MPLS Working Group                                            M. Taillon
Internet-Draft                                       Cisco Systems, Inc.
Updates: RFC4090 4090 (if approved)                                 T. Saad, Ed.
Intended status: Standards Track                        Juniper Networks
Expires: June 13, July 15, 2020                                         R. Gandhi
                                                     Cisco Systems, Inc.
                                                             A. Deshmukh
                                                        Juniper Networks
                                                                 M. Jork
                                                          128 Technology
                                                               V. Beeram
                                                        Juniper Networks
                                                       December 11, 2019
                                                        January 12, 2020

        RSVP-TE Summary Fast Reroute Extensions for LSP Tunnels
                 draft-ietf-mpls-summary-frr-rsvpte-07
                 draft-ietf-mpls-summary-frr-rsvpte-08

Abstract

   This document updates RFC 4090 for the Resource Reservation Protocol
   (RSVP) Traffic-Engineering (TE) procedures that are defined in RFC 4090 for facility
   backup protection.  The updates include extensions that reduce the
   amount of signaling and processing that occurs during Fast Reroute
   (FRR), and subsequently, improves scalability when undergoing FRR
   convergence after a link or node failure.  These extensions allow the
   RSVP message exchange between the Point of Local Repair (PLR) and the
   Merge Point (MP) to be independent of the number of protected Label
   Switched Paths (LSPs) traversing between them when facility bypass
   FRR protection is used.  The signaling extensions are fully backwards
   compatible with nodes that do not support them.

Status of This Memo

   This Internet-Draft is submitted 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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on June 13, July 15, 2020.

Copyright Notice

   Copyright (c) 2019 2020 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
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   4
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Acronyms and Abbreviations  . . . . . . . . . . . . . . .   4
   3.  Extensions for Summary FRR Signaling  . . . . . . . . . . . .   4   5
     3.1.  B-SFRR-Ready Extended ASSOCIATION Object  . . . . . . . .   6
       3.1.1.  IPv4 B-SFRR-Ready IPv4 Extended ASSOCIATION ID  . . .   6   7
       3.1.2.  IPv6 B-SFRR-Ready IPv6 Extended ASSOCIATION ID  . . .   7   8
     3.2.  B-SFRR-Active Extended ASSOCIATION Object . . . . . . . .  10  11
       3.2.1.  IPv4 B-SFRR-Active Extended ASSOCIATION ID  . . . . .  11  12
       3.2.2.  IPv6 B-SFRR-Active Extended ASSOCIATION ID  . . . . .  12  13
     3.3.  Signaling Procedures Prior to Failure . . . . . . . . . .  13  14
       3.3.1.  PLR Signaling Procedure . . . . . . . . . . . . . . .  14  15
       3.3.2.  MP Signaling Procedure  . . . . . . . . . . . . . . .  14  15
     3.4.  Signaling Procedures Post Failure . . . . . . . . . . . .  15  16
       3.4.1.  PLR Signaling Procedure . . . . . . . . . . . . . . .  15  16
       3.4.2.  MP Signaling Procedure  . . . . . . . . . . . . . . .  16  17
     3.5.  Refreshing Summary FRR Active LSPs  . . . . . . . . . . .  17  18
   4.  Backwards Compatibility . . . . . . . . . . . . . . . . . . .  17  18
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  17  18
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  17  18
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  17  19
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  17  19
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  18  19
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  18  19
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  19  20
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  19  20

1.  Introduction

   The Fast Reroute (FRR) procedures defined in [RFC4090] describe the
   mechanisms for the Point of Local Repair (PLR) to reroute traffic and
   signaling of a protected RSVP-TE LSP onto the bypass tunnel in the
   event of a TE link or node failure.  Such signaling procedures are
   performed individually for each affected protected LSP.  This may
   eventually lead to control plane scalability and latency issues on
   the PLR and/or the MP Merge Point (MP) due to limited memory and CPU
   processing resources.  This condition is exacerbated when the failure
   affects a large number of protected LSPs that traverse the same PLR
   and Merge
   Point (MP) MP nodes.

