OSPF Stub Router Advertisement
draft-ietf-ospf-rfc3137bis-01

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Document Type Active Internet-Draft (ospf WG)
Last updated 2012-06-29
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Network Working Group                                          A. Retana
Internet-Draft                                       Hewlett-Packard Co.
Obsoletes: RFC3137 (if approved)                               L. Nguyen
Intended status: Informational                                  A. Zinin
Expires: December 31, 2012                           Cisco Systems, Inc.
                                                                R. White
                                                            D. McPherson
                                                          Verisign, Inc.
                                                           June 29, 2012

                     OSPF Stub Router Advertisement
                     draft-ietf-ospf-rfc3137bis-01

Abstract

   This memo describes a backward-compatible technique that may be used
   by OSPF (Open Shortest Path First) implementations to advertise
   unavailability to forward transit traffic or to lower the preference
   level for the paths through such a router.  In some cases, it is
   desirable not to route transit traffic via a specific OSPF router.
   However, OSPF does not specify a standard way to accomplish this.

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 http://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 December 31, 2012.

Copyright Notice

   Copyright (c) 2012 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

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   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.  Motivation  . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . . . 3
   3.  Proposed Solution . . . . . . . . . . . . . . . . . . . . . . . 3
   4.  Deployment Considerations . . . . . . . . . . . . . . . . . . . 4
     4.1.  Other Solutions . . . . . . . . . . . . . . . . . . . . . . 4
   5.  Maximum Link Metric . . . . . . . . . . . . . . . . . . . . . . 4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 5
     8.1.  Normative References  . . . . . . . . . . . . . . . . . . . 5
     8.2.  Informative References  . . . . . . . . . . . . . . . . . . 5
   Appendix A.  Changes between the -00 and -01 versions.  . . . . . . 5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 6

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1.  Motivation

   In some situations, it may be advantageous to inform routers in a
   network not to use a specific router as a transit point, but still
   route to it.  Possible situations include the following:

   o  The router is in a critical condition (for example, has very high
      CPU load or does not have enough memory to store all LSAs or build
      the routing table).

   o  Graceful introduction and removal of the router to/from the
      network.

   o  Other (administrative or traffic engineering) reasons.

   Note that the proposed solution does not remove the router from the
   topology view of the network (as could be done by just flushing that
   router's router-LSA), but prevents other routers from using it for
   transit routing, while still routing packets to the router's own IP
   addresses, i.e., the router is announced as a stub.

   It must be emphasized that the proposed solution provides real
   benefits in networks designed with at least some level of redundancy
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