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MPLS-TP protection for interconnected rings
draft-liu-mpls-tp-interconnected-ring-protection-01

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This is an older version of an Internet-Draft whose latest revision state is "Expired".
Authors Guoman Liu , Yaacov Weingarten
Last updated 2012-04-26
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draft-liu-mpls-tp-interconnected-ring-protection-01
MPLS Working Group                                                G. Liu
Internet-Draft                                           ZTE Corporation
Intended status: Informational                             Y. Weingarten
Expires: October 28, 2012                                 April 26, 2012

              MPLS-TP protection for interconnected rings
          draft-liu-mpls-tp-interconnected-ring-protection-01

Abstract

   According to the ring protection Requirements in RFC 5654,
   Requirement 93 : When a network is constructed from interconnected
   rings, MPLS-TP MUST support recovery mechanisms that protect user
   data that traverses more than one ring.  This includes the
   possibility of failure of the ring-interconnect nodes and links,so
   this document will describle all kinds of interconnected ring
   Scenarios and several protection solutions for recovery the failure
   of the ring-interconnect nodes and Links. .

   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

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   This Internet-Draft will expire on October 28, 2012.

Copyright Notice

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   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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions used in this document  . . . . . . . . . . . . . .  7
   3.  recovery mechanisms  . . . . . . . . . . . . . . . . . . . . .  8
     3.1.  recovery mechanism for Dual-node interconnected-ring . . .  8
     3.2.  recovery mechanism for Chained interconnected-ring . . . .  8
     3.3.  recovery mechanism for Dual-node and Single-node mixed
           interconnected-ring  . . . . . . . . . . . . . . . . . . .  9
     3.4.  recovery mechanism for Dual-node and Chained mixed
           interconnected-ring  . . . . . . . . . . . . . . . . . . .  9
     3.5.  recovery mechanism for Single-node and Chained mixed
           interconnected-ring  . . . . . . . . . . . . . . . . . . .  9
     3.6.  recovery mechanism for Dual-node ,Single-node and
           Chained mixed interconnected-ring  . . . . . . . . . . . .  9
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   6.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .  9
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 10
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 10
     7.3.  URL References . . . . . . . . . . . . . . . . . . . . . . 10
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10

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1.  Introduction

   This document describles different interconnected ring scenarios and
   several protection solutions to protect against the failure of the
   ring-interconnect nodes and links. there are mainly three common
   interconnection scenarios that we will address in this document:

   Dual-node interconnection - when the interconnected rings are
   interconnected by two nodes from each ring (see Figure 1);

   Single-node interconnection - when the connection between the
   interconnected rings are through a single node (see Figure 2).As the
   interconnnection node(LSR-A) is a single-point of failure, such the
   interconnection scenario should be avoided in real network;

   Chain of rings - when a series of rings are connected through
   interconnection nodes that are part of both interconnected rings (see
   Figure 3)

               /LSR\******/LSR\******/LSR\xxxx/LSR\*****/LSR\******/LSR\
               \_C_/      \_B_/      \_A_/    \_6_/     \_1_/      \_2_/
                 *                     * x   x  *                    *
                 *     Ring #1         *  x x   *        Ring #2     *
                _*_        ___        _*_  x   _*_       ___        _*_
               /LSR\      /LSR\      /LSR\x x /LSR\     /LSR\      /LSR\
               \_D_/******\_E_/******\_F_/xxxx\_5_/*****\_4_/******\_3_/

                             *** physical link
                             xxx interconnection link

                                 Figure 1

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                 ___            ___                 ___           ___
                /LSR\**********/LSR\               /LSR\*********/LSR\
                \_C_/          \_B_/*             *\_1_/         \_2_/
                  *                  *           *                 *
                  *                   *         *                  *
                  *                    *       *                   *
                 _*_                    * ___ *                   _*_
                /LSR\    Ring #1         /LSR\       Ring #2     /LSR\
                \_D_/                   *\_A_/*                  \_3_/
                  *                    *       *                   *
                  *                   *         *                  *
                  *                  *           *                 *
                 _*_             ___*             *___            _*_
                /LSR\           /LSR\             /LSR\          /LSR\
                \_E_/***********\_F_/             \_5_/**********\_4_/

                                    *** physical link

                                 Figure 2

                     ___        ___        ___       ___        ___
                    /LSR\******/LSR\******/LSR\*****/LSR\******/LSR\
                    \_C_/      \_B_/      \_A_/     \_1_/      \_2_/
                      *                     x                    *
                      *     Ring #1         x       Ring #2      *
                     _*_        ___        _x_       ___        _*_
                    /LSR\      /LSR\      /LSR\     /LSR\      /LSR\
                    \_D_/******\_E_/******\_F_/*****\_4_/******\_3_/

                                  *** physical link
                                  xxx shared link

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                                 Figure 3

   Regarding traffic that traveres more than two rings.the different
   interconnection scenarios could be mixed.

