Network Working Group Z. Li
Internet-Draft Z. Hu
Intended status: Standards Track J. Dong
Expires: September 22, 2022 Huawei Technologies
March 21, 2022
Topology Identifier in IPv6 Extension Header
draft-li-6man-topology-id-00
Abstract
This document proposes a new Hop-by-Hop option of IPv6 extension
header to carry the topology identifier, which is used to identify
the forwarding table instance created by the Multi Topology Routing
or Flexible Algorithm.
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.
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This Internet-Draft will expire on September 22, 2022.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminologies . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 2
4. New IPv6 Extension Header Option for Topologies . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 3
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
7.1. Normative References . . . . . . . . . . . . . . . . . . 4
7.2. Informative References . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
This document proposes a new Hop-by-Hop option of IPv6 extension
header to carry the topology identifier, which is used to identify
the forwarding table instance created by the Multi Topology Routing
or Flexible Algorithm.
2. Terminologies
The following terminologies are used in this document.
MT: Multi Topology
3. Problem Statement
[RFC4915] defines Multi-Topology Routing in OSPF and [RFC5120]
defines Multi Topology Routing in ISIS. Through Multi Topology
Routing, there can be multiple forwarding tables in the data plane.
[I-D.ietf-lsr-flex-algo] can also implement the similar purpose to
install multiple forwarding tables for different Flexible Algorithm
instances.
In the MT IP Forwarding Considerations of [RFC5120],it is explained
when multiple MTs share an Interface with overlapping addresses, some
additional mechanism is needed to select the correct RIBs for the
incoming IP packets to determine the correct RIB to make a forwarding
decision. But there is lack of the generic approach of packet to
multiple MT RIB mapping over the same inbound interface.
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4. New IPv6 Extension Header Option for Topologies
In order to solve the above issue, in the scenario of IPv6, the
topology identifier information can be carried in the packet. A new
Hop-by-Hop option type "Topology" is defined to carry the topology
related Identifier in an IPv6 packet. Its format is shown 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opt Type | Opt Data Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Topology ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1. Topology Option
where:
o Opt Type: Type value is TBD. 8-bit unsigned integer. Identifier of
the type of this Topology Option.
o Opt Data Len: 8-bit unsigned integer. It indicates the length of
the option Data field of this option, in octets. The value of Opt
Data Len of Topology option SHOULD be set to 4.
o Topology ID: 2-octet identifier which uniquely identifies the
topology associated with the specific forwarding table created by the
Multi Topology Routing or Flexible Algorithm.
o Reserved: 2-octet reserved field. It MUST be set as 0 and ignored
when received.
5. Security Considerations
TBD
6. IANA Considerations
This document requests IANA to assign a new option type from "Hop-by-
Hop Options" registry.
Value Description Reference
------------------------------------------
TBD Topology Option this document
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7. References
7.1. Normative References
[I-D.ietf-lsr-flex-algo]
Psenak, P., Hegde, S., Filsfils, C., Talaulikar, K., and
A. Gulko, "IGP Flexible Algorithm", draft-ietf-lsr-flex-
algo-18 (work in progress), October 2021.
[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>.
[RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
RFC 4915, DOI 10.17487/RFC4915, June 2007,
<https://www.rfc-editor.org/info/rfc4915>.
[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>.
7.2. Informative References
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
Authors' Addresses
Zhenbin Li
Huawei Technologies
Beijing 100095
China
Email: lizhenbin@huawei.com
Zhibo Hu
Huawei Technologies
Beijing 100095
China
Email: huzhibo@huawei.com
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Jie Dong
Huawei Technologies
Beijing 100095
China
Email: jie.dong@huawei.com
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