Advertising SRv6 SIDs for Layer 2 Bundle Member Links in IGP
draft-dong-lsr-l2bundle-srv6-02
This document is an Internet-Draft (I-D).
Anyone may submit an I-D to the IETF.
This I-D is not endorsed by the IETF and has no formal standing in the
IETF standards process.
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Jie Dong , Zhibo Hu | ||
| Last updated | 2024-10-21 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-dong-lsr-l2bundle-srv6-02
LSR Working Group J. Dong
Internet-Draft Z. Hu
Intended status: Standards Track Huawei Technologies
Expires: 24 April 2025 21 October 2024
Advertising SRv6 SIDs for Layer 2 Bundle Member Links in IGP
draft-dong-lsr-l2bundle-srv6-02
Abstract
There are deployments where the Layer-3 interface on which IGP
operates is a Layer-2 interface bundle. Existing IGP advertisements
only support advertising link attributes of the Layer-3 interface.
If entities external to IGP wish to control traffic flows on the
individual physical links that comprise the Layer-2 interface bundle,
link attribute information about the bundle members is advertised by
IGP extensions for Layer-2 (L2) bundle.
When Segment Routing over IPv6 (SRv6) is used with Layer-2 interface
bundle to control traffic flows on the individual member links, the
SRv6 SIDs which represent the Layer 2 member links of the L2 bundle
needs to be advertised in IGP.
This document proposes the IGP extensions to advertise the SRv6 SIDs
of the Layer 2 (L2) bundle member links.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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."
Dong & Hu Expires 24 April 2025 [Page 1]
Internet-Draft IGP L2 bundle for SRv6 October 2024
This Internet-Draft will expire on 24 April 2025.
Copyright Notice
Copyright (c) 2024 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 . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. SRv6 SIDs for L2 Bundle Member Links . . . . . . . . . . . . 3
4. Advertising SRv6 SIDs for L2 Bundle Members . . . . . . . . . 3
4.1. SRv6 SIDs Encodings for IS-IS L2 Bundle . . . . . . . . . 3
4.1.1. L2 Bundle Member SRv6 End.X SID Sub-TLV . . . . . . . 3
4.1.2. L2 Bundle Member SRv6 LAN End.X SID Sub-TLV . . . . . 5
4.2. SRv6 SIDs Encodings for OSPF L2 Bundle . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
There are deployments where the Layer-3 interface on which an IGP
adjacency is established is a Layer-2 interface bundle, for instance,
a Link Aggregation Group (LAG) [IEEE802.1AX]. This reduces the
number of adjacencies that need to be maintained by the routing
protocol in cases where there are parallel links between the
neighbors. Entities external to IS-IS such as Path Computation
Elements (PCEs) [RFC4655] may wish to control traffic flows on
individual members of the underlying Layer-2 bundle. In order to do
so, link attribute information about individual bundle members is
required.
Dong & Hu Expires 24 April 2025 [Page 2]
Internet-Draft IGP L2 bundle for SRv6 October 2024
[RFC8668] and [RFC9356] specify the IGP extensions to advertise link
attribute information for each of the L2 Bundle members which
comprise the Layer-3 interface, in which the encoding and
advertisement of SR-MPLS adjacency SIDs of each bundle member link is
defined. When SRv6 is used with Layer-2 interface bundle, to control
traffic flows on the individual member links, the SRv6 SIDs which
represent the Layer-2 member links of the L2 bundle needs to be
advertised.
This document proposes the IGP extensions to advertise the SRv6 SIDs
of the Layer-2 (L2) bundle member links.
2. 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
BCP14 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they
appear in all capitals, as shown here.
3. SRv6 SIDs for L2 Bundle Member Links
As defined in [RFC8986], the SRv6 End.X behavior means "Endpoint with
cross-connect to an array of layer-3 adjacencies". An SRv6 SID
associated with a Layer 2 bundle member link of an L3 adjacency can
be considered as an instance of the End.X SID, which identifies a
subset of the L3 adjacency. Thus separate End.X SID can be allocated
for each L2 bundle member link.
