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Versions: (draft-ietf-mpls-rsvp-ingress-protection) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 RFC 8424

Internet Engineering Task Force                             H. Chen, Ed.
Internet-Draft                                       Huawei Technologies
Intended status: Standards Track                           R. Torvi, Ed.
Expires: July 14, 2015                                  Juniper Networks
                                                        January 10, 2015


         Extensions to RSVP-TE for LSP Ingress Local Protection
             draft-ietf-teas-rsvp-ingress-protection-01.txt

Abstract

   This document describes extensions to Resource Reservation Protocol -
   Traffic Engineering (RSVP-TE) for locally protecting the ingress node
   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
   Task Force (IETF).  Note that other groups may also distribute
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   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."

   This Internet-Draft will expire on July 14, 2015.

Copyright Notice

   Copyright (c) 2015 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
   described in the Simplified BSD License.



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Table of Contents

   1.  Co-authors . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     2.1.  An Example of Ingress Local Protection . . . . . . . . . .  3
     2.2.  Ingress Local Protection with FRR  . . . . . . . . . . . .  4
   3.  Ingress Failure Detection  . . . . . . . . . . . . . . . . . .  4
     3.1.  Source Detects Failure . . . . . . . . . . . . . . . . . .  4
     3.2.  Backup and Source Detect Failure . . . . . . . . . . . . .  5
   4.  Backup Forwarding State  . . . . . . . . . . . . . . . . . . .  5
     4.1.  Forwarding State for Backup LSP  . . . . . . . . . . . . .  5
   5.  Protocol Extensions  . . . . . . . . . . . . . . . . . . . . .  6
     5.1.  INGRESS_PROTECTION Object  . . . . . . . . . . . . . . . .  6
       5.1.1.  Subobject: Backup Ingress IPv4/IPv6 Address  . . . . .  7
       5.1.2.  Subobject: Ingress IPv4/IPv6 Address . . . . . . . . .  8
       5.1.3.  Subobject: Traffic Descriptor  . . . . . . . . . . . .  8
       5.1.4.  Subobject: Label-Routes  . . . . . . . . . . . . . . .  9
   6.  Behavior of Ingress Protection . . . . . . . . . . . . . . . .  9
     6.1.  Overview . . . . . . . . . . . . . . . . . . . . . . . . .  9
     6.2.  Ingress Behavior . . . . . . . . . . . . . . . . . . . . .  9
     6.3.  Backup Ingress Behavior  . . . . . . . . . . . . . . . . . 11
       6.3.1.  Backup Ingress Behavior in Off-path Case . . . . . . . 11
       6.3.2.  Backup Ingress Behavior in On-path Case  . . . . . . . 13
       6.3.3.  Failure Detection and Refresh PATH Messages  . . . . . 13
     6.4.  Revertive Behavior . . . . . . . . . . . . . . . . . . . . 14
       6.4.1.  Revert to Primary Ingress  . . . . . . . . . . . . . . 14
       6.4.2.  Global Repair by Backup Ingress  . . . . . . . . . . . 14
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 15
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
   9.  Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 15
   10. Acknowledgement  . . . . . . . . . . . . . . . . . . . . . . . 16
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 16
     11.2. Informative References . . . . . . . . . . . . . . . . . . 17
   A.  Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 17
















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1.  Co-authors

   Ning So, Autumn Liu, Alia Atlas, Yimin Shen, Tarek Saad, Fengman Xu,
   Mehmet Toy, Lei Liu


2.  Introduction

   For MPLS LSPs it is important to have a fast-reroute method for
   protecting its ingress node as well as transit nodes.  This is not
   covered either in the fast-reroute method defined in [RFC4090] or in
   the P2MP fast-reroute extensions to fast-reroute in [RFC4875].

   An alternate approach to local protection (fast-reroute) is to use
   global protection and set up a second backup LSP (whether P2MP or
   P2P) from a backup ingress to the egresses.  The main disadvantage of
   this is that the backup LSP may reserve additional network bandwidth.

   This specification defines a simple extension to RSVP-TE for local
   protection of the ingress node of a P2MP or P2P LSP.

