Internet Engineering Task Force                                  H. Chen
Internet-Draft                                       Huawei Technologies
Intended status: Standards Track                                   N. So
Expires: June 1, August 14, 2014                             Tata Communications
                                                                  A. Liu
                                                                Ericsson
                                                                   F. Xu
                                                                 Verizon
                                                                  M. Toy
                                                                 Comcast
                                                                L. Huang
                                                            China Mobile
                                                                  L. Liu
                                                                UC Davis
                                                       November 28, 2013
                                                       February 10, 2014

         Extensions to RSVP-TE for LSP Egress Local Protection
             draft-chen-mpls-p2mp-egress-protection-10.txt
             draft-chen-mpls-p2mp-egress-protection-11.txt

Abstract

   This document describes extensions to Resource Reservation Protocol -
   Traffic Engineering (RSVP-TE) for locally protecting egress nodes of
   a Traffic Engineered (TE) 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
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   This Internet-Draft will expire on June 1, August 14, 2014.

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   Copyright (c) 2013 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  An Example of Egress Local Protection  . . . . . . . . . .  3
     1.2.  Egress Local Protection with FRR . . . . . . . . . . . . .  4
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  4
   3.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   4.  Protocol Extensions  . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  EGRESS_BACKUP_SUB_LSP IPv4/IPv6
     4.1.  EGRESS_BACKUP Object . . . . . . . . . . . . . . . . . . .  4
     2.2.  EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE Object
     4.2.  Flags in FAST_REROUTE  . . . . . .  5
     2.3. . . . . . . . . . . . .  6
     4.3.  Path Message . . . . . . . . . . . . . . . . . . . . . . .  6
   3.
   5.  Egress Protection Behaviors  . . . . . . . . . . . . . . . . .  6
     3.1.
     5.1.  Ingress Behavior . . . . . . . . . . . . . . . . . . . . .  7
     3.2.  6
     5.2.  Intermediate Node and PLR Behavior . . . . . . . . . . . .  7
       3.2.1.
       5.2.1.  Signaling for One-to-One Protection  . . . . . . . . .  8
       3.2.2.
       5.2.2.  Signaling for Facility Protection  . . . . . . . . . .  8
       3.2.3.
       5.2.3.  Signaling for S2L Sub LSP Protection . . . . . . . . .  9
       3.2.4.
       5.2.4.  PLR Procedures during Local Repair . . . . . . . . . .  9
   4. 10
   6.  Considering Application Traffic  . . . . . . . . . . . . . . . 10
     4.1.
     6.1.  A Typical Application  . . . . . . . . . . . . . . . . . . 10
     4.2.
     6.2.  PLR Procedure for Applications . . . . . . . . . . . . . . 11
     4.3.
     6.3.  Egress Procedures for Applications . . . . . . . . . . . . 11
   5.
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   6.
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   7.
   9.  Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 12
   8.
   10. Acknowledgement  . . . . . . . . . . . . . . . . . . . . . . . 12
   9. 13
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     9.1.
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 13
     9.2.
     11.2. Informative References . . . . . . . . . . . . . . . . . . 13 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14

1.  Introduction

   RFC 4090 describes two methods for protecting the transit nodes of a
   P2P LSP: one-to-one protection and facility bypass protection.  RFC 4875 specifies how
   to use them to protect the transit nodes of a P2MP LSP.  However, there is no
   they do not mention of locally protecting any local protection for an egress of a protected P2P or P2MP LSP in these RFCs. an LSP.

   To protect the egresses of an LSP (P2P or P2MP), an existing approach
   sets up a backup LSP from a backup ingress (or the ingress of the
   LSP) to the backup egresses, where each egress is paired with a
   backup egress and protected by the backup egress.

   The main disadvantage of this

   This approach is that may use more network resources
   such as double bandwidths may be used. and provide slow fault recovery.
   This document specifies extensions to RSVP-TE for locally protecting local protection of
   an egress of a P2MP or P2P an LSP, which overcome this disadvantage. overcomes these disadvantages.