   For example, in a large scale large-scale RSVP-TE LSPs deployment, a single LSR
   acting as a PLR node may host tens of thousands of protected RSVP-TE
   LSPs egressing the same link, and also act as a an MP node for a
   similar number of LSPs that ingress on the same link.  In the event
   of the failure of the link or neighbor node, the RSVP-TE control
   plane of the node when acting as a PLR becomes busy rerouting
   protected LSPs signaling over the bypass tunnel(s) in one direction,
   and when acting as an MP node becomes busy merging RSVP states from
   signaling received over bypass tunnels for LSP(s) in the reverse
   direction.  Subsequently, the head-end LER(s) that are notified of
   the local repair at downstream LSR will attempt to (re)converge the
   affected RSVP-TE LSPs onto newly computed paths - possibly traversing
   the same previously affected LSR(s).  As a result, the RSVP-TE
   control plane at the PLR and MP becomes overwhelmed by the amount of
   FRR RSVP-TE processing overhead following the link or node failure,
   and due to other control plane protocol(s) (e.g. the IGP) that
   undergo convergence on the same node at the same time too.

   Today, each protected RSVP-TE LSP is signaled individually over the
   bypass tunnel after FRR.  The changes introduced in this document
   allow the PLR to assign multiple protected LSPs to a bypass tunnel
   group and to communicate this assignment to the MP, such that upon
   failure, the signaling over the bypass tunnel happens on bypass
   tunnel group(s).  New extensions are defined in this document to
   update the procedures defined in [RFC4090] for facility backup
   protection to enable a the MP node to become aware of the PLR node's
   bypass tunnel assignment group group(s) and to allow the FRR procedures between
   the PLR node and the MP node nodes to be signaled and processed on groups of protected LSPs. per bypass
   tunnel group(s).

   As defined in [RFC2961], Summary Refresh procedures use MESSAGE_ID to
   refresh the RSVP Path and Resv states to help with the scale. scaling.  The
   extensions defined
   Summary FRR procedures introduced in this document build on those
   concepts to allow the MESSAGE_ID information
   for the rerouted Path and Resv states MESSAGE_ID(s) to be exchanged between PLR on per bypass
   tunnel assignment group, and
   MP nodes a priori to the fault such that continue use Summary Refresh procedures
   can continue to be used to refresh
   while reducing the rerouted state(s) amount of messaging that occurs after FRR
   has occurred. rerouting
   signaling over the bypass tunnel post FRR.

2.  Conventions Used in This Document

2.1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.2.  Acronyms and Abbreviations

   The reader is assumed to be familiar with terms and abbreviations
   used in [RFC3209] and [RFC4090].

   The following abbreviations are also used in this document:

      LSR: Label Switching Router

      LER: Label Edge Router

      MPLS: Multiprotocol Label Switching

      LSP: Label Switched Path

      MP: Merge Point node as defined in [RFC4090]

      PLR: Point of Local Repair node as defined in [RFC4090]

      FRR: Fast Reroute as defined in [RFC4090]

      B-SFRR-Ready: Bypass Summary FRR Ready Extended ASSOCIATION
      object.  Added by the PLR for each LSP protected by the bypass
      tunnel.

      B-SFRR-Active: Bypass Summary FRR Active Extended ASSOCIATION
      object.  Used to notify the MP node of that one ore or more groups of
      protected LSP(s) that are being protected by have been rerouted over the specified associated bypass
      tunnel are being rerouted.
      tunnel.

      MTU: Maximum transmission unit.

3.  Extensions for Summary FRR Signaling

   The RSVP ASSOCIATION object is defined in [RFC4872] as a means to
   associate LSPs with each other.  For example, in the context of
   GMPLS-controlled LSP(s), the object is used to associate recovery
   LSPs with the LSP they are protecting.  The Extended ASSOCIATION
   object is introduced in [RFC6780] to expand on the possible usage of
   the ASSOCIATION object and generalize the definition of the Extended
   Association ID field.

   This document defines the use of the Extended ASSOCIATION object to
   carry the Summary FRR information and associate the protected LSP(s)
   with the bypass tunnel that protects them.  Two new Association Types
   for the Extended ASSOCIATION object, and new Extended Association IDs
   are proposed in this draft document to describe the Bypass Summary FRR
   Ready (B-SFRR-Ready) and the Bypass Summary FRR Active (B-SFRR-Active) (B-SFRR-
   Active) associations.

   The PLR creates and manages the Summary FRR LSP groups (identified by
   Bypass_Group_Identifiers) and shares the group identifier(s) with the
   MP via signaling.

   The PLR SHOULD assign the same Bypass_Group_Identifier to all
   protected LSPs that egress the same protected interface and are
   protected by the same bypass tunnel.  This minimizes the number of
   bypass tunnel SFRR groups, and optimizes the amount of signaling
   needed between the PLR and the MP after FRR.

   The PLR MUST ensure all protected LSP(s) that are assigned the same
   Bypass_Group_Identifier use the same modified tunnel sender address
   for the backup path identification after FRR as described in
   [RFC4090].