   Dual-node and single-node mixed interconnection-when there not only
   exist two interconnected rings are interconnected by two nodes from
   each ring. but also there exist two interconnected rings are
   interconnected by single node( see figure 5);

   Dual-node and chained mixed interconnection-when there exist two
   interconnnected rings are interconnected by two nodes from each ring.
   in addtion, there still exist two interconnnected rings are
   interconnected by a common chained link(see figure 4);

   single-node and chained mixed interconnection-when there exist two
   interconnected rings are interconnected by single node, in addtion,
   there still exist two interconnected rings are interconnected by a
   common chained link(see figure 6);

   Dual-node, single-node and chained mixed interconnection-when there
   exist all three interconnection scenrios in the network domain
   including Dual-node interconnnection, single-node interconnection and
   chained interconnnection( see figure 7);

                                                                    ___
            /LSR\******/LSR\xx/LSR\****/LSR\     /LSR\**** /LSR\***/LSR\
            \_C_/      \_B_/  \_A_/    \_6_/     \_1_/     \_2_/   \_H_/
              *          * x x  *         *       *          x       *
                            x                     *          x       *
              * Ring  1  * x x  * Ring 2  *  .....*Ring  3   x Ring 4*
             _*_         *x  x_*_       _*_      ___        ___    ___
            /LSR\      /LSR\  /LSR\     /LSR\     /LSR\*****/LSR\**/LSR\
            \_D_/******\_E_/xx\_5_/*****\_4_/    \_k_/      \_L_/  \_M_/

                          *** physical link
                          xxx interconnection link

                                 Figure 4

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                                                                    ___
            /LSR\******/LSR\xx/LSR\****/LSR\     /LSR\             /LSR\
            \_C_/      \_B_/  \_A_/    \_6_/     \_1_/            *\_H_/
              *          * x x  *         *       *   *         *    *
                            x                     *    *  ___ *      *
              * Ring  1  * x x  * Ring 2  *  .....*Ring 3/LSR\ Ring 4*
             _*_         *x  x_*_       _*_      ___  * \_L_/*     ___
            /LSR\      /LSR\  /LSR\     /LSR\    /LSR\*          * /LSR\
            \_D_/******\_E_/xx\_5_/*****\_4_/    \_k_/             \_M_/

                          *** physical link
                          xxx interconnection link

                                 Figure 5

                                                                    ___
            /LSR\******/LSR\**/LSR\****/LSR\     /LSR\             /LSR\
            \_C_/      \_B_/  \_A_/    \_6_/     \_1_/            *\_H_/
              *                 x         *       *   *         *    *
                                                  *    *  ___ *      *
              * Ring  1         x Ring 2  *  .....*Ring 3/LSR\ Ring 4*
             _*_          _    _x_       _*_      ___  * \_L_/*     ___
            /LSR\      /LSR\  /LSR\     /LSR\    /LSR\*          * /LSR\
            \_D_/******\_E_/**\_5_/*****\_4_/    \_k_/            *\_M_/

                          *** physical link
                          xxx interconnection link

                                 Figure 6

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                                                                    ___
            /LSR\******/LSR\xx/LSR\****/LSR\**** /LSR\             /LSR\
            \_C_/      \_B_/  \_A_/    \_6_/     \_1_/            *\_H_/
              *          * x x  *         x       x   *         *    *
                            x                     x    *  ___ *      *
              * Ring  1  * x  x * Ring 2  xRing 5 xRing 3/LSR\ Ring 4*
             _*_         *x   x_*_       _x_      ___  * \_L_/*     ___
            /LSR\      /LSR\  /LSR\     /LSR\****/LSR\*          * /LSR\
            \_D_/******\_E_/xx\_5_/*****\_4_/    \_k_/            *\_M_/

                          *** physical link
                          xxx interconnection link

                                 Figure 7

   For a multi-ring service, it will be accross more than one ring just
   like above seven scenrios. if a failur happens on a multi-ring path,
   quickly recovery is necessary requirement for MPLS-TP network, so
   there are describles for recoverying the failure in the multi-ring
   interconnection sencrios in the following sections .

