Pseudowire Control Word Negotiation Mechanism Update
draft-ietf-pwe3-cbit-negotiation-03

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Network Working Group                             Lizhong Jin (ed.), ZTE
Internet-Draft                                 Raymond Key (ed.), Huawei
Updates: 4447 (if approved)                 Simon Delord, Alcatel-Lucent
Category: Standards Track                         Thomas Nadeau, Juniper
Expires: October 13, 2012                Vishwas Manral, Hewlett-Packard 
                                                     Sami Boutros, Cisco
                                                    Reshad Rahman, Cisco

                                                          April 13, 2012

          Pseudowire Control Word Negotiation Mechanism Update
                  draft-ietf-pwe3-cbit-negotiation-03

Abstract

   This document describes the problem of control word negotiation 
   mechanism specified in [RFC4447].  Based on the problem analysis, a 
   message exchanging mechanism is introduced to solve this control word 
   negotiation issue.  This document is to update [RFC4447] control word 
   negotiation mechanism.

Status of this Memo 

   This Internet-Draft is submitted to IETF in full conformance with the 
   provisions of BCP 78 and BCP 79. 
 
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   This Internet-Draft will expire on April 13, 2012.

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Copyright Notice 
    
   Copyright (c) 2012 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. Problem Statement  . . . . . . . . . . . . . . . . . . . . . . . 3
   3. Control word re-negotiation by label request message . . . . . . 4
   4. Backward Compatibility . . . . . . . . . . . . . . . . . . . . . 6
   5. Security Considerations  . . . . . . . . . . . . . . . . . . . . 6
   6. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . . 6
   7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 6
   8. References . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
   8.1. Normative References . . . . . . . . . . . . . . . . . . . . . 6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 7
   Appendix A. Updated C-bit Handling Procedures Diagram . . . . . . . 8

Conventions used in this document 
    
   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 [RFC2119]. 

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1. Introduction

   This document describes the problem of control word negotiation 
   mechanism specified in [RFC4447].  Based on the problem analysis, a 
   message exchanging mechanism is introduced to solve this negotiation 
   issue. The control word negotiation mechanism in this document is to 
   update [RFC4447] section 6.2 "PW Types for Which the Control Word is 
   NOT Mandatory".

2. Problem Statement

   [RFC4447] section 6 describes the control word negotiation mechanism. 
   Each PW endpoint has the capability of being configurable with a 
   parameter that specifies whether the use of the control word is 
   PREFERRED or NOT PREFERRED.  While in some case of control word 
   negotiation, PE will advertise C-bit=0 in label mapping message with 
   its locally configured control word PREFERRED.  This kind of behavior