2.1.  An Example of Ingress Local Protection

   Figure 1 shows an example of using a backup P2MP LSP to locally
   protect the ingress of a primary P2MP LSP, which is from ingress R1
   to three egresses: L1, L2 and L3.  The backup LSP is from backup
   ingress Ra to the next hops R2 and R4 of ingress R1.

                     [R2]******[R3]*****[L1]
                    *  |                               **** Primary LSP
                   *   |                               ---- Backup LSP
                  *    /                               .... BFD Session
                 *    /                                  $  Link
         ....[R1]*******[R4]****[R5]*****[L2]           $
         :  $  $    /     /        *                   $
         : $   $   /     /          *
        [S]    $  /     /            *
           $   $ /     /              *
            $  $/     /                *
             [Ra]----[Rb]               [L3]


         Figure 1: Backup P2MP LSP for Locally Protecting Ingress

   In normal operations, source S sends the traffic to primary ingress
   R1.  R1 imports the traffic into the primary LSP.

   When source S detects the failure of R1, it switches the traffic to



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   backup ingress Ra, which imports the traffic from S into the backup
   LSP to R1's next hops R2 and R4, where the traffic is merged into the
   primary LSP, and then sent to egresses L1, L2 and L3.

   Source S should be able to detect the failure of R1 and switch the
   traffic within 10s of ms.

   Note that the backup ingress must be one logical hop away from the
   ingress.  A logical hop is a direct link or a tunnel such as a GRE
   tunnel, over which RSVP-TE messages may be exchanged.

2.2.  Ingress Local Protection with FRR

   Through using the ingress local protection and the FRR, we can
   locally protect the ingress, all the links and the transit nodes of
   an LSP.  The traffic switchover time is within 10s of ms whenever the
   ingress, any of the links and the transit nodes of the LSP fails.

   The ingress node of the LSP can be locally protected through using
   the ingress local protection.  All the links and all the transit
   nodes of the LSP can be locally protected through using the FRR.


3.  Ingress Failure Detection

   Exactly how to detect the failure of the ingress is out of scope.
   However, it is necessary to discuss different modes for detecting the
   failure because they determine what is the required behavior for the
   source and backup ingress.

3.1.  Source Detects Failure

   Source Detects Failure or Source-Detect for short means that the
   source is responsible for fast detecting the failure of the primary
   ingress of an LSP.  The backup ingress is ready to import the traffic
   from the source into the backup LSP after the backup LSP is up.

   In normal operations, the source sends the traffic to the primary
   ingress.  When the source detects the failure of the primary ingress,
   it switches the traffic to the backup ingress, which delivers the
   traffic to the next hops of the primary ingress through the backup
   LSP, where the traffic is merged into the primary LSP.

   For a P2P LSP, after the primary ingress fails, the backup ingress
   must use a method to reliably detect the failure of the primary
   ingress before the PATH message for the LSP expires at the next hop
   of the primary ingress.  After reliably detecting the failure, the
   backup ingress sends/refreshes the PATH message to the next hop



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   through the backup LSP as needed.

   After the primary ingress fails, it will not be reachable after
   routing convergence.  Thus checking whether the primary ingress
   (address) is reachable is a possible method.

3.2.  Backup and Source Detect Failure

   Backup and Source Detect Failure or Backup-Source-Detect for short
   means that both the backup ingress and the source are concurrently
   responsible for fast detecting the failure of the primary ingress.

   In normal operations, the source sends the traffic to the primary
   ingress.  It switches the traffic to the backup ingress when it
   detects the failure of the primary ingress.

   The backup ingress does not import any traffic from the source into
   the backup LSP in normal operations.  When it detects the failure of
   the primary ingress, it imports the traffic from the source into the
   backup LSP to the next hops of the primary ingress, where the traffic
   is merged into the primary LSP.

   The source-detect is preferred.  It is simpler than the backup-
   source-detect, which needs both the source and the backup ingress
   detect the ingress failure quickly.


4.  Backup Forwarding State

   Before the primary ingress fails, the backup ingress is responsible
   for creating the necessary backup LSPs.  These LSPs might be multiple
   bypass P2P LSPs that avoid the ingress.  Alternately, the backup
   ingress could choose to use a single backup P2MP LSP as a bypass or
   detour to protect the primary ingress of a primary P2MP LSP.

