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Versions: (draft-lm-pwe3-mpls-tp-gal-in-pw) 00 01 RFC 6423

Network Working Group                                            Han Li
Internet Draft                                             China Mobile
Updates (if published): RFC5586
Intended status: Standards Track                           Luca Martini
                                                           Cisco System

                                                                 Jia He
                                                                 Huawei

                                                             Feng Huang
                                                         Alcatel-Lucent


Expires: November 2011                                     May 11, 2011



    Using the Generic Associated Channel Label for Pseudowire in MPLS-TP
                 draft-ietf-pwe3-mpls-tp-gal-in-pw-01.txt


Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
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   This Internet-Draft will expire on November 11, 2011.

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   Copyright (c) 2011 IETF Trust and the persons identified as the
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   This document is subject to BCP 78 and the IETF Trust's Legal
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   publication of this document (http://trustee.ietf.org/license-info).
   Please review these documents carefully, as they describe your rights
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Abstract

   This document describes the requirements for using the Generic
   Associated Channel Label (GAL) in Pseudowires (PWs) in MPLS-TP
   networks, and provides an update to the description of GAL usage in
   [RFC5586] by removing the restriction that is imposed on using GAL
   for PWs especially in MPLS-TP environments.

   .

Table of Contents


   1. Introduction ................................................ 2
   2. Conventions used in this document ........................... 3
      2.1. Terminology ............................................ 3
   3. GAL Usage for MPLS-TP PW .................................... 3
   4. Security Considerations ..................................... 4
   5. IANA Considerations ......................................... 4
   6. Acknowledgments ............................................. 5
   7. References .................................................. 5
      7.1. Normative References ................................... 5
      7.2. Informative References ................................. 5
   8. Authors' Addresses .......................................... 5

1. Introduction

   [RFC5586] generalizes the associated control channel mechanism of
   [RFC5085] to be used for Sections, Label Switched Paths (LSPs), and
   Pseudowires (PWs) in MPLS networks. [RFC5085] defines the Associated
   Channel Header (ACH), and [RFC5586] generalizes this for use in the
   Generic Associated Channel (G-ACh).

   [RFC5586] defines a generalized label-based exception mechanism using
   the Generic Associated Channel Label (GAL) to work together with the
   ACH for use with LSPs but places restrictions on GAL usage with PWs.

   This document removes the restriction imposed by [RFC5586].





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2. 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 [RFC 2119].

2.1. Terminology

   ACH      Associated Channel Header

   CW       Control Word

   G-ACh    Generic Associated Channel

   GAL      G-ACh Label

   MPLS-TP  MPLS Transport Profile

   OAM      Operation, Administration, and Maintenance

3. GAL Usage for MPLS-TP PW

   According to the MPLS-TP requirement document [RFC5654], it is
   necessary that MPLS-TP mechanisms and capabilities be able to
   interoperate with the existing IETF MPLS [RFC3031] and IETF PWE3
   [RFC3985] architectures appropriate. [RFC5586] differentiates between
   the usage of the GAL with PWs in MPLS and MPLS-TP environments in
   section 4.2 as follows:

       In MPLS-TP, the GAL MUST be used with packets on a G-ACh on LSPs,
       Concatenated Segments of LSPs, and with Sections, and MUST NOT be
       used with PWs.

   This indicates that the GAL can be used for MPLS-TP LSPs and Sections,
   but not for PWs using an MPLS-TP PSN.

   However, there is no restriction imposed on the usage of the GAL in
   MPLS PWs, which is described immediately afterwards in the same
   section of [RFC5586] (Section 4.2):

       However, in other MPLS environments, this document places no
       restrictions on where the GAL may appear within the label stack
       or its use with PWs.

   The inconsistency between the usage of the GAL with MPLS PWs and
   MPLS-TP PWs may cause unnecessary implementation differences and is
   in disagreement with the MPLS-TP requirements.


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   Therefore, this document specifies that the GAL can be used with
   packets on a G-ACh on LSPs, Concatenated Segments of LSPs, Sections,
   and PWs in both MPLS and MPLS-TP environments without discrimination.

   [RFC5586] is updated by removing the restrictions on using GAL for PW
   as follows:

   -  Section 1 (Introduction) in [RFC5586], the original text:

          The GAL mechanism is defined to work together with the ACH for
          LSPs and MPLS Sections.

      is replaced by:

          The GAL mechanism is defined to work together with the ACH for
          LSPs and MPLS Sections, and for PWs.

   -  Section 4.2. (GAL Applicability and Usage) in [RFC5586], the
      original text:

          In MPLS-TP, the GAL MUST be used with packets on a G-ACh on
          LSPs, Concatenated Segments of LSPs, and with Sections, and
          MUST NOT be used with PWs. It MUST always be at the bottom of
          the label stack (i.e., S bit set to 1). However, in other MPLS
          environments, this document places no restrictions on where
          the GAL may appear within the label stack or its use with PWs.

      is replaced by:

          In MPLS-TP, the GAL MUST be used with packets on a G-ACh on
          LSPs, Concatenated Segments of LSPs, and with Sections, and
          MAY be used with PWs. It MUST always be at the bottom of the
          label stack (i.e., S bit set to 1). However, in other MPLS
          environments, this document places no restrictions on where
          the GAL may appear within the label stack.

4. Security Considerations

   No further security considerations than [RFC5586].

5. IANA Considerations

   There are no IANA actions required.






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6. Acknowledgments

   The authors would like to thank Luyuan Fang, Adrian Farrel, Haiyan
   Zhang, Guanghui Sun, Italo Busi, Matthew Bocci for their
   contributions to this work.

   The authors would also like to thank the authors of [RFC5586] and
   people who were involved in the development of [RFC5586].

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

   [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
             Label Switching Architecture", RFC 3031, January 2001.

   [RFC3985] Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to-Edge
             (PWE3) Architecture", RFC 3985, March 2005.

   [RFC5586] Bocci, M., Vigoureux, M., and S. Bryant, "MPLS Generic
             Associated Channel", RFC5586, June 2009

7.2. Informative References

   [RFC5085] Nadeau, T. and C. Pignataro, "Pseudowire Virtual Circuit
             Connectivity Verification (VCCV): A Control Channel for
             Pseudowires", RFC 5085, December 2007.

   [RFC5654] Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N.,
             and S. Ueno, "Requirements of an MPLS Transport Profile",
             RFC 5654, September 2009.



8. Authors' Addresses

   Han Li
   China Mobile Communications Corporation
   Email: lihan@chinamobile.com







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   Luca Martini
   Cisco Systems, Inc.
   Email: lmartini@cisco.com


   Jia He
   Huawei Technologies Co., Ltd.
   Email: hejia@huawei.com


   Feng Huang
   Alcatel-Lucent shanghai Bell
   Email: feng.f.huang@alcatel-sbell.com.cn



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   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
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