Updates to PSC
draft-ietf-mpls-psc-updates-00

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Network Working Group                                         E. Osborne
Internet-Draft                                             Cisco Systems
Intended status: Standards Track                        October 21, 2013
Expires: April 24, 2014

                             Updates to PSC
                     draft-ietf-mpls-psc-updates-00

Abstract

   This document contains four updates to the Protection State
   Coordination (PSC) logic defined in RFC6378, "MPLS Transport Profile
   (MPLS-TP) Linear Protection" . Two of the updates correct existing
   behavior.  The third clears up a behavior which was not explained in
   the RFC, and the fourth adds rules around handling capabilities
   mismatches.

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].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on April 24, 2014.

Copyright Notice

   Copyright (c) 2013 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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   (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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Incorrect local status after failure  . . . . . . . . . . . .   2
   3.  Reversion deadlock due to a race condition  . . . . . . . . .   3
   4.  Clarifying PSC's behavior in the face of multiple inputs  . .   4
   5.  Handling a capabilities mismatch  . . . . . . . . . . . . . .   6
     5.1.  PT mismatch . . . . . . . . . . . . . . . . . . . . . . .   6
     5.2.  R mismatch  . . . . . . . . . . . . . . . . . . . . . . .   6
     5.3.  Unsupported modes . . . . . . . . . . . . . . . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   This document contains four updates to PSC [RFC6378].  Three of them
   fix 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].  The fourth clears up a
   behavior which was not well explained in RFC6378.  These updates are
   not changes to the protocol's packet format or to PSC's design, but
   are corrections and clarifications to specific aspects of the
   protocol's procedures.

2.  Incorrect local status after failure

   Issue #2 in the liaison identifies a case where a strict reading of
   RFC6378 leaves a node reporting an inaccurate status:

   . A node can end up sending incorrect status - NR(0,1) - despite the
   failure of the protection LSP (P-LSP).  This is clearly not correct,
   as a node should not be sending NR if it has a local failure.  To
   address this issue, the fourth bullet in section 4.3.3.3 is replaced
   with the following three bullets:

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   o  If the current state is due to a local or remote Manual Switch, a