   The backup ingress may be off-path or on-path of an LSP.  If a backup
   ingress is not any node of the LSP, we call it is off-path.  If a
   backup ingress is a next-hop of the primary ingress of the LSP, we
   call it is on-path.  If it is on-path, the primary forwarding state
   associated with the primary LSP SHOULD be clearly separated from the
   backup LSP(s) state.

4.1.  Forwarding State for Backup LSP

   A forwarding entry for a backup LSP is created on the backup ingress
   after the LSP is set up.  Depending on the failure-detection mode
   (e.g., source-detect), it may be used to forward received traffic or
   simply be inactive (e.g., backup-source-detect) until required.  In



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   either case, when the primary ingress fails, this entry is used to
   import the traffic into the backup LSP to the next hops of the
   primary ingress, where the traffic is merged into the primary LSP.

   The forwarding entry for a backup LSP is a local implementation
   issue.  In one device, it may have an inactive flag.  This inactive
   forwarding entry is not used to forward any traffic normally.  When
   the primary ingress fails, it is changed to active, and thus the
   traffic from the source is imported into the backup LSP.


5.  Protocol Extensions

   A new object INGRESS_PROTECTION is defined for signaling ingress
   local protection.  It is backward compatible.

5.1.  INGRESS_PROTECTION Object

   The INGRESS_PROTECTION object with the FAST_REROUTE object in a PATH
   message is used to control the backup for protecting the primary
   ingress of a primary LSP.  The primary ingress MUST insert this
   object into the PATH message to be sent to the backup ingress for
   protecting the primary ingress.  It has the following format:

       Class-Num = TBD      C-Type = TBD
      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Length (bytes)        |    Class-Num  |    C-Type     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |       Secondary LSP ID        |      Flags    |    Options    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ~                         (Subobjects)                          ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

        Flags
         0x01    Ingress local protection available
         0x02    Ingress local protection in use
         0x04    Bandwidth protection

        Options
         0x01    Revert to Ingress
         0x02    P2MP Backup


   The Secondary LSP ID in the object is an LSP ID that the primary
   ingress has allocated for a protected LSP tunnel.  The backup ingress
   may use this LSP ID to set up a new LSP from the backup ingress to



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   the destinations of the protected LSP tunnel.  This allows the new
   LSP to share resources with the old one.

   The flags are used to communicate status information from the backup
   ingress to the primary ingress.

    o Ingress local protection available: The backup ingress sets this
      flag after backup LSPs are up and ready for locally protecting the
      primary ingress.  The backup ingress sends this to the primary
      ingress to indicate that the primary ingress is locally protected.

    o Ingress local protection in use: The backup ingress sets this flag
      when it detects a failure in the primary ingress.  The backup
      ingress keeps it and does not send it to the primary ingress since
      the primary ingress is down.

    o Bandwidth protection: The backup ingress sets this flag if the
      backup LSPs guarantee to provide desired bandwidth for the
      protected LSP against the primary ingress failure.

   The options are used by the primary ingress to specify the desired
   behavior to the backup ingress.

    o Revert to Ingress: The primary ingress sets this option indicating
      that the traffic for the primary LSP successfully re-signaled will
      be switched back to the primary ingress from the backup ingress
      when the primary ingress is restored.

    o P2MP Backup: This option is set to ask for the backup ingress to
      use P2MP backup LSP to protect the primary ingress.  Note that one
      spare bit of the flags in the FAST-REROUTE object can be used to
      indicate whether P2MP or P2P backup LSP is desired for protecting
      an ingress and transit node.

   The INGRESS_PROTECTION object may contain some sub objects below.

5.1.1.  Subobject: Backup Ingress IPv4/IPv6 Address

   When the primary ingress of a protected LSP sends a PATH message with
   an INGRESS_PROTECTION object to the backup ingress, the object may
   have a Backup Ingress IPv4/IPv6 Address sub object containing an
   IPv4/IPv6 address belonging to the backup ingress.  The Type of the
   sub object is TBD-1/TBD-2 for Backup Ingress IPv4/IPv6 Address.  The
   body of the sub object is given below:







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      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               IPv4/IPv6 address (4/16 bytres)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       IPv4/IPv6 address: A 32/128-bit unicast, host address.


