Internet DRAFT - draft-chen-lsr-adv-lkno
draft-chen-lsr-adv-lkno
Network Working Group H. Chen
Internet-Draft D. Eastlake
Intended status: Standards Track Futurewei
Expires: 13 July 2024 A. Wang
China Telecom
G. Mishra
Verizon Inc.
Y. Liu
China Mobile
Y. Fan
Casa Systems
L. Liu
Fujitsu
X. Liu
Alef Edge
10 January 2024
IGP Extensions for Advertising Link Numbers
draft-chen-lsr-adv-lkno-03
Abstract
This document describes OSPF and IS-IS extensions for distributing
the link numbers assigned to the links originating at a node.
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 [RFC2119] [RFC8174]
when, and only when, they appear in all capitals, as shown here.
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
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
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This Internet-Draft will expire on 13 July 2024.
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/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Extensions to OSPFv2 . . . . . . . . . . . . . . . . . . . . 3
3. Extensions to OSPFv3 . . . . . . . . . . . . . . . . . . . . 4
4. Extensions to IS-IS . . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
When the links originating at each node in a network are numbered
from 1 to the number of the such links for that node, an efficient
stateless multicast along an explicit P2MP path can be achieved
through using the link numbers of the links on the path to represent
the path.
This document proposes OSPF and IS-IS extensions for distributing the
link numbers assigned to the links originating at a node which will
support such multicast. After a controller such as PCE as a
controller has the link numbers of the links originating at every
node, for an explicit P2MP path, the controller can send the ingress
the path represented by the link numbers of the links on the path.
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1.1. Terminology
LSA: Link State Advertisement.
OSPF: Open Shortest Path First.
LSP: Link State Protocol data unit.
IS-IS: Intermediate System to Intermediate System.
MT: Multi-Topology.
TE: Traffic Engineering.
2. Extensions to OSPFv2
This section describes extensions to OSPFv2 for distributing the link
numbers assigned to the links of a node.
[RFC7684] defines the OSPFv2 Extended Link TLV to advertise the
information about a link. Multiple Link TLVs for the links of a
router are included in the OSPFv2 Extended Link Opaque LSA of the
router. The OSPFv2 Extended Link TLV has the following format:
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 (1) | Length (Variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs (variable) |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: OSPFv2 Extended Link TLV
Type: 1.
Length: Variable, dependent on Sub-TLVs.
Link Type, Link ID and Link Data: They are defined in Section A.4.2
of [RFC2328].
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Reserved: MUST be set to 0 on transmission and MUST be ignored on
reception.
Under the OSPFv2 Extended Link TLV for a link, a Link Number Sub-TLV
is defined for distributing the link number assigned to the link by
the router originating the LSA. A Link Number Sub-TLV is included in
the Link TLV for a link of Link Type Point-to-Point, Broadcast (i.e.,
link to LAN or Transit Network), or stub (i.e., link to stub
network). The Link Number Sub-TLV has the following format:
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 (TBD1) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Link Number Sub-TLV
Type: TBD1. (Note this is the Sub-TLV Type, not the Link Type.)
Length: 2.
Link Number: A 2-octet field carrying the link number assigned to
the link when the Link Type of the link in the OSPFv2 Extended
Link TLV containing this Sub-TLV is 1 (i.e., Point-to-Point
connection to another router), 2 (i.e., connection to a Transit
Network or LAN), or 3 (i.e., connection to a stub network).
3. Extensions to OSPFv3
This section describes extensions to OSPFv3 for distributing the link
numbers assigned to the links of a node.
[RFC8362] defines the OSPFv3 Extended Router LSA, which may include
multiple Router-Link TLVs.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Age |1|0|1| 0x21 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link State ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Advertising Router |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Checksum | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 |N|x|V|E|B| Options |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLVs |
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Extended Router-LSA
A Router-Link TLV defines a single router link.
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 (1 - Router-Link) | Length (Variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Type | 0 | Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Neighbor Interface ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Neighbor Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs |
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Router-Link TV
Under the Router-Link TLV for a link, a Link Number Sub-TLV is
defined. This Sub-TLV has the same format as the Link Number Sub-TLV
defined above for the OSPFv2 Extended Link TLV.
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The Router-Link TLV for a link may include a Link Number Sub-TLV for
distributing the link number assigned to the link by the router
originating the LSA.