1.1.  An Example of Egress Local Protection

   Figure 1 illustrates shows an example of using backup LSPs to locally protect egress nodes
   egresses of a primary P2MP LSP, which is LSP from ingress
   node R1 to two egress nodes: egresses: L1
   and L2.  The primary LSP is represented by star(*) lines and backup
   LSPs by hyphen(-) lines.

   La and Lb are the designated backup egress nodes egresses for egress nodes egresses L1 and L2 of the P2MP LSP
   respectively.  To distinguish between an egress (e.g., L1 in the figure) and L1) from a backup
   egress (e.g., La in the
   figure), La), an egress is called a primary egress if necessary. needed.

   The backup LSP for protecting primary egress L1 is from its upstream node R3 to
   backup egress La.  The backup LSP one for protecting primary
   egress L2 is from its upstream node R5 to backup egress Lb.

                     [R2]*****[R3]*****[L1]
                    *          \ :.....:   $            **** Primary LSP
                   *            \           $           ---- Backup LSP
                  *               \          [CE1]      .... BFD Session
                 *                  \       $              $ Link
                *                     \    $              $
               *                       [La]              $
              *
          [R1]******[R4]*******[R5]*****[L2]
         $                      \ :.....:   $
        $                        \           $
     [S]                           \          [CE2]
                                     \       $
                                       \    $
                                        [Lb]

            Figure 1: Backup LSP for Locally Protecting Egress

   During normal operations, the traffic carried by the P2MP LSP is sent
   through R3 to L1, which delivers the traffic to its destination CE1.
   When R3 detects the failure of L1, R3 switches the traffic to the
   backup LSP to backup egress La, which delivers the traffic to CE1.
   The time for switching the traffic is within tens of milliseconds.

   The failure of a primary egress (e.g., L1 in the figure) MAY be
   detected by its upstream node (e.g., R3 in the figure) through a BFD
   session
   between the upstream node and the egress in MPLS networks.  Exactly
   how the failure is detected is out of scope for this document.

                     [R2]*****[R3]*****[L1]
                    *          \ :.....:   $            **** Primary LSP
                   *            \           $           ---- Backup LSP
                  *               \          [CE1]      .... BFD Session
                 *                  \       $              $ Link
                *                     \    $              $
               *                       [La]              $
              *
          [R1]******[R4]*******[R5]*****[L2]
         $                      \ :.....:   $
        $                        \           $
     [S]                           \          [CE2]
                                     \       $
                                       \    $
                                        [Lb]

            Figure 1: Backup LSP for Locally Protecting Egress

1.2.  Egress Local Protection with FRR

   Using the egress local protection and the FRR, we can locally protect
   the egresses, the links and the intermediate nodes of an LSP.  The
   traffic switchover time is within tens of milliseconds whenever an
   egress, any of the links and the intermediate nodes of the LSP fails.

   The egress nodes of the LSP can be locally protected via the egress
   local protection.  All the links and the intermediate nodes of the
   LSP can be locally protected through using the FRR.

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.

3.  Terminology

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

4.  Protocol Extensions

   A new object EGRESS_BACKUP_SUB_LSP EGRESS_BACKUP is defined for signaling egress local protection.
   It contains a backup egress for a primary egress.

2.1.  EGRESS_BACKUP_SUB_LSP IPv4/IPv6

4.1.  EGRESS_BACKUP Object

   The class of the EGRESS_BACKUP_SUB_LSP IPv4/IPv6 EGRESS_BACKUP object is 50, which
   is the same as that of the S2L_SUB_LSP IPv4/IPv6 object defined in
   RFC 4875. TBD-1 to be assigned by
   IANA.  The C-Type of the EGRESS_BACKUP_SUB_LSP IPv4 EGRESS_BACKUP IPv4/IPv6 object is a
   new number 3 or another number TBD-2/
   TBD-3 to be assigned by IANA.