5.1.2.  Subobject: Ingress IPv4/IPv6 Address

   The INGRESS_PROTECTION object may have an Ingress IPv4/IPv6 Address
   sub object containing an IPv4/IPv6 address belonging to the primary
   ingress.  The Type of the sub object is TBD-3/TBD-4 for Ingress IPv4/
   IPv6 Address.  The sub object has the following body:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               IPv4/IPv6 address (4/16 bytres)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       IPv4/IPv6 address: A 32/128-bit unicast, host address.


5.1.3.  Subobject: Traffic Descriptor

   The INGRESS_PROTECTION object may have a Traffic Descriptor sub
   object describing the traffic to be mapped to the backup LSP on the
   backup ingress for locally protecting the primary ingress.  The Type
   of the sub object is TBD-5/TBD-6/TBD-7 for Interface/IPv4/6 Prefix
   respectively.  The sub object has the following body:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                        Traffic Element 1                      |
     ~                                                               ~
     |                        Traffic Element n                      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The Traffic Descriptor sub object may contain multiple Traffic
   Elements of same type as follows:







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    o Interface Traffic (Type TBD-5): Each of the Traffic Elements is a
      32 bit index of an interface, from which the traffic is imported
      into the backup LSP.

    o IPv4/6 Prefix Traffic (Type TBD-6/TBD-7): Each of the Traffic
      Elements is an IPv4/6 prefix, containing an 8-bit prefix length
      followed by an IPv4/6 address prefix, whose length, in bits, was
      specified by the prefix length, padded to a byte boundary.

5.1.4.  Subobject: Label-Routes

   The INGRESS_PROTECTION object in a PATH message from the primary
   ingress to the backup ingress will have a Label-Routes sub object
   containing the labels and routes that the next hops of the ingress
   use.  The Type of the sub object is TBD-8.  The sub object has the
   following body:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ~                           Subobjects                          ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The Subobjects in the Label-Routes are copied from those in the
   RECORD_ROUTE objects in the RESV messages that the primary ingress
   receives from its next hops for the primary LSP.  They MUST contain
   the first hops of the LSP, each of which is paired with its label.


6.  Behavior of Ingress Protection

6.1.  Overview

   There are four parts of ingress protection: 1) setting up the
   necessary backup LSP forwarding state; 2) identifying the failure and
   providing the fast repair (as discussed in Sections 3 and 4); 3)
   maintaining the RSVP-TE control plane state until a global repair can
   be done; and 4) performing the global repair(see Section 6.4).

6.2.  Ingress Behavior

   The primary ingress must be configured with a couple of pieces of
   information for ingress protection.







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    o Backup Ingress Address: The primary ingress must know an IP
      address for it to be included in the INGRESS_PROTECTION object.

    o Application Traffic Identifier: The primary ingress and backup
      ingress must both know what application traffic should be directed
      into the LSP.  If a list of prefixes in the Traffic Descriptor
      sub-object will not suffice, then a commonly understood
      Application Traffic Identifier can be sent between the primary
      ingress and backup ingress.  The exact meaning of the identifier
      should be configured similarly at both the primary ingress and
      backup ingress.  The Application Traffic Identifier is understood
      within the unique context of the primary ingress and backup
      ingress.

   With this additional information, the primary ingress can create and
   signal the necessary RSVP extensions to support ingress protection.

   The primary ingress relays the information for ingress protection of
   an LSP to the backup ingress via PATH messages.  Once the LSP is
   created, the ingress of the LSP sends the backup ingress a PATH
   message with an INGRESS_PROTECTION object with Label-Routes
   subobject, which is populated with the next-hops and labels.  This
   provides sufficient information for the backup ingress to create the
   appropriate forwarding state and backup LSP(s).

   The ingress also sends the backup ingress all the other PATH messages
   for the LSP with an empty INGRESS_PROTECTION object.  Thus, the
   backup ingress has access to all the PATH messages needed for
   modification to refresh control-plane state after a failure.

   To protect the ingress of an LSP, the ingress does the following
   after the LSP is up.

   1.  Select a PATH message.

   2.  If the backup ingress is off-path, then send it a PATH message
       with the content from the selected PATH message and an
       INGRESS_PROTECTION object; else (the backup ingress is a next
       hop, i.e., on-path case) add an INGRESS_PROTECTION object into
       the existing PATH message to the backup ingress (i.e., the next
       hop).  The object contains the Traffic-Descriptor sub-object, the
       Backup Ingress Address sub-object and the Label-Routes sub-
       object.  The flags is set to indicate whether a Backup P2MP LSP
       is desired.  A second LSP-ID is allocated (if it is not allocated
       yet) and used in the object.  The Label-Routes sub-object
       contains the next-hops of the ingress and their labels.





