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A Framework for IP and MPLS Fast Reroute Using Not-Via Addresses
RFC 6981

Internet Engineering Task Force (IETF)                         S. Bryant
Request for Comments: 6981                                    S. Previdi
Category: Informational                                    Cisco Systems
ISSN: 2070-1721                                                 M. Shand
                                                  Individual Contributor
                                                             August 2013

    A Framework for IP and MPLS Fast Reroute Using Not-Via Addresses

Abstract

   This document presents an illustrative framework for providing fast
   reroute in an IP or MPLS network through encapsulation and forwarding
   to "not-via" addresses.  The general approach described here uses a
   single level of encapsulation and could be used to protect unicast,
   multicast, and LDP traffic against link, router, and shared risk
   group failure, regardless of network topology and metrics.

   The mechanisms presented in this document are purely illustrative of
   the general approach and do not constitute a protocol specification.
   The document represents a snapshot of the work of the Routing Area
   Working Group at the time of publication and is published as a
   document of record.  Further work is needed before implementation or
   deployment.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   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).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see 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/rfc6981.

Bryant, et al.                Informational                     [Page 1]
RFC 6981              IPFRR Using Not-Via Addresses          August 2013

Copyright Notice

   Copyright (c) 2013 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.

Bryant, et al.                Informational                     [Page 2]
RFC 6981              IPFRR Using Not-Via Addresses          August 2013

Table of Contents

   1. Introduction ....................................................4
      1.1. The Purpose of This Document ...............................4
      1.2. Overview ...................................................4
   2. Requirements Language ...........................................5
   3. Overview of Not-Via Repairs .....................................5
      3.1. Use of Equal-Cost Multi-Path ...............................6
      3.2. Use of LFA Repairs .........................................6
   4. Not-Via Repair Path Computation .................................7
      4.1. Computing Not-Via Repairs in Distance and Path
           Vector Routing Protocols ...................................8
   5. Operation of Repairs ............................................8
      5.1. Node Failure ...............................................8
      5.2. Link Failure ...............................................9
           5.2.1. Loop Prevention under Node Failure ..................9
      5.3. Multi-Homed Prefixes .......................................9
      5.4. Installation of Repair Paths ..............................11
   6. Compound Failures ..............................................12
      6.1. Shared Risk Link Groups ...................................12
      6.2. Local Area Networks .......................................17
           6.2.1. Simple LAN Repair ..................................18
           6.2.2. LAN Component Repair ...............................19
           6.2.3. LAN Repair Using Diagnostics .......................19
      6.3. Multiple Independent Failures .............................20
           6.3.1. Looping Repairs ....................................20
           6.3.2. Outline Solution ...................................21

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