constraints and optimization criteria. [RFC8231] specifies
extensions to PCEP that allow a stateful PCE to compute and recommend
network paths in compliance with [RFC4657] and defines objects and
TLVs for MPLS-TE LSPs. Stateful PCEP extensions provide
synchronization of LSP state between a PCC and a PCE or between a
pair of PCEs, delegation of LSP control, reporting of LSP state from
a PCC to a PCE, controlling the setup and path routing of an LSP from
a PCE to a PCC. Stateful PCEP extensions are intended for an
operational model in which LSPs are configured on the PCC, and
control over them is delegated to the PCE.
A mechanism to dynamically initiate LSPs on a PCC based on the
requests from a stateful PCE or a controller using stateful PCE is
specified in [RFC8281]. As per [RFC8664], it is possible to use a
stateful PCE for computing one or more SR-TE paths taking into
account various constraints and objective functions. Once a path is
chosen, the stateful PCE can initiate an SR-TE path on a PCC using
PCEP extensions specified in [RFC8281] using the SR specific PCEP
extensions specified in [RFC8664]. [RFC8664] specifies PCEP
extensions for supporting a SR-TE LSP for MPLS data plane. This
document extends [RFC8664] to support SR for IPv6 data plane.
Additionally, using procedures described in this document, a PCC can
request an SRv6 path from either stateful or a stateless PCE. This
specification relies on the PATH-SETUP-TYPE TLV and procedures
specified in [RFC8408].
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This specification provides a mechanism for a network controller
(acting as a PCE) to instantiate candidate paths for an SR Policy
onto a head-end node (acting as a PCC) using PCEP. For more
information on the SR Policy Architecture, see [RFC9256] which is
applicable to both SR-MPLS and SRv6.
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
This document uses the following terms defined in [RFC5440]: PCC,
PCE, PCEP, PCEP Peer.
This document uses the following terms defined in [RFC8051]: Stateful
PCE, Delegation.
The message formats in this document are specified using Routing
Backus-Naur Format (RBNF) encoding as specified in [RFC5511].
Further, following terms are used in the document:
MSD: Maximum SID Depth.
PST: Path Setup Type.
SR: Segment Routing.
SID: Segment Identifier.
SRv6: Segment Routing for IPv6 forwarding plane.
SRH: IPv6 Segment Routing Header.
SR Path: IPv6 Segment List (List of IPv6 SIDs representing a path in
IPv6 SR domain in the context of this document)
Further, note that the term LSP used in the PCEP specifications,
would be equivalent to a SRv6 Path (represented as a list of SRv6
segments) in the context of supporting SRv6 in PCEP.
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3. Overview of PCEP Operation in SRv6 Networks
Basic operations for PCEP speakers is as per [RFC8664]. SRv6 Paths
computed by a PCE can be represented as an ordered list of SRv6
segments of 128-bit value.
[RFC8664] defined a new Explicit Route Object (ERO) subobject denoted
by "SR-ERO subobject" capable of carrying a SID as well as the
identity of the node/adjacency represented by the SID for SR-MPLS.
SR-capable PCEP speakers should be able to generate and/or process
such an ERO subobject. An ERO containing SR-ERO subobjects can be
included in the PCEP Path Computation Reply (PCRep) message defined
in [RFC5440], the PCEP LSP Initiate Request message (PCInitiate)
defined in [RFC8281], as well as in the PCEP LSP Update Request
(PCUpd) and PCEP LSP State Report (PCRpt) messages defined in defined
in [RFC8231].
This document define new subobjects "SRv6-ERO" and "SRv6-RRO" in the
ERO and the RRO respectively to carry the SRv6 SID (IPv6 Address).
SRv6-capable PCEP speakers MUST be able to generate and/or process
these subobjects.
When a PCEP session between a PCC and a PCE is established, both PCEP
speakers exchange their capabilities to indicate their ability to
support SRv6 specific functionality as described in Section 4.1.1.
In summary, this document:
* Defines a new PCEP capability for SRv6.
* Defines a new subobject SRv6-ERO in ERO.
* Defines a new subobject SRv6-RRO in RRO.
* Defines a new path setup type (PST) [RFC8408] carried in the PATH-
SETUP-TYPE TLV and the PATH-SETUP-TYPE-CAPABILITY TLV.
3.1. Operation Overview
In SR networks, an ingress node of an SR path appends all outgoing
packets with an SR header consisting of a list of SIDs (IPv6 Prefix
in case of SRv6). The header has all necessary information to guide
the packets from the ingress node to the egress node of the path, and
hence there is no need for any signaling protocol.
For the use of IPv6 in control plane only with MPLS data plane,
mechanism remains the same as specified in [RFC8664].
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This document describes an extension to the SR path for the IPv6 data
plane. SRv6 Path (i.e. ERO) consists of an ordered set of SRv6 SIDs
(see details in Figure 2).
