Signaling MSD (Maximum SID Depth) using IS-IS
draft-ietf-isis-segment-routing-msd-14

Document Type Active Internet-Draft (lsr WG)
Last updated 2018-08-19
Replaces draft-tantsura-isis-segment-routing-msd
Stream IETF
Intended RFC status Proposed Standard
Formats plain text xml pdf html bibtex
Stream WG state Submitted to IESG for Publication (wg milestones: Jul 2018 - IS-IS Reverse Metric..., Jul 2018 - IS-IS Segment Routin... )
Document shepherd Christian Hopps
Shepherd write-up Show (last changed 2018-06-16)
IESG IESG state AD Evaluation::AD Followup
Consensus Boilerplate Yes
Telechat date
Responsible AD Alvaro Retana
Send notices to Christian Hopps <chopps@chopps.org>, aretana.ietf@gmail.com
IS-IS Working Group                                          J. Tantsura
Internet-Draft                                            Nuage Networks
Intended status: Standards Track                             U. Chunduri
Expires: February 20, 2019                           Huawei Technologies
                                                               S. Aldrin
                                                             Google, Inc
                                                             L. Ginsberg
                                                           Cisco Systems
                                                         August 19, 2018

             Signaling MSD (Maximum SID Depth) using IS-IS
                 draft-ietf-isis-segment-routing-msd-14

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
   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 February 20, 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 February 20, 2019               [Page 1]
Internet-Draft                                               August 2018

   (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
   to this document.  Code Components extracted from this document must
   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
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Node MSD Advertisement  . . . . . . . . . . . . . . . . . . .   3
   3.  Link MSD Advertisement  . . . . . . . . . . . . . . . . . . .   4
   4.  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
Show full document text