Pseudowire Status for Static Pseudowires
RFC 6478

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Internet Engineering Task Force (IETF)                        L. Martini
Request for Comments: 6478                                    G. Swallow
Updates: 5885                                                   G. Heron
Category: Standards Track                                          Cisco
ISSN: 2070-1721                                                 M. Bocci
                                                          Alcatel-Lucent
                                                                May 2012

                Pseudowire Status for Static Pseudowires

Abstract

   This document specifies a mechanism to signal Pseudowire (PW) status
   messages using a PW associated channel (ACh).  Such a mechanism is
   suitable for use where no PW dynamic control plane exits, known as
   static PWs, or where a Terminating Provider Edge (T-PE) needs to send
   a PW status message directly to a far-end T-PE.  The mechanism allows
   PW Operations, Administration, and Maintenance (OAM) message mapping
   and PW redundancy to operate on static PWs.  This document also
   updates RFC 5885 in the case when Bi-directional Forwarding Detection
   (BFD) is used to convey PW status-signaling information.

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/rfc6478.

Martini, et al.              Standards Track                    [Page 1]
RFC 6478        Pseudowire Status for Static Pseudowires        May 2012

Copyright Notice

   Copyright (c) 2011 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. Specification of Requirements ...................................3
   3. Terminology .....................................................3
   4. Applicability ...................................................3
   5. Pseudowire Status Operation .....................................4
      5.1. PW OAM Message .............................................4
      5.2. Sending a PW Status Message ................................5
      5.3. PW OAM Status Message Transmit and Receive .................6
           5.3.1. Acknowledgment of PW Status .........................7
      5.4. MPLS Label Stack ...........................................7
           5.4.1. Label Stack for a Message Destined to the Next PE ...8
           5.4.2. Label Stack for a Message Destined to the Egress PE .8
      5.5. S-PE Bypass Mode ...........................................8
           5.5.1. S-PE Bypass Mode LDP Flag Bit .......................9
   6. S-PE Operation .................................................10
      6.1. Static PW to Another Static PW ............................10
      6.2. Dynamic PW to Static PW or Vice Versa .....................10
   7. Security Considerations ........................................11
   8. IANA Considerations ............................................11
   9. References .....................................................11
      9.1. Normative References ......................................11
      9.2. Informative References ....................................12

Martini, et al.              Standards Track                    [Page 2]
RFC 6478        Pseudowire Status for Static Pseudowires        May 2012

1.  Introduction

   The default control plane for Pseudowire (PW) technology, as defined
   in [RFC4447], is based on the Label Distribution Protocol (LDP).
   However, that document also describes a static provisioning mode
   without a control plane.  When a static PW is used, there is no
   method to transmit the status of the PW or attachment circuit (AC)
   between the two Provider Edge (PE) devices at each end of the PW.
   This document defines a method to transport the PW status codes
   defined in Section 5.4.2 of [RFC4447] and elsewhere [REDUNDANCY] in-