Applying BGP-LS Segment Routing Extensions to BGP-LS SPF
draft-li-lsvr-bgp-spf-sr-00
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 | Li Zhang , Jie Dong | ||
| 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-li-lsvr-bgp-spf-sr-00
IDR L. Zhang
Internet-Draft J. Dong
Intended status: Standards Track Huawei Technologies
Expires: 24 April 2025 21 October 2024
Applying BGP-LS Segment Routing Extensions to BGP-LS SPF
draft-li-lsvr-bgp-spf-sr-00
Abstract
For network scenarios such as Massively Scaled Data Centers (MSDCs),
BGP is extended for Link-State (LS) distribution and the Shortest
Path First (SPF) algorithm based calculation. BGP-LS SPF leverages
the mechanisms of both BGP protocol and BGP-LS protocol extensions.
Segment Routing (SR) provides a source routing mechanism that allows
a flow to be restricted to a specific topological path, while
maintaining per-flow state only at the ingress node(s) to the SR
domain. In some networks, it may be useful to enable SR based source
routing mechanism together with BGP-LS SPF. This document proposes
to introduce the BGP Link-State (BGP-LS) extensions for segment
routing to the BGP-LS SPF SAFI.
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 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.
Zhang & Dong Expires 24 April 2025 [Page 1]
Internet-Draft BGP-SPF SR October 2024
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
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. SR-MPLS TLVs applicable to BGP-LS SPF . . . . . . . . . . . . 3
2.1. SR-MPLS Node Attribute TLVs . . . . . . . . . . . . . . . 3
2.2. SR-MPLS Link Attribute TLVs . . . . . . . . . . . . . . . 3
2.3. SR-MPLS Prefix Attribute TLVs . . . . . . . . . . . . . . 4
3. SRv6 Extensions Applicable to BGP-LS SPF . . . . . . . . . . 4
3.1. SRv6 Node Attribute TLVs . . . . . . . . . . . . . . . . 4
3.2. SRv6 Link Attribute TLVs . . . . . . . . . . . . . . . . 5
3.3. SRv6 Prefix Attribute TLVs . . . . . . . . . . . . . . . 5
3.4. SRv6 SID NLRI . . . . . . . . . . . . . . . . . . . . . . 5
3.4.1. SRv6 SID Information NLRI . . . . . . . . . . . . . . 6
3.4.2. SRv6 SID Attribute TLVs . . . . . . . . . . . . . . . 6
4. Operational Considerations . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
8. Normative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
For network scenarios such as Massively Scaled Data Centers (MSDCs),
BGP is extended for Link-State (LS) distribution and the Shortest
Path First (SPF) algorithm based calculation. BGP-LS-SPF leverages
the mechanisms of both BGP protocol [RFC4271] and BGP-LS protocol
extensions [RFC9552], with the extensions to BGP-LS attribute and new
NLRI selection rules defined in [I-D.ietf-lsvr-bgp-spf].
Segment Routing (SR) leverages the source routing paradigm. A node
steers a packet through an ordered list of instructions, called
"segments". SR provides a mechanism that allows a flow to be
restricted to a specific topological path, while maintaining per-flow
state only at the ingress node(s) to the SR domain. SR can be
applied to the MPLS architecture (SR-MPLS) as defined in [RFC8660],
and can also be applied to the IPv6 architecture (SRv6) as defined in
[RFC8754] and [RFC8986].
Zhang & Dong Expires 24 April 2025 [Page 2]
Internet-Draft BGP-SPF SR October 2024
In networks where BGP-LS-SPF is used as the underlay routing
protocol, it may be useful to enable SR based source routing
mechanism for traffic engineering and optimization. This document
proposes to introduce the BGP Link-State (BGP-LS) extensions for
segment routing to the BGP-LS-SPF SAFI. Both the extensions for SR-
MPLS and SRv6 are specified.
In general, most of the BGP-LS extensions for SR can be applied to
BGP-LS SPF SAFI, only a few extensions are not applicable to BGP-LS
SPF. For accuracy and documentation, the following subsections list
the BGP-LS SR extensions which are introduced to BGP-LS SPF.
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. SR-MPLS TLVs applicable to BGP-LS SPF
When SR-MPLS is enabled in BGP-LS SPF, The following TLVs SHOULD be
supported.
2.1. SR-MPLS Node Attribute TLVs
+======+=================+===========+
| Type | Description | Reference |
+======+=================+===========+
| 1161 | SID/Label | RFC 9085 |
+------+-----------------+-----------+
| 1034 | SR Capabilities | RFC 9085 |
+------+-----------------+-----------+
| 1035 | SR Algorithm | RFC 9085 |
+------+-----------------+-----------+
| 1036 | SR Local Block | RFC 9085 |
+------+-----------------+-----------+
| 1037 | SRMS Preference | RFC 9085 |
+------+-----------------+-----------+
Table 1: Node Attribute TLVs for
SR-MPLS with BGP-LS SPF
2.2. SR-MPLS Link Attribute TLVs
The following Link Attribute TLVs SHOULD be supported:
Zhang & Dong Expires 24 April 2025 [Page 3]
Internet-Draft BGP-SPF SR October 2024
+======+=================================+===========+
| Type | Description | Reference |
+======+=================================+===========+
| 1099 | Adjacency SID TLV | RFC 9085 |
+------+---------------------------------+-----------+
| 1172 | L2 Bundle Member Attributes TLV | RFC 9085 |
+------+---------------------------------+-----------+
Table 2: Link Attribute TLVs for SR-MPLS with BGP-
LS SPF
2.3. SR-MPLS Prefix Attribute TLVs
+======+==========================+===========+
| Type | Description | Reference |
+======+==========================+===========+
| 1158 | Prefix-SID | RFC 9085 |
+------+--------------------------+-----------+
| 1159 | Range | RFC 9085 |
+------+--------------------------+-----------+
| 1170 | Prefix Attribute Flags | RFC 9085 |
+------+--------------------------+-----------+
| 1171 | Source Router Identifier | RFC 9085 |
+------+--------------------------+-----------+
| 1174 | Source OSPF Router-ID | RFC 9085 |
+------+--------------------------+-----------+
Table 3: Prefix Attribute TLVs for SR-MPLS
with BGP-LS SPF
3. SRv6 Extensions Applicable to BGP-LS SPF
When SRv6 is enabled with BGP-LS SPF, The following extensions SHOULD
be supported.