    EGRESS_BACKUP_SUB_LSP_IPv4

      EGRESS_BACKUP Class Num = TBD-1, IPv4/IPv6 C-Type = 3 TBD-2/TBD-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 Sub LSP destination IPv4 IPv4/IPv6 address        |          ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |
     ~          Egress Primary Sub LSP destination IPv4 IPv4/IPv6 address       |         ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         (Subobjects)                          |
     ~                         (Subobjects)                          ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      o Egress Backup Sub LSP destination IPv4 address
       IPv4 IPv4/IPv6 address:
         IPv4/IPv6 address of the backup egress node
      o Egress Primary Sub LSP destination IPv4 address
       IPv4 IPv4/IPv6 address:
         IPv4/IPv6 address of the primary egress node

   The Subobjects are optional

   The C-Type optional.  One of them is P2P LSP ID IPv4/IPv6
   subobject, whose body has the EGRESS_BACKUP_SUB_LSP IPv6 object following format and Type is TBD-4/
   TBD-5.  It may be used to identify a new number 4
   or another number assigned by IANA.

    EGRESS_BACKUP_SUB_LSP_IPv6 C-Type = 4 backup LSP.

      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 Sub LSP destination IPv6 address        |
       ~                         (16 bytes)
     ~
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Egress Primary Sub     P2P LSP destination IPv6 address       |
       ~                         (16 Tunnel Egress IPv4/IPv6 Address (4/16 bytes)      ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         (Subobjects)         Reserved              |            Tunnel ID          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ~               Extended Tunnel ID (4/16 bytes)                 ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Egress Backup Sub

   o P2P LSP destination IPv6 address
       IPv6 Tunnel Egress IPv4/IPv6 Address:
       IPv4/IPv6 address of the backup egress node
    Egress Primary Sub LSP destination IPv6 address
       IPv6 address of the primary egress node
    Subobjects are optional

2.2.  EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE Object

   An EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE (EB-SERO) object tunnel
   o Tunnel ID:
       A 16-bit identifier that is defined
   for signaling protection for a primary egress constant over the life of a P2MP LSP in a new
   S2L Sub LSP backup protection method.  It contains a path from the
   upstream node tunnel
   o Extended Tunnel ID:
       A 4/16-byte identifier being constant over the life of the primary egress to a backup egress.  Its tunnel

   Another one is Label subobject, whose body has the format below and
   Type is identical TBD-6 to an ERO's.

   The class of an EB-SERO is the same as that of a SERO defined in RFC
   4873.  The EB-SERO uses a new C-Type 3, or another number be assigned by IANA.  The formats

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                              Label                            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4.2.  Flags in FAST_REROUTE

   A bit of sub-objects the flags in an EB-SERO are identical the FAST_REROUTE object may be used to
   those indicate
   whether S2L Sub LSP is desired for protecting an egress of sub-objects in a P2MP LSP
   or One-to-One Backup is preferred for protecting an ERO defined in RFC 3209.

2.3. egress of a P2P
   LSP when the "Facility Backup Desired" flag is set.  This bit is
   called "S2L Sub LSP Backup Desired" or "One-to-One Backup Preferred".

4.3.  Path Message

   A Path message is enhanced to carry the information about a backup
   egress for a primary egress of an LSP through including an egress
   backup sub LSP descriptor list.  The format of the enhanced Path message is
   illustrated below.

  <Path Message> ::= <Common Header> [ <INTEGRITY> ]
                     [ [<MESSAGE_ID_ACK> | <MESSAGE_ID_NACK>] ...]
                     [ <MESSAGE_ID> ]
                        <SESSION> ]<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 sub LSP descriptor list>]

   The egress backup sub LSP descriptor list in the message is defined below.
   It is a sequence of EGRESS_BACKUP_SUB_LSP EGRESS_BACKUP objects, each of which describes a
   pair of a primary egress and a backup egress.

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

      <egress backup sub LSP descriptor> ::=
                        <EGRESS_BACKUP_SUB_LSP>
                        [ <EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE> ]

3. <EGRESS_BACKUP>

5.  Egress Protection Behaviors
3.1.

5.1.  Ingress Behavior

   To protect a primary egress of an LSP, a backup egress must be
   configured on the ingress of the LSP.

