Loop-free convergence using oFIB
draft-ietf-rtgwg-ordered-fib-07

The information below is for an old version of the document
Document Type Active Internet-Draft (rtgwg WG)
Last updated 2012-10-01 (latest revision 2012-09-07)
Stream IETF
Intended RFC status Informational
Formats plain text pdf html bibtex
Reviews
Stream WG state Submitted to IESG for Publication
Document shepherd Alvaro Retana
IESG IESG state AD Evaluation::Revised I-D Needed
Consensus Boilerplate Unknown
Telechat date
Responsible AD Adrian Farrel
IESG note Alvaro Retana (aretana@cisco.com) is the Document Shepherd.
Send notices to rtgwg-chairs@tools.ietf.org, draft-ietf-rtgwg-ordered-fib@tools.ietf.org
Network Working Group                                           M. Shand
Internet-Draft                                    Individual Contributor
Intended status: Informational                                 S. Bryant
Expires: March 11, 2013                                       S. Previdi
                                                             C. Filsfils
                                                           Cisco Systems
                                                             P. Francois
                                                Institute IMDEA Networks
                                                          O. Bonaventure
                                        Universite catholique de Louvain
                                                       September 7, 2012

                    Loop-free convergence using oFIB
                    draft-ietf-rtgwg-ordered-fib-07

Abstract

   This document describes a mechanism for use in conjunction with link
   state routing protocols which prevents the transient loops which
   would otherwise occur during topology changes.  It does this by
   correctly sequencing the forwarding information base (FIB) updates on
   the routers.

   This mechanism can be used in the case of non-urgent link or node
   shutdowns and restarts or link metric changes.  It can also be used
   in conjunction with a fast re-route mechanism which converts a sudden
   link or node failure into a non-urgent topology change.  This is
   possible where a complete repair path is provided for all affected
   destinations.

   After a non-urgent topology change, each router computes a rank that
   defines the time at which it can safely update its FIB.  A method for
   accelerating this loop-free convergence process by the use of
   completion messages is also described.

   The technology described in this document has been subject to
   extensive simulation using real network topologies and costs, and
   pathological convergence behaviour.

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-

Shand, et al.            Expires March 11, 2013                 [Page 1]
Internet-Draft      Loop-free convergence using oFIB      September 2012

   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 March 11, 2013.

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
   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.

Shand, et al.            Expires March 11, 2013                 [Page 2]
Internet-Draft      Loop-free convergence using oFIB      September 2012

Table of Contents

   1.  Conventions used in the document . . . . . . . . . . . . . . .  4
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  The required FIB update order  . . . . . . . . . . . . . . . .  5
     3.1.  Single Link Events . . . . . . . . . . . . . . . . . . . .  5
       3.1.1.  Link Down / Metric Increase  . . . . . . . . . . . . .  5
       3.1.2.  Link Up / Metric Decrease  . . . . . . . . . . . . . .  6
     3.2.  Multi-link events  . . . . . . . . . . . . . . . . . . . .  7
       3.2.1.  Router Down events . . . . . . . . . . . . . . . . . .  7
       3.2.2.  Router Up events . . . . . . . . . . . . . . . . . . .  7
       3.2.3.  Linecard Failure/Restoration Events  . . . . . . . . .  7
   4.  Applying ordered FIB updates . . . . . . . . . . . . . . . . .  8
     4.1.  Deducing the topology change . . . . . . . . . . . . . . .  8
     4.2.  Deciding if ordered FIB updates applies  . . . . . . . . .  8
   5.  Computation of the ordering  . . . . . . . . . . . . . . . . .  9
     5.1.  Link or Router Down or Metric Increase . . . . . . . . . .  9
     5.2.  Link or Router Up or Metric Decrease . . . . . . . . . . . 10
   6.  Acceleration of Ordered Convergence  . . . . . . . . . . . . . 10
Show full document text