A PCC or PCE indicates its ability to support SRv6 during the PCEP
session Initialization Phase via a new SRv6-PCE-CAPABILITY sub-TLV
(see details in Section 4.1.1).
3.2. SRv6-Specific PCEP Message Extensions
As defined in [RFC5440], a PCEP message consists of a common header
followed by a variable length body made up of mandatory and/or
optional objects. This document does not require any changes in the
format of PCReq and PCRep messages specified in [RFC5440], PCInitiate
message specified in [RFC8281], and PCRpt and PCUpd messages
specified in [RFC8231]. However, PCEP messages pertaining to SRv6
MUST include PATH-SETUP-TYPE TLV in the RP or SRP object to clearly
identify that SRv6 is intended.
4. Object Formats
4.1. The OPEN Object
4.1.1. The SRv6 PCE Capability sub-TLV
This document defines a new Path Setup Type (PST) [RFC8408] for SRv6,
as follows:
* PST = 3 (early allocated by IANA): Path is setup using SRv6.
A PCEP speaker MUST indicate its support of the function described in
this document by sending a PATH-SETUP-TYPE-CAPABILITY TLV in the OPEN
object with this new PST "3" included in the PST list.
This document also defines the SRv6-PCE-CAPABILITY sub-TLV. PCEP
speakers use this sub-TLV to exchange information about their SRv6
capability. If a PCEP speaker includes PST=3 (early allocated by
IANA) in the PST List of the PATH-SETUP-TYPE-CAPABILITY TLV then it
MUST also include the SRv6-PCE-CAPABILITY sub-TLV inside the PATH-
SETUP-TYPE-CAPABILITY TLV.
The format of the SRv6-PCE-CAPABILITY sub-TLV is shown in the
following figure:
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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=27 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags |N|X|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MSD-Type | MSD-Value | MSD-Type | MSD-Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// ... //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MSD-Type | MSD-Value | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: SRv6-PCE-CAPABILITY sub-TLV format
The code point for the TLV type is 27 (early allocated by IANA). The
TLV length is variable.
The value comprises of -
Reserved: 2 octet, this field MUST be set to 0 on transmission,
and ignored on receipt.
Flags: 2 octet, two bits are currently assigned in this document.
- N bit: A PCC sets this flag bit to 1 to indicate that it is
capable of resolving a Node or Adjacency Identifier (NAI) to a
SRv6-SID.
- X bit: A PCC sets this bit to 1 to indicate that it does not
impose any limit on MSD (irrespective of the MSD-Type).
- Unassigned bits MUST be set to 0 and ignored on receipt.
A pair of (MSD-Type, MSD-Value): Where MSD-Type (1 octet) is as
per the IGP MSD Type registry created by [RFC8491] and populated
with SRv6 MSD types as per [I-D.ietf-lsr-isis-srv6-extensions];
MSD-Value (1 octet) is as per [RFC8491].
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This sub-TLV format is compliant with the PCEP TLV format defined in
[RFC5440]. That is, the sub-TLV is composed of 2 octets for the
type, 2 octets specifying the length, and a Value field. The Type
field when set to 27 (early allocated by IANA) identifies the SRv6-
PCE-CAPABILITY sub-TLV and the presence of the sub-TLV indicates the
support for the SRv6 paths in PCEP. The Length field defines the
length of the value portion in octets. The TLV is padded to 4-octet
alignment, and padding is not included in the Length field. The
number of (MSD-Type,MSD-Value) pairs can be determined from the
Length field of the TLV.
4.2. The RP/SRP Object
In order to indicate the SRv6 path, RP or SRP object MUST include the
PATH-SETUP-TYPE TLV specified in [RFC8408]. This document defines a
new Path Setup Type (PST=3 (early allocated by IANA)) for SRv6.
The LSP-IDENTIFIERS TLV MAY be present for the above PST type.
4.3. ERO
In order to support SRv6, new subobject "SRv6-ERO" is defined in ERO.
4.3.1. SRv6-ERO Subobject
An SRv6-ERO subobject is formatted as shown in the following figure.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type=40 | Length | NT | Flags |V|T|F|S|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Endpoint Behavior |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| SRv6 SID (optional) |
| (128-bit) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// NAI (variable, optional) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID Structure (optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: SRv6-ERO Subobject Format
The fields in the SRv6-ERO subobject are as follows:
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The 'L' Flag: Indicates whether the subobject represents a loose-hop
(see [RFC3209]). If this flag is set to zero, a PCC MUST NOT
overwrite the SID value present in the SRv6-ERO subobject.
Otherwise, a PCC MAY expand or replace one or more SID values in the
received SRv6-ERO based on its local policy.
Type: indicates the content of the subobject, i.e. when the field is
set to 40 (early allocated by IANA), the suboject is a SRv6-ERO
subobject representing a SRv6 SID.
