Compressed SRv6 Segment List Encoding in SRH
draft-ietf-spring-srv6-srh-compression-03
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Active".
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|
|---|---|---|---|
| Authors | Weiqiang Cheng , Clarence Filsfils , Zhenbin Li , Bruno Decraene , Francois Clad | ||
| Last updated | 2023-01-11 | ||
| Replaces | draft-filsfilscheng-spring-srv6-srh-compression | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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| Reviews |
SECDIR Early Review due 2024-04-19
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OPSDIR Early Review due 2024-04-19
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RTGDIR Early Review due 2024-04-19
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INTDIR Early Review due 2024-04-19
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| Additional resources | Mailing list discussion | ||
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draft-ietf-spring-srv6-srh-compression-03
SPRING W. Cheng, Ed.
Internet-Draft China Mobile
Intended status: Standards Track C. Filsfils
Expires: 15 July 2023 Cisco Systems, Inc.
Z. Li
Huawei Technologies
B. Decraene
Orange
F. Clad, Ed.
Cisco Systems, Inc.
11 January 2023
Compressed SRv6 Segment List Encoding in SRH
draft-ietf-spring-srv6-srh-compression-03
Abstract
This document specifies new flavors for the SR endpoint behaviors
defined in RFC 8986, which enable a compressed SRv6 Segment-List
encoding in the Segment Routing Header (SRH).
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."
This Internet-Draft will expire on 15 July 2023.
Copyright Notice
Copyright (c) 2023 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
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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
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
3. Basic Concepts . . . . . . . . . . . . . . . . . . . . . . . 4
4. SR Endpoint Flavors . . . . . . . . . . . . . . . . . . . . . 5
4.1. NEXT-C-SID Flavor . . . . . . . . . . . . . . . . . . . . 5
4.1.1. End with NEXT-C-SID . . . . . . . . . . . . . . . . . 6
4.1.2. End.X with NEXT-C-SID . . . . . . . . . . . . . . . . 7
4.1.3. Combination with PSP, USP and USD flavors . . . . . . 7
4.2. REPLACE-C-SID Flavor . . . . . . . . . . . . . . . . . . 7
4.2.1. End with REPLACE-C-SID . . . . . . . . . . . . . . . 8
4.2.2. End.X with REPLACE-C-SID . . . . . . . . . . . . . . 9
4.2.3. Combination with PSP, USP, and USD flavors . . . . . 9
4.3. Combined NEXT-and-REPLACE-C-SID Flavor . . . . . . . . . 10
5. C-SID Allocation . . . . . . . . . . . . . . . . . . . . . . 11
5.1. Global C-SID . . . . . . . . . . . . . . . . . . . . . . 12
5.2. Local C-SID . . . . . . . . . . . . . . . . . . . . . . . 12
6. C-SID and Locator-Block Length . . . . . . . . . . . . . . . 12
6.1. C-SID Length . . . . . . . . . . . . . . . . . . . . . . 12
6.2. Locator-Block Length . . . . . . . . . . . . . . . . . . 13
6.3. GIB/LIB Usage . . . . . . . . . . . . . . . . . . . . . . 13
7. Efficient SID-list Encoding . . . . . . . . . . . . . . . . . 14
8. Inter Routing Domains with the End.XPS behavior . . . . . . . 14
9. Control Plane . . . . . . . . . . . . . . . . . . . . . . . . 16
10. Operational Considerations . . . . . . . . . . . . . . . . . 16
10.1. Ping a SID without a Segment List . . . . . . . . . . . 16
10.2. Ping a SID via a Segment List . . . . . . . . . . . . . 16
10.3. ICMP Error Processing . . . . . . . . . . . . . . . . . 16
11. Illustrations . . . . . . . . . . . . . . . . . . . . . . . . 17
12. Deployment Model . . . . . . . . . . . . . . . . . . . . . . 17
13. Implementation Status . . . . . . . . . . . . . . . . . . . . 17
13.1. Cisco Systems . . . . . . . . . . . . . . . . . . . . . 18
13.2. Huawei Technologies . . . . . . . . . . . . . . . . . . 18
13.3. Open Source . . . . . . . . . . . . . . . . . . . . . . 19
13.4. Interoperability Report . . . . . . . . . . . . . . . . 19
14. Security Considerations . . . . . . . . . . . . . . . . . . . 21
15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
15.1. SRv6 Endpoint Behaviors . . . . . . . . . . . . . . . . 21
16. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 23
17. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
17.1. Normative References . . . . . . . . . . . . . . . . . . 23
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17.2. Informative References . . . . . . . . . . . . . . . . . 23
Appendix A. Open Issues . . . . . . . . . . . . . . . . . . . . 26
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28
1. Introduction
The Segment Routing (SR) architecture and SR for IPv6 (SRv6) are
defined in [RFC8402].
SRv6 Network Programming [RFC8986] defines a framework to build a
network program with topological and service segments (also referred
to by their segment identifier (SID)) carried in a Segment Routing
header (SRH) [RFC8754].
This document specifies new flavors to the SR endpoint behaviors
defined in Section 4 of [RFC8986]. These flavors enable a compressed
encoding of the SRv6 Segment-List in the SRH and therefore address
the requirements described in
[I-D.srcompdt-spring-compression-requirement].
The flavors defined in this document leverage the SRv6 data plane
defined in [RFC8754] and [RFC8986], and are compatible with the SRv6
control plane extensions for IS-IS
[I-D.ietf-lsr-isis-srv6-extensions], OSPF
[I-D.ietf-lsr-ospfv3-srv6-extensions], and BGP
[I-D.ietf-bess-srv6-services].
2. Terminology
This document leverages the terms defined in [RFC8402], [RFC8754],
and [RFC8986]. The reader is assumed to be familiar with this
terminology.
This document introduces the following new terms:
* Locator-Block: The SRv6 SID block (IPv6 prefix allocated for SRv6
SIDs by the operator) of an SRv6 SID Locator, as defined in
Section 3.1 of [RFC8986].
