S-PE Outage Protection for Static Multi-Segment Pseudowires
draft-shawam-pwe3-ms-pw-protection-01

Network Working Group                                           A. Malis
Internet-Draft                                              L. Andersson
Updates: 6870 (if approved)                 Huawei Technologies Co., Ltd
Intended status: Standards Track                         H. van Helvoort
Expires: March 30, 2015                                   Hai Gaoming BV
                                                                 J. Shin
                                                              SK Telecom
                                                                 L. Wang
                                                            China Mobile
                                                         A. D'Alessandro
                                                          Telecom Italia
                                                      September 26, 2014

      S-PE Outage Protection for Static Multi-Segment Pseudowires
               draft-shawam-pwe3-ms-pw-protection-01.txt

Abstract

   In MPLS and MPLS-TP environments, statically provisioned Single-
   Segment Pseudowires (SS-PWs) are protected against tunnel failure via
   MPLS-level and MPLS-TP-level tunnel protection.  With statically
   provisioned Multi-Segment Pseudowires (MS-PWs), each segment of the
   MS-PW is likewise protected from tunnel failures via MPLS-level and
   MPLS-TP-level tunnel protection.  However, static MS-PWs are not
   protected end-to-end against failure of one of the switching PEs
   (S-PEs) along the path of the MS-PW.  This document describes how to
   achieve this protection by updating the existing procedures in RFC
   6870.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on March 30, 2015.

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Copyright Notice

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Extension to RFC 6870 to Protect Statically Provisioned SS-
       PWs and MS-PWs  . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Operational Considerations  . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   As described in RFC 5659 [RFC5659], Multi-Segment Pseudowires (MS-
   PWs) consist of terminating PEs (T-PEs), switching PEs (S-PEs), and
   PW segments between the T-PEs at each of the MS-PW and the interior
   S-PEs.  In MPLS and MPLS-TP environments, statically provisioned
   Single-Segment Pseudowires (SS-PWs) are protected against tunnel
   failure via MPLS-level and MPLS-TP-level tunnel protection.  With
   statically provisioned Multi-Segment Pseudowires (MS-PWs), each PW
   segment of the MS-PW is likewise protected from tunnel failure via
   MPLS-level and MPLS-TP-level tunnel protection.  However, PSN tunnel
   protection does not protect static MS-PWs from failures of S-PEs
   along the path of the MS-PW.

   RFC 6718 [RFC6718] provides a general framework for PW protection,
   and RFC 6870 [RFC6870], which is based upon that framework, describes
   protection procedures for MS-PWs that are dynamically signaled using
   LDP.  This document describes how to achieve protection against S-PE

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   failure in a static MS-PW by extending RFC 6870 to be applicable for
   statically provisioned MS-PWs pseudowires (PWs) as well.

1.1.  Requirements Language

   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].

2.  Extension to RFC 6870 to Protect Statically Provisioned SS-PWs and
    MS-PWs

   Section 3.2.3 of RFC 6718 and Section A.5 of RFC 6870 document how to
   use redundant MS-PWs to protect an MS-PW against S-PE failure.  The
   procedures in these RFCs rely on LDP-based PW status signaling to
   signal the state of the primary MS-PW that is being protected, and
   the precedence in which redundant MS-PW(s) should be used to protect
   the primary MS-PW should it fail.  These procedures make use of
   information carried by the PW Status TLV, which for dynamically
   signaled PWs is carried by the LDP protocol.

   However, statically provisioned PWs (SS-PWs or MS-PWs) do not use the
   LDP protocol for PW set and signaling, rather they are provisioned by
   network management systems or other means at each T-PE and S-PE along
   their path.  They also do not use the LDP protocol for status
   signaling.  Rather, they use procedures defined in RFC 6478 [RFC6478]
   for status signaling via the PW OAM message using the PW Associated
   Channel Header (ACH).  The PW Status TLV carried via this status
   signaling is itself identical to the PW Status TLV carried via LDP-
   based status signaling, including the identical PW Status Codes.

   Sections 6 and 7 of RFC 6870 describes the management of a primary PW
   and its secondary PW(s) to provide resiliency to the failure of the
   primary PW.  They use status codes transmitted between endpoint T-PEs
   using the PW Status TLV transmitted by LDP.  For this management to
   apply to statically provisioned PWs, the PW status signaling defined
   in RFC 6478 MUST be used for the primary and secondary PWs.  In that
   case, the endpoint T-PEs can then use the PW status signaling
   provided by RFC 6478 in the place of LDP-based status signaling, but
   otherwise operate identically as described in RFC 6870.

3.  Operational Considerations

   Because LDP is not used between the T-PEs for statically provisioned
   MS-PWs, the negotiation procedures described in RFC 6870 cannot be
   used.  Thus, operational care must be taken so that the endpoint
   T-PEs are identically provisioned regarding the use of this document,
   specifically whether or not MS-PW redundancy is being used, and for

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   each protected MS-PW, the identity of the primary MS-PW and the
   precedence of the secondary MS-PWs.

4.  Security Considerations

   The security considerations defined for RFC 6478 apply to this
   document as well.  As the security considerations in RFCs 6718 and
   6870 are related to their use of LDP, they are not required for this
   document.

5.  IANA Considerations

   There are no requests for IANA actions in this document.

   Note to the RFC Editor - this section can be removed before
   publication.

6.  Acknowledgements

   The authors would like to thank Matthew Bocci, Yaakov Stein, and
   David Sinicrope for their comments on this document.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC6478]  Martini, L., Swallow, G., Heron, G., and M. Bocci,
              "Pseudowire Status for Static Pseudowires", RFC 6478, May
              2012.

   [RFC6870]  Muley, P. and M. Aissaoui, "Pseudowire Preferential
              Forwarding Status Bit", RFC 6870, February 2013.

7.2.  Informative References

   [RFC5659]  Bocci, M. and S. Bryant, "An Architecture for Multi-
              Segment Pseudowire Emulation Edge-to-Edge", RFC 5659,
              October 2009.

   [RFC6718]  Muley, P., Aissaoui, M., and M. Bocci, "Pseudowire
              Redundancy", RFC 6718, August 2012.

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Authors' Addresses

   Andrew G. Malis
   Huawei Technologies Co., Ltd

   Email: agmalis@gmail.com

   Loa Andersson
   Huawei Technologies Co., Ltd

   Email: loa@mail01.huawei.com

   Huub van Helvoort
   Hai Gaoming BV

   Email: huubatwork@gmail.com

   Jongyoon Shin
   SK Telecom

   Email: jongyoon.shin@sk.com

   Lei Wang
   China Mobile

   Email: wangleiyj@chinamobile.com

   Alessandro D'Alessandro
   Telecom Italia

   Email: alessandro.dalessandro@telecomitalia.it

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