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MPLS-TP protection for interconnected rings
draft-liu-mpls-tp-interconnected-ring-protection-03

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This is an older version of an Internet-Draft whose latest revision state is "Expired".
Authors Guoman Liu , Masahiro Daikoku , Takeshi Maruyama
Last updated 2012-10-21
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draft-liu-mpls-tp-interconnected-ring-protection-03
MPLS Working Group                                                G. Liu
Internet-Draft                                           ZTE Corporation
Intended status: Informational                              Y. Weigarten
Expires: April 22, 2013
                                                              M. Daikoku
                                                             T. Maruyama
                                                        KDDI Corporation
                                                        October 19, 2012

              MPLS-TP protection for interconnected rings
          draft-liu-mpls-tp-interconnected-ring-protection-03

Abstract

   The requirements for MPLS Transport Profile include a requirement
   (R93) that requires that MPLS-TP must support recovery mechanisms for
   a network constructed from interconnected rings that protect user
   data that traverses more than one ring.  In particular, this includes
   protecting against cases of failure at the ring interconnect nodes
   and links.  This document presents different configurations of
   interconnected rings and special mechanisms to address the recovery
   of ring-interconnect nodes and links. .

   This document is a product of a joint Internet Engineering 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   and derivative works of it may not be created, and it may not be
   published except as an Internet-Draft.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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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   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 April 22, 2013.

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.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Conventions used in this document  . . . . . . . . . . . . . .  8
   3.  recovery mechanism . . . . . . . . . . . . . . . . . . . . . .  9
     3.1.  recovery mechanism for Dual-node interconnection . . . . .  9
     3.2.  recovery mechanism for Chained interconnection . . . . . . 11
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   6.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 12
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 12
     7.3.  URL References . . . . . . . . . . . . . . . . . . . . . . 12
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13

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1.  Introduction

   This document describes different interconnected ring scenarios and a
   few special solutions to protect against the failure of the ring-
   interconnect nodes and links. there are three common interconnection
   scenarios that we will address in this document:

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

   Single-node interconnection - when the connection between the two
   rings is through a single node (see Figure 2).As the interconnnection
   node(LSR-A) is a single-point of failure, This configuration should
   be avoided in real networks;

   Chained interconnection - 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. many
   interconnection scenarios could be existed in the same scenario, they
   will be mixed interconnection scenario:

   Dual-node and single-node mixed interconnection- when there exist a
   multi-ring traffic which traveres more than two ring. two of these
   rings are dual-node interconnection. while another two are single-
   node interconnection (see figure 5);

   Dual-node and chained mixed interconnection-when there exist both
   dual-node interconnection and chained interconnection in this
   scenario (see figure 4);

   single-node and chained mixed interconnection-when there exist both
   single-node interconnection and chained interconnection in this
   scenario(see figure 6);

   Dual-node, single-node and chained mixed interconnection-when there
   exist all three interconnection scenrios in this scenario 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 traffic, it will be across more than one ring just
   like above seven scenarios. if a failure happens on a multi-ring
   path, quick recovery is necessary requirement for multi-ring traffic.

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

   PSC:Protection Switching Coordination

   SD:Signal Degrade

   SF:Signal Fail

   MPLS-TP:Multi-Protocol Label Switching Transport Profile

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3.  recovery mechanism

   In the following subsections we propose different mechanisms that may
   be applied for traffic recovery in the different interconnection
   scenarios.  In general, it is possible to provide protection against
   the failure of a ring node/link by using the single-ring protection
   mechanism.  These cases are out of scope for this document.  It is
   also possible to configure an end-to-end protection to protect the
   entire working path across all of the interconnected rings.  However,
   this protection scheme does not scale very well.  Therefore, we need
   to consider special mechanisms to address recovery from failures of
   the interconnecting nodes and links

3.1.  recovery mechanism for Dual-node interconnection

   Under this scenario , when interconnection link(LSRA-LSR6) has a
   failure as shown in figure 8. it is possible use 1:1 linear
   protection mechanism to protect the failure of segment(LSRA-LSR6) by
   using one of the protection paths (LSRA-LSRF-LSR5-LSR6 or LSRA-LSRF-
   LSR6 or LSRA-LSR5-LSR6) .

