Pseudowire Redundancy on the Switching Provider Edge (S-PE)
RFC 7795

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Internet Engineering Task Force (IETF)                           J. Dong
Request for Comments: 7795                                       H. Wang
Category: Standards Track                            Huawei Technologies
ISSN: 2070-1721                                            February 2016

      Pseudowire Redundancy on the Switching Provider Edge (S-PE)

Abstract

   This document describes Multi-Segment Pseudowire (MS-PW) protection
   scenarios in which pseudowire redundancy is provided on the Switching
   Provider Edge (S-PE) as defined in RFC 5659.  Operations of the S-PEs
   that provide PW redundancy are specified in this document.  Signaling
   of the Preferential Forwarding status as defined in RFCs 6870 and
   6478 is reused.  This document does not require any change to the
   Terminating Provider Edges (T-PEs) of MS-PW.

Status of This Memo

   This is an Internet Standards Track document.

   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).  Further information on
   Internet Standards is available in 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/rfc7795.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Dong & Wang                  Standards Track                    [Page 1]
RFC 7795                  PW Redundancy on S-PE            February 2016

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Typical Scenarios of PW Redundancy on S-PE  . . . . . . . . .   3
     2.1.  MS-PW Redundancy on S-PE  . . . . . . . . . . . . . . . .   3
     2.2.  MS-PW Redundancy on S-PE with S-PE Protection . . . . . .   4
   3.  S-PE Operations . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Applications of PW Redundancy on S-PE . . . . . . . . . . . .   5
     4.1.  Applications in Scenario 1  . . . . . . . . . . . . . . .   5
     4.2.  Applications in Scenario 2  . . . . . . . . . . . . . . .   6
   5.  VCCV Considerations . . . . . . . . . . . . . . . . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   [RFC6718] describes the framework and requirements for pseudowire
   (PW) redundancy, and [RFC6870] specifies a PW redundancy mechanism
   for scenarios where a set of redundant PWs are configured between
   Provider Edge (PE) nodes in Single-Segment Pseudowire (SS-PW)
   [RFC3985] applications, or between Terminating Provider Edge (T-PE)
   nodes in Multi-Segment Pseudowire (MS-PW) [RFC5659] applications.

   In some MS-PW scenarios, there are benefits of providing PW
   redundancy on Switching Provider Edges (S-PEs), such as reducing the
   burden on the access T-PE nodes and enabling faster protection
   switching compared to the end-to-end MS-PW protection mechanisms.

   This document describes some scenarios in which PW redundancy is
   provided on S-PEs and specifies the operations of the S-PEs.  The
   S-PEs connect to the neighboring T-PEs or S-PEs with PW segments.
   For the S-PE that provides PW redundancy for an MS-PW, there is a
   single PW segment on one side, which is called the single-homed side,
   and there are multiple PW segments on the other side, which is called
   the multi-homed side.  The scenario in which the S-PE has two multi-
   homed sides is out of scope.  Signaling of the Preferential
   Forwarding status as defined in [RFC6870] and [RFC6478] is reused.
   This document does not require any change to the T-PEs of MS-PW.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].