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MPLS Working Group                                                G. Liu
Internet-Draft                                                     J. Yu
Intended status: Informational                                     X. Tu
Expires: July 2, 2012                                              X. Xu
                                                         ZTE Corporation
                                                       December 30, 2011


                 p2mp pw protection for mpls-tp network
              draft-liu-pwe3-mpls-tp-p2mp-pw-protection-00

Abstract

   According to one protection Requirement in RFC 5654, Requirement 63
   :It MUST be possible to provide protection for the MPLS-TP data plane
   without any IP forwarding capability in the MPLS-TP data plane. and
   it requires mpls-tp date plane should be independent of its control
   plane. so it is necessary for the 1:1 protection of p2mp pw to have a
   return path to coordinate the switch state between root node and each
   leaf node. for the above problem statement, the document provides a
   solution to protect p2mp pw by using one leaf node as protector for
   another leaf node. so it may avoid setting up a return path for each
   leaf node.


   This document is a product of a joint Internet Task Force(IETF) /
   International Telecommunications Union Telecommunications
   Standardization Sector (ITU-T) effort to include an MPLS Transport
   Profile within the IETF MPLS and PWE3 architectures to support the
   capabilities and functionalities of a packet transport network as
   defined by the ITU-T.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.  This document may not be modified,
   and derivative works of it may not be created, and it may not be
   published except as an Internet-Draft.

   Internet-Drafts are working documents of the Internet Engineering
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."



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   This Internet-Draft will expire on July 2, 2012.

Copyright Notice

   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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   described in the Simplified BSD License.



































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Table of Contents

   1.  Problem statement . . . . . . . . . . . . . . . . . . . . . . . 4
   2.  Conventions used in this document . . . . . . . . . . . . . . . 4
   3.  protection solution . . . . . . . . . . . . . . . . . . . . . . 5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . . . 8
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 8
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 9
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 9
     7.2.  Informative References  . . . . . . . . . . . . . . . . . . 9
     7.3.  URL References  . . . . . . . . . . . . . . . . . . . . . . 9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 9






































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1.  Problem statement

   according to mpls-tp requirement(RFC 5654), it requires mpls-tp data
   plane is independent of control plane. it means that mpls-tp data
   plane can still work without control plane or under the condition of
   failure on the control plane. at the same time, mpls-tp data plane
   can forward traffic packet without any IP forwarding capability.so it
   must be essential for uni-directional path including p2p or p2mp pw
   to set up a return path between two end nodes in order to communicate
   and associate between the two end nodes. so it needs to set up more
   return paths for p2mp pw, it will need more configuration and
   maintenece cost. so the document provide one protection solution for
   p2mp pw under the condition without return path,IP forwarding
   capability and control plane.


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.

   OAM: Operations, Administration, Maintenance

   LSP: Label Switched Path.

   PW: Pseudowire

   P2MP:Point to Multi-Point

   P2P:Point to Point

   PSC:Protection Switching Coordination

   CE:Customer Equipment

   LER:Label Edge Router

   LSR:Label Switch Router

   PSN:Packet Switch Network

   MPLS-TP:Multi-Protocol Label Switching Transport Profile

   ME: Maintenance Entity

   MEP:MEG End Point




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   ACH: Associated Channel Header

   CC-V: Contunuity Check-Verification;


3.  protection solution

   This section will describle the protection solution for p2mp pw in
   detail,which use one leaf node as protector node of another leaf
   node. and the two leaf nodes is backup for each other.in addtion, in
   order to be easy to access to CE node, it should set up backup node
   to directly access to CE node. if backup node is still a leaf node of
   the p2mp pw, protector node and backup node are the same node. at the
   same time, it should set up a bidirectional p2p pw between protected
   node, backup node and protector node .just as the following figure 1:


                               ___              ___             ___
                             */LSR\ *********  /LER\********** /CE1\
                           *  \ A /            \_1_/        +  \___/
                    __   *     - -               +       +
                  /LER\*        .               _+_   +
                                               /LER\+
                  \_O_/*        .              \_2_/+
                        *       .                +    +
                         *    ___               _+_      +       ___
                          *  /LSR\             /LER\        +   /CE3\
                           * \ B / **********  \_3_/*********** \___/
                              - -
                                       ***** working pw
                                       +++++ protection pw




                                 Figure 1


   LER 0 is the root node of the p2mp pw, LER 1 and LER 3 are leaf nodes
   of the p2mp pw.  LER 2 is backup node for LER 1 and LER 3. when
   protected node LER 1 or LER 3 has the failure, backup node LER 2 will
   replace of protected node LER 1 or LER 3 to transmit traffic packet
   to CE1 or CE3. for CE1 or CE3 node, if it detect a failure on its
   working access link(*), it will select protection access link(+) to
   receive the traffic.for example, just as the following figure 2:






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                               ___              ___             ___
                             */LSR\ *********  /LER\****X***** /CE1\
                           *  \ A /            \_1_/        +  \___/
                    __   *     - -               X       +
                  /LER\*        .               _+_   +
                                               /LER\+
                  \_O_/*        .              \_2_/+
                        *       .                +    +
                         *    ___               _+_      +       ___
                          *  /LSR\             /LER\        +   /CE3\
                           * \ B / **********  \_3_/*********** \___/
                              - -
                                       ***** working pw
                                       +++++ protection pw
                                       X failure