* Locator-Node: The identifier of the parent node instantiating a
SID in an SRv6 SID Locator, as defined in Section 3.1 of
[RFC8986].
* Compressed-SID (C-SID): The Locator-Node and Function bits of a
SID that supports compressed encoding of SIDs.
* C-SID container: A 128-bit container holding a list of C-SIDs.
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* C-SID sequence: A group of one or more consecutive C-SID
containers in a segment list.
* Uncompressed SID sequence: A group of one or more uncompressed
SIDs in a segment list.
* Compressed Segment List encoding: A segment list encoding that
reduces the packet header length thanks to one or more C-SID
sequences. A compressed Segment List encoding may contain any
number of uncompressed SID sequences.
2.1. 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.
3. Basic Concepts
In an SRv6 domain, the SIDs are allocated from a particular IPv6
prefix: the Locator-Block. All SRv6 SIDs instantiated from the same
Locator-Block share the same most significant bits.
When the combined length of the SRv6 SID Locator, Function, and
Argument is smaller than 128 bits, the trailing bits are set to zero.
When a sequence of consecutive SIDs in a Segment List shares a common
Locator-Block, a compressed Segment-List encoding can optimize the
packet header length by avoiding the repetition of the Locator-Block
and trailing bits with each individual SID.
The compressed Segment List encoding is fully compliant with the
specifications in [RFC8402], [RFC8754], and [RFC8986]. Efficient
encoding is achieved by combining a compressed Segment List encoding
logic on the SR policy headend with new flavors of the base SRv6
endpoint behaviors that decode this compressed encoding.
A Segment List can be encoded in the packet header using any
combination of compressed and uncompressed sequences. The C-SID
sequences leverage the flavors defined in this document, while the
uncompressed sequences use behaviors and flavors defined in other
documents, such as [RFC8986]. An SR Policy headend constructs and
compresses the SID-list depending on the capabilities of each SR
endpoint node that the packet should traverse, as well as its own
compression capabilities.
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It is expected that compressed encoding flavors be available on
devices with limited packet manipulation capabilities, such as legacy
ASICs.
The compressed Segment List encoding supports any Locator-Block
allocation. While other options are supported and may provide higher
efficiency, each routing domain can be allocated a /48 prefix from a
global IPv6 block (see Section 6.2).
4. SR Endpoint Flavors
This section defines several options to achieve compressed Segment
List encoding in the form of two new flavors for the End, End.X, and
End.T behaviors of [RFC8986]. These flavors could also be combined
with behaviors defined in other documents.
The compressed encoding can be achieved by leveraging any of these SR
endpoint flavors. The NEXT-C-SID flavor and the REPLACE-C-SID flavor
expose the same high-level behavior in their use of the SID argument
to determine the next segment to be processed, but they have
different low-level characteristics that can make one more or less
efficient than the other for a particular SRv6 deployment. The NEXT-
and-REPLACE-C-SID flavor is the combination of the NEXT-C-SID flavor
and the REPLACE-C-SID flavor. It provides the best efficiency in
terms of encapsulation size at the cost of increased complexity.
It is RECOMMENDED, for ease of operation, that a single compressed
encoding flavor be used in a given SRv6 domain. However, in a multi-
domain deployment, different flavors can be used in different
domains.
All three flavors leverage the following variables:
* Variable B is the Locator-Block length of the SID.
* Variable NF is the sum of the Locator-Node and the Function
lengths of the SID. It is also referred to as C-SID length.
* Variable A is the Argument length of the SID.
4.1. NEXT-C-SID Flavor
A SID instantiated with the NEXT-C-SID flavor takes an argument that
carries the remaining C-SIDs in the current C-SID container.
The length A of the argument is equal to 128-B-NF and should be a
multiple of NF.
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+------------------------------------------------------------------+
| Locator-Block |Loc-Node| Argument |
| |Function| |
+------------------------------------------------------------------+
<--------- B ----------> <- NF -> <------------- A -------------->
Figure 1: Example of a NEXT-C-SID flavored SID structure using a
48-bit Locator-Block, 16-bit combined locator and function, and
64-bit argument
4.1.1. End with NEXT-C-SID
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an End SID with the NEXT-C-SID flavor, the procedure
described in Section 4.1 of [RFC8986] is executed with the following
modifications.
The below pseudocode is inserted between lines S01 and S02 of the SRH
processing in Section 4.1 of [RFC8986], and a second time before line
S01 of the upper-layer header processing in Section 4.1.1 of
[RFC8986], or prior to processing any extension header other than
Hop-by-Hop or Destination Option.
S01. If (DA.Argument != 0) {
S02. If (IPv6 Hop Limit <= 1) {
S03. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (Hop limit exceeded in transit),
interrupt packet processing and discard the packet.
S04. }
S05. Copy the value of DA.Argument into the bits [B..(B+A-1)]
of the Destination Address.
S06. Set the bits [(B+A)..127] of the Destination Address to
zero.
S07. Decrement Hop Limit by 1.
S08. Submit the packet to the egress IPv6 FIB lookup for
transmission to the next destination.
S09. }
Notes:
* DA.Argument identifies the bits [(B+NF)..127] in the Destination
Address of the IPv6 header.
* The value in the Segments Left field of the SRH is not modified
when DA.Argument in the received packet has a non-zero value.
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4.1.2. End.X with NEXT-C-SID
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an End.X SID with the NEXT-C-SID flavor, the
procedure described in Section 4.2 of [RFC8986] is executed with the
same modifications as in Section 4.1.1 of this document, except for
line S08 that is replaced as follows.
S08. Submit the packet to the IPv6 module for transmission to the
new destination via a member of J.
4.1.3. Combination with PSP, USP and USD flavors
PSP: The PSP flavor defined in Section 4.16.1 of [RFC8986] is
unchanged when combined with the NEXT-C-SID flavor.
USP: The USP flavor defined in Section 4.16.2 of [RFC8986] is
unchanged when combined with the NEXT-C-SID flavor.