   The ingress initiates a Path message for the LSP with an egress
   backup sub LSP descriptor list.  For each primary egress of the LSP
   to be protected, the ingress MUST add an EGRESS_BACKUP_SUB_LSP object
   into the list.  The object contains set the primary egress
   "label recording desired" flag and the backup
   egress for protecting "node protection desired" flag
   in the primary egress.

   To SESSION_ATTRIBUTE object.

   If one-to-one backup or facility backup method is desired to protect
   a primary egress of an LSP via one-to-one backup or
   facility backup method, LSP, the ingress SHOULD include a FAST_REROUTE
   object and set the One-to-One "One-to-One Backup Desired Desired" or Facility "Facility Backup
   Desired
   Desired" flag.

   To protect a primary

   If S2L Sub LSP backup method is desired to protect a primary egress
   of a P2MP LSP via S2L LSP, the ingress SHOULD include a FAST_REROUTE object and
   set the "S2L Sub LSP backup
   method, Backup Desired" flag.

   Note that if "Facility Backup Desired" flag is set for protecting the
   intermediate nodes of a primary P2P LSP, but we want to use "One-to-
   One Backup" for protecting the egress of the LSP, then the ingress
   SHOULD add an EB-SERO object following set "One-to-One Backup Preferred" flag.

   Optionally, a backup egress may be configured on the
   EGRESS_BACKUP_SUB_LSP object into ingress of an
   LSP to protect a primary egress of the list. LSP.

   The EB-SERO object
   contains ingress sends a path from Path message for the upstream node of LSP with the objects above
   and an optional egress backup descriptor list.  For each primary
   egress of the LSP to be protected, the
   backup egress.  The ingress computes adds an EGRESS_BACKUP
   object into the path list if the P2MP LSP backup egress is in
   one area; otherwise, given.  The object
   contains the path may be computed by primary egress and the Path Computation
   Element (PCE).

3.2. backup egress for protecting the
   primary egress.

5.2.  Intermediate Node and PLR Behavior

   If an intermediate node of an LSP receives the Path message with an
   egress backup sub LSP descriptor list and it is not an upstream node of any
   primary egress of the LSP, it forwards the list in the message unchanged.

   If the intermediate node is the upstream node of a primary egress to
   be protected, it gets determines the backup egress egress, obtains a path for the
   backup LSP and sets up the backup LSP along the path.

   The PLR (upstream node of the primary egress) tries to get the backup
   egress from EGRESS_BACKUP in the egress backup descriptor list if the
   Path message contains the list.  If the PLR can not get it, the PLR
   tries to find the backup egress, which is not the primary egress but
   has the same IP address as the destination IP address of the LSP.

   Note that the primary egress and the backup egress SHOULD have a same
   local address configured, and the cost to the local address on the
   backup egress SHOULD be much bigger than the cost to the local
   address on the primary egress.  Thus another name such as virtual
   node based egress protection may be used for egress local protection.

   After obtaining the backup egress, the PLR tries to compute a path
   from itself to the backup egress.

   The PLR then sets up the EGRESS_BACKUP_SUB_LSP object in backup LSP along the list. path obtained.  It acts as a PLR to
   provide
   provides one-to-one or facility backup protection for the primary
   egress.  It provides one-to-one backup protection egress if the One-to-One
   "One-to-One Backup Desired Desired" or "One-to-One Backup Preferred" flag is
   set in the message; otherwise, it provides facility backup protection
   if the Facility "Facility Backup Desired flag flag" is set.

   The PLR (upstream node of the primary egress) sets the protection flags in the RRO Sub-object for the
   primary egress in the Resv message according to the status of the
   primary egress and the backup LSP protecting the primary egress.  For
   example, it will set the "local protection available" and the "node
   protection" flag to one indicating that the primary egress is protected when
   the backup LSP
   to the backup egress is set up and ready for protecting the primary egress.

3.2.1.

5.2.1.  Signaling for One-to-One Protection

   The behavior of the upstream node of a primary egress of an LSP as a
   PLR is the same as that of a PLR for one-to-one backup method
   described in RFC 4090 except for that the upstream node creates a
   backup LSP from itself to a backup egress.

