Pseudowire Redundancy
RFC 6718

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Internet Engineering Task Force (IETF)                          P. Muley
Request for Comments: 6718                                   M. Aissaoui
Category: Informational                                         M. Bocci
ISSN: 2070-1721                                           Alcatel-Lucent
                                                             August 2012

                         Pseudowire Redundancy

Abstract

   This document describes a framework comprised of a number of
   scenarios and associated requirements for pseudowire (PW) redundancy.
   A set of redundant PWs is configured between provider edge (PE) nodes
   in single-segment PW applications or between terminating PE (T-PE)
   nodes in multi-segment PW applications.  In order for the PE/T-PE
   nodes to indicate the preferred PW to use for forwarding PW packets
   to one another, a new PW status is required to indicate the
   preferential forwarding status of active or standby for each PW in
   the redundant set.

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/rfc6718.

Muley, et al.                 Informational                     [Page 1]
RFC 6718                      PW Redundancy                  August 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
   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. Introduction ....................................................3
   2. Terminology .....................................................4
      2.1. Requirements Language ......................................6
   3. Reference Models ................................................6
      3.1. PE Architecture ............................................6
      3.2. PW Redundancy Network Reference Scenarios ..................7
           3.2.1. PW Redundancy for AC and PE Protection: One
                  Dual-Homed CE with Redundant SS-PWs .................7
           3.2.2. PW Redundancy for AC and PE Protection: Two
                  Dual-Homed CEs with Redundant SS-PWs ................8
           3.2.3. PW Redundancy for S-PE Protection:
                  Single-Homed CEs with Redundant MS-PWs .............10
           3.2.4. PW Redundancy for PE-rs Protection in
                  H-VPLS Using SS-PWs ................................11
           3.2.5. PW Redundancy for PE Protection in a VPLS
                  Ring Using SS-PWs ..................................13
           3.2.6. PW Redundancy for VPLS n-PE Protection
                  Using SS-PWs .......................................14
   4. Generic PW Redundancy Requirements .............................15
      4.1. Protection Switching Requirements .........................15
      4.2. Operational Requirements ..................................15
   5. Security Considerations ........................................16
   6. Contributors ...................................................16
   7. Acknowledgements ...............................................17
   8. References .....................................................17
      8.1. Normative References ......................................17
      8.2. Informative Reference .....................................18

Muley, et al.                 Informational                     [Page 2]
RFC 6718                      PW Redundancy                  August 2012

1.  Introduction

   The objective of pseudowire (PW) redundancy is to maintain
   connectivity across the packet switched network (PSN) used by the
   emulated service if a component in the path of the emulated service
   fails or a backup component is activated.  For example, PW redundancy
   will enable the correct PW to be used for forwarding emulated service
   packets when the connectivity of an attachment circuit (AC) changes