IS-IS Extensions for Advertising Router Information
RFC 7981

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Internet Engineering Task Force (IETF)                       L. Ginsberg
Request for Comments: 7981                                    S. Previdi
Obsoletes: 4971                                            Cisco Systems
Category: Standards Track                                        M. Chen
ISSN: 2070-1721                             Huawei Technologies Co., Ltd
                                                            October 2016

          IS-IS Extensions for Advertising Router Information

Abstract

   This document defines a new optional Intermediate System to
   Intermediate System (IS-IS) TLV named CAPABILITY, formed of multiple
   sub-TLVs, which allows a router to announce its capabilities within
   an IS-IS level or the entire routing domain.  This document obsoletes
   RFC 4971.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7981.

Copyright Notice

   Copyright (c) 2016 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
   (http://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.

Ginsberg, et al.             Standards Track                    [Page 1]
RFC 7981          IS-IS Ext for Advertising Router Info     October 2016

Table of Contents

   1. Introduction ....................................................2
      1.1. Requirements Language ......................................3
   2. IS-IS Router CAPABILITY TLV .....................................3
   3. Elements of Procedure ...........................................4
   4. Interoperability with Routers Not Supporting the IS-IS Router
      CAPABILITY TLV ..................................................6
   5. Security Considerations .........................................6
   6. IANA Considerations .............................................7
   7. References ......................................................7
      7.1. Normative References .......................................7
      7.2. Informative References .....................................8
   Appendix A.  Changes to RFC 4971 ...................................9
   Acknowledgements ..................................................10
   Authors' Addresses ................................................10

1.  Introduction

   There are several situations where it is useful for the IS-IS
   [ISO10589] [RFC1195] routers to learn the capabilities of the other
   routers of their IS-IS level, area, or routing domain.  For the sake
   of illustration, three examples related to MPLS Traffic Engineering
   (TE) are described here:

   1.  Mesh-group: The setting up of a mesh of TE Label Switched Paths
       (LSPs) [RFC5305] requires some significant configuration effort.
       [RFC4972] proposes an auto-discovery mechanism whereby every
       Label Switching Router (LSR) of a mesh advertises its mesh-group
       membership by means of IS-IS extensions.

   2.  Point-to-Multipoint TE LSP (RFC4875): A specific sub-TLV
       [RFC5073] allows an LSR to advertise its Point-to-Multipoint
       capabilities ([RFC4875] and [RFC4461]).

   3.  Inter-area traffic engineering: Advertisement of the IPv4 and/or
       the IPv6 Traffic Engineering Router IDs.

   The use of IS-IS for Path Computation Element (PCE) discovery may
   also be considered and will be discussed in the PCE WG.

   The capabilities mentioned above require the specification of new
   sub-TLVs carried within the IS-IS Router CAPABILITY TLV defined in
   this document.

Ginsberg, et al.             Standards Track                    [Page 2]
RFC 7981          IS-IS Ext for Advertising Router Info     October 2016

   Note that the examples above are provided for the sake of
   illustration.  This document proposes a generic capability
   advertising mechanism that is not limited to MPLS Traffic
   Engineering.

   This document defines a new optional IS-IS TLV named CAPABILITY,
   formed of multiple sub-TLVs, which allows a router to announce its