   The PLR SHOULD assign the same Bypass_Group_Identifier to all
   protected LSPs that share the egress link, and bypass tunnel as long
   as the protected LSP(s) have the common group attributes, including
   the modified tunnel sender address used for backup path
   identification as described in [RFC4090].

   The MP maintains the PLR group assignments learned via signaling, and
   acknowledges the group assignments via signaling.  Once the PLR
   receives the acknowledgment, FRR signaling can proceed as group
   based.

   The PLR node that supports Summary FRR procedures adds the an Extended
   ASSOCIATION object with Type B-SFRR-Ready and respective Extended Association ID in the
   RSVP Path message of the protected LSP to
   inform LSP.  The PLR adds the MP of protected
   LSP Bypass_Group_Identifier, information from the PLR's assigned bypass
   tunnel, Summary FRR
   Bypass_Group_Identifier, and the MESSAGE_ID that object into the PLR will use B-SFRR-Ready Extended
   Association ID.  The MP uses the information contained in the
   received B-SFRR-Ready Extended Association ID to refresh and merge
   the protected LSP Path state after FRR occurs.

   The MP node that supports Summary FRR procedures adds the B-SFRR-
   Ready Extended ASSOCIATION object and respective Extended Association
   ID in the RSVP Resv message of the protected LSP to acknowledge the
   PLR's bypass tunnel assignment, and provide the MESSAGE_ID object
   that the MP node will use to refresh the protected LSP Resv state
   after FRR occurs.

   This document also defines a new Association Type for the Extended
   ASSOCIATION object and new Extended Association ID to describe the B-
   SFRR-Active association.  The B-SFRR-Active Extended ASSOCIATION
   object and Extended Association ID are sent by the PLR after
   activating FRR procedures on the PLR.  The B-SFRR-Active Extended
   ASSOCIATION object and Extended Association ID are sent within the
   RSVP Path message of the bypass tunnel to inform the MP node that one
   or more groups of protected LSPs protected by the bypass tunnel are
   now being rerouted over the bypass tunnel.

3.1.  B-SFRR-Ready Extended ASSOCIATION Object

   The Extended ASSOCIATION object is populated using the rules defined
   below to associate a protected LSP with the bypass tunnel that is
   protecting it when Summary FRR procedures are enabled.

   The Association Type, Association ID, and Association Source MUST be
   set as defined in [RFC4872] for the ASSOCIATION Object.  More
   specifically:

   Association Source:

     The Association Source is set to an address of the PLR node.

   Association Type:

     A new Association Type is defined for B-SFRR-Ready as follows:

     Value      Type
     -------    ------
     (TBD-1)    Bypass Summary FRR Ready Association (B-SFRR-Ready)

   Extended ASSOCIATION ID for B-SFRR-Ready:

     The B-SFRR-Ready Extended ASSOCIATION ID is
     populated by the PLR for the Bypass Summary FRR Ready association.
     The rules to populate the Extended ASSOCIATION ID in this case are
     described below.

3.1.1.  IPv4 B-SFRR-Ready IPv4 Extended ASSOCIATION ID

   The IPv4 Extended ASSOCIATION ID for the B-SFRR-Ready association
   type has the following format:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Bypass_Tunnel_ID      |           Reserved            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                Bypass_Source_IPv4_Address                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                Bypass_Destination_IPv4_Address                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                Bypass_Group_Identifier                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                MESSAGE_ID                                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

        Figure 1: The IPv4 Extended ASSOCIATION ID for B-SFRR-Ready

     Bypass_Tunnel_ID: 16 bits

           The bypass tunnel identifier.

     Reserved: 16 bits

           Reserved for future use.

     Bypass_Source_IPv4_Address: 32 bits

           The bypass tunnel source IPV4 address.

     Bypass_Destination_IPv4_Address: 32 bits

           The bypass tunnel destination IPV4 address.

     Bypass_Group_Identifier: 32 bits

           The bypass tunnel group identifier.

     MESSAGE_ID

           A MESSAGE_ID object as defined by [RFC2961].

3.1.2.  IPv6 B-SFRR-Ready IPv6 Extended ASSOCIATION ID

   The IPv6 Extended ASSOCIATION ID field for the B-SFRR-Ready
   association type has the following format:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Bypass_Tunnel_ID      |           Reserved            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                                                               |
       +                Bypass_Source_IPv6_Address                     +
       |                                                               |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                                                               |
       +                Bypass_Destination_IPv6_Address                +
       |                                                               |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                Bypass_Group_Identifier                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                MESSAGE_ID                                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

        Figure 2: The IPv6 Extended ASSOCIATION ID for B-SFRR-Ready

     Bypass_Tunnel_ID: 16 bits

           The bypass tunnel identifier.