3.1. SRv6 Node Attribute TLVs
The following Node Attribute TLVs SHOULD be supported for SRv6:
Zhang & Dong Expires 24 April 2025 [Page 4]
Internet-Draft BGP-SPF SR October 2024
+======+=======================+===========+
| Type | Description | Reference |
+======+=======================+===========+
| 1138 | SRv6 Capabilities TLV | RFC 9514 |
+------+-----------------------+-----------+
| 266 | Node MSD TLV | RFC 8814 |
+------+-----------------------+-----------+
Table 4: Node Attribute TLVs for SRv6
with BGP-LS SPF
3.2. SRv6 Link Attribute TLVs
The following Link Attribute TLVs SHOULD be supported for SRv6:
+======+====================+===========+
| Type | Description | Reference |
+======+====================+===========+
| 1106 | SRv6 End.X SID TLV | RFC 9514 |
+------+--------------------+-----------+
Table 5: Link Attribute TLVs for SRv6
with BGP-LS SPF
3.3. SRv6 Prefix Attribute TLVs
The following Prefix Attribute TLVs SHOULD be supported for SRv6:
+======+==================+===========+
| Type | Description | Reference |
+======+==================+===========+
| 1162 | SRv6 Locator TLV | RFC 9514 |
+------+------------------+-----------+
Table 6: Prefix Attribute TLVs for
SRv6 with BGP-LS SPF
3.4. SRv6 SID NLRI
When SRv6 SIDs need to be advertised in BGP-SPF, the NLRI type for
SRv6 SID SHOULD be supported in BGP-LS SPF SAFI:
Zhang & Dong Expires 24 April 2025 [Page 5]
Internet-Draft BGP-SPF SR October 2024
+======+===============+===========+
| Type | NLRI Type | Reference |
+======+===============+===========+
| 6 | SRv6 SID NLRI | RFC 9514 |
+------+---------------+-----------+
Table 7: SRv6 SID NLRI with BGP-
LS SPF
3.4.1. SRv6 SID Information NLRI
The SRv6 SID Information TLV SHOULD be carried in the SRv6 SID NLRI.
+======+==========================+===========+
| Type | NLRI Type | Reference |
+======+==========================+===========+
| 518 | SRv6 SID Information TLV | RFC 9514 |
+------+--------------------------+-----------+
Table 8: SRv6 SID Information TLV with BGP-
LS SPF
3.4.2. SRv6 SID Attribute TLVs
The following TLVs MAY be carried in the BGP-LS Attribute associated
with the SRv6 SID NLRI:
+======+============================+===========+
| Type | NLRI Type | Reference |
+======+============================+===========+
| 1250 | SRv6 Endpoint Behavior TLV | RFC 9514 |
+------+----------------------------+-----------+
| 1251 | SRv6 PeerNode SID TLV | RFC 9514 |
+------+----------------------------+-----------+
| 1252 | SRv6 SID Structure TLV | RFC 9514 |
+------+----------------------------+-----------+
Table 9: SRv6 SID Attribute TLVs with BGP-LS SPF
4. Operational Considerations
TBD
5. Security Considerations
This document introduces no additional security vulnerabilities in
addition to the ones as described in [RFC9552].
Zhang & Dong Expires 24 April 2025 [Page 6]
Internet-Draft BGP-SPF SR October 2024
6. IANA Considerations
7. Acknowledgements
The authors would like to thank XXX for the review and discussion of
this document.
8. Normative References
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC9552] Talaulikar, K., Ed., "Distribution of Link-State and
Traffic Engineering Information Using BGP", RFC 9552,
DOI 10.17487/RFC9552, December 2023,
<https://www.rfc-editor.org/info/rfc9552>.
[I-D.ietf-lsvr-bgp-spf]
Patel, K., Lindem, A., Zandi, S., and W. Henderickx, "BGP
Link-State Shortest Path First (SPF) Routing", Work in
Progress, Internet-Draft, draft-ietf-lsvr-bgp-spf-38, 10
October 2024, <https://datatracker.ietf.org/doc/html/
draft-ietf-lsvr-bgp-spf-38>.
[RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing with the MPLS Data Plane", RFC 8660,
DOI 10.17487/RFC8660, December 2019,
<https://www.rfc-editor.org/info/rfc8660>.
[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>.
[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>.
Zhang & Dong Expires 24 April 2025 [Page 7]
Internet-Draft BGP-SPF SR October 2024
[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>.
Authors' Addresses
Li Zhang
Huawei Technologies
No. 156 Beiqing Road
Beijing
China
Email: zhangli344@huawei.com
Jie Dong
Huawei Technologies
No. 156 Beiqing Road
Beijing
China
Email: jie.dong@huawei.com
Zhang & Dong Expires 24 April 2025 [Page 8]