USD: The USD flavor is unchanged when combined with the NEXT-C-SID
flavor. The pseudocodes defined in Section 4.1.1 and Section 4.1.2
of this document are inserted at the beginning of the modified upper-
layer header processing defined in Section 4.16.3 of [RFC8986] for
End and End.X, respectively.
4.2. REPLACE-C-SID Flavor
A SID instantiated with the REPLACE-C-SID flavor takes an argument
that indicates the index of the next C-SID in the appropriate C-SID
container.
The length A of the argument should be at least ceil(log_2(128/NF)).
All SIDs that are part of a C-SID sequence using the REPLACE-C-SID
flavor have the same C-SID length NF.
+-------------------------------------------------------------------+
| Locator-Block | Locator-Node |Argument| 0 |
| | + Function | | |
+-------------------------------------------------------------------+
<--------- B ----------> <----- NF -----> <- A -->
Figure 2: Example of a REPLACE-C-SID flavored SID structure using
a 48-bit Locator-Block, 32-bit combined locator and function, and
16-bit argument
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4.2.1. End with REPLACE-C-SID
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an End SID with the REPLACE-C-SID flavor, the SRH
processing described in Section 4.1 of [RFC8986] is replaced as
follows.
S01. When an SRH is processed {
S02. If (Segments Left == 0 and DA.Argument == 0) {
S03. Stop processing the SRH, and proceed to process the next
header in the packet, whose type is identified by
the Next Header field in the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (Hop limit exceeded in transit),
interrupt packet processing and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
S09. If (DA.Argument != 0) {
S10. If ((Last Entry > max_LE) or (Segments Left > Last Entry)) {
S11. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
S12. }
S13. Decrement DA.Argument by 1.
S14. } Else {
S15. If((Last Entry > max_LE) or (Segments Left > Last Entry+1)){
S16. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field,
interrupt packet processing and discard the packet.
S17. }
S18. Decrement Segments Left by 1.
S19. Set DA.Argument to (128/NF - 1).
S20. }
S21. Decrement IPv6 Hop Limit by 1
S22. Write Segment List[Segments Left][DA.Argument] into the bits
[B..B+NF-1] of the Destination Address of the IPv6 header.
S23. Submit the packet to the egress IPv6 FIB lookup for
transmission to the new destination.
S24. }
Notes:
* DA.Argument identifies the bits [(B+NF)..(B+NF+A-1)] in the
Destination Address of the IPv6 header.
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* Segment List[Segments Left][DA.Argument] identifies the bits
[DA.Argument*NF..(DA.Argument+1)*NF-1] in the SRH Segment List
entry at index Segments Left.
The upper-layer header processing described in Section 4.1.1 of
[RFC8986] is unchanged.
4.2.2. End.X with REPLACE-C-SID
When processing an IPv6 packet that matches a FIB entry locally
instantiated as an End.X SID with the REPLACE-C-SID flavor, the
procedure described in Section 4.2 of [RFC8986] is executed with the
same modifications as in Section 4.2.1 of this document, except for
line S23 that is replaced as follows.
S23. Submit the packet to the IPv6 module for transmission to the
new destination via a member of J.
4.2.3. Combination with PSP, USP, and USD flavors
PSP: When combined with the REPLACE-C-SID flavor, the additional PSP
flavor instructions defined in Section 4.16.1.2 of [RFC8986] are
inserted after line S22 of the pseudocode in Section 4.2.1, and the
first line of the inserted instructions is modified as follows.
S22.1. If (Segments Left == 0 and (DA.Argument == 0 or
Segment List[Segments Left][DA.Argument-1] == 0)) {
Note:
* Segment List[Segments Left][DA.Argument-1] identifies the bits
[(DA.Argument-1)*NF..DA.Argument*NF-1] in the SRH Segment List
entry at index Segments Left.
USP: When combined with the REPLACE-C-SID flavor, the lines S02-S04
of the pseudocode in Section 4.2.1 are substituted by the USP flavor
instructions defined in Section 4.16.2 of [RFC8986], with the
following modification.
S02. If (Segments Left == 0 and DA.Argument == 0) {
USD: The USD flavor defined in Section 4.16.3 of [RFC8986] is
unchanged when combined with the REPLACE-C-SID flavor.
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4.3. Combined NEXT-and-REPLACE-C-SID Flavor
A SID instantiated with the NEXT-and-REPLACE-C-SID flavor takes a
two-parts argument comprising, Arg.Next and Arg.Index, and encoded in
the SID in this order.
The length A_I of Arg.Index should be at least ceil(log_2(128/NF)).
The length A_N of Arg.Next is equal to 128-B-NF-A_I and must be a
multiple of NF.
The total SID argument length A is the sum of A_I and A_N.
The NEXT-and-REPLACE-C-SID flavor also leverages an additional
variable, C_DA, that is equal to (1 + (A_N/NF)) and represents the
number of C-SIDs that can be encoded in the IPv6 Destination Address.
All SIDs that are part of a C-SID sequence using the NEXT-and-
REPLACE-C-SID flavor must have the same C-SID length NF.
Furthermore, this NF must be a divisor of 128.
+-------------------------------------------------------------------+
| Locator-Block |Loc-Node| Arg.Next | Arg. |
| |Function| | Index |
+-------------------------------------------------------------------+
<--------- B ----------> <- NF -> <-------- A_N ---------> <- A_I ->
Figure 3: Example of a NEXT-and-REPLACE-C-SID flavored SID
structure using a 48-bit Locator-Block, 16-bit combined locator
and function, 48-bit Arg.Next and 16-bit Arg.Index
Pseudo-code:
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1. If (DA.Arg.Next != 0) {
2. Copy DA.Arg.Next into the bits [B..(B+A_N-1)] of the
Destination Address of the IPv6 header.
3. Set the bits [(B+A_N)..(B+NF+A_N-1)] of the Destination
Address of the IPv6 header to zero.
4. } Else If (DA.Arg.Index >= C_DA) {
5. Decrement DA.Arg.Index by C_DA.
6. Copy C_DA*NF bits from
Segment List[Segments Left][DA.Arg.Index] into the bits
[B..B+C_DA*NF-1] of the Destination Address of the IPv6
header.