Length: Contains the total length of the subobject in octets. The
Length MUST be at least 24, and MUST be a multiple of 4. An SRv6-ERO
subobject MUST contain at least one of a SRv6-SID or an NAI. The S
and F bit in the Flags field indicates whether the SRv6-SID or NAI
fields are absent.
NAI Type (NT): Indicates the type and format of the NAI contained in
the object body, if any is present. If the F bit is set to one (see
below) then the NT field has no meaning and MUST be ignored by the
receiver. This document reuses NT types defined in [RFC8664]:
If NT value is 0, the NAI MUST NOT be included.
When NT value is 2, the NAI is as per the 'IPv6 Node ID' format
defined in [RFC8664], which specifies an IPv6 address. This is
used to identify the owner of the SRv6 Identifier. This is
optional, as the LOC (the locater portion) of the SRv6 SID serves
a similar purpose (when present).
When NT value is 4, the NAI is as per the 'IPv6 Adjacency' format
defined in [RFC8664], which specify a pair of IPv6 addresses.
This is used to identify the IPv6 Adjacency and used with the SRv6
Adj-SID.
When NT value is 6, the NAI is as per the 'link-local IPv6
addresses' format defined in [RFC8664], which specify a pair of
(global IPv6 address, interface ID) tuples. It is used to
identify the IPv6 Adjacency and used with the SRv6 Adj-SID.
SR-MPLS specific NT types are not valid in SRv6-ERO.
Flags: Used to carry additional information pertaining to the
SRv6-SID. This document defines the following flag bits. The other
bits MUST be set to zero by the sender and MUST be ignored by the
receiver.
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* S: When this bit is set to 1, the SRv6-SID value in the subobject
body is absent. In this case, the PCC is responsible for choosing
the SRv6-SID value, e.g., by looking up in the SR-DB using the NAI
which, in this case, MUST be present in the subobject. If the S
bit is set to 1 then F bit MUST be set to zero.
* F: When this bit is set to 1, the NAI value in the subobject body
is absent. The F bit MUST be set to 1 if NT=0, and otherwise MUST
be set to zero. The S and F bits MUST NOT both be set to 1.
* T: When this bit is set to 1, the SID Structure value in the
subobject body is present. The T bit MUST be set to 0 when S bit
is set to 1. If the T bit is set when the S bit is set, the T bit
MUST be ignored. Thus, the T bit indicates the presence of an
optional 8-byte SID Structure when SRv6 SID is included. The SID
Structure is defined in Section 4.3.1.1.
* V: The "SID verification" bit usage is as per Section 5.1 of
[RFC9256].
Reserved: MUST be set to zero while sending and ignored on receipt.
Endpoint Behavior: A 16-bit field representing the behavior
associated with the SRv6 SIDs. This information is optional and
plays no role in the fields in SRH imposed on the packet. It could
be used for maintainability and diagnostic purpose. If behavior is
not known, the value '0' is used. The list of Endpoint behaviors are
defined in [RFC8986].
SRv6 SID: SRv6 Identifier is an 128-bit IPv6 addresses representing
the SRv6 segment.
NAI: The NAI associated with the SRv6-SID. The NAI's format depends
on the value in the NT field, and is described in [RFC8664].
At least one of the SRv6-SID or the NAI MUST be included in the
SRv6-ERO subobject, and both MAY be included.
4.3.1.1. SID Structure
The SID Structure is an optional part of the SR-ERO subobject, as
described in Section 4.3.1.
[RFC8986] defines an SRv6 SID as consisting of LOC:FUNCT:ARG, where a
locator (LOC) is encoded in the L most significant bits of the SID,
followed by F bits of function (FUNCT) and A bits of arguments (ARG).
A locator may be represented as B:N where B is the SRv6 SID locator
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block (IPv6 prefix allocated for SRv6 SIDs by the operator) and N is
the identifier of the parent node instantiating the SID called
locator node.
It is formatted as shown in the following figure.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LB Length | LN Length | Fun. Length | Arg. Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: SID Structure Format
where:
LB Length: 1 octet. SRv6 SID Locator Block length in bits.
LN Length: 1 octet. SRv6 SID Locator Node length in bits.
Fun. Length: 1 octet. SRv6 SID Function length in bits.
Arg. Length: 1 octet. SRv6 SID Arguments length in bits.
The sum of all four sizes in the SID Structure must be lower or equal
to 128 bits. If the sum of all four sizes advertised in the SID
Structure is larger than 128 bits, the corresponding SRv6 SID MUST be
considered invalid and a PCErr message with Error-Type = 10
("Reception of an invalid object") and Error-Value = 37 (early
allocated by IANA) ("Invalid SRv6 SID Structure") is returned.
Reserved: MUST be set to zero while sending and ignored on receipt.
Flags: Currently no flags are defined. Unassigned bits must be set
to zero while sending and ignored on receipt.
