Updates to MPLS Transport Profile Linear Protection
RFC 7324

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Internet Engineering Task Force (IETF)                        E. Osborne
Request for Comments: 7324                                     July 2014
Updates: 6378
Category: Standards Track
ISSN: 2070-1721

          Updates to MPLS Transport Profile Linear Protection

Abstract

   This document contains a number of updates to the Protection State
   Coordination (PSC) logic defined in RFC 6378, "MPLS Transport Profile
   (MPLS-TP) Linear Protection".  These updates provide some rules and
   recommendations around the use of TLVs in PSC, address some issues
   raised in an ITU-T liaison statement, and clarify PSC's behavior in a
   case not well explained in RFC 6378.

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/rfc7324.

Copyright Notice

   Copyright (c) 2014 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
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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   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.

Osborne                      Standards Track                    [Page 1]
RFC 7324                       PSC Updates                     July 2014

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Message Formatting and Error Handling . . . . . . . . . . . .   3
     2.1.  PSC TLV Format  . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Error Handling  . . . . . . . . . . . . . . . . . . . . .   4
       2.2.1.  Malformed Messages  . . . . . . . . . . . . . . . . .   4
       2.2.2.  Well-Formed but Unknown or Unexpected TLV . . . . . .   4
   3.  Incorrect Local Status after Failure  . . . . . . . . . . . .   5
   4.  Handling a Capabilities Mismatch  . . . . . . . . . . . . . .   5
     4.1.  Protection Type Mismatch  . . . . . . . . . . . . . . . .   5
     4.2.  R Mismatch  . . . . . . . . . . . . . . . . . . . . . . .   6
     4.3.  Unsupported Modes . . . . . . . . . . . . . . . . . . . .   6
   5.  Reversion Deadlock Due to a Race Condition  . . . . . . . . .   7
   6.  Clarifying PSC's Behavior in the Face of Multiple Inputs  . .   8
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     10.2.  Informative References . . . . . . . . . . . . . . . . .  10

1.  Introduction

   This document contains a number of updates to PSC [RFC6378].  One
   provides some rules and recommendations around the use of TLVs in
   PSC.  Three of the updates address issues #2, #7, and #8 as
   identified in the ITU's liaison statement "Recommendation ITU-T
   G.8131/Y.1382 revision - Linear protection switching for MPLS-TP
   networks" [LIAISON].  Another clears up a behavior that was not well
   explained in RFC 6378.  These updates are not changes to the
   protocol's packet format or to PSC's design; they are corrections and
   clarifications to specific aspects of the protocol's procedures.
   This document does not introduce backward compatibility issues with
   implementations of RFC 6378.

   It should be noted that [RFC7271] contains protocol mechanisms for an
   alternate mode of operating MPLS-TP PSC.  Those modes are built on
   the message structures and procedures of [RFC6378], and so, while
   this document does not update [RFC7271], it has an impact on that
   work through its update to [RFC6378].

   This document assumes familiarity with RFC 6378 and its terms,
   conventions, and acronyms.  Any term used in this document but not
   defined herein can be found in RFC 6378.  In particular, this
   document shares the acronyms defined in Section 2.1 of RFC 6378.

Osborne                      Standards Track                    [Page 2]
RFC 7324                       PSC Updates                     July 2014