7. } Else If (Segments Left != 0) {
8. Decrement Segments Left by 1.
9. Set DA.Arg.Index to ((DA.Arg.Index - C_DA) % (128/NF)).
10. Copy C_DA*NF bits from
Segment List[Segments Left][DA.Arg.Index] into the bits
[B..B+C_DA*NF-1] of the Destination Address of the IPv6
header.
11. } Else {
12. Copy DA.Arg.Index*NF bits from Segment List[0][0] into the
bits [B..B+DA.Arg.Index*NF-1] of the Destination Address of
the IPv6 header.
13. Set the bits [B+DA.Arg.Index*NF..B+NF+A_N-1] of the
Destination Address of the IPv6 header to zero.
14. Set DA.Arg.Index to 0.
15. }
Notes:
* DA.Arg.Next identifies the bits [(B+NF)..(B+NF+A_N-1)] in the
Destination Address of the IPv6 header.
* DA.Arg.Index identifies the bits [(B+NF+A_N)..(B+NF+A_N+A_I-1)] in
the Destination Address of the IPv6 header.
* Segment List[Segments Left][DA.Arg.Index] identifies the bits
[DA.Arg.Index*NF..(DA.Arg.Index+1)*NF-1] in the SRH Segment List
entry at index Segments Left.
5. C-SID Allocation
The C-SID value of 0 is RESERVED. It is used to indicate the end of
a C-SID container.
In order to efficiently manage the C-SID numbering space, it may be
beneficial to divide it into two non-overlapping sub-spaces: a Global
Identifiers Block (GIB) and a Local Identifiers Block (LIB).
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* The GIB is the pool of C-SID values available for global
allocation.
* The LIB is the pool of C-SID values available for local
allocation.
The concept of LIB is applicable to SRv6 and specifically to its
NEXT-C-SID and REPLACE-C-SID flavors. The shorter the C-SID, the
more benefit the LIB brings.
The opportunity to use these sup-spaces, their size, and their C-SID
allocation policy depends on the C-SID length relative to the size of
the network (e.g., number of nodes, links, service routes). Some
guidelines for a typical deployment scenario are provided in
Section 6.3.
5.1. Global C-SID
A C-SID from the GIB.
A Global C-SID typically identifies a shortest path to a node in the
SRv6 domain. An IP route is advertised by the parent node to each of
its global C-SIDs, under the associated Locator-Block. The parent
node executes a variant of the End behavior.
A node can have multiple global C-SIDs under the same Locator-Block
(e.g., one per IGP flexible algorithm). Multiple nodes may share the
same global C-SID (anycast).
5.2. Local C-SID
A C-SID from the LIB.
A local C-SID may identify a cross-connect to a direct neighbor over
a specific interface or a VPN context.
No IP route is advertised by a parent node for its local C-SIDs.
If N1 and N2 are two different physical nodes of the SRv6 domain and
I is a local C-SID value, then N1 and N2 may bind two different
behaviors to I.
6. C-SID and Locator-Block Length
6.1. C-SID Length
The NEXT-C-SID flavor supports both 16- and 32-bit C-SID lengths. A
C-SID length of 16-bit is RECOMMENDED.
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The REPLACE-C-SID flavor supports both 16- and 32-bit C-SID lengths.
A C-SID length of 32-bit is RECOMMENDED.
6.2. Locator-Block Length
The RECOMMENDED Locator-Block sizes for the NEXT-C-SID flavor are 16,
32, or 48 bits. The smaller the block, the higher the compression
efficiency.
The RECOMMENDED Locator-Block size for the REPLACE-C-SID flavor can
be 48, 56, 64, 72, or 80 bits, depending on the needs of the
operator.
6.3. GIB/LIB Usage
GIB and LIB usage is a local implementation and/or configuration
decision, however, some guidelines for determining usage for specific
SID behaviors and recommendations are provided.
The GIB number space is shared among all segment endpoint nodes using
SRv6 locators under a Block space. The more SIDs assigned from this
space, per node, the faster it is exhausted. Therefore its use is
prioritized for SIDs that identify a node, like End behavior SIDs.
The LIB number space is unique per node. Each node is able to fully
utilize the entire LIB number space without consideration of
assignments at other nodes. Therefore its use is prioritized for
SIDs that identify services (of which there may be many) at nodes,
like cross-connects, adjacencies, etc.
While a longer C-SID length permits more flexibility in which SID
behaviors may be assigned from the GIB, it also reduces compression.
Given the previous Locator-Block and C-SID length recommendations,
the following GIB/LIB usage is RECOMMENDED:
* NEXT-C-SID:
- GIB: End, End.T
- LIB: End.X, End.DT4/6/46/2U/2M, End.DX4/6/2/2V (including
large-scale pseudowire), End.B6.Encaps, End.B6.Encaps.Red,
End.BM
* REPLACE-C-SID:
- GIB: End, End.X, End.T, End.DT4/6/46/2U/2M, End.DX4/6/2/2V,
End.B6.Encaps, End.B6.Encaps.Red, End.BM
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- LIB: End.DX2/2V for large-scale pseudowire
7. Efficient SID-list Encoding
The compressed SID-list encoding logic is a local behavior of the SR
Policy headend node and hence out of the scope of this document.
8. Inter Routing Domains with the End.XPS behavior
The End.XPS behavior described in this section is OPTIONAL.
Some SRv6 traffic may need to cross multiple routing domains, such as
different Autonomous Systems (ASes) or different routing areas.
Different routing domains may use different addressing schema and
Locator-Blocks.
This section defines an optional solution and SID behavior allowing
for the use of different Locator-Blocks between routing domains.
The solution requires a new SID behavior, called "Endpoint with
cross-connect to an array of layer-3 adjacencies and SRv6 Prefix
Swap" (End.XPS for short) allowing for this transition of Locator-
Block between two routing domains.