The SRv6 SID Structure provides the detailed encoding information of
an SRv6 SID, which is useful in the use cases that require to know
the SRv6 SID structure. When a PCEP speaker receives the SRv6 SID
and its structure information, the SRv6 SID can be parsed based on
the SRv6 SID Structure and/or possible local policies. The SRv6 SID
Structure could be used by the PCE for ease of operations and
monitoring. For example, this information could be used for
validation of SRv6 SIDs being instantiated in the network and checked
for conformance to the SRv6 SID allocation scheme chosen by the
operator as described in Section 3.2 of [RFC8986]. In the future,
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PCE could also be used for verification and the automation for
securing the SRv6 domain by provisioning filtering rules at SR domain
boundaries as described in Section 5 of [RFC8754]. The details of
these potential applications are outside the scope of this document.
4.3.1.2. Order of the Optional fields
The optional elements in the SRv6-ERO subobject i.e. SRv6 SID, NAI
and the SID Structure MUST be encoded in the order as depicted in
Figure 2. The presence of each of them is indicated by the
respective flags i.e. S flag, F flag and T flag.
To allow for future compatibility, any optional element added to the
SRv6-ERO subobject in future MUST specify the order of the optional
element and request IANA to allocate a flag to indicate its presence
from the subregistry created in Section 9.2.
4.4. RRO
In order to support SRv6, new subobject "SRv6-RRO" is defined in RRO.
4.4.1. SRv6-RRO Subobject
A PCC reports an SRv6 path to a PCE by sending a PCRpt message, per
[RFC8231]. The RRO on this message represents the SID list that was
applied by the PCC, that is, the actual path taken. The procedures
of [RFC8664] with respect to the RRO apply equally to this
specification without change.
An RRO contains one or more subobjects called "SRv6-RRO subobjects"
whose format is shown below:
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=40 | Length | NT | Flags |V|T|F|S|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Endpoint Behavior |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| SRv6 SID |
| (128-bit) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// NAI (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID Structure (optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Figure 4: SRv6-RRO Subobject Format
The format of the SRv6-RRO subobject is the same as that of the
SRv6-ERO subobject, but without the L flag.
The V flag has no meaning in the SRv6-RRO and is ignored on receipt
at the PCE.
Ordering of SRv6-RRO subobjects by PCC in PCRpt message remains as
per [RFC8664].
The ordering of optional elements in the SRv6-RRO subobject as same
as described in Section 4.3.1.2.
5. Procedures
5.1. Exchanging the SRv6 Capability
A PCC indicates that it is capable of supporting the head-end
functions for SRv6 by including the SRv6-PCE-CAPABILITY sub-TLV in
the Open message that it sends to a PCE. A PCE indicates that it is
capable of computing SRv6 paths by including the SRv6-PCE-CAPABILITY
sub-TLV in the Open message that it sends to a PCC.
If a PCEP speaker receives a PATH-SETUP-TYPE-CAPABILITY TLV with a
PST list containing PST=3 (early allocated by IANA), but the SRv6-
PCE-CAPABILITY sub-TLV is absent, then the PCEP speaker MUST send a
PCErr message with Error- Type = 10 (Reception of an invalid object)
and Error-Value = 34 (early allocated by IANA) (Missing PCE-
SRv6-CAPABILITY sub-TLV) and MUST then close the PCEP session. If a
PCEP speaker receives a PATH-SETUP- TYPE-CAPABILITY TLV with a SRv6-
PCE-CAPABILITY sub-TLV, but the PST list does not contain PST=3
(early allocated by IANA), then the PCEP speaker MUST ignore the
SRv6-PCE-CAPABILITY sub-TLV.
The number of SRv6 SIDs that can be imposed on a packet depends on
the PCC's IPv6 data plane's capability. If a PCC sets the X flag to
1 then the MSD is not used and MUST NOT be included. If a PCE
receives an SRv6-PCE-CAPABILITY sub-TLV with the X flag set to 1 then
it MUST ignore any MSD-Type, MSD-Value fields and MUST assume that
the sender can impose any length of SRH. If a PCC sets the X flag to
zero, then it sets the SRv6 MSD-Type, MSD-Value fields that it can
impose on a packet. If a PCE receives an SRv6-PCE-CAPABILITY sub-TLV
with the X flag as set, and SRv6 MSD-Type or MSD-Value fields are set
to zero then it is considered as an error and the PCE MUST respond
with a PCErr message (Error-Type = 1 "PCEP session establishment
failure" and Error-Value = 1 "reception of an invalid Open message or
a non Open message."). In case the MSD-Type in SRv6-PCE-CAPABILITY
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sub-TLV received by the PCE does not correspond to one of the SRv6
MSD types, the PCE MUST respond with a PCErr message (Error-Type = 1
"PCEP session establishment failure" and Error-Value = 1 "reception
of an invalid Open message or a non Open message.").