   In the case that

   If the LSP is a P2MP LSP and a primary egress of the LSP is a transit
   node (i.e., bud node), the upstream node of the primary egress as a
   PLR also creates a backup LSP from itself to each of the next hops of
   the primary egress.

   When the PLR detects a the failure in of the primary egress, it MUST rapidly
   switch the packets from the primary LSP to the backup LSP to the
   backup egress.  For a the failure in of the bud node of an a P2MP LSP, the
   PLR MUST also rapidly switch the packets to the backup LSPs to the bud node's
   next hops, where the packets are merged into the primary LSP.

3.2.2.

5.2.2.  Signaling for Facility Protection

   Except for backup LSP and downstream label, the behavior of the
   upstream node of the primary egress of a primary LSP as a PLR follows
   the PLR behavior for facility backup method described in RFC 4090.

   For a number of primary P2P LSPs going through the same PLR to the
   same primary egress, the primary egress of these LSPs may be
   protected by one backup LSP from the PLR to the backup egress
   designated for protecting the primary egress.

   The PLR selects or creates a backup LSP from itself to the backup
   egress.  If there exists is a backup LSP that satisfies the constraints
   given in the Path message, then this one is selected; otherwise, a
   new backup LSP to the backup egress will be created.

   For a primary LSP carrying IP packets,

   After getting the backup LSP, the PLR does not need any
   downstream label as an inner label for associates the backup LSP when binding the with
   a primary LSP with for protecting its primary egress.  The PLR records
   that the backup LSP.  When LSP is used to protect the PLR detects a primary LSP against its
   primary egress failure and includes an EGRESS_BACKUP object in the
   Path message to the primary egress, it redirects egress.  The object contains the IP packets from backup
   egress and the primary backup LSP
   into ID.  It indicates that the primary egress
   SHOULD send the backup egress the primary LSP to label as UA label.

   After receiving the backup egress, where Path message with the IP packets are
   forwarded according to IP destinations in EGRESS_BACKUP, the primary
   egress includes the information about the packets.

   For a primary LSP carrying packets label in the
   Resv message with application or service
   labels, an EGRESS_BACKUP object as UA label.  When the PLR may not need any downstream label as an inner label
   receives the Resv message with the information about the UA label, it
   includes the information in the Path message for the backup LSP either when binding to
   the backup egress.  Thus the primary LSP with label as UA label is sent to
   the backup LSP. egress from the primary egress.

   When the PLR detects a the failure in of the primary egress, it redirects
   the packets from the primary LSP into the backup LSP to backup egress
   through switching
   using the top primary LSP label with from the backup LSP primary egress as an inner
   label.  The backup egress delivers the packets to the same
   destinations as the primary egress (see details in section "Considering Application
   Traffic" below).

3.2.3. using the backup LSP label as
   context label and the inner label as UA label.

5.2.3.  Signaling for S2L Sub LSP Protection

   The S2L Sub LSP Protection is used to protect a primary egress of a
   P2MP LSP.  Its major advantage is that the application traffic
   carried by the P2MP LSP may be is easily protected against the egress failure.

   The PLR determines to protect a primary egress of a P2MP LSP via S2L
   sub LSP protection when it receives a Path message with an EB-SERO
   object following the EGRESS_BACKUP_SUB_LSP containing the primary
   egress and a backup egress. flag "S2L Sub
   LSP Backup Desired" set.

   The PLR sets up the backup S2L sub LSP to the backup egress, creates
   and maintains its state in the same way as of setting up a source to
   leaf (S2L) sub LSP defined in RFC 4875 from the signaling's point of
   view.  It computes a path for the backup LSP from itself to the
   backup egress, constructs and sends a PATH Path message along the path given in
   the EB-SERO for the backup LSP, path,
   receives and processes a RESV Resv message
   that responses responding to the PATH Path message.

   After receiving the RESV Resv message for the backup LSP, the PLR creates
   a forwarding entry with an inactive state or flag called inactive
   forwarding entry.  This inactive forwarding entry is not used to
   forward any data traffic during normal operations.

   When the PLR detects a the failure in of the primary egress failure, egress, it changes
   the forwarding entry for the backup LSP to active.  Thus, the PLR
   forwards the traffic to the backup egress through the backup LSP,
   which sends the traffic to its destination.