End.XPS is a variant of End.X, performing both "End.X Layer-3 Cross-
Connect" and the translation of the Locator-Block between the two
routing domains.
The processing takes as an additional parameter the prefix B2/m
corresponding the Locator-Block in the second domain. This parameter
is a property of the (received) SID and is given as a result of the
lookup on the IPv6 destination address which identifies the SRv6 SID
and its properties.
The End.XPS behavior is compatible with the NEXT-C-SID, REPLACE-
C-SID, and NEXT-and-REPLACE-C-SID flavors described in this document.
When a router R receives a packet whose IPv6 DA matches a local
End.XPS SID with the NEXT-C-SID flavor, that is associated with a set
J of one or more Layer-3 adjacencies and the Locator-Block B2/m of
the neighbor routing domain, R processes the packet as follows.
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1. If (DA.Argument != 0) {
2. Write B2 into the most significant bits of the Destination
Address of the IPv6 header.
3. Write DA.Argument into the bits [m..(m+A-1)] of the
Destination Address of the IPv6 header.
4. Set the bits [(m+A)..127] of the Destination Address
of the IPv6 header to zero.
5. } Else {
6. Decrement Segments Left by 1.
7. Copy Segment List[Segments Left] from the SRH to the
Destination Address of the IPv6 header.
8. }
9. Submit the packet to the IPv6 module for transmission to the
new destination via a member of J.
When a router R receives a packet whose IPv6 DA matches a local
End.XPS SID with the REPLACE-C-SID flavor, that is associated with a
set J of one or more Layer-3 adjacencies and the Locator-Block B2/m
of the neighbor routing domain, R processes the packet as follows.
1. If (DA.Argument != 0) {
2. Decrement DA.Argument by 1.
3. } Else {
4. Decrement Segments Left by 1.
5. Set DA.Argument to (128/NF - 1).
6. }
7. Write B2 into the most significant bits of the Destination
Address of the IPv6 header.
8. Write Segment List[Segments Left][DA.Argument] into the bits
[m..m+NF-1] of the Destination Address of the IPv6 header.
9. Write DA.Argument into the bits [m+NF..m+NF+A-1] of the
Destination Address of the IPv6 header.
10. Set the bits [(m+NF+A)..127] of the Destination Address
of the IPv6 header to zero.
11. Submit the packet to the IPv6 module for transmission to the
new destination via a member of J.
Note: the way the Locator-Block B2 of the next routing domain is
known is out of scope of this document. As examples, it could be
learnt via configuration, or using a signaling protocol either with
the peer domain or with a central controller (e.g. Path Computation
Element (PCE)).
When End.XPS SID behavior is used, the restriction on the C-SID
length for the REPLACE-C-SID and the NEXT-and-REPLACE-C-SID flavors
is relaxed and becomes: all SID the are part of a C-SID sequence
*within a domain* MUST have the same SID length NF.
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9. Control Plane
This document does not require any control plane modification.
10. Operational Considerations
10.1. Ping a SID without a Segment List
An SR source node may ping a routable SRv6 SID by sending an ICMPv6
echo request packet destined to the SRv6 SID, as illustrated in
Appendix A.1.2 of [RFC9259].
When the SRv6 SID in the destination address of the ICMPv6 echo
request is one of the SID flavors defined in this document, the SR
source node MUST set the arguments of the SID to 0.
10.2. Ping a SID via a Segment List
An SR source node may ping a routable or non-routable SRv6 SID via a
segment list as illustrated in Appendix A.1.2 of [RFC9259].
Regardless of the behavior of the SIDs in the SID list, the SR source
node computes the ICMP echo request checksum using the ultimate
segment in the segment list, i.e., the IPv6 destination address as it
is expected to appear at the final destination of the packet.
10.3. ICMP Error Processing
When an IPv6 node encounters an error while processing a packet, it
may report that error by sending an IPv6 error message to the packet
source with an enclosed copy of the invoking packet. For the source
of an invoking packet to process the ICMP error message, the ultimate
destination address of the IPv6 header may be required.
Section 5.4 of [RFC8754] defines the logic that an SR source node
should follow to determine the ultimate destination of an invoking
packet containing an SRH.
For an SR source node that supports the compressed segment list
encoding defined in this document, the logic to determine the
ultimate destination is generalized as follows.
* If the destination address of the invoking IPv6 packet matches a
known SRv6 SID, modify the invoking IPv6 packet by applying the
SID behavior associated with the matched SRv6 SID;
* Repeat until the application of the SID behavior would result in
the processing of the upper-layer header.
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The destination address of the resulting IPv6 packet may be used as
the ultimate destination of the invoking IPv6 packet.
Since the SR source node that needs to determine the ultimate
destination is the same node that originally built the segment list
in the invoking packet, it is able to perform this operation for all
the SIDs in the packet.
11. Illustrations
Illustrations for the functionalities defined in this document are
provided in [I-D.clad-spring-srv6-srh-compression-illus].
12. Deployment Model
Section 5 of [RFC8754] defines the intra-SR-domain deployment model
and associated security procedures.
The same deployment model applies to the SIDs defined in this
document.
13. Implementation Status
This section is to be removed before publishing as an RFC.
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".
This section is provided in compliance with the SPRING working group
policies ([SPRING-WG-POLICIES]).
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13.1. Cisco Systems
Cisco Systems reported the following implementations of the SR
endpoint node NEXT-C-SID flavor (Section 4.1) for NEXT-C-SID flavored
SIDs. These are used as part of its SRv6 TI-LFA, micro-loop
avoidance, and traffic engineering functionalities.
* Cisco NCS 540 Series routers running IOS XR 7.3.x or above
[IMPL-CISCO-NCS540]
* Cisco NCS 560 Series routers running IOS XR 7.6.x or above
[IMPL-CISCO-NCS560]
* Cisco NCS 5500 Series routers running IOS XR 7.3.x or above
[IMPL-CISCO-NCS5500]
* Cisco NCS 5700 Series routers running IOS XR 7.5.x or above
[IMPL-CISCO-NCS5700]
* Cisco 8000 Series routers running IOS XR 7.5.x or above
[IMPL-CISCO-8000]
* Cisco ASR 9000 Series routers running IOS XR 7.5.x or above
[IMPL-CISCO-ASR9000]
At the time of this report, all the implementations listed above are
in production and follow the specification in the latest version of
this document, including all the "MUST" and "SHOULD" clauses for the
NEXT-C-SID flavor.
