Signaling MSD (Maximum SID Depth) using IS-IS
draft-ietf-isis-segment-routing-msd-15
| The information below is for an old version of the document | |||
|---|---|---|---|
| Document | Type | Active Internet-Draft (lsr WG) | |
| Last updated | 2018-09-12 (latest revision 2018-08-29) | ||
| Replaces | draft-tantsura-isis-segment-routing-msd | ||
| Stream | IETF | ||
| Intended RFC status | Proposed Standard | ||
| Formats | pdf htmlized (tools) htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Christian Hopps | ||
| Shepherd write-up | Show (last changed 2018-06-16) | ||
| IESG | IESG state | IESG Evaluation | |
| Consensus Boilerplate | Yes | ||
| Telechat date |
Needs 4 more YES or NO OBJECTION positions to pass. |
||
| Responsible AD | Alvaro Retana | ||
| Send notices to | Christian Hopps <chopps@chopps.org>, aretana.ietf@gmail.com | ||
| IANA | IANA review state | IANA OK - Actions Needed | |
IS-IS Working Group J. Tantsura
Internet-Draft Nuage Networks
Intended status: Standards Track U. Chunduri
Expires: March 2, 2019 Huawei Technologies
S. Aldrin
Google, Inc
L. Ginsberg
Cisco Systems
August 29, 2018
Signaling MSD (Maximum SID Depth) using IS-IS
draft-ietf-isis-segment-routing-msd-15
Abstract
This document defines a way for an Intermediate System to
Intermediate System (IS-IS) Router to advertise multiple types of
supported Maximum SID Depths (MSDs) at node and/or link granularity.
Such advertisements allow entities (e.g., centralized controllers) to
determine whether a particular SID stack can be supported in a given
network. This document only defines one type of MSD maximum label
imposition, but defines an encoding that can support other MSD types.
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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and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 2, 2019.
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
Tantsura, et al. Expires March 2, 2019 [Page 1]
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Node MSD Advertisement . . . . . . . . . . . . . . . . . . . 3
3. Link MSD Advertisement . . . . . . . . . . . . . . . . . . . 4
4. Procedures for using Node and Link MSD Advertisements . . . . 5
5. Base MPLS Imposition MSD . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 7
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
10.1. Normative References . . . . . . . . . . . . . . . . . . 8
10.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
When Segment Routing (SR) paths are computed by a centralized
controller, it is critical that the controller learns the Maximum SID
Depth (MSD) that can be imposed at each node/link a given SR path to
insure that the Segment Identifier (SID) stack depth of a computed
path doesn't exceed the number of SIDs the node is capable of
imposing.
Path Computation Element Protocol (PCEP) SR extensions draft
[I-D.ietf-pce-segment-routing] signals MSD in SR Path Computation
Element (PCE) Capability TLV and METRIC Object. However, if PCEP is
not supported/configured on the head-end of an SR tunnel or a
Binding-SID anchor node and controller does not participate in IGP
routing, it has no way to learn the MSD of nodes and links. BGP-LS
(Distribution of Link-State and TE Information using Border Gateway
Protocol) [RFC7752] defines a way to expose topology and associated
attributes and capabilities of the nodes in that topology to a
centralized controller. MSD signaling by BGP-LS has been defined in
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