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Versions: 00                                                            
Network Working Group                                              X. Fu
Internet-Draft                                                    Y. Bao
Intended status: Standards Track                         ZTE Corporation
Expires: September 2, 2010                                 March 1, 2010


 Framework for MPLS-TP Ownership Transfer Between Management Plane and
                             Control Plane
                draft-fuxh-mpls-tp-transfer-framework-00

Abstract

   In MPLS-TP architecture, LSP and PW provisioning can be done either
   by Control Plane (CP) or Management Plane (MP).  The MPLS-TP control
   plane must provide a mechanism for dynamic ownership transfer of the
   control of MPLS-TP transport paths from MP to CP and vice versa.
   [draft-bao-mpls-tp-path-transfer-reqs-00] defines requirement for
   MPLS-TP paths ownership transfer from MP to CP and vice versa.

   This document provides a framework to allow the development of
   protocol extensions to support the MPLS-TP paths ownership transfer
   between MP and CP and vice versa.

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 [RFC2119].

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
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   The list of Internet-Draft Shadow Directories can be accessed at



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   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on September 2, 2010.

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Ownership Transfer Procedures . . . . . . . . . . . . . . . . . 3
     2.1.  Ownership Transfer Procedure for Associated LSP . . . . . . 3
       2.1.1.  Associated LSP Ownership Transfer From MP to CP . . . . 3
       2.1.2.  Associated LSP Ownership Transfer From CP to MP . . . . 4
     2.2.  Ownership Transfer Procedures for PW  . . . . . . . . . . . 4
       2.2.1.  PW Ownership Transfer From MP to CP . . . . . . . . . . 4
       2.2.2.  PW Ownership Transfer From CP to MP . . . . . . . . . . 7
   3.  Security Considerations . . . . . . . . . . . . . . . . . . . . 8
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 8
     5.1.  Normative References  . . . . . . . . . . . . . . . . . . . 8
     5.2.  Informative References  . . . . . . . . . . . . . . . . . . 8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 9



































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1.  Introduction

   In terms of MPLS-TP requirement, an MPLS-TP control plane MUST
   provide a mechanism for dynamic ownership transfer of the control of
   MPLS-TP transport paths from the Management Plane (MP) to the Control
   Plane (CP) and vice versa.  In MPLS-TP architecture, LSP and PW
   provisioning can be done either by Control Plane or Management Plane.

   The MPLS-TP control plane must support unidirectional, associated
   bidirectional and co-routed bidirectional point-to-point transport
   paths.  [RFC5493] defines the specific requirements for an LSP
   ownership transfer procedure.  [PC-SPC] describes an extension to
   GMPLS RSVP-TE signaling that enables the LSP ownership transfer
   between the Management Plane and the Control Plane.

   Ownership transfers of the forward and the backward directions
   belonging to the same associated bidirectional transport path can't
   be done in the same signaling procedure.  Edge nodes (i.e., ingress,
   egress and intermediate) must be aware about the pairing relationship
   of the forward and the backward directions belonging to the same
   associated bidirectional transport path.  Ownership transfer
   procedures of the forward and the backward directions must be
   associated.  This document describes the ownership transfer related
   procedures for associated LSP.

   [draft-bao-mpls-tp-path-transfer-reqs-00] defines the requirements
   for ownership transfer of existing PWs provisioned by NMS from the MP
   to the CP without disrupting user traffic flowing on them.  This
   document describes the ownership transfer related procedures for PWs.


2.  Ownership Transfer Procedures

   The ownership transfer of unidirectional and co-routed bidirectional
   LSPs is based on the [RFC5493] and [PC-SPC]

2.1.  Ownership Transfer Procedure for Associated LSP

2.1.1.  Associated LSP Ownership Transfer From MP to CP

   Forward and backward paths belonging to the same associated LSP are
   signalled/routed independently in MPLS-TP networks.  So ownership
   transfers from MP to CP of the forward and the backward directions
   belonging to the same associated bidirectional transport path can't
   be done in the same signaling procedure.  But ownership transfer of
   each direction should be based on [RFC5493] and [PC-SPC].