Note that the MSD-Type, MSD-Value exchanged via the SRv6-PCE-
CAPABILITY sub-TLV indicates the SRv6 SID imposition limit for the
PCC node. However, if a PCE learns these via different means, e.g
routing protocols, as specified in:
[I-D.ietf-lsr-ospfv3-srv6-extensions];
[I-D.ietf-lsr-isis-srv6-extensions]; [I-D.ietf-idr-bgpls-srv6-ext],
then it ignores the values in the SRv6-PCE-CAPABILITY sub-TLV.
Furthermore, whenever a PCE learns the other advanced SRv6 MSD via
different means, it MUST use that value regardless of the values
exchanged in the SRv6-PCE-CAPABILITY sub-TLV.
Once an SRv6-capable PCEP session is established with a non-zero SRv6
MSD value, the corresponding PCE MUST NOT send SRv6 paths with a
number of SIDs exceeding that SRv6 MSD value (based on the SRv6 MSD
Type). If a PCC needs to modify the SRv6 MSD value, it MUST close
the PCEP session and re-establish it with the new value. If a PCEP
session is established with a non-zero SRv6 MSD value, and the PCC
receives an SRv6 path containing more SIDs than specified in the SRv6
MSD value (based on the SRv6 MSD type), the PCC MUST send a PCErr
message with Error-Type = 10 (Reception of an invalid object) and
Error-Value = TBD1 (Unsupported number of SRv6-ERO subobjects). If a
PCEP session is established with an SRv6 MSD value of zero, then the
PCC MAY specify an SRv6 MSD for each path computation request that it
sends to the PCE, by including a "maximum SID depth" metric object on
the request similar to [RFC8664].
The N flag, X flag and (MSD-Type,MSD-Value) pair inside the SRv6-PCE-
CAPABILITY sub-TLV are meaningful only in the Open message sent from
a PCC to a PCE. As such, a PCE MUST set the flags to zero and not
include any (MSD-Type,MSD-Value) pair in the SRv6-PCE-CAPABILITY sub-
TLV in an outbound message to a PCC. Similarly, a PCC MUST ignore
N,X flag and any (MSD-Type,MSD-Value) pair received from a PCE. If a
PCE receives multiple SRv6-PCE-CAPABILITY sub-TLVs in an Open
message, it processes only the first sub-TLV received.
5.2. ERO Processing
The ERO processing remains as per [RFC5440] and [RFC8664].
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5.2.1. SRv6 ERO Validation
If a PCC does not support the SRv6 PCE Capability and thus cannot
recognize the SRv6-ERO or SRv6-RRO subobjects, it will respond
according to the rules for a malformed object per [RFC5440].
On receiving an SRv6-ERO, a PCC MUST validate that the Length field,
the S bit, the F bit, the T bit, and the NT field are consistent, as
follows.
* If NT=0, the F bit MUST be 1, the S bit MUST be zero and the
Length MUST be 24.
* If NT=2, the F bit MUST be zero. If the S bit is 1, the Length
MUST be 24, otherwise the Length MUST be 40.
* If NT=4, the F bit MUST be zero. If the S bit is 1, the Length
MUST be 40, otherwise the Length MUST be 56.
* If NT=6, the F bit MUST be zero. If the S bit is 1, the Length
MUST be 48, otherwise the Length MUST be 64.
* NT types (1,3, and 5) are not valid for SRv6.
* If T bit is 1, then S bit MUST be zero.
If a PCC finds that the NT field, Length field, S bit, F bit, and T
bit are not consistent, it MUST consider the entire ERO invalid and
MUST send a PCErr message with Error-Type = 10 ("Reception of an
invalid object") and Error-Value = 11 ("Malformed object").
If a PCC does not recognize or support the value in the NT field, it
MUST consider the entire ERO invalid and MUST send a PCErr message
with Error-Type = 10 ("Reception of an invalid object") and Error-
value = TBD2 ("Unsupported NAI Type in the SRv6-ERO/SRv6-RRO
subobject").
If a PCC receives an SRv6-ERO subobject in which the S and F bits are
both set to 1 (that is, both the SID and NAI are absent), it MUST
consider the entire ERO invalid and send a PCErr message with Error-
Type = 10 ("Reception of an invalid object") and Error-value = TBD3
("Both SID and NAI are absent in the SRv6-ERO subobject").
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If a PCC receives an SRv6-ERO subobject in which the S bit is set to
1 and the F bit is set to zero (that is, the SID is absent and the
NAI is present), but the PCC does not support NAI resolution, it MUST
consider the entire ERO invalid and send a PCErr message with Error-
Type = 4 ("Not supported object") and Error-value = 4 ("Unsupported
parameter").
If a PCC detects that the subobjects of an ERO are a mixture of SRv6-
ERO subobjects and subobjects of other types, then it MUST send a
PCErr message with Error-Type = 10 ("Reception of an invalid object")
and Error-value = TBD4 ("ERO mixes SRv6-ERO subobjects with other
subobject types").