This report was last updated on January 11, 2023.
13.2. Huawei Technologies
Huawei Technologies reported the following implementations of the SR
endpoint node REPLACE-C-SID flavor (Section 4.2) for REPLACE-C-SID
flavored SIDs. These are used as part of its SRv6 TI-LFA, micro-loop
avoidance, and traffic engineering functionalities.
* Huawei ATN8XX,ATN910C,ATN980B routers running VRPV800R021C00 or
above.
* Huawei CX600-M2 routers running VRPV800R021C00 or above.
* Huawei NE40E,ME60-X1X2,ME60-X3X8X16 routers running VRPV800R021C00
or above.
* Huawei NE5000E,NE9000 routers running VRPV800R021C00 or above.
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* Huawei NCE-IP Controller running V1R21C00 or above.
At the time of this report, all the implementations listed above are
in production and follow the specification in the latest version of
this document, including all the "MUST" and "SHOULD" clauses for the
REPLACE-C-SID flavor.
This report was last updated on January 11, 2023.
13.3. Open Source
The authors found the following open source implementations of the SR
endpoint node NEXT-C-SID flavor (Section 4.1).
* The Linux kernel, version 6.1 [IMPL-OSS-LINUX]
* The Software for Open Networking in the Cloud (SONiC), version
202212 [IMPL-OSS-SONIC], and Switch Abstraction Interface (SAI),
version 1.9.0 [IMPL-OSS-SAI]
* The Vector Packet Processor (VPP), version 20.05 [IMPL-OSS-VPP]
* A generic P4 implementation [IMPL-OSS-P4]
The authors found the following open source implementations of the SR
endpoint node REPLACE-C-SID flavor (Section 4.2).
* ONOS and P4 Programmable Switch based [IMPL-OSS-ONOS]
* Open SRv6 Project [IMPL-OSS-OPEN-SRV6]
This section was last updated on January 11, 2023.
13.4. Interoperability Report
In November 2020, China Mobile successfully validated multiple
interoperable implementations of the NEXT-C-SID and REPLACE-C-SID
flavors defined in this document.
This testing covered two different implementations of the SRv6
endpoint flavors defined in this document:
* Hardware implementation in Cisco ASR 9000 running IOS XR
* Software implementation in Cisco IOS XRv9000 virtual appliance
* Hardware implementation in Huawei NE40E and NE5000E running VRP
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The interoperability testing consisted of a packet flow sent by an SR
source node N0 via an SR traffic engineering policy with a segment
list "<S1, S2, S3, S4, S5, S6, S7>", where S1..S7 are SIDs
instantiated on SR segment endpoint nodes N1..N7, respectively.
N0 --- N1 --- N2 --- N3 --- N4 --- N5 --- N6 --- N7
(S1) (S2) (S3) (S4) (S5) (S6) (S7)
* N0 is a generic packet generator.
* N1, N2, and N3 are Huawei routers.
* N4, N5, and N6 are Cisco routers.
* N7 is a generic traffic generator acting as a packet receiver.
The SR source node N0 steers the packets onto the SR policy by
setting the IPv6 destination address and creating an SRH (as
described in Section 4.1 of [RFC8754]) using a compressed segment
list encoding. The length of the compressed segment list encoding
varies for each scenario.
All SR segment endpoint nodes execute a variant of the End behavior:
regular End behavior (as defined in Section 4.1 of [RFC8986]), End
behavior with Next-C-SID flavor, and End behavior with Replace-C-SID
flavor. The variant being used at each segment endpoint varies for
each scenario.
The interoperability was validated for the following scenarios:
*Scenario 1:*
* S1 and S2 are associated with the End behavior with the Replace-
C-SID flavor
* S3 is associated with the regular End behavior (no flavor)
* S4, S5, and S6 are associated with the End behavior with the Next-
C-SID flavor
* The SR source node imposes a compressed segment list encoding of 3
SIDs.
*Scenario 2:*
* S1, S2..., S6 are associated with the End behavior with the Next-
C-SID flavor
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* The SR source node imposes a compressed segment list encoding of 2
SIDs.
*Scenario 3:*
* S1, S2..., S6 are associated with the End behavior with the
Replace-C-SID flavor
* The SR source node imposes a compressed segment list encoding of 3
SIDs.
14. Security Considerations
The security requirements and mechanisms described in [RFC8402] and
[RFC8754] also apply to this document.
This document does not introduce any new security considerations.