   In order to make edge nodes (i.e., ingress, egress and intermediate)



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   be aware about the pairing relationship of the forward and the
   backward directions belonging to the same associated bidirectional
   transport path, ownership transfer procedures of the forward and the
   backward directions must be associated.

   The ASSOCIATION object, as defined in RFC 4872 and RFC 4873
   respectively, is used to provide end-to-end and segment recovery.
   Furthermore, draft-berger-ccamp-assoc-info-00.txt described how to
   utilize it in detail.

   [draft-zhang-mpls-tp-rsvpte-ext-associated-lsp-00] defines a
   mechanism to associated the forward and the backward direction LSPs
   to be an associated LSP.  It extends the ASSOCIATION Object and
   defines a new Association Type.  An ASSOCIATION object with an
   Association Type set to the value "Association" is used to bind two
   reverse unidirectional LSP to be an associated bidirectional LSP.

   Any node originating the forward or backward direction LSP MUST
   insert an ASSOCIATION object with an Association Type set to the
   value "Association".  The Association ID MUST be set to a value that
   uniquely identifies the reverse direction LSP.  Egress or
   intermediate nodes MUST use ASSOCIATION object(s) with the
   Association Type set to the value "Association" to bind the two
   reverse unidirectional LSPs together.

2.1.2.  Associated LSP Ownership Transfer From CP to MP

   Ownership transfers from CP to MP of the forward and the backward
   directions belonging to the same associated bidirectional transport
   path also can't be done in the same signaling procedure.  But
   ownership transfer from CP to MP of each direction should be based on
   [RFC5493] and [PC-SPC].

2.2.  Ownership Transfer Procedures for PW

2.2.1.  PW Ownership Transfer From MP to CP

2.2.1.1.  SS-PW Ownership Transfer From MP to CP

   SS-PW in MPLS-TP network signaling control plane is based on LDP with
   specific procedures defined in [RFC4447].  [Segmented-PW] and [MS-PW]
   allow for static switching of multi-segment pseudowires whereby
   signaling is still based on Targeted LDP (T-LDP).  The ownership
   transfer procedure from MP to CP for PW (SS-PW and MS-PW) MUST create
   LDP sessions along the path which is transfered.

   The ownership transfer procedure for SS-PW must create an LDP session
   between PE1 and PE2.  The ownership transfer procecure for SS-PW MUST



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   NOT cause any disruption of user traffic flowing over the PW whose
   control is being transferred.  If the ownership transfer fails, the
   data plane MUST not be affected.

   The operator can synchronously instruct PE1 and PE2 to transfer
   control of the PW from the MP to the CP.  PE1 initiates the ownership
   transfer by sending a Label Mapping Message to the ingress PE (PE2).
   PE2 also initiates the ownership transfer by sending a Label Mapping
   Message to the ingress PE (PE1).  The Label Mapping message contains
   an FEC TLV, a Label TLV, and optional parameter TLVs.  The signaling
   procedure must be based on [RFC4447].

   The Status TLV defined in [RFC3337] is transported to the remote PW
   peer via the LDP Notification message.
   [draft-bao-pw3-pw-transfer-ldp-ext-00] defines an LDP extension by
   adding a PW Ownership Handover TLV to provide a mechanism to identify
   the LDP message of ownership transfer.  The Egress node originating
   the LDP Mapping message of ownership transfer must insert a PW
   Ownership Handover TLV with a flag set to the value "Handover".  The
   ingress that receives a LDP message must use the flag set to the
   value "Handover" to identify ownership transfer.  It should not do
   the FEC and Label Mapping anymore.


          |<-------------- Emulated Service ---------------->|
          |                                                  |
          |          |<------- Pseudowire ------->|          |
          |          |                            |          |
          |Attachment|    |<-- PSN Tunnel -->|    |Attachment|
          |  Circuit V    V                  V    V  Circuit |
          V   (AC)   +----+                  +----+   (AC)   V
    +-----+    |     | PE1|==================| PE2|     |    +-----+
    |     |----------|............PW1.............|----------|     |
    | CE1 |    |     |    |                  |    |     |    | CE2 |
    |     |----------|............PW2.............|----------|     |
    +-----+  ^ |     |    |==================|    |     | ^  +-----+
          ^  |       +----+                  +----+     | |  ^
          |  |   Provider Edge 1         Provider Edge 2  |  |
          |  |                                            |  |
    Customer |                                            | Customer
    Edge 1   |                                            | Edge 2
             |                                            |
       native service                               native service

                      Figure 1: SS-PWE Reference Model






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2.2.1.2.  MS-PW Ownership Transfer From MP to CP

   The ownership transfer procedure for MS-PW must also create LDP
   sessions between T-PE1 and S-PE1, S-PE1 and S-PE2, and the other one
   between S-PE2 and T-PE2.