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   3.  For each of the other PATH messages, send the backup ingress a
       PATH message with the content copied from the message and an
       empty INGRESS_PROTECTION object, which is an object without any
       Traffic-Descriptor sub-object.

6.3.  Backup Ingress Behavior

   An LER determines that the ingress local protection is requested for
   an LSP if the INGRESS_PROTECTION object is included in the PATH
   message it receives for the LSP.  The LER can further determine that
   it is the backup ingress if one of its addresses is in the Backup
   Ingress Address sub-object of the INGRESS_PROTECTION object.  The LER
   as the backup ingress will assume full responsibility of the ingress
   after the primary ingress fails.  In addition, the LER determines
   that it is off-path if it is not a next hop of the primary ingress.

6.3.1.  Backup Ingress Behavior in Off-path Case

   The backup ingress considers itself as a PLR and the primary ingress
   as its next hop and provides a local protection for the primary
   ingress.  It behaves very similarly to a PLR providing fast-reroute
   where the primary ingress is considered as the failure-point to
   protect.  Where not otherwise specified, the behavior given in
   [RFC4090] for a PLR should apply.

   The backup ingress SHOULD follow the control-options specified in the
   INGRESS_PROTECTION object and the flags and specifications in the
   FAST-REROUTE object.  This applies to providing a P2MP backup if the
   "P2MP backup" is set, a one-to-one backup if "one-to-one desired" is
   set, facility backup if the "facility backup desired" is set, and
   backup paths that support the desired bandwidth, and administrative-
   colors that are requested.

   If multiple non empty INGRESS_PROTECTION objects have been received
   via multiple PATH messages for the same LSP, then the most recent one
   MUST be the one used.

   The backup ingress creates the appropriate forwarding state for the
   backup LSP tunnel(s) to the merge point(s).

   When the backup ingress sends a RESV message to the primary ingress,
   it should add an INGRESS_PROTECTION object into the message.  It
   SHOULD set or clear the flags in the object to report "Ingress local
   protection available", "Ingress local protection in use", and
   "bandwidth protection".

   If the backup ingress doesn't have a backup LSP tunnel to all the
   merge points, it SHOULD clear "Ingress local protection available".



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   [Editor Note: It is possible to indicate the number or which are
   unprotected via a sub-object if desired.]

   When the primary ingress fails, the backup ingress redirects the
   traffic from a source into the backup P2P LSPs or the backup P2MP LSP
   transmitting the traffic to the next hops of the primary ingress,
   where the traffic is merged into the protected LSP.

   In this case, the backup ingress keeps the PATH message with the
   INGRESS_PROTECTION object received from the primary ingress and the
   RESV message with the INGRESS_PROTECTION object to be sent to the
   primary ingress.  The backup ingress sets the "local protection in
   use" flag in the RESV message, indicating that the backup ingress is
   actively redirecting the traffic into the backup P2P LSPs or the
   backup P2MP LSP for locally protecting the primary ingress failure.

   Note that the RESV message with this piece of information will not be
   sent to the primary ingress because the primary ingress has failed.

   If the backup ingress has not received any PATH message from the
   primary ingress for an extended period of time (e.g., a cleanup
   timeout interval) and a confirmed primary ingress failure did not
   occur, then the standard RSVP soft-state removal SHOULD occur.  The
   backup ingress SHALL remove the state for the PATH message from the
   primary ingress, and tear down the one-to-one backup LSPs for
   protecting the primary ingress if one-to-one backup is used or unbind
   the facility backup LSPs if facility backup is used.

   When the backup ingress receives a PATH message from the primary
   ingress for locally protecting the primary ingress of a protected
   LSP, it checks to see if any critical information has been changed.
   If the next hops of the primary ingress are changed, the backup
   ingress SHALL update its backup LSP(s) accordingly.

   When the backup ingress receives a PATH message with an non empty
   INGRESS_PROTECTION object, it examines the object to learn what
   traffic associated with the LSP.  It determines the next-hops to be
   merged to by examining the Label-Routes sub-object in the object.

