IS-IS Extensions for Path MTU
draft-hu-lsr-isis-path-mtu-00
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Network Working Group Z. Hu
Internet-Draft Huawei
Intended status: Informational Y. Zhu
Expires: January 1, 2019 China Telecom
Z. Li
L. Dai
Huawei
June 30, 2018
IS-IS Extensions for Path MTU
draft-hu-lsr-isis-path-mtu-00
Abstract
Segment routing (SR) leverages the source routing mechanism. It
allows for a flexible definition of end-to-end paths with IGP
topologies by encoding paths as sequences of topological sub-paths
which is called segments. These segments are advertised by the link-
state routing protocols (IS-IS and OSPF). Unlike the MPLS, SR does
not have the specific path construction signaling so that it cannot
support the Path MTU. This draft provides the necessary IS-IS
extensions about the Path MTU that need to be used on SR.
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."
This Internet-Draft will expire on January 1, 2019.
Hu, et al. Expires January 1, 2019 [Page 1]
Internet-Draft IS-IS Extensions for Path MTU June 2018
Copyright Notice
Copyright (c) 2018 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
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include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Extendsion of IS-IS . . . . . . . . . . . . . . . . . . . . . 4
3.1. Protocol Extension . . . . . . . . . . . . . . . . . . . 4
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Segment routing (SR) leverages the source routing mechanism. SR
allows for a flexible definition of end-to-end paths within IGP
topologies by encoding paths as sequences of toplogical sub-paths
which is called segments. These segments are advertised by the link-
state routing protocols (IS-SI and OSPF). The SR architecture as
well as the routing policy is proposed in
[I-D.ietf-spring-segment-routing] and
[I-D.filsfils-spring-segment-routing-policy]. Two types of segments
are defined, Prefix segments and Adjacency segments. Prefix segments
represent an ecmp-aware shortest-path to a prefix, as per the state
of the IGP topology. Adjacency segments represent a hop over a
specific adjacency between two nodes in the IGP. A prefix segment is
typically a multi-hop path while an adjacency segment, in most of the
cases, is a one-hop path. SR can compute the paths from end to end
and without requiring any LDP or RSVP-TE signaling. SR supports per-
flow explict routing while just maintaining per-flow state only at
the source node.
Hu, et al. Expires January 1, 2019 [Page 2]
Internet-Draft IS-IS Extensions for Path MTU June 2018
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