4. Advertising SRv6 SIDs for L2 Bundle Members
4.1. SRv6 SIDs Encodings for IS-IS L2 Bundle
This section defines the IS-IS sub-TLVs to advertise SRv6 SIDs for L2
Bundle Members. Following the encoding mechanism used in [RFC8668]
for the advertisement of SR-MPLS adj-SIDs for L2 Bundle Members, this
allows the advertisement of a set of SRv6 End.X SIDs (one per L2
Bundle Member) in a single sub-TLV.
4.1.1. L2 Bundle Member SRv6 End.X SID Sub-TLV
[RFC9352] defines the SRv6 End.X SID sub-TLV to advertise an SRv6 SID
associated with a point-to-point adjacency. This document defines a
new sub-TLV of called "L2 Bundle Member SRv6 End.X SIDs" to advertise
the SRv6 End.X SIDs for the L2 Bundle Members. This sub-TLV is
allowed to be carried in TLV 25 "L2 Bundle Member Attributes" only.
The format of the sub-TLV is as below:
Dong & Hu Expires 24 April 2025 [Page 3]
Internet-Draft IGP L2 bundle for SRv6 October 2024
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Algorithm | Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Endpoint Behavior |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID #1 (128 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID #2 (128 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID #n (128 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Sub-sub-tlv-len| Sub-sub-TLVs (variable) . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
* Type: TBA.
* Length: Variable.
* Flags: 1 octet. The format is the same as the Flags field in the
SRv6 End.X SID sub-TLV as defined in [RFC9352].
* Algorithm: 1 octet. The algorithm values are defined in the IGP
Algorithm Type registry.
* Weight: 1 octet. The value represents the weight of the SID for
the purpose of load balancing.
* Endpoint Behavior: 2 octets. It SHOULD be set to the End.X.
* SIDs. One or multiple 16-octet SRv6 SIDs. The number of the SIDs
is determined by the "Number of L2 Bundle Member Descriptors"
field as defined in [RFC8668].
* Sub-sub-tlv-length: 1 octet. Number of octets used by sub-sub-
TLVs.
* Optional Sub-sub-TLVs: Supported sub-sub-TLVs are specified in
Section 11.6 of [RFC9352].
Dong & Hu Expires 24 April 2025 [Page 4]
Internet-Draft IGP L2 bundle for SRv6 October 2024
Multiple L2 Bundle Member SRv6 End.X SID Sub-TLV may be required in
order to advertise all the SRv6 End.X SIDs associated with the member
links of an L2 bundle.
4.1.2. L2 Bundle Member SRv6 LAN End.X SID Sub-TLV
[RFC9352] defines the SRv6 LAN End.X SID sub-TLV to advertise an SRv6
SID associated with a LAN adjacency. This document defines a new
sub-TLV called "L2 Bundle Member SRv6 LAN End.X SIDs" to advertise
the SRv6 LAN End.XU SIDs for the L2 Bundle Members. The format of
the sub-TLV is as 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 | Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Neighbor System-ID (ID length octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Algorithm | Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Endpoint Behavior |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID #1 (128 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID #2 (128 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID #n (128 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Sub-sub-tlv-len| Sub-sub-TLVs (variable) . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where:
* Type: TBA.
* Length: Variable.
* Neighbor System-ID: IS-IS System-ID of length "ID Length" as
defined in [ISO10589].
* Flags: 1 octet, the format is the same as the Flags field in the
SRv6 End.X SID sub-TLV as defined in [RFC9352].
* Algorithm: 1 octet. The algorithm values are defined in the IGP
Algorithm Type registry.
Dong & Hu Expires 24 April 2025 [Page 5]
Internet-Draft IGP L2 bundle for SRv6 October 2024
* Weight: 1 octet. The value represents the weight of the End.X SID
for the purpose of load balancing.
* Endpoint Behavior: 2 octets. It SHOULD be set to the End.X
function.
* SIDs. One or multiple 16-octet SRv6 SIDs. The number of the SIDs
is determined by the "Number of L2 Bundle Member Descriptors"
field as defined in [RFC8668].
* Sub-sub-tlv-length: 1 octet. Number of octets used by sub-sub-
TLVs.
* Optional Sub-sub-TLVs: Supported sub-sub-TLVs are specified in
Section 11.6 of [RFC9352].