   The backup ingress stores the PATH message received from the primary
   ingress, but does NOT forward it.

   The backup ingress responds with a RESV to the PATH message received
   from the primary ingress.  If the INGRESS_PROTECTION object is not
   "empty", the backup ingress SHALL send the RESV message with the
   state indicating protection is available after the backup LSP(s) are
   successfully established.




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6.3.2.  Backup Ingress Behavior in On-path Case

   An LER as the backup ingress determines that it is on-path if one of
   its addresses is a next hop of the primary ingress.  The LER on-path
   sends the corresponding PATH messages without any INGRESS_PROTECTION
   object to its next hops.  It creates a number of backup P2P LSPs or a
   backup P2MP LSP from itself to the other next hops (i.e., the next
   hops other than the backup ingress) of the primary ingress.  The
   other next hops are from the Label-Routes sub object.

   It also creates a forwarding entry, which sends/multicasts the
   traffic from the source to the next hops of the backup ingress along
   the protected LSP when the primary ingress fails.  The traffic is
   described by the Traffic-Descriptor.

   After the forwarding entry is created, all the backup P2P LSPs or the
   backup P2MP LSP is up and associated with the protected LSP, the
   backup ingress sends the primary ingress the RESV message with the
   INGRESS_PROTECTION object containing the state of the local
   protection such as "local protection available" flag set to one,
   which indicates that the primary ingress is locally protected.

   When the primary ingress fails, the backup ingress sends/multicasts
   the traffic from the source to its next hops along the protected LSP
   and imports the traffic into each of the backup P2P LSPs or the
   backup P2MP LSP transmitting the traffic to the other next hops of
   the primary ingress, where the traffic is merged into protected LSP.

   During the local repair, the backup ingress continues to send the
   PATH messages to its next hops as before, keeps the PATH message with
   the INGRESS_PROTECTION object received from the primary ingress and
   the RESV message with the INGRESS_PROTECTION object to be sent to the
   primary ingress.  It sets the "local protection in use" flag in the
   RESV message.

6.3.3.  Failure Detection and Refresh PATH Messages

   As described in [RFC4090], it is necessary to refresh the PATH
   messages via the backup LSP(s).  The Backup Ingress MUST wait to
   refresh the PATH messages until it can accurately detect that the
   ingress node has failed.  An example of such an accurate detection
   would be that the IGP has no bi-directional links to the ingress node
   and the last change was long enough in the past that changes should
   have been received (i.e., an IGP network convergence time or
   approximately 2-3 seconds) or a BFD session to the primary ingress'
   loopback address has failed and stayed failed after the network has
   reconverged.




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   As described in [RFC4090 Section 6.4.3], the backup ingress, acting
   as PLR, SHOULD modify and send any saved PATH messages associated
   with the primary LSP to the corresponding next hops through backup
   LSP(s).  Any PATH message sent will not contain any
   INGRESS_PROTECTION object.  The RSVP_HOP object in the message
   contains an IP source address belonging to the backup ingress.  The
   sender template object has the backup ingress address as its tunnel
   sender address.

6.4.  Revertive Behavior

   Upon a failure event in the (primary) ingress of a protected LSP, the
   protected LSP is locally repaired by the backup ingress.  There are a
   couple of basic strategies for restoring the LSP to a full working
   path.

    - Revert to Primary Ingress: When the primary ingress is restored,
      it re-signals each of the LSPs that start from the primary
      ingress.  The traffic for every LSP successfully re-signaled is
      switched back to the primary ingress from the backup ingress.

    - Global Repair by Backup Ingress: After determining that the
      primary ingress of an LSP has failed, the backup ingress computes
      a new optimal path, signals a new LSP along the new path, and
      switches the traffic to the new LSP.

6.4.1.  Revert to Primary Ingress

   If "Revert to Primary Ingress" is desired for a protected LSP, the
   (primary) ingress of the LSP re-signals the LSP that starts from the
   primary ingress after the primary ingress restores.  After the LSP is
   re-signaled successfully, the traffic can be switched back to the
   primary ingress from the backup ingress on the source node and
   redirected into the LSP starting from the primary ingress.