   The operator instructs T-PE1 to transfer control of the PW from the
   MP to the CP.  In order to creat LDP sessions along the path of
   MS-PW, operator must give full information about the explicit route
   of MS-PW including the S-PEs (S-PE1 and S-PE2) traversed by PW.

   The ownership transfer procedure of each PW segment is based on the
   section 2.2.1.1, but the Label Mapping message must carry the
   explicit route of MS-PW including S-PE1 and S-PE2 encoded in S-PE
   TLV.  After S-PE1 receive the Label Mapping message, it needs to get
   the next S-PEs (S-PE2) from the S-PE TLV and create the LDP session
   between S-PE1 and S-PE2.

   The node originating the LDP Mapping message of ownership transfer
   must insert a PW Ownership Handover TLV with a flag set to the value
   "Handover" defined in [draft-bao-pw3-pw-transfer-ldp-ext-00].  The
   ingress that receives a LDP Mapping message must use the flag set to
   the value "Handover" to identify ownership transfer.  It should not
   do the FEC and Label Mapping anymore.


    Native  |<---------------------- MS-PW ---------------------->|  Native
    Service |     |<-PSN1-->|     |<--PSN2->|     |<--PSN3->|     |  Service
     (AC)   V     V         V     V         V     V         V     V   (AC)
       |    +-----+         +-----+         +-----+         +-----+
+----+ |    |T-PE1|         |S-PE1|         |S-PE2|         |T-PE2|   | +----+
|    | |    |     |=========|     |=========|     |=========|     |   | |    |
|    |------|......PW.Seg't1.......PW Seg't3.......PW Seg't5......|-----|    |
| CE1| |    |     |         |     |         |     |         |     |   | |CE2 |
|    |------|......PW.Seg't2......|PW Seg't4......|PW Seg't6......|-----|    |
|    | |    |     |=========|     |=========|     |=========|     |   | |    |
+----+      +-----+         +-----+         +-----+         +-----+     +----+
     ^                                                                  ^
     |                                                                  |
     |                                                                  |
     |<----------------------- Emulated Service ----------------------->|

             Figure 2: MS-PW switching Reference Model








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2.2.2.  PW Ownership Transfer From CP to MP

   The CP has the ownership and control of the PW.  The CP to MP
   transfer procedure MUST delete the existing LDP session information
   and MUST NOT affect the cross-connected resources, but just move
   their ownership to the MP.

2.2.2.1.  SS-PW Ownership Transfer From MP to CP

   The ownership transfer procedure for SS-PW must delete the existing
   LDP session between PE1 and PE2. .

   The operator can synchronously instruct PE1 and PE2 to transfer
   control of the PW from the CP to the MP.  PE1 initiates the ownership
   transfer by sending a Label Withdraw message to the ingress PE (PE2).
   PE2 also initiates the ownership transfer by sending a Label Withdraw
   message to the ingress PE (PE1).  The signaling procedure must be
   based on [RFC4447].

   [draft-bao-pw3-pw-transfer-ldp-ext-00] defines an LDP extension by
   adding a PW Ownership Handover TLV to provide a mechanism to identify
   the LDP message of ownership transfer.  The Egress node originating
   the Label Withdraw message of ownership transfer must insert a PW
   Ownership Handover TLV with a flag set to the value "Handover".  The
   ingress that receives a Label Withdraw message must use the flag set
   to the value "Handover" to identify ownership transfer.  There is no
   any action is taken over the Data Plane anymore.

2.2.2.2.  MS-PW Ownership Transfer From MP to CP

   The ownership transfer procedure for MS-PW must also delete LDP
   sessions between T-PE1 and S-PE1, S-PE1 and S-PE2, and the other one
   between S-PE2 and T-PE2.