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.

   TLV: Type Length Value

   P2MP:Point to Multi-Point

   P2P:Point to Point

   PSC:Protection Switching Coordination

   SD:Signal Degrade

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   SF:Signal Fail

   RDI:Remote Defect Indication

   SPME:Sub-Path Maintenance Entity

   MPLS-TP:Multi-Protocol Label Switching Transport Profile

   ME: Maintenance Entity

   MEP:MEG End Point

   ACH: Associated Channel Header

   CC-V: Contunuity Check-Verification;

3.  recovery mechanisms

   This following sections propose different mechanisms that may be used
   to protect traffic that traverses multiple rings in the different
   interconnection scenarios.

3.1.  recovery mechanism for Dual-node interconnected-ring

   Under the interconnected-ring scenrio just as figure 1,multi-ring
   traffic will be transported by interconnection link(LSR C-LSR
   6).protecting against a failure on the interconnection link could be
   based on 1:1 linear protection of the segment from LSR-A to LSR-6 by
   using the protection path LSR-A to LSR-F to LSR-6.  Alternatively, an
   end-to-end protection path(LSR-C to LSR-2 through D-E-F-5-4-3) could
   be used to protect all traffic.  For the two alternatives, they both
   have different advantage and disadvantage. 1:1 linear segment
   protection may be faster than end-to-end protection. but when the
   interconnection node(LSR-A or LSR-6) has a failure, it maybe need
   another protection solution to recovery it. but end-to-end protection
   may protect one or multiple failures on multi-ring working path.in
   specially, it may protect the failure of interconnection node. .

3.2.  recovery mechanism for Chained interconnected-ring

   For the chained interconnected-ring scenrio, if the interconnection
   nodes(LSR-A and LSR-F) or the shared link(LSR-A-LSR-F) have failures,
   protecting each single ring will fail to provide recovery of the
   failure, so the affected multi-ring traffic should be protected by an
   end-to-end protection path. .

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3.3.  recovery mechanism for Dual-node and Single-node mixed
      interconnected-ring

   For the mixed interconnected-ring scenrio, As the single-node
   interconnection scenario should be avoided. if we only consider
   segment protection between two rings, the solution is the same as
   dual-node interconnected-ring. .

3.4.  recovery mechanism for Dual-node and Chained mixed interconnected-
      ring

   . for the mixed interconnected-ring scenrio, each interconnection
   nodes or shared interconnection link will be protected by setting up
   segment protection path seperately. in addition, it may still use end
   to end multi-ring protection path to protect multiple interconnection
   nodes or shared interconnection link failure.

3.5.  recovery mechanism for Single-node and Chained mixed
      interconnected-ring

   for the mixed interconnected-ring scenrios, As the single-node
   interconnection scenario should be avoided. if we only consider
   segment protection between two rings, the solution is the same as
   chained interconnected-ring.

3.6.  recovery mechanism for Dual-node ,Single-node and Chained mixed
      interconnected-ring

   for the mixed interconnected-ring scenrios, As the single-node
   interconnection scenario should be avoided. here we can consider the
   protection solution maybe like solution of dual-node and chained
   mixed interconnected-ring scenario.

4.  Security Considerations

   TBD

5.  IANA Considerations

   TBD.

6.  Acknowledgments

   TBD .

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7.  References

7.1.  Normative References

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

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

   [RFC 6372]
              N. Sprecher, A. Farrel, "Multiprotocol Label Switching
              Transport Profile Survivability Framework",
              September 2011.

   [RFC 6378]
              S. Bryant, N. Sprecher, A. Fulignoli Y. Weingarten, "MPLS
              transport profile Linear Protection", September 2011.

7.2.  Informative References

   [MPLS-TP Ring Protection]
              Y. Weingarten, "Multiprotocol Label Switching Transport
              Profile Ring Protection", Sep 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 52871606
   Email: liu.guoman@zte.com.cn

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   Yaacov Weingarten
   34 Hagefen St Karnei
   Shomron  44853
   Israel

   Phone: +972-9-775 1827
   Email: wyaacov@gmail.com

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