3.2.4.

5.2.4.  PLR Procedures during Local Repair

   When the upstream node of a primary egress of an LSP as a PLR detects
   a
   the failure in of the primary egress, it follows the procedures defined
   in section 6.5 of RFC 4090.

   The PLR (i.e., the upstream node of the primary egress)  It SHOULD notify the ingress about the
   failure of the primary egress in the same way as a PLR notifies the
   ingress about the failure of an intermediate node.

   In the local revertive mode, the PLR re-signals each of the primary
   LSPs that used to be were routed over the restored resource once it detects that
   the resource is restored.  Every primary LSP successfully re-signaled
   along the restored resource is switched back.

   Moreover, the PLR lets the upstream part of the primary LSP stay
   after the primary egress fails.  The downstream part of the primary
   LSP from the PLR to the primary egress SHOULD be removed.

4.

6.  Considering Application Traffic

   This section focuses on the application traffic carried by P2P LSPs.
   When a primary egress of a P2MP LSP fails, the application traffic
   carried by the P2MP LSP may be delivered to the same destination by
   the backup egress since the inner label if any for the traffic is a
   upstream assigned label for every egress of the P2MP LSP.

4.1.

6.1.  A Typical Application

   L3VPN is a typical application that an LSP carries. application.  An existing solution (refer to
   Figure 2) for protecting L3VPN traffic against egress failure
   includes: 1) A multi-hop BFD session between ingress R1 and egress L1
   of primary LSP; 2) A backup LSP from ingress R1 to backup egress La;
   3) La sends R1 VPN backup label and related information via BGP; 4)
   R1 has a VRF with two sets of routes: one uses primary LSP and L1 as
   next hop; the other uses backup LSP and La as next hop.

     CE1,CE2 in    [R2]*****[R3]*****[L1]             **** Primary LSP
     one VPN      *                  :   $            ---- Backup LSP
                 *  .................:    $           .... BFD Session
             [R1] ..:                      [CE2]         $ Link
            $    \                        $             $
           $      \                      $
      [CE1]        [R4]-----[R5]-----[La](BGP sends R1 VPN backup label)

                Figure 2: Protect Egress for L3VPN Traffic

   In normal operations, R1 sends the traffic from CE1 through primary
   LSP with VPN label received from L1 as inner label to L1, which
   delivers the traffic to CE2 using VPN label.

   When R1 detects a the failure in of L1, R1 sends the traffic from CE1 via
   backup LSP with VPN bakup backup label received from La as inner label to
   La, which delivers the traffic to CE2 using VPN backup label.

   A new solution (refer to Figure 3) with egress local protection for
   protecting L3VPN traffic includes: 1) A BFD session between R3 and
   egress L1 of primary LSP; 2) A backup LSP from R3 to backup egress
   La; 3) L1 sends La VPN label as UA label and related information via
   BGP or another protocol; information; 4)
   L1 and La is virtualized as one from R1's
   point one.  This can be achieved by configuring
   a same local address on L1 and La, using the address as a destination
   of view. the LSP and BGP next hop for VPN traffic.

     CE1,CE2 in    [R2]*****[R3]*****[L1]             **** Primary LSP
     one VPN      *          \ :.....:   $            ---- Backup LSP
                 *            \           $           .... BFD Session
             [R1]               \          [CE2]         $ Link
            $                     \       $             $
           $                        \    $
      [CE1]                          [La](VPN label from L1 as UA label)

            Figure 3: Locally Protect Egress for L3VPN Traffic

   When R3 detects a failure in L1, L1's failure, R3 sends the traffic from primary LSP
   via backup LSP to La, which delivers the traffic to CE2 using VPN
   label as UA label under the backup LSP label as a context label.

4.2.

6.2.  PLR Procedure for Applications

   When the PLR creates gets a backup LSP from itself to a backup egress for
   protecting a primary egress, egress of a primary LSP, it includes an EGRESS_BACKUP_SUB_LSP
   EGRESS_BACKUP object in the Path message for the primary LSP.  The
   object contains the
   primary egress and ID information of the backup egress LSP and indicates
   that the backup primary egress SHOULD consider send the backup LSP label as a context label and egress the inner label as application
   traffic label (e.g., VPN label) as UA label when needed.