In case a PCEP speaker receives the SRv6-ERO subobject, when the PST
is not set to 3 (early allocated by IANA) or SRv6-PCE-CAPABILITY sub-
TLV was not exchanged, it MUST send a PCErr message with Error-Type =
19 ("Invalid Operation") and Error-Value = 19 (early allocated by
IANA) ("Attempted SRv6 when the capability was not advertised").
If a PCC receives a list of SRv6 segments, and the number of SRv6
segments exceeds the SRv6 MSD that the PCC can impose on the packet
(SRH), it MUST send a PCErr message with Error-Type = 10 ("Reception
of an invalid object") and Error-Value = TBD5 ("Unsupported number of
SRv6-ERO subobjects") as per [RFC8664].
5.2.2. Interpreting the SRv6-ERO
The SRv6-ERO contains a sequence of subobjects. According to
[RFC9256], each SRv6-ERO subobject in the sequence identifies a
segment that the traffic will be directed to, in the order given.
That is, the first subobject identifies the first segment the traffic
will be directed to, the second SRv6-ERO subobject represents the
second segment, and so on.
The PCC interprets the SRv6-ERO by converting it to an SRv6 SRH plus
a next hop. The PCC sends packets along the segment routed path by
prepending the SRH onto the packets and sending the resulting,
modified packet to the next hop.
5.3. RRO Processing
The syntax checking rules that apply to the SRv6-RRO subobject are
identical to those of the SRv6-ERO subobject, except as noted below.
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If a PCEP speaker receives an SRv6-RRO subobject in which both SRv6
SID and NAI are absent, it MUST consider the entire RRO invalid and
send a PCErr message with Error-Type = 10 ("Reception of an invalid
object") and Error-Value = 35 (early allocated by IANA) ("Both SID
and NAI are absent in SRv6-RRO subobject").
If a PCE detects that the subobjects of an RRO are a mixture of
SRv6-RRO subobjects and subobjects of other types, then it MUST send
a PCErr message with Error-Type = 10 ("Reception of an invalid
object") and Error-Value = 36 (early allocated by IANA) ("RRO mixes
SRv6-RRO subobjects with other subobject types").
6. Security Considerations
The security considerations described in [RFC5440], [RFC8231] and
[RFC8281], [RFC8664], are applicable to this specification. No
additional security measure is required.
Note that this specification enables a network controller to
instantiate an SRv6 path in the network. This creates an additional
vulnerability if the security mechanisms of [RFC5440], [RFC8231], and
[RFC8281] are not used. If there is no integrity protection on the
session, then an attacker could create an SRv6 path that may not
subjected to the further verification checks. Further, the MSD field
in the Open message could disclose node forwarding capabilities if
suitable security mechanisms are not in place.
7. Manageability Considerations
All manageability requirements and considerations listed in
[RFC5440], [RFC8231], [RFC8281], and [RFC8664] apply to PCEP protocol
extensions defined in this document. In addition, requirements and
considerations listed in this section apply.
7.1. Control of Function and Policy
A PCEP implementation SHOULD allow the operator to configure the SRv6
capability. Further a policy to accept NAI only for the SRv6 SHOULD
be allowed to set.
7.2. Information and Data Models
The PCEP YANG module is defined in [I-D.ietf-pce-pcep-yang]. An
augmented YANG module for SRv6 is specified in
[I-D.li-pce-pcep-srv6-yang] that allows for SRv6 capability and MSD
configurations as well as to monitor the SRv6 paths set in the
network.
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7.3. 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].
7.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
[RFC5440], [RFC8231], and [RFC8664].
7.5. Requirements On Other Protocols
Mechanisms defined in this document do not imply any new requirements
on other protocols.
7.6. Impact On Network Operations
Mechanisms defined in [RFC5440], [RFC8231], and [RFC8664] also apply
to PCEP extensions defined in this document.
8. Implementation Status
[Note to the RFC Editor - remove this section before publication, as
well as remove the reference to [RFC7942].
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".
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8.1. Cisco's Commercial Delivery
* Organization: Cisco Systems, Inc.
* Implementation: IOS-XR PCE and PCC.
* Description: Implementation with experimental codepoints.
* Maturity Level: Production
* Coverage: Partial
* Contact: ssidor@cisco.com
9. IANA Considerations
9.1. PCEP ERO and RRO subobjects
This document defines a new subobject type for the PCEP explicit
route object (ERO), and a new subobject type for the PCEP record
route object (RRO). The code points for subobject types of these
objects is maintained in the RSVP parameters registry, under the
EXPLICIT_ROUTE and ROUTE_RECORD objects. IANA is requested to
confirm the following early allocations in the RSVP Parameters
registry for each of the new subobject types defined in this
document.
