\
Internet Engineering Task Force                                  H. Chen
Internet-Draft                                       Huawei Technologies
Intended status: Standards Track                                   N. So
Expires: July 15, 2011                                  Verison Business
                                                        January 11, 2011


       Extensions to RSVP-TE for P2MP LSP Egress Local Protection
             draft-chen-mpls-p2mp-egress-protection-02.txt

Abstract

   This document describes extensions to Resource Reservation Protocol -
   Traffic Engineering (RSVP-TE) for locally protecting egress nodes of
   a Traffic Engineered (TE) point-to-multipoint (P2MP) Label Switched
   Path (LSP) in a Multi-Protocol Label Switching (MPLS) and Generalized
   MPLS (GMPLS) network.

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).  Note that other groups may also distribute
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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
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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."

   This Internet-Draft will expire on July 15, 2011.

Copyright Notice

   Copyright (c) 2011 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
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as



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   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Conventions Used in This Document  . . . . . . . . . . . . . .  3
   4.  Mechanism  . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     4.1.  An Example of Egress Local Protection  . . . . . . . . . .  4
     4.2.  Set up of Backup P2MP sub LSP  . . . . . . . . . . . . . .  5
     4.3.  Forwarding State for Backup P2MP sub LSP . . . . . . . . .  5
     4.4.  Detection of Failure in Egress . . . . . . . . . . . . . .  6
   5.  Representation of a backup P2MP Sub LSP  . . . . . . . . . . .  6
     5.1.  EGRESS_BACKUP_P2MP_SUB_LSP Object  . . . . . . . . . . . .  7
       5.1.1.  EGRESS_BACKUP_P2MP_SUB_LSP IPv4 Object . . . . . . . .  7
       5.1.2.  EGRESS_BACKUP_P2MP_SUB_LSP IPv6 Object . . . . . . . .  8
     5.2.  EGRESS_BACKUP_P2MP_SECONDARY_EXPLICIT_ROUTE Object . . . .  8
   6.  Path Message . . . . . . . . . . . . . . . . . . . . . . . . .  8
     6.1.  Format of Path Message . . . . . . . . . . . . . . . . . .  9
     6.2.  Processing of Path Message . . . . . . . . . . . . . . . .  9
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   8.  Acknowledgement  . . . . . . . . . . . . . . . . . . . . . . . 10
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 10
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 11
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
























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1.  Introduction

   RFC 4090 "Fast Reroute Extensions to RSVP-TE for LSP Tunnels"
   describes two methods for protecting P2P LSP tunnels or paths at
   local repair points.  For a P2P LSP, the local repair points are the
   intermediate nodes between the ingress node and the egress node of
   the P2P LSP.  The first method is a one-to-one protection method,
   where a detour backup P2P LSP for each protected P2P LSP is created
   at each potential point of local repair.  The second method is a
   facility bypass backup protection method, where a bypass backup P2P
   LSP tunnel is created using MPLS label stacking to protect a
   potential failure point for a set of P2P LSP tunnels.  The bypass
   backup tunnel can protect a set of P2P LSPs that have similar backup
   constraints.

   RFC 4875 "Extensions to RSVP-TE for P2MP TE LSPs" describes how to
   use the one-to-one protection method and facility bypass backup
   protection method to protect a link or intermediate node failure on
   the path of a P2MP LSP.  However, there is no mention of locally
   protecting any egress node failure in a protected P2MP LSP.

   This document defines extensions to RSVP-TE for locally protecting an
   egress node of a Traffic Engineered (TE) point-to-multipoint (P2MP)
   Label Switched Path through using a backup P2MP sub LSP.


2.  Terminology

   This document uses terminologies defined in RFC 2205, RFC 3031, RFC
   3209, RFC 3473, RFC 4090, RFC 4461, and RFC 4875.


3.  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.


4.  Mechanism

   This section briefly describes a solution that locally protects an
   egress node of a P2MP LSP through using a backup P2MP sub LSP.  We
   first show an example, and then present different parts of the
   solution, which includes the creation of the backup P2MP sub LSP, the
   forwarding state for the backup P2MP sub LSP, and the detection of a
   failure in the egress node.




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4.1.  An Example of Egress Local Protection

   The figure 1 illustrates an example of using a backup P2MP sub LSP to
   locally protect an egress of a P2MP LSP.  The P2MP LSP to be
   protected is from ingress node R1 to three egress/leaf nodes: L1, L2
   and L3.  The P2MP LSP is represented by double lines in the figure.