   The operator instructs T-PE1 to transfer control of the PW from the
   CP to the MP.  In order to delete LDP sessions along the path of
   MS-PW, the CP must give full information about the explicit route of
   MS-PW including the S-PEs (S-PE1 and S-PE2) traversed by PW.

   The ownership transfer procedure of each PW segment is based on the
   section 2.2.2.1, but the Label Withdraw message must carry the
   explicit route of MS-PW including S-PE1 and S-PE2 encoded in S-PE
   TLV.  After S-PE1 receive the Label Withdraw message, it needs to get
   the next S-PEs (S-PE2) from the S-PE TLV and delete the LDP session
   between S-PE1 and S-PE2.

   The node originating the LDP Withdraw message of ownership transfer
   must insert a PW Ownership Handover TLV with a flag set to the value



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   "Handover" defined in [draft-bao-pw3-pw-transfer-ldp-ext-00].  The
   ingress that receives a LDP Withdraw message must use the flag set to
   the value "Handover" to identify ownership transfer.  There is no any
   action is taken over the Data Plane anymore.


3.  Security Considerations

   TBD


4.  IANA Considerations

   TBD


5.  References

5.1.  Normative References

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

   [RFC3036]  Andersson, L., Doolan, P., Feldman, N., Fredette, A., and
              B. Thomas, "LDP Specification", RFC 3036, January 2001.

   [RFC5036]  Andersson, L., Minei, I., and B. Thomas, "LDP
              Specification", RFC 5036, October 2007.

   [RFC4447]  Martini, L., Rosen, E., El-Aawar, N., Smith, T., and G.
              Heron, "Pseudowire Setup and Maintenance Using the Label
              Distribution Protocol (LDP)", RFC 4447, April 2006.

   [RFC5493]  Caviglia, D., Bramanti, D., Li, D., and D. McDysan,
              "Requirements for the Conversion between Permanent
              Connections and Switched Connections in a Generalized
              Multiprotocol Label Switching (GMPLS) Network", RFC 5493,
              April 2009.

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

5.2.  Informative References

   [I-D.ietf-ccamp-pc-spc-rsvpte-ext]
              Caviglia, D., Ceccarelli, D., Li, D., and S. Bardalai,
              "RSVP-TE Signaling Extension For Management Plane To



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              Control Plane LSP Handover In A GMPLS Enabled Transport
              Network.", draft-ietf-ccamp-pc-spc-rsvpte-ext-07 (work in
              progress), February 2010.

   [I-D.ietf-pwe3-ms-pw-arch]
              Bocci, M. and S. Bryant, "An Architecture for Multi-
              Segment Pseudowire Emulation Edge-to-Edge",
              draft-ietf-pwe3-ms-pw-arch-07 (work in progress),
              July 2009.

   [I-D.abfb-mpls-tp-control-plane-framework]
              Andersson, L., Berger, L., Fang, L., Bitar, N., Takacs,
              A., Vigoureux, M., and E. Bellagamba, "MPLS-TP Control
              Plane Framework",
              draft-abfb-mpls-tp-control-plane-framework-02 (work in
              progress), February 2010.

   [I-D.ietf-mpls-tp-framework]
              Bocci, M., Bryant, S., Frost, D., Levrau, L., and L.
              Berger, "A Framework for MPLS in Transport Networks",
              draft-ietf-mpls-tp-framework-10 (work in progress),
              February 2010.


Authors' Addresses

   Xihua Fu
   ZTE Corporation
   West District,ZTE Plaza,No.10,Tangyan South Road,Gaoxin District
   Xi An  710065
   P.R.China

   Phone: +8613798412242
   Email: fu.xihua@zte.com.cn
   URI:   http://wwwen.zte.com.cn/


   Yuanlin Bao
   ZTE Corporation
   5F,R&D Building 3, ZTE Industrial Park, XiLi LiuXian Road
   Nanshan District,Shenzhen  518055
   P.R.China

   Phone: +86 755 26773731
   Email: bao.yuanlin@zte.com.cn
   URI:   http://wwwen.zte.com.cn/





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