4.3.

6.3.  Egress Procedures for Applications

   When a primary egress of an LSP sends the ingress of the LSP a label
   for an application such as a VPN, it SHOULD sends send the backup egress
   for protecting the primary egress the label as a upstream assigned UA label via BGP or
   another protocol.  Exactly how the label is sent is out of scope for
   this document.

   When the backup egress receives a upstream assigned UA label from the primary egress,
   it adds a forwarding entry with the label into the LFIB for the
   primary egress.  Using this entry, the backup egress
   delivers the traffic with this label as inner label from the backup
   LSP to the same destination as the primary egress.  When the backup egress receives a packet from the
   backup LSP, it uses the top label as a context label to find the LFIB
   for the primary egress and the inner label to deliver the packet to
   the same destination as the primary egress according to the LFIB.

5.

7.  Security Considerations

   In principle this document does not introduce new security issues.
   The security considerations pertaining to RFC 4090, RFC 4875 and
   other RSVP protocols remain relevant.

6.

8.  IANA Considerations

   TBD

7.

   IANA considerations for new objects will be specified after the
   objects used are decided upon.

9.  Contributors

      Boris Zhang
      Telus Communications
      200 Consilium Pl Floor 15
      Toronto, ON  M1H 3J3
      Canada
      Email: Boris.Zhang@telus.com

      Zhenbin Li
      Huawei Technologies
      Huawei Bld., No.156 Beiqing Rd.
      Beijing  100095
      China
      Email: lizhenbin@huawei.com

      Nan Meng
      Huawei Technologies
      Huawei Bld., No.156 Beiqing Rd.
      Beijing  100095
      China
      Email: mengnan@huawei.com

      Vic Liu
      China Mobile
      No.32 Xuanwumen West Street, Xicheng District
      Beijing, 100053
      China

8.
      Email: liuzhiheng@chinamobile.com

10.  Acknowledgement

   The authors would like to thank Richard Li, Tarek Saad, Lizhong Jin,
   Ravi Torvi, Eric Gray, Olufemi Komolafe, Michael Yue, Rob Rennison,
   Neil Harrison, Kannan Sampath, Yimin Shen, Ronhazli Adam and Quintin
   Zhao for their valuable comments and suggestions on this draft.

9.

11.  References

9.1.

11.1.  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
              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.

   [RFC5331]  Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream
              Label Assignment and Context-Specific Label Space",
              RFC 5331, August 2008.

   [RFC5786]  Aggarwal, R. and K. Kompella, "Advertising a Router's
              Local Addresses in OSPF Traffic Engineering (TE)
              Extensions", RFC 5786, March 2010.

   [P2MP FRR]
              Le Roux, J., Aggarwal, R., Vasseur, J., and M. Vigoureux,
              "P2MP MPLS-TE Fast Reroute with P2MP Bypass Tunnels",
              draft-leroux-mpls-p2mp-te-bypass , March 1997.

9.2.

11.2.  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: huaimo.chen@huawei.com

   Ning So
   Tata Communications
   2613 Fairbourne Cir.
   Plano, TX  75082
   USA

   Email: ning.so@tatacommunications.com

   Autumn Liu
   Ericsson
   CA
   USA

   Email: autumn.liu@ericsson.com
   Fengman Xu
   Verizon
   2400 N. Glenville Dr
   Richardson, TX  75082
   USA

   Email: fengman.xu@verizon.com

   Mehmet Toy
   Comcast
   1800 Bishops Gate Blvd.
   Mount Laurel, NJ  08054
   USA

   Email: mehmet_toy@cable.comcast.com

   Lu Huang
   China Mobile
   No.32 Xuanwumen West Street, Xicheng District
   Beijing,   100053
   China

   Email: huanglu@chinamobile.com

   Lei Liu
   UC Davis
   USA

   Email: liulei.kddi@gmail.com