   La, Lb and Lc are the designated backup egress/leaf nodes for the
   egress/leaf nodes L1, L2 and L3 of the P2MP LSP respectively.  The
   backup P2MP sub LSP used to protect the egress node L1 is from the
   previous hop node R3 of L1 to the backup egress node La.  The backup
   P2MP sub LSP used to protect the egress node L2 is from the previous
   hop node R5 of L2 to the backup egress node Lb.  The backup P2MP sub
   LSP used to protect the egress node L3 is from the previous hop node
   R5 of L3 to the backup egress node Lc via intermediate node Rc.

   At a previous hop node such as R3 of an egress node such as L1 of the
   P2MP LSP, the traffic transported by the P2MP LSP is forwarded to the
   egress node such as L1 in a normal operation, which delivers the
   traffic towards its destination such as CE1.  When the failure in an
   egress node such as L1 is detected, the previous hop node such as R3
   of the egress node such as L1 forwards the traffic toward the
   corresponding backup egress node such as La, which delivers the
   traffic towards its destination such as CE1.

   There may be a BFD session between an egress node such as L1 and the
   previous hop node such as R3 of the egress node such as L1.  The
   previous hop node uses this BFD session to detect the failure of the
   egress node.  When it detects the failure of the egress node, it
   forwards the traffic carried by the P2MP LSP into the backup P2MP sub
   LSP to the corresponding backup egress node.  The traffic from the
   sub LSP is delivered from the backup egress node towards its
   destination.


















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                         [R2]=====[R3]=====[L1]----[CE1]
                        //           \            /
                       //             \          /
                      //               \___[La]_/
                     //
                    //
                   //
                  //
              +---[R1]====[R4]====[R5]=====[L2]----[CE2]
              |                   |\\ \           /
              |                   | \\ \         /
         [S]--|                   |  \\ \__[Lb]_/
              |                   |   \\
              |                   |    \\
                                  |     \\
                                  |      \\
                                  |       \\
                                  |        [L3]----[CE3]
                                  |               /
                                  |              /
                                [Rc]_______[Lc]_/


           Figure 1: P2MP sub LSP for Locally Protecting Egress

4.2.  Set up of Backup P2MP sub LSP

   For an egress node of a P2MP LSP, a backup egress node is designated
   to protect the egress node.  The previous-hop node of the egress node
   of the P2MP LSP sets up a backup P2MP sub LSP from itself to the
   backup egress node after receiving the information about the backup
   egress node.

   The previous-hop node sets up the backup P2MP sub LSP, creates and
   maintains its state in the same way as setting up a P2MP S2L sub LSP
   from the signalling's point of view.  It constructs and sends a
   RSVP-TE PATH message along the path for the backup P2MP sub LSP,
   receives and processes a RSVP-TE RESV message that responses to the
   PATH message.

4.3.  Forwarding State for Backup P2MP sub LSP

   The forwarding state for the backup P2MP sub LSP is different from
   that for a P2MP S2L sub LSP.  After receiving the RSVP-TE RESV
   message for the backup P2MP sub LSP, the previous-hop node creates a
   forwarding entry with an inactive state or flag.  This forwarding
   entry with an inactive state or flag is called an inactive forwarding
   entry.  In a normal operation, this inactive forwarding entry is not



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   used to forward any data traffic.  However, the forwarding entry for
   a P2MP S2L sub LSP is with an active state or flag, and used to
   forward the data traffic if the failure of the egress is detected.

   When a failure of the egress node happens, the state or flag of the
   forwarding entry for the backup P2MP sub LSP is set to be active.
   Thus, on the previous-hop node of the egress node, the data traffic
   will be forwarded to the backup egress node instead of to the egress
   node through the backup P2MP sub LSP from the P2MP LSP.  From the
   backup egress node, the data traffic is sent towards its destination.

4.4.  Detection of Failure in Egress

   There are a number of failures in an egress node of a P2MP LSP.  The
   failures in the egress that the previous hop node of the egress node
   should detect include two classes of failures.  One class of failures
   is such a failure that the traffic can not be delivered to the egress
   node of the P2MP LSP.  The death of the egress node and the failure
   of the link between the egress node and the previous hop node belong
   to this class of failures.

   Another class of failures are such failures that the egress node can
   not deliver the traffic from the P2MP LSP towards its destination.
   The failure of the link over which the traffic is delivered towards
   its destination such as CE1 is such a failure.

   After a previous hop node detects any above failure in the egress
   node, it imports the traffic from the P2MP LSP into the backup P2MP
   sub LSP.  The traffic from the backup P2MP sub LSP is delivered
   towards its destination at the backup egress node.