               /LSR\******/LSR\******/LSR\x||x/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
                             || failure

                                 Figure 8

   When the interconnection node(LSRA or LSR6) detects a SF or SD on the
   interconnection link(LSRA-LSR6), LSRA or LSR6 will send SF or SD
   failure message to its peer node.  Then it switchs the multi-ring
   traffic from the working path to its corresponding protection path to
   another end point(LSRA or LSR6) of the segment . when the peer node
   (LSR6 or LSRA) receives the traffic packet from its protection

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   protection path, it will POP the outer label of protection tunnel and
   return back to the original working tunnel(LSRA-LSRB-LSRC or LSR6-
   LSR1-LSR2) of another ring(ring 1 or ring 2) to transport the multi-
   ring traffic.

   when interconnection node(LSRA or LSR6) has a failure as shown in
   figure 9. the end node of the segment detects the failure of the
   interconnection node, it should send failure messge to the backup
   interconnection node(LSRF or LSR5) to active the protection path that
   goes to the backup interconnection node(LSRF or LSR5) to trasnport
   the multi-ring traffic. at the same time, the backup interconnection
   node should active its corresponding protection path that goes to
   another primary interconnection node(LSR6 or LSRA).Then the multi-
   ring traffic should return back to the original working path to be
   transported in another primary interconnection node..

                                      ##
               /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
                             ## node failure

                                 Figure 9

   for example , LSRC detects a failure on the interconnection node
   LSRA. it will send the failure message to notify the backup
   interconnection node LSRF to switch over to the protection path(LSRC-
   LSRD-LSRE-LSRF) to transport the multi-ring traffic.at the same time,
   LSRF should active its corresponding protection path that goes to
   another primary interconnection node LSR6 to transport the multi-ring
   traffic.The corresponding protection path may be one of the two
   paths(LSRF-LSR5-LSR6 or LSRF-LSR6).  Then the multi-ring traffic will
   be transported by its original working path(LSR6-LSR1-LSR2) to the
   exit node LSR2.

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3.2.  recovery mechanism for Chained interconnection

   For this scenario , when only a failure is detected on the
   interconnection link.  Since the failure should not affect the multi-
   ring traffic. no action is taken. when a failure happens on the
   segment of the multi-ring path just as shown in figure 10.  The end
   node of the segment detects the failures, it will active the
   protection path that goes to the backup interconnection node to
   transport the multi-ring traffic.  After the backup interconnection
   node receives the failure message , it will active its corresponding
   protection path that goes to the exit node of another ring to
   trasnport the multi-ring traffic.

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

                                  *** physical link
                                  xxx shared link
                                  || failure

                                 Figure 10

   for example, there are failures on both link(LSRC-LSRB) and (LSRA-
   LSRF) at the same time as shown in figure.10. when LSRC detects or is
   notified of the failures on both the segment of the working path and
   the interconnection link. so it will send a failure message to the
   backup interconnection node LSRF, Then LSRF will active its
   corresponding protection path(LSRF-LSR4-LSR3-LSR2) of ring 2 to
   transport the multi-ring traffic.

   (Editor's note:should supply text that describes protection against
   the failure of interconnection node in the chained interconnection

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   scenario in the future. welcome all experts provide good solution for
   the failure)

4.  Security Considerations

   TBD

5.  IANA Considerations

   TBD.

6.  Acknowledgments

   TBD .

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,

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              <http://www.example.com/dominator.html>.

Authors' Addresses

   Guoman Liu
   ZTE Corporation
   No.50, Ruanjian Ave, Yuhuatai District
   Nanjing  210012
   P.R.China

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

   Yaacov Weingarten
   34 Hagefen St Karnei
   Shomron  44853
   Israel

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

   Masahiro Daikoku
   KDDI Corporation
   Garden Air Tower,Iidabashi, Chiyoda-ku
   Tokyo  102-8460
   Japan

   Email: ms-daikoku@kddi.com

   Takeshi Maruyama
   KDDI Corporation
   Garden Air Tower,Iidabashi, Chiyoda-ku
   Tokyo  102-8460
   Japan

   Email: ta-maruyama@kddi.com

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