     Reserved: 16 bits

           Reserved for future use.

     Bypass_Source_IPv6_Address: 128 bits

           The bypass tunnel source IPV6 address.

     Bypass_Destination_IPv6_Address: 128 bits

           The bypass tunnel destination IPV6 address.

     Bypass_Group_Identifier: 32 bits

           The bypass tunnel group identifier.

     MESSAGE_ID

           A MESSAGE_ID object as defined by [RFC2961].

   The PLR assigns a bypass tunnel and Bypass_Group_Identifier for each
   protected LSP.  The same Bypass_Group_Identifier is used for the set
   of protected LSPs that share the same bypass tunnel, traverse the
   same egress link, link and are not already rerouted.  The PLR also
   generates MUST generate
   a MESSAGE_ID object (flags SHOULD be clear, with Epoch and Message_Identifier MUST be set according
   to [RFC2961]). [RFC2961].  The MESSAGE_ID object flags SHOULD be cleared when
   transmitted by the PLR and ignored when received at the MP.

   The PLR MUST generate a new Message_Identifier each time the contents
   of the B-SFRR-Ready Extended ASSOCIATION ID changes (e.g. when PLR
   node changes the bypass tunnel assignment).

   The PLR node notifies the MP node of the bypass tunnel assignment via
   adding a B-SFRR-Ready Extended ASSOCIATION object and Extended
   Association ID in the RSVP Path message for the protected LSP using
   procedures described in Section 3.4. 3.3.

   The MP node acknowledges the assignment to the PLR node by signaling
   the B-SFRR-Ready Extended ASSOCIATION object and Extended Association
   ID within the RSVP Resv message of the protected LSP.  With the
   exception of the MESSAGE_ID objects, all other fields of the received
   in the B-
   SFRR-Ready B-SFRR-Ready Extended ASSOCIATION ID in the RSVP Path message
   are copied into the B-SFRR-Ready Extended ASSOCIATION ID to be added
   in the Resv message.  The MESSAGE_ID object is set according to

   [RFC2961] with the Flags being clear.  A new Message_Identifier MUST
   be used to acknowledge an updated PLR assignment.

   The PLR considers the protected LSP as Summary FRR capable only if
   all the fields in the B-SFRR-Ready Extended ASSOCIATION ID that are
   sent in the RSVP Path message and match the ones fields received in the RSVP
   Resv message (with exception of the MESSAGE_ID) match. MESSAGE_ID).  If it does the fields do
   not match, or if B-SFRR-Ready Extended ASSOCIATION object is absent
   in a subsequent refresh, the PLR node MUST consider the protected LSP
   as not Summary FRR capable.

3.2.  B-SFRR-Active Extended ASSOCIATION Object

   The Extended ASSOCIATION object for B-SFRR-Active association type is
   populated by a PLR node to indicate to the MP node (bypass tunnel
   destination) that one or more groups of Summary FRR protected LSPs
   that are being protected by the bypass tunnel are being rerouted over
   the bypass tunnel.

   The B-SFRR-Active Extended ASSOCIATION object is carried in the RSVP
   Path message of the bypass tunnel and signaled downstream towards the
   MP (bypass tunnel destination).

   The Association Type, Association ID, and Association Source MUST be
   set as defined in [RFC4872] for the ASSOCIATION Object.  More
   specifically:

   Association Source:

     The Association Source is set to an address of the PLR node.

   Association Type:

     A new Association Type is defined for B-SFRR-Active as follows:

     Value      Type
     -------    ------
     (TBD-2)    Bypass Summary FRR Active Association (B-SFRR-Active)

   Extended ASSOCIATION ID for B-SFRR-Active:

     The B-SFRR-Active Extended ASSOCIATION ID is
     populated by the PLR for the Bypass Summary FRR Active association.
     The rules to populate the Extended ASSOCIATION ID in this case are
     described below.

3.2.1.  IPv4 B-SFRR-Active Extended ASSOCIATION ID

   The IPv4 Extended ASSOCIATION ID for the B-SFRR-Active association
   type is carried inside the IPv4 Extended ASSOCIATION object and has
   the following format:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Num-BGIDs          |          Reserved             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Bypass_Group_Identifier                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                               :                               |
      //                              :                              //
      |                               :                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Bypass_Group_Identifier                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      //                      RSVP_HOP_Object                        //
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      //                      TIME_VALUES                            //
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       IPv4 tunnel sender address              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 3: The IPv4 Extended ASSOCIATION ID for B-SFRR-Active

   Num-BGIDs: 16 bits

      Number of Bypass_Group_Identifier fields.