5.  Representation of a backup P2MP Sub LSP

   A backup P2MP sub LSP exists within the context of a P2MP LSP in a
   way similar to a P2MP S2L sub LSP.  It is identified by the P2MP ID,
   Tunnel ID, and Extended Tunnel ID in the P2MP SESSION object, the
   tunnel sender address and LSP ID in the P2MP SENDER_TEMPLATE object,
   and the backup P2MP sub LSP destination address in the
   EGRESS_BACKUP_P2MP_SUB_LSP object.  The EGRESS_BACKUP_P2MP_SUB_LSP
   object is defined in the section below.

   An EGRESS_BACKUP_P2MP_SECONDARY_EXPLICIT_ROUTE Object (EB-SERO) is
   used to optionally specify the explicit route of a backup P2MP sub
   LSP that is from a previous-hop node to a backup egress node.  The
   EGRESS_BACKUP_P2MP_SECONDARY_EXPLICIT_ROUTE object is defined in the
   following section.




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5.1.  EGRESS_BACKUP_P2MP_SUB_LSP Object

   An EGRESS_BACKUP_P2MP_SUB_LSP object identifies a particular backup
   P2MP sub LSP belonging to the P2MP LSP.

5.1.1.  EGRESS_BACKUP_P2MP_SUB_LSP IPv4 Object

    EGRESS_BACKUP_P2MP_SUB_LSP Class = 50,
    EGRESS_BACKUP_P2MP_SUB_LSP_IPv4 C-Type = 3


        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      Egress Backup P2MP Sub LSP IPv4 destination address      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     Egress IPv4 address                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


    Egress Backup P2MP Sub LSP IPv4 destination address
       IPv4 address of the backup P2MP sub LSP destination, which is the
       backup egress node.
    Egress IPv4 address
       IPv4 address of the egress node

   The class of the EGRESS_BACKUP_P2MP_SUB_LSP IPv4 object is the same
   as that of the S2L_SUB_LSP IPv4 object defined in RFC 4875.  The
   C-Type of the EGRESS_BACKUP_P2MP_SUB_LSP IPv4 object is a new number
   3, or may be another number assigned by Internet Assigned Numbers
   Authority (IANA).




















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5.1.2.  EGRESS_BACKUP_P2MP_SUB_LSP IPv6 Object

    EGRESS_BACKUP_P2MP_SUB_LSP Class = 50,
    EGRESS_BACKUP_P2MP_SUB_LSP_IPv6 C-Type = 4


        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      Egress Backup P2MP Sub LSP IPv6 destination address      |
       |                         (16 bytes)                            |
       |                         ....                                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     Egress IPv6 address                       |
       |                         (16 bytes)                            |
       |                         ....                                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


    Egress Backup P2MP Sub LSP IPv6 destination address
       IPv6 address of the backup P2MP sub LSP destination, which is the
       backup egress node.
    Egress IPv6 address
       IPv6 address of the egress node

   The class of the EGRESS_BACKUP_P2MP_SUB_LSP IPv6 object is the same
   as that of the S2L_SUB_LSP IPv6 object defined in RFC 4875.  The
   C-Type of the EGRESS_BACKUP_P2MP_SUB_LSP IPv6 object is a new number
   4, or may be another number assigned by Internet Assigned Numbers
   Authority (IANA).

5.2.  EGRESS_BACKUP_P2MP_SECONDARY_EXPLICIT_ROUTE Object

   The format of an EGRESS_BACKUP_P2MP_SECONDARY_EXPLICIT_ROUTE (EB-
   SERO) object is defined as identical to that of the ERO.  The class
   of the EB-SERO is the same as the SERO defined in RFC 4873.  The EB-
   SERO uses a new C-Type = 3, or may use another number assigned by
   Internet Assigned Numbers Authority (IANA).  The formats of sub-
   objects in an EB-SERO are identical to those of sub-objects in an ERO
   defined in RFC 3209.


6.  Path Message

   This section describes extensions to the Path message defined in RFC
   4875.  The Path message is enhanced to transport the information
   about a backup egress node to the previous-hop node of an egress node
   of a P2MP LSP through including an egress backup P2MP sub LSP



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   descriptor list.

6.1.  Format of Path Message

   The format of the enhanced Path message is illustrated below.


      <Path Message> ::=  <Common Header> [ <INTEGRITY> ]
                          [ [<MESSAGE_ID_ACK> | <MESSAGE_ID_NACK>] ...]
                          [ <MESSAGE_ID> ]
                          <SESSION> <RSVP_HOP>
                          <TIME_VALUES>
                          [ <EXPLICIT_ROUTE> ]
                          <LABEL_REQUEST>
                          [ <PROTECTION> ]
                          [ <LABEL_SET> ... ]
                          [ <SESSION_ATTRIBUTE> ]
                          [ <NOTIFY_REQUEST> ]
                          [ <ADMIN_STATUS> ]
                          [ <POLICY_DATA> ... ]
                          <sender descriptor>
                          [<S2L sub-LSP descriptor list>]
                          [<egress backup P2MP sub LSP descriptor list>]


   The format of the egress backup P2MP sub LSP descriptor list in the
   enhanced Path message is defined as follows.