Object Subobject Subobject Type
--------------------- -------------------------- ------------------
EXPLICIT_ROUTE SRv6-ERO (PCEP-specific) 40
ROUTE_RECORD SRv6-RRO (PCEP-specific) 40
9.2. New SRv6-ERO Flag Registry
IANA is requested to create a new sub-registry, named "SRv6-ERO Flag
Field", within the "Path Computation Element Protocol (PCEP) Numbers"
registry to manage the Flag field of the SRv6-ERO subobject. New
values are to be assigned by Standards Action [RFC8126]. Each bit
should be tracked with the following qualities:
* Bit number (counting from bit 0 as the most significant bit)
* Capability description
* Defining RFC
The following values are defined in this document:
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Bit Description Reference
----- ------------------ --------------
0-7 Unassigned
8 SID Verification (V) This document
9 SID Structure is This document
present (T)
10 NAI is absent (F) This document
11 SID is absent (S) This document
9.3. PATH-SETUP-TYPE-CAPABILITY Sub-TLV Type Indicators
IANA maintains a sub-registry, named "PATH-SETUP-TYPE-CAPABILITY Sub-
TLV Type Indicators", within the "Path Computation Element Protocol
(PCEP) Numbers" registry to manage the type indicator space for sub-
TLVs of the PATH-SETUP-TYPE-CAPABILITY TLV. IANA is requested to
confirm the following early allocations in the sub-registry:
Value Meaning Reference
----- ------- ---------
27 SRv6-PCE-CAPABILITY This Document
9.4. SRv6 PCE Capability Flags
IANA is requested to create a new sub-registry, named "SRv6
Capability Flag Field", within the "Path Computation Element Protocol
(PCEP) Numbers" registry to manage the Flag field of the SRv6-PCE-
CAPABILITY sub-TLV. New values are to be assigned by Standards
Action [RFC8126]. Each bit should be tracked with the following
qualities:
* Bit number (counting from bit 0 as the most significant bit)
* Capability description
* Defining RFC
The following values are defined in this document:
Bit Description Reference
0-13 Unassigned
14 Node or Adjacency This document
Identifier (NAI) is
supported (N)
15 Unlimited Maximum SID This document
Depth (X)
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9.5. New Path Setup Type
[RFC8408] created a sub-registry within the "Path Computation Element
Protocol (PCEP) Numbers" registry called "PCEP Path Setup Types".
IANA is requested to confirm the following early allocations in the
sub-registry:
Value Description Reference
----- ----------- ---------
3 Traffic engineering path is This Document
setup using SRv6.
9.6. ERROR Objects
IANA is requested to confirm the following early allocations in the
PCEP-ERROR Object Error Types and Values registry for the following
new error-values:
Error-Type Meaning
---------- -------
10 Reception of an invalid object
Error-value = 34 (Missing
PCE-SRv6-CAPABILITY sub-TLV)
Error-value = 35 (Both SID and NAI are absent
in SRv6-RRO subobject)
Error-value = 36 (RRO mixes SRv6-RRO subobjects
with other subobject types)
Error-value = 37 (Invalid SRv6 SID Structure)
19 Invalid Operation
Error-value = 19 (Attempted SRv6 when the
capability was not advertised)
IANA is requested to make a new allocations in the PCEP-ERROR Object
Error Types and Values registry for the following new error-values:
Error-Type Meaning
---------- -------
10 Reception of an invalid object
Error-value = TBD1 (Unsupported number of
SRv6-ERO subobjects)
Error-value = TBD2 (Unsupported NAI Type
in the SRv6-ERO/SRv6-RRO subobject)
Error-value = TBD3 (Both SID and NAI are
absent in the SRv6-ERO subobject)
Error-value = TBD4 (ERO mixes SRv6-ERO
subobjects with other subobject types)
Error-value = TBD5 (Unsupported number
of SRv6-ERO subobjects)
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10. Acknowledgements
The authors would like to thank Jeff Tantsura, Adrian Farrel, Aijun
Wang, Khasanov Boris, and Robert Varga for valuable 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>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>.
[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>.
[RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax
Used to Form Encoding Rules in Various Routing Protocol
Specifications", RFC 5511, DOI 10.17487/RFC5511, April
2009, <https://www.rfc-editor.org/info/rfc5511>.
[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>.
[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>.
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[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>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[RFC8408] Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J.
Hardwick, "Conveying Path Setup Type in PCE Communication
Protocol (PCEP) Messages", RFC 8408, DOI 10.17487/RFC8408,
July 2018, <https://www.rfc-editor.org/info/rfc8408>.
[RFC8491] Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg,
"Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491,
DOI 10.17487/RFC8491, November 2018,
<https://www.rfc-editor.org/info/rfc8491>.
[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>.
[RFC8986] Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer,
D., Matsushima, S., and Z. Li, "Segment Routing over IPv6
(SRv6) Network Programming", RFC 8986,
DOI 10.17487/RFC8986, February 2021,
<https://www.rfc-editor.org/info/rfc8986>.