   The primary ingress can specify the "Revert to Ingress" control-
   option in the INGRESS_PROTECTION object in the PATH messages to the
   backup ingress.  After receiving the "Revert to Ingress" control-
   option, the backup ingress stops sending/refreshing PATH messages for
   the protected LSP.

6.4.2.  Global Repair by Backup Ingress

   When the backup ingress has determined that the primary ingress of
   the protected LSP has failed (e.g., via the IGP), it can compute a
   new path and signal a new LSP along the new path so that it no longer
   relies upon local repair.  To do this, the backup ingress uses the
   same tunnel sender address in the Sender Template Object and uses the



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   previously allocated second LSP-ID in the INGRESS_PROTECTION object
   of the PATH message as the LSP-ID of the new LSP.  This allows the
   new LSP to share resources with the old LSP.  In addition, if the
   Ingress recovers, the Backup Ingress SHOULD send it RESVs with the
   INGRESS_PROTECTION object where the "Revert to Ingress" is specified.
   The Secondary LSP ID should be the unused LSP ID - while the LSP ID
   signaled in the RESV will be that currently active.  The Ingress can
   learn from the RESVs what to signal.  Even if the Ingress does not
   take over, the RESVs notify it that the particular LSP IDs are in
   use.  The Backup Ingress can reoptimize the new LSP as necessary
   until the Ingress recovers.  Alternately, the Backup Ingress can
   create a new LSP with no bandwidth reservation that duplicates the
   path(s) of the protected LSP, move traffic to the new LSP, delete the
   protected LSP, and then resignal the new LSP with bandwidth.


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.


8.  IANA Considerations

   TBD


9.  Contributors


        Renwei Li
        Huawei Technologies
        2330 Central Expressway
        Santa Clara, CA  95050
        USA
        Email: renwei.li@huawei.com



        Quintin Zhao
        Huawei Technologies
        Boston, MA
        USA
        Email: quintin.zhao@huawei.com






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        Zhenbin Li
        Huawei Technologies
        2330 Central Expressway
        Santa Clara, CA  95050
        USA
        Email: zhenbin.li@huawei.com



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



        Markus Jork
        Juniper Networks
        10 Technology Park Drive
        Westford, MA 01886
        USA
        Email: mjork@juniper.net



10.  Acknowledgement

   The authors would like to thank Nobo Akiya, Rahul Aggarwal, Eric
   Osborne, Ross Callon, Loa Andersson, Daniel King, Michael Yue,
   Olufemi Komolafe, Rob Rennison, Neil Harrison, Kannan Sampath, and
   Ronhazli Adam for their valuable comments and suggestions on this
   draft.


11.  References

11.1.  Normative References

   [RFC1700]  Reynolds, J. and J. Postel, "Assigned Numbers", RFC 1700,
              October 1994.

   [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.



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   [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.

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

   [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.

   [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.

11.2.  Informative References

   [RFC2702]  Awduche, D., Malcolm, J., Agogbua, J., O'Dell, M., and J.
              McManus, "Requirements for Traffic Engineering Over MPLS",
              RFC 2702, September 1999.

   [RFC3032]  Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
              Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
              Encoding", RFC 3032, January 2001.


Appendix A.  Authors' Addresses






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        Huaimo Chen
        Huawei Technologies
        Boston, MA
        USA
        Email: huaimo.chen@huawei.com



        Raveendra Torvi
        Juniper Networks
        10 Technology Park Drive
        Westford, MA 01886
        USA
        Email: rtorvi@juniper.net



        Ning So
        Tata Communications
        2613 Fairbourne Cir.
        Plano, TX 75082
        USA
        Email: ningso01@gmail.com



        Autumn Liu
        Ericsson
        300 Holger Way
        San Jose, CA 95134
        USA
        Email: autumn.liu@ericsson.com



        Alia Atlas
        Juniper Networks
        10 Technology Park Drive
        Westford, MA 01886
        USA
        Email: akatlas@juniper.net










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        Yimin Shen
        Juniper Networks
        10 Technology Park Drive
        Westford, MA 01886
        USA
        Email: yshen@juniper.net



        Tarek Saad
        Cisco Systems
        Email: tsaad@cisco.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



        Lei Liu
        UC Davis
        USA
        Email: liulei.kddi@gmail.com














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