4. Extensions to IS-IS
This section describes extensions to IS-IS for distributing the link
numbers assigned to the links of a node.
The Extended IS Reachability TLV (Type 22) defined in [RFC5305] may
contain Sub-TLVs (such as those for TE (Traffic Engineering)) that
apply to a link/interface to a neighbor. To encode multiple links or
interfaces to neighbors, the structure inside TLV is repeated.
The Multi-Topology (MT) Intermediate Systems TLV (Type 222) defined
in [RFC5120] may contain Sub-TLVs (such as those for TE) that apply
to a link/interface. It is aligned with the Extended IS Reachability
TLV (Type 22) but has an additional two bytes in front at the
beginning of the TLV for MT-ID.
A Link Number Sub-TLV is defined and used in the Extended IS
Reachability TLV (Type 22) and/or MT Intermediate Systems TLV (Type
222) to advertise the link numbers assigned to the links of a node.
The Link Number Sub-TLV has the following format:
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 (TBD3) | Length | Link Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: IS-IS Link Number Sub-TLV
Type: TBD3.
Length: 2.
Link Number: A 2-octet field carrying the link number assigned to
the link.
5. Security Considerations
TBD.
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6. IANA Considerations
Under "OSPFv2 Extended Link TLV Sub-TLVs registry" as defined in
[RFC7684], IANA is requested to assign a registry value for Link
Number Sub-TLV as follows:
+==============+======================+=====================+
| Value | Description | reference |
+==============+======================+=====================+
| TBD1 | Link Number | This document |
+--------------+----------------------+---------------------+
Under "OSPFv3 Extended-LSA Sub-TLVs registry" as defined in
[RFC8362], IANA is requested to assign a registry value for Link
Number Sub-TLV as follows:
+==============+======================+=====================+
| Value | Description | reference |
+==============+======================+=====================+
| TBD2 | Link Number | This document |
+--------------+----------------------+---------------------+
Under "Sub-TLVs for TLVs 22, 23, 25, 141, 222, and 223" for IS-IS TLV
Codepoints, IANA is requested to assign a codepoint for Link Number
Sub-TLV as follows:
+============+===================+==+==+==+===+===+===+=============+
|Sub-TLV Type|Sub-TLV Name |22|23|25|141|222|223|reference |
+============+===================+==+==+==+===+===+===+=============+
| TBD3 |Link Number |y |n |n | n | y | n |This document|
+------------+-------------------+--+--+--+---+---+---+-------------+
7. Acknowledgements
TBD.
8. References
8.1. 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>.
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[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998,
<https://www.rfc-editor.org/info/rfc2328>.
[RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120,
DOI 10.17487/RFC5120, February 2008,
<https://www.rfc-editor.org/info/rfc5120>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<https://www.rfc-editor.org/info/rfc5226>.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <https://www.rfc-editor.org/info/rfc5305>.
[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
2015, <https://www.rfc-editor.org/info/rfc7684>.
[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>.
[RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
F. Baker, "OSPFv3 Link State Advertisement (LSA)
Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
2018, <https://www.rfc-editor.org/info/rfc8362>.
8.2. Informative References
[RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The
OSPF Opaque LSA Option", RFC 5250, DOI 10.17487/RFC5250,
July 2008, <https://www.rfc-editor.org/info/rfc5250>.
Authors' Addresses
Huaimo Chen
Futurewei
Boston, MA,
United States of America
Email: Huaimo.chen@futurewei.com
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Donald E. Eastlake 3rd
Futurewei
2386 Panoramic Circle
Apopka, FL, 32703
United States of America
Phone: +1-508-333-2270
Email: d3e3e3@gmail.com
Aijun Wang
China Telecom
Beiqijia Town, Changping District
Beijing
102209
China
Email: wangaj3@chinatelecom.cn
Gyan S. Mishra
Verizon Inc.
13101 Columbia Pike
Silver Spring, MD 20904
United States of America
Phone: 301 502-1347
Email: gyan.s.mishra@verizon.com
Yisong Liu
China Mobile
Email: liuyisong@chinamobile.com
Yanhe Fan
Casa Systems
United States of America
Email: yfan@casa-systems.com
Lei Liu
Fujitsu
United States of America
Email: liulei.kddi@gmail.com
Xufeng Liu
Alef Edge
United States of America
Email: xufeng.liu.ietf@gmail.com
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