4.2. SRv6 SIDs Encodings for OSPF L2 Bundle
This section describes the mechanism to advertise SRv6 SIDs for L2
Bundle Members in OSPF. In [RFC9356], the SR-MPLS Adjacency SID sub-
TLVs for the L3 adjacency is reused for the advertisement of
Adjacency SIDs of L2 Bundle Members. For SRv6 data plane , the SRv6
End.X SID sub-TLV and SRv6 LAN End.X SID Sub-TLV as defined in
[RFC9513] are reused for the advertisement of SRv6 End.X SIDs of the
L2 bundle members. Thus in OSPFv3, the L2 Bundle Member Attributes
sub-TLV shares the sub-TLVs defined for SRv6 under the E-Router-Link
TLV .
5. IANA Considerations
IANA is requested to assign two new code points from the IS-IS "Sub-
TLVs for TLVs 22, 23, 25, 141, 222, and 223" registry.
+------+--------------------------+----+----+----+-----+-----+-----+
| Type | Description | 22 | 23 | 25 | 141 | 222 | 223 |
+======+==========================+====+====+====+=====+=====+=====+
| TBD | L2 Bundle Member SRv6 | n | n | y | n | n | n |
| | End.X SID | | | | | | |
+------+--------------------------+----+----+----+-----+-----+-----+
| TBD | L2 Bundle Member SRv6 | n | n | y | n | n | n |
| | LAN End.X SID | | | | | | |
+------+--------------------------+----+----+----+-----+-----+-----+
In the "OSPFv3 Extended- LSA Sub-TLVs" registry, IANA has already set
the L2BM flag for the code points 30, 31 and 32 to "Y", per the
request of [RFC9513].
Dong & Hu Expires 24 April 2025 [Page 6]
Internet-Draft IGP L2 bundle for SRv6 October 2024
6. Security Considerations
The security considerations in [RFC8668] and [RFC9356] apply. This
document introduces no additional security vulnerabilities to IS-IS
and OSPF.
7. Acknowledgements
The authors would like to thank Zhenbin Li for the review and
discussion of this document.
8. References
8.1. Normative References
[IEEE802.1AX]
IEEE, "IEEE Standard for Local and metropolitan area
networks -- Link Aggregation", 2016,
<https://ieeexplore.ieee.org/document/7055197>.
[ISO10589] ISO, "Information technology -- Telecommunications and
information exchange between systems -- Intermediate
System to Intermediate System intra-domain routing
information exchange protocol for use in conjunction with
the protocol for providing the connectionless-mode network
service (ISO 8473)", November 2002,
<https://ieeexplore.ieee.org/document/7055197>.
[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>.
[RFC8668] Ginsberg, L., Ed., Bashandy, A., Filsfils, C., Nanduri,
M., and E. Aries, "Advertising Layer 2 Bundle Member Link
Attributes in IS-IS", RFC 8668, DOI 10.17487/RFC8668,
December 2019, <https://www.rfc-editor.org/info/rfc8668>.
[RFC9352] Psenak, P., Ed., Filsfils, C., Bashandy, A., Decraene, B.,
and Z. Hu, "IS-IS Extensions to Support Segment Routing
over the IPv6 Data Plane", RFC 9352, DOI 10.17487/RFC9352,
February 2023, <https://www.rfc-editor.org/info/rfc9352>.
Dong & Hu Expires 24 April 2025 [Page 7]
Internet-Draft IGP L2 bundle for SRv6 October 2024
[RFC9356] Talaulikar, K., Ed. and P. Psenak, "Advertising Layer 2
Bundle Member Link Attributes in OSPF", RFC 9356,
DOI 10.17487/RFC9356, January 2023,
<https://www.rfc-editor.org/info/rfc9356>.
[RFC9513] Li, Z., Hu, Z., Talaulikar, K., Ed., and P. Psenak,
"OSPFv3 Extensions for Segment Routing over IPv6 (SRv6)",
RFC 9513, DOI 10.17487/RFC9513, December 2023,
<https://www.rfc-editor.org/info/rfc9513>.
8.2. Informative References
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[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>.
Authors' Addresses
Jie Dong
Huawei Technologies
Huawei Campus, No. 156 Beiqing Road
Beijing
100095
China
Email: jie.dong@huawei.com
Zhibo Hu
Huawei Technologies
Huawei Campus, No. 156 Beiqing Road
Beijing
100095
China
Email: huzhibo@huawei.com
Dong & Hu Expires 24 April 2025 [Page 8]