   <egress backup P2MP sub LSP descriptor list> ::=
                       <egress backup P2MP sub LSP descriptor>
                       [ <egress backup P2MP sub LSP descriptor list> ]

   <egress backup P2MP sub LSP descriptor> ::=
                       <EGRESS_BACKUP_P2MP_SUB_LSP>
                       [ <EGRESS_BACKUP_P2MP_SECONDARY_EXPLICIT_ROUTE> ]


6.2.  Processing of Path Message

   The ingress node of a P2MP LSP initiates a Path message with an
   egress backup P2MP sub LSP descriptor list for protecting egress
   nodes of the P2MP LSP.  In order to protect an egress node of the
   P2MP LSP, the ingress node MUST add an EGRESS_BACKUP_P2MP_SUB_LSP
   object into the Path message.  The object contains the information
   about the backup egress node to be used to protect the failure of the
   egress node.  An EGRESS_BACKUP_P2MP_SECONDARY_EXPLICIT_ROUTE object,
   which describes an explicit path to the backup egress node, SHOULD
   follow the EGRESS_BACKUP_P2MP_SUB_LSP.



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   After an intermediate node (a transit or branch node) receives the
   Path message with an egress backup P2MP sub LSP descriptor list, for
   each EGRESS_BACKUP_P2MP_SUB_LSP containing a backup egress node in
   the list, the intermediate node of the P2MP LSP MUST put the
   EGRESS_BACKUP_P2MP_SUB_LSP with the directly following
   EGRESS_BACKUP_P2MP_SECONDARY_EXPLICIT_ROUTE into the Path message
   that is to be sent toward the direction to the previous-hop node of
   the egress node that is to be protected by the backup egress node if
   the intermediate node is not the previous-hop node of the egress
   node.

   If the intermediate node is the previous-hop node of an egress node,
   when it receives the Path message with the EGRESS_BACKUP_P2MP_SUB_LSP
   containing the backup egress node to be assigned for protecting the
   egress node, the intermediate node generates a new Path message based
   on the information in the EGRESS_BACKUP_P2MP_SUB_LSP and the possible
   directly following EGRESS_BACKUP_P2MP_SECONDARY_EXPLICIT_ROUTE.  The
   format of this new Path message is the same as that of the Path
   message defined in RFC 4875.  This new Path message is used to signal
   the segment of a special S2L sub-LSP of the P2MP LSP from the
   previous-hop node to the backup egress node.  The new Path message is
   sent to the next-hop node along the path for the backup P2MP sub LSP.

   When an egress node of the P2MP LSP receives the Path message with an
   egress backup P2MP sub LSP descriptor list, it SHOULD ignore the
   egress backup P2MP sub LSP descriptor list and generate a PathErr
   message.


7.  IANA Considerations

   TBD


8.  Acknowledgement

   The author would like to thank Richard Li and Quintin Zhao for their
   valuable comments on this draft.


9.  References

9.1.  Normative References

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

   [RFC3692]  Narten, T., "Assigning Experimental and Testing Numbers



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              Considered Useful", BCP 82, RFC 3692, January 2004.

   [RFC2205]  Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
              Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
              Functional Specification", RFC 2205, September 1997.

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

   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, December 2001.

   [RFC3473]  Berger, L., "Generalized Multi-Protocol Label Switching
              (GMPLS) Signaling Resource ReserVation Protocol-Traffic
              Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.

   [RFC4090]  Pan, P., Swallow, G., and A. Atlas, "Fast Reroute
              Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
              May 2005.

   [RFC4875]  Aggarwal, R., Papadimitriou, D., and S. Yasukawa,
              "Extensions to Resource Reservation Protocol - Traffic
              Engineering (RSVP-TE) for Point-to-Multipoint TE Label
              Switched Paths (LSPs)", RFC 4875, May 2007.

9.2.  Informative References

   [RFC4461]  Yasukawa, S., "Signaling Requirements for Point-to-
              Multipoint Traffic-Engineered MPLS Label Switched Paths
              (LSPs)", RFC 4461, April 2006.


Authors' Addresses

   Huaimo Chen
   Huawei Technologies
   Boston, MA
   USA

   Email: Huaimochen@huawei.com










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   Ning So
   Verison Business
   2400 North Glenville Drive
   Richardson, TX  75082
   USA

   Email: Ning.So@verizonbusiness.com












































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