Recommendations for Interoperable IP Networks using Intermediate System to Intermediate System (IS-IS)
RFC 3787

Network Working Group                                     J. Parker, Ed.
Request for Comments: 3787                             Axiowave Networks
Category: Informational                                         May 2004

             Recommendations for Interoperable IP Networks
        using Intermediate System to Intermediate System (IS-IS)

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).  All Rights Reserved.

Abstract

   This document discusses a number of differences between the
   Intermediate System to Intermediate System (IS-IS) protocol used to
   route IP traffic as described in RFC 1195 and the protocol as it is
   deployed today.  These differences are discussed as a service to
   those implementing, testing, and deploying the IS-IS Protocol to
   route IP traffic.  A companion document describes the differences
   between the protocol described in ISO 10589 and current practice.

Table of Contents

    1.  Introduction. . . . . . . . . . . . . . . . . . . . . . . . .  2
    2.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  2
    3.  Unused Features . . . . . . . . . . . . . . . . . . . . . . .  2
    4.  Overload Bit. . . . . . . . . . . . . . . . . . . . . . . . .  3
    5.  Migration from Narrow Metrics to Wide . . . . . . . . . . . .  4
    6.  Intermediate System Hello (ISH) PDU . . . . . . . . . . . . .  6
    7.  Attached Bit. . . . . . . . . . . . . . . . . . . . . . . . .  7
    8.  Default Route . . . . . . . . . . . . . . . . . . . . . . . .  8
    9.  Non-homogeneous Protocol Networks . . . . . . . . . . . . . .  8
   10.  Adjacency Creation and IP Interface Addressing. . . . . . . .  9
   11.  Security Considerations . . . . . . . . . . . . . . . . . . .  9
   12.  References. . . . . . . . . . . . . . . . . . . . . . . . . . 10
        12.1. Normative References. . . . . . . . . . . . . . . . . . 10
        12.2. Informative References. . . . . . . . . . . . . . . . . 10
   13.  Author's Address. . . . . . . . . . . . . . . . . . . . . . . 10
   14.  Full Copyright Statement. . . . . . . . . . . . . . . . . . . 11

Parker                       Informational                      [Page 1]
RFC 3787         Interoperable IP Networks using IS-IS          May 2004

1.  Introduction

   Interior Gateway Protocols such as IS-IS are designed to provide
   timely information about the best routes in a routing domain.  The
   original design of IS-IS, as described in ISO 10589 [1] has proved to
   be quite durable.  However, a number of original design choices have
   been modified.  This document describes some of the differences
   between the protocol as described in RFC 1195 [2] and the protocol
   that can be observed on the wire today.  A companion document
   describes the differences between the protocol described in ISO 10589
   and current practice [8].

   The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT" and "MAY" in
   this document are to be interpreted as described in RFC 2119 [3].

2.  Acknowledgments

   This document is the work of many people, and is the distillation of
   over a thousand mail messages.  Thanks to Vishwas Manral, who pushed
   to create such a document.  Thanks to Danny McPherson, the original
   editor, for kicking things off.  Thanks to Mike Shand, for his work
   in creating the protocol, and his uncanny ability to remember what
   everything is for.  Thanks to Micah Bartell and Philip Christian, who
   showed us how to document difference without displaying discord.
   Thanks to Les Ginsberg, Neal Castagnoli, Jeff Learman, and Dave Katz,
   who spent many hours educating the editor.  Thanks to Radia Perlman,
   who is always ready to explain anything.  Thanks to Satish Dattatri,
   who was tenacious in seeing things written up correctly, and to Bryan
   Boulton for his work on the IP adjacency issue.  Thanks to Russ
   White, whose writing improved the treatment of every topic he
   touched.  Thanks to Shankar Vemulapalli, who read several drafts with
   close attention.  Thanks to Don Goodspeed, for his close reading of
   the text.  Thanks to Michael Coyle for identifying the quotation from
   Jan L.A. van de Snepscheut.  Thanks for Alex Zinin's ministrations
   behind the scenes.  Thanks to Tony Li and Tony Przygienda, who kept
   us on track as the discussions veered into the weeds.  And thanks to
   all those who have contributed, but whose names I have carelessly
   left from this list.

3.  Unused Features

   Some features defined in RFC 1195 are not in current use.