Advertising Generic Information in IS-IS
RFC 6823

Internet Engineering Task Force (IETF)                       L. Ginsberg
Request for Comments: 6823                                    S. Previdi
Category: Standards Track                                       M. Shand
ISSN: 2070-1721                                            Cisco Systems
                                                           December 2010

                Advertising Generic Information in IS-IS

Abstract

   This document describes the manner in which generic application
   information (i.e., information not directly related to the operation
   of the Intermediate System to Intermediate System (IS-IS) protocol)
   should be advertised in IS-IS Link State Protocol Data Units (LSPs)
   and defines guidelines that should be used when flooding such
   information.

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 5741.

   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/rfc6823.

Copyright Notice

   Copyright (c) 2010 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 6823        Advertising Generic Information in IS-IS   December 2010

Table of Contents

   1.  Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  3
   3.  Encoding Format for GENINFO  . . . . . . . . . . . . . . . . .  3
     3.1.  GENINFO TLV  . . . . . . . . . . . . . . . . . . . . . . .  3
     3.2.  Use of Sub-TLVs in GENINFO TLV . . . . . . . . . . . . . .  5
   4.  GENINFO Flooding Procedures  . . . . . . . . . . . . . . . . .  5
     4.1.  Leaking Procedures . . . . . . . . . . . . . . . . . . . .  6
     4.2.  Minimizing Update Confusion  . . . . . . . . . . . . . . .  7
     4.3.  Interpreting Attribute Information . . . . . . . . . . . .  7
   5.  Use of a Separate Protocol Instance  . . . . . . . . . . . . .  7
   6.  Applicability of GENINFO TLV . . . . . . . . . . . . . . . . .  8
   7.  Standardization Requirements . . . . . . . . . . . . . . . . .  8
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  9
   11. Normative References . . . . . . . . . . . . . . . . . . . . . 10

1.  Overview

   [ISO10589] defines the format of Type-Length-Values (TLVs) that may
   be sent in IS-IS Protocol Data Units (PDUs).  The first octet of a
   TLV encodes the "type" or "codepoint" that provides a scope for the
   information and information format that follows.  The protocol is
   therefore limited to 256 different codepoints that may be assigned.
   This number has proved generous as regards the information required
   for correct operation of the IS-IS protocol.  However, the increasing
   use of IS-IS Link State Protocol Data Units (LSPs) for advertisement
   of generic information (GENINFO) not directly related to the
   operation of the IS-IS protocol places additional demands on the TLV
   encoding space that have the potential to consume a significant
   number of TLV codepoints.  This document therefore defines an
   encoding format for GENINFO that minimizes the consumption of TLV
   codepoints and also maximizes the flexibility of the formats that can
   be used to represent GENINFO.

   This document also discusses optimal behavior associated with the
   advertisement and flooding of LSPs containing GENINFO in order to
   avoid the advertisement of stale information and minimize the
   presence of duplicate or conflicting information when advertisements
   are updated.

   The manner in which the information contained in GENINFO TLVs is
   exchanged between an instance of the IS-IS protocol and the