                                 Figure 2


   if the LER 1 has the failure, CE1 and LER 2 MUST detect the failure
   by OAM or other function. then LER 2 will notify protector node LER 3
   of the failure by pw status message[1]. then LER 3 will begin to
   duplicate the service packet of the p2mp pw to transmit to LER 2 by
   pre-configured p2p protection pw. then the LER 2 send the service
   packet of the p2mp pw to CE1 by protection access link(LER2-CE1).and
   CE1 detects the failure on its working access link(LER1-CE1), it must
   switch to protection access link(LER2-CE1) to receive the service. at
   the same time, if another protected node LER3 has the failure, it may
   use the same method to protect the failure of LER3.

   when there is only the failure on the working access link just as the
   following figure 3:
















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                               ___              ___             ___
                             */LSR\ *********  /LER\****X***** /CE1\
                           *  \ A /            \_1_/        +  \___/
                    __   *     - -               +       +
                  /LER\*        .               _+_   +
                                               /LER\+
                  \_O_/*        .              \_2_/+
                        *       .                +    +
                         *    ___               _+_      +       ___
                          *  /LSR\             /LER\        +   /CE3\
                           * \ B / **********  \_3_/*********** \___/
                              - -
                                       ***** working pw
                                       +++++ protection pw
                                       X failure




                                 Figure 3


   when CE1 and LER1 detect a failure on the working access link(LER1-
   CE1), LER1 firstly notify backup node LER2 of the egress AC failure
   by pw status message. then LER1 will send the service packet of the
   p2mp pw to LER2 by protection pw between LER1 and LER2. and LER2 will
   transmit the service packet of the p2mp pw to CE1 by protection
   access link(LER2-CE1). at the same time, CE1 will switch to
   protection access link(LER2-CE1) to receive the service packet.

   when the protected node detects a failure on its working pw , it will
   notify the failure of its backup node or protector node. so that the
   backup node will transmit the service packet of the p2mp pw to the
   protected node.it is just as the following figure 4:

















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                               ___              ___             ___
                             */LSR\ *****X**** /LER\*********  /CE1\
                           *  \ A /            \_1_/        +  \___/
                    __   *     - -               +       +
                  /LER\*        .               _+_   +
                                               /LER\+
                  \_O_/*        .              \_2_/+
                        *       .                +    +
                         *    ___               _+_      +       ___
                          *  /LSR\             /LER\        +   /CE3\
                           * \ B / **********  \_3_/*********** \___/
                              - -
                                       ***** working pw
                                       +++++ protection pw
                                       X failure




                                 Figure 4


   when the failure happens on the branch working path(LER0-LSR A-LER
   1), the protector node LER1 will notify the failure message of the
   backup node LER2 or protector node LER3. and then LER2 or LER3
   receives the failure message from LER1 ,LER3 will duplicate the
   service packet of the p2mp pw to transmit it to backup node LER2
   firstly. then LER2 continue to transmit the service packet of the
   p2mp pw to the protector node LER1. at last LER1 will transmit it to
   CE1 by its working access link(LER1-CE1).


4.  Security Considerations

   TBD


5.  IANA Considerations

   TBD.


6.  Acknowledgments

   TBD .


7.  References



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7.1.  Normative References

   [RFC 5654]
              IETF, "IETF RFC5654(MPLS-TP requirement)", September 2009.

   [RFC 5921]
              IETF, "IETF RFC5654(MPLS-TP framework)", July 2010.

7.2.  Informative References

   [draft-ietf-pwe3-redundancy-05]
              Praveen Muley, Mustapha Aissaoui,Matthew Bocci,
              "Pseudowire Redundancy", September 2011.

   [draft-ietf-pwe3-redundancy-bit-05]
              Praveen Muley, Mustapha Aissaoui, "Pseudowire Preferential
              Forwarding Status Bit", September 2011.

   [draft-ietf-pwe3-static-pw-status-10]
              Luca Martini,George Swallow,Giles Heron,Matthew Bocci,
              "Pseudowire Status for Static Pseudowires", November 2011.

7.3.  URL References

   [MPLS-TP-22]
              IETF - ITU-T Joint Working Team, "", 2008,
              <http://www.example.com/dominator.html>.


Authors' Addresses

   Liu guoman
   ZTE Corporation
   No.50, Ruanjian Road, Yuhuatai District
   Nanjing  210012
   P.R.China

   Phone: +86 025 88014227
   Email: liu.guoman@zte.com.cn












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   Yu jinghai
   ZTE Corporation
   No.50, Ruanjian Road, Yuhuatai District
   Nanjing  45241
   P.R China

   Phone: +86 025 88014226
   Email: yu.jinghai@zte.com.cn


   Tu xiaoping
   ZTE Corporation
   No.50, Ruanjian Road, Yuhuatai District
   Nanjing  45241
   P.R China

   Phone: +86 025 88014226
   Email: Tu.xiaoping@zte.com.cn


   xu xueqiong
   ZTE Corporation
   No.50, Ruanjian Road, Yuhuatai District
   Nanjing  45241
   P.R China

   Phone: +86 025 88014226
   Email: Xu.xueqiong@zte.com.cn























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