[I-D.ietf-lsr-isis-srv6-extensions]
Psenak, P., Filsfils, C., Bashandy, A., Decraene, B., and
Z. Hu, "IS-IS Extensions to Support Segment Routing over
IPv6 Dataplane", Work in Progress, Internet-Draft, draft-
ietf-lsr-isis-srv6-extensions-18, 20 October 2021,
<https://www.ietf.org/archive/id/draft-ietf-lsr-isis-srv6-
extensions-18.txt>.
11.2. Informative References
[RFC4657] Ash, J., Ed. and J.L. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol Generic
Requirements", RFC 4657, DOI 10.17487/RFC4657, September
2006, <https://www.rfc-editor.org/info/rfc4657>.
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[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>.
[RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B.,
Litkowski, S., Horneffer, M., and R. Shakir, "Source
Packet Routing in Networking (SPRING) Problem Statement
and Requirements", RFC 7855, DOI 10.17487/RFC7855, May
2016, <https://www.rfc-editor.org/info/rfc7855>.
[RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a
Stateful Path Computation Element (PCE)", RFC 8051,
DOI 10.17487/RFC8051, January 2017,
<https://www.rfc-editor.org/info/rfc8051>.
[RFC8354] Brzozowski, J., Leddy, J., Filsfils, C., Maglione, R.,
Ed., and M. Townsley, "Use Cases for IPv6 Source Packet
Routing in Networking (SPRING)", RFC 8354,
DOI 10.17487/RFC8354, March 2018,
<https://www.rfc-editor.org/info/rfc8354>.
[RFC8666] Psenak, P., Ed. and S. Previdi, Ed., "OSPFv3 Extensions
for Segment Routing", RFC 8666, DOI 10.17487/RFC8666,
December 2019, <https://www.rfc-editor.org/info/rfc8666>.
[RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C.,
Bashandy, A., Gredler, H., and B. Decraene, "IS-IS
Extensions for Segment Routing", RFC 8667,
DOI 10.17487/RFC8667, December 2019,
<https://www.rfc-editor.org/info/rfc8667>.
[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/info/rfc8754>.
[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>.
[I-D.ietf-lsr-ospfv3-srv6-extensions]
Li, Z., Hu, Z., Talaulikar, K., and P. Psenak, "OSPFv3
Extensions for SRv6", Work in Progress, Internet-Draft,
draft-ietf-lsr-ospfv3-srv6-extensions-08, 14 September
2022, <https://www.ietf.org/archive/id/draft-ietf-lsr-
ospfv3-srv6-extensions-08.txt>.
Li, et al. Expires 26 April 2023 [Page 25]
Internet-Draft PCEP-SRv6 October 2022
[I-D.ietf-idr-bgpls-srv6-ext]
Dawra, G., Filsfils, C., Talaulikar, K., Chen, M.,
Bernier, D., and B. Decraene, "BGP Link State Extensions
for SRv6", Work in Progress, Internet-Draft, draft-ietf-
idr-bgpls-srv6-ext-11, 14 October 2022,
<https://www.ietf.org/archive/id/draft-ietf-idr-bgpls-
srv6-ext-11.txt>.
[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-20, 23 October
2022, <https://datatracker.ietf.org/api/v1/doc/document/
draft-ietf-pce-pcep-yang/>.
[I-D.li-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-li-pce-pcep-srv6-yang-07, 11 July
2022, <https://www.ietf.org/archive/id/draft-li-pce-pcep-
srv6-yang-07.txt>.
Appendix A. Contributor
The following persons contributed to this document:
Li, et al. Expires 26 April 2023 [Page 26]
Internet-Draft PCEP-SRv6 October 2022
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
EMail: dhruv.ietf@gmail.com
Huang Wumin
Huawei Technologies
Huawei Building, No. 156 Beiqing Rd.
Beijing 100095
China
Email: huangwumin@huawei.com
Shuping Peng
Huawei Technologies
Huawei Building, No. 156 Beiqing Rd.
Beijing 100095
China
Email: pengshuping@huawei.com
Authors' Addresses
Cheng Li(Editor)
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing
100095
China
Email: c.l@huawei.com
Mahendra Singh Negi
RtBrick Inc
Bangalore
Karnataka
India
Email: mahend.ietf@gmail.com
Siva Sivabalan
Ciena Corporation
Email: msiva282@gmail.com
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Internet-Draft PCEP-SRv6 October 2022
Mike Koldychev
Cisco Systems, Inc.
Canada
Email: mkoldych@cisco.com
Prejeeth Kaladharan
RtBrick Inc
Bangalore
Karnataka
India
Email: prejeeth@rtbrick.com
Yongqing Zhu
China Telecom
109 West Zhongshan Ave, Tianhe District
Bangalore
Guangzhou,
P.R. China
Email: zhuyq8@chinatelecom.cn
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