15. IANA Considerations
15.1. SRv6 Endpoint Behaviors
This I-D. requests IANA to make the following registrations from the
"SRv6 Endpoint Behaviors" sub-registry under the top-level "Segment
Routing" registry (https://www.iana.org/assignments/segment-
routing/):
+-------+-----------------------------------------+-----------+
| Value | Description | Reference |
+=======+=========================================+===========+
| 43 | End with NEXT-CSID | This I-D. |
+-------+-----------------------------------------+-----------+
| 44 | End with NEXT-CSID & PSP | This I-D. |
+-------+-----------------------------------------+-----------+
| 45 | End with NEXT-CSID & USP | This I-D. |
+-------+-----------------------------------------+-----------+
| 46 | End with NEXT-CSID, PSP & USP | This I-D. |
+-------+-----------------------------------------+-----------+
| 47 | End with NEXT-CSID & USD | This I-D. |
+-------+-----------------------------------------+-----------+
| 48 | End with NEXT-CSID, PSP & USD | This I-D. |
+-------+-----------------------------------------+-----------+
| 49 | End with NEXT-CSID, USP & USD | This I-D. |
+-------+-----------------------------------------+-----------+
| 50 | End with NEXT-CSID, PSP, USP & USD | This I-D. |
+-------+-----------------------------------------+-----------+
| 52 | End.X with NEXT-CSID | This I-D. |
+-------+-----------------------------------------+-----------+
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| 53 | End.X with NEXT-CSID & PSP | This I-D. |
+-------+-----------------------------------------+-----------+
| 54 | End.X with NEXT-CSID & USP | This I-D. |
+-------+-----------------------------------------+-----------+
| 55 | End.X with NEXT-CSID, PSP & USP | This I-D. |
+-------+-----------------------------------------+-----------+
| 56 | End.X with NEXT-CSID & USD | This I-D. |
+-------+-----------------------------------------+-----------+
| 57 | End.X with NEXT-CSID, PSP & USD | This I-D. |
+-------+-----------------------------------------+-----------+
| 58 | End.X with NEXT-CSID, USP & USD | This I-D. |
+-------+-----------------------------------------+-----------+
| 59 | End.X with NEXT-CSID, PSP, USP & USD | This I-D. |
+-------+-----------------------------------------+-----------+
| 101 | End with REPLACE-CSID | This I-D. |
+-------+-----------------------------------------+-----------+
| 102 | End with REPLACE-CSID & PSP | This I-D. |
+-------+-----------------------------------------+-----------+
| 103 | End with REPLACE-CSID & USP | This I-D. |
+-------+-----------------------------------------+-----------+
| 104 | End with REPLACE-CSID, PSP & USP | This I-D. |
+-------+-----------------------------------------+-----------+
| 105 | End.X with REPLACE-CSID | This I-D. |
+-------+-----------------------------------------+-----------+
| 106 | End.X with REPLACE-CSID & PSP | This I-D. |
+-------+-----------------------------------------+-----------+
| 107 | End.X with REPLACE-CSID & USP | This I-D. |
+-------+-----------------------------------------+-----------+
| 108 | End.X with REPLACE-CSID, PSP & USP | This I-D. |
+-------+-----------------------------------------+-----------+
| 128 | End with REPLACE-CSID & USD | This I-D. |
+-------+-----------------------------------------+-----------+
| 129 | End with REPLACE-CSID, USP & USD | This I-D. |
+-------+-----------------------------------------+-----------+
| 130 | End with REPLACE-CSID, PSP & USD | This I-D. |
+-------+-----------------------------------------+-----------+
| 131 | End with REPLACE-CSID, PSP, USP & USD | This I-D. |
+-------+-----------------------------------------+-----------+
| 132 | End.X with REPLACE-CSID & USD | This I-D. |
+-------+-----------------------------------------+-----------+
| 133 | End.X with REPLACE-CSID, PSP & USD | This I-D. |
+-------+-----------------------------------------+-----------+
| 134 | End.X with REPLACE-CSID, USP & USD | This I-D. |
+-------+-----------------------------------------+-----------+
| 135 | End.X with REPLACE-CSID, PSP, USP & USD | This I-D. |
+-------+-----------------------------------------+-----------+
Table 1: Registration List
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16. Acknowledgements
The authors would like to thank Kamran Raza, Xing Jiang, YuanChao Su,
Han Li and Yisong Liu.
17. References
17.1. 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>.
[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>.
[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>.
[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>.
[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>.
17.2. Informative References
[EMAIL1] "SPRING chairs email on the adoption of draft-
filsfilscheng-spring-srv6-srh-compression-02", October
2021, <https://mailarchive.ietf.org/arch/msg/spring/
VjVIxo7fZFhsIHJ5wFQXIBvvtNM/>.
[EMAIL2] "SPRING chairs email on working group process", February
2022, <https://mailarchive.ietf.org/arch/msg/spring/
vCc9Ckvwu5HA-RCleV712dsA5OA/>.
[I-D.clad-spring-srv6-srh-compression-illus]
Clad, F. and D. Dukes, "Illustrations for Compressed SRv6
Segment List Encoding in SRH", Work in Progress, Internet-
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Draft, draft-clad-spring-srv6-srh-compression-illus-02, 24
October 2022, <https://www.ietf.org/archive/id/draft-clad-
spring-srv6-srh-compression-illus-02.txt>.
[I-D.ietf-bess-srv6-services]
Dawra, G., Talaulikar, K., Raszuk, R., Decraene, B.,
Zhuang, S., and J. Rabadan, "BGP Overlay Services Based on
Segment Routing over IPv6 (SRv6)", Work in Progress,
Internet-Draft, draft-ietf-bess-srv6-services-15, 22 March
2022, <https://www.ietf.org/archive/id/draft-ietf-bess-
srv6-services-15.txt>.
[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-19, 14 November 2022,
<https://www.ietf.org/archive/id/draft-ietf-lsr-isis-srv6-
extensions-19.txt>.
[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>.
[I-D.srcompdt-spring-compression-requirement]
Cheng, W., Xie, C., Bonica, R., Dukes, D., Li, C., Peng,
S., and W. Henderickx, "Compressed SRv6 SID List
Requirements", Work in Progress, Internet-Draft, draft-
srcompdt-spring-compression-requirement-07, 11 July 2021,
<https://www.ietf.org/archive/id/draft-srcompdt-spring-
compression-requirement-07.txt>.
[IMPL-CISCO-8000]
Cisco Systems, "Segment Routing Configuration Guide for
Cisco 8000 Series Routers", 4 November 2022,
<https://www.cisco.com/c/en/us/td/docs/iosxr/cisco8000/
segment-routing/75x/b-segment-routing-cg-cisco8000-75x/
configuring-segment-routing-over-ipv6-srv6-micro-
sids.html>.
[IMPL-CISCO-ASR9000]
Cisco Systems, "Segment Routing Configuration Guide for
Cisco ASR 9000 Series Routers", 6 November 2022,
<https://www.cisco.com/c/en/us/td/docs/routers/asr9000/
software/asr9k-r7-5/segment-routing/configuration/guide/b-
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segment-routing-cg-asr9000-75x/configure-srv6-micro-
sid.html>.
[IMPL-CISCO-NCS540]
Cisco Systems, "Segment Routing Configuration Guide for
Cisco NCS 540 Series Routers", 2 November 2022,
<https://www.cisco.com/c/en/us/td/docs/iosxr/ncs5xx/
segment-routing/73x/b-segment-routing-cg-73x-ncs540/
configure-srv6.html>.
[IMPL-CISCO-NCS5500]
Cisco Systems, "Segment Routing Configuration Guide for
Cisco NCS 5500 Series Routers", 6 November 2022,
<https://www.cisco.com/c/en/us/td/docs/iosxr/ncs5500/
segment-routing/73x/b-segment-routing-cg-ncs5500-73x/
configure-srv6-micro-sid.html>.
[IMPL-CISCO-NCS560]
Cisco Systems, "Segment Routing Configuration Guide for
Cisco NCS 560 Series Routers", 14 October 2022,
<https://www.cisco.com/c/en/us/td/docs/iosxr/ncs560/
segment-routing/76x/b-segment-routing-cg-76x-ncs560/m-
configure-srv6-usid-ncs5xx.html>.
[IMPL-CISCO-NCS5700]
Cisco Systems, "Segment Routing Configuration Guide for
Cisco NCS 5700 Series Routers", 6 November 2022,
<https://www.cisco.com/c/en/us/td/docs/iosxr/ncs5500/
segment-routing/75x/b-segment-routing-cg-ncs5500-75x/
configure-srv6-micro-sid.html>.
[IMPL-OSS-LINUX]
Abeni, P., "Add NEXT-C-SID support for SRv6 End behavior",
20 September 2022,
<https://git.kernel.org/pub/scm/linux/kernel/git/netdev/
net-next.git/
commit/?id=cec9d59e89362809f17f2d854faf52966216da13>.
[IMPL-OSS-ONOS]
Open Networking Foundation, "Stratum CMCC G-SRv6 Project",
24 March 2021,
<https://wiki.opennetworking.org/display/COM/
Stratum+CMCC+G-SRv6+Project>.
[IMPL-OSS-OPEN-SRV6]
"Open SRv6 Project", n.d.,
<http://opensrv6.org.cn/en/srv6-2/>.
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[IMPL-OSS-P4]
Salsano, S. and A. Tulumello, "SRv6 uSID (micro SID)
implementation on P4", 3 January 2021,
<https://github.com/netgroup/p4-srv6-usid>.
[IMPL-OSS-SAI]
Agrawal, A., "Added new behaviors to support uSID
instruction", 8 June 2021,
<https://github.com/opencomputeproject/SAI/pull/1231/
commits/02e58d95ad966ca9efc24eb9e0c0fa10b21de2a4>.
[IMPL-OSS-SONIC]
Shah, S. and R. Sudarshan, "SONiC uSID", 21 August 2022,
<https://github.com/sonic-net/SONiC/blob/master/doc/srv6/
SRv6_uSID.md>.
[IMPL-OSS-VPP]
FD.io, "Srv6 cli reference", n.d., <https://s3-
docs.fd.io/vpp/23.02/cli-reference/clis/
clicmd_src_vnet_srv6.html>.
[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>.
[RFC9259] Ali, Z., Filsfils, C., Matsushima, S., Voyer, D., and M.
Chen, "Operations, Administration, and Maintenance (OAM)
in Segment Routing over IPv6 (SRv6)", RFC 9259,
DOI 10.17487/RFC9259, June 2022,
<https://www.rfc-editor.org/info/rfc9259>.
[SPRING-WG-POLICIES]
SPRING Working Group Chairs, "SPRING Working Group
Policies", 14 October 2022,
<https://wiki.ietf.org/en/group/spring/WG_Policies>.
Appendix A. Open Issues
This section was added as requested by the SPRING chair in [EMAIL1].
Issues raised during and after the adoption call for this draft are
tracked in an issue tracker. The remainder of this section
identifies the most significant open issues, from the adoption call,
for the working group to keep track of.
As a reminder to those reading this section, this document is a work
in progress, and subject to change by the working group. As noted at
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the front of this document, "It is inappropriate to use Internet-
Drafts as reference material"
* Given that the working group has said that it wants to standardize
one data plane solution, and given that the document contains
multiple SRv6 EndPoint behaviors that some WG members have stated
are multiple data plane solutions, the working group will address
whether this is valid and coherent with its one data plane
solution objective.
* As reminded in the conclusion of the adoption call, this document
is subject to the policy announced by the SPRING chairs in
[EMAIL2]. In particular, this means that this document can not go
to WG last call until 6man completes handling of an Internet Draft
that deals with the relationship of C-SIDs to RFC 4291. It is
hoped and expected that said resolution will be a WG last call and
document approval in 6man of a document providing for the way that
C-SIDs use the IPv6 destination address field.
Contributors
Liu Aihua
ZTE Corporation
China
Email: liu.aihua@zte.com.cn
Dennis Cai
Alibaba
United States of America
Email: d.cai@alibaba-inc.com
Darren Dukes
Cisco Systems, Inc.
Canada
Email: ddukes@cisco.com
James N Guichard
Futurewei Technologies Ltd.
United States of America
Email: james.n.guichard@futurewei.com
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Cheng Li
Huawei Technologies
China
Email: chengli13@huawei.com
Robert Raszuk
NTT Network Innovations
United States of America
Email: robert@raszuk.net
Daniel Voyer
Bell Canada
Canada
Email: daniel.voyer@bell.ca
Shay Zadok
Broadcom
Israel
Email: shay.zadok@broadcom.com
Authors' Addresses
Weiqiang Cheng (editor)
China Mobile
China
Email: chengweiqiang@chinamobile.com
Clarence Filsfils
Cisco Systems, Inc.
Belgium
Email: cf@cisco.com
Zhenbin Li
Huawei Technologies
China
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Email: lizhenbin@huawei.com
Bruno Decraene
Orange
France
Email: bruno.decraene@orange.com
Francois Clad (editor)
Cisco Systems, Inc.
France
Email: fclad@cisco.com
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