   Reserved: 16 bits

      Reserved for future use.

   Bypass_Group_Identifier: 32 bits

      The Bypass_Group_Identifier that is previously signaled by the PLR
      using the Extended Association object.  One or more
      Bypass_Group_Identifiers may MAY be included.

   RSVP_HOP_Object: Class 3, as defined by [RFC2205]

      Replacement RSVP HOP object to be applied to all LSPs associated
      with each of the following Bypass_Group_Identifiers.  This
      corresponds to C-Type = 1 for IPv4 RSVP HOP.

   TIME_VALUES object: Class 5, as defined by [RFC2205]

      Replacement TIME_VALUES object to be applied to all LSPs
      associated with each of the following Bypass_Group_Identifiers
      after receiving the B-SFRR-Active Extended ASSOCIATION Object.

   IPv4 tunnel sender address:

      The IPv4 address that the PLR sets to identify backup path(s) as
      described in Section 6.1.1 of [RFC4090].  This address is
      applicable to all groups identified by Bypass_Group_Identifier(s)
      carried in the B-SFRR-Active Extended ASSOCIATION ID.

3.2.2.  IPv6 B-SFRR-Active Extended ASSOCIATION ID

   The IPv6 Extended ASSOCIATION ID for the B-SFRR-Active association
   type is carried inside the IPv6 Extended ASSOCIATION object and has
   the following format:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Num-BGIDs          |          Reserved             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Bypass_Group_Identifier                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                               :                               |
      //                              :                              //
      |                               :                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Bypass_Group_Identifier                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      //                      RSVP_HOP_Object                        //
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      //                      TIME_VALUES                            //
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +                                                               +
      |                                                               |
      +                       IPv6 tunnel sender address              +
      |                                                               |
      +                                                               +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 4: The IPv6 Extended ASSOCIATION ID for B-SFRR-Active

   Num-BGIDs: 16 bits

      Number of Bypass_Group_Identifier fields.

   Reserved: 16 bits

      Reserved for future use.

   Bypass_Group_Identifier: 32 bits

      The Bypass_Group_Identifier that is previously signaled by the PLR
      using the Extended Association object.  One or more
      Bypass_Group_Identifiers may be included.

   RSVP_HOP_Object: Class 3, as defined by [RFC2205]

      Replacement RSVP HOP object to be applied to all LSPs associated
      with each of the following Bypass_Group_Identifiers.  This
      corresponds to C-Type = 2 for IPv6 RSVP HOP.

   TIME_VALUES object: Class 5, as defined by [RFC2205]

      Replacement TIME_VALUES object to be applied to all LSPs
      associated with each of the following Bypass_Group_Identifiers
      after receiving the B-SFRR-Active Extended ASSOCIATION Object.

   IPv6 tunnel sender address:

      The IPv6 address that the PLR sets to identify backup path(s) as
      described in Section 6.1.1 of [RFC4090].  This address is
      applicable to all groups identified by Bypass_Group_Identifier(s)
      carried in the B-SFRR-Active Extended ASSOCIATION ID.

3.3.  Signaling Procedures Prior to Failure

   Before Summary FRR procedures can be used, a handshake MUST be
   completed between the PLR and MP.  This handshake is performed using
   the Extended ASSOCIATION object that carries the B-SFRR-Ready
   Extended Association ID in both the RSVP Path and Resv messages of
   the protected LSP.

   The facility backup method introduced in [RFC4090] takes advantage of
   MPLS label stacking (PLR imposing additional MPLS label post FRR) to
   allow rerouting of protected traffic over backup path.  The backup
   path may have stricter MTU requirement and due to label stacking at
   PLR, the protected traffic may exceed the backup path MTU.  The
   operator is assumed to engineer their network to allow rerouting of
   protected traffic and the additional label stacking at PLR to not
   exceed the backup path MTU.

   When using procedures defined in this document, the PLR MUST ensure
   the bypass tunnel assignment can satisfy the protected LSP MTU
   requirements post FRR.  This avoids any packets from being dropped
   due to exceeding the MTU size of the bypass tunnel backup path after traffic is
   rerouted on to the bypass tunnel post the failure.

3.3.1.  PLR Signaling Procedure

   The B-SFRR-Ready Extended ASSOCIATION object is added by each PLR in
   the RSVP Path message of the protected LSP to record the bypass
   tunnel assignment.  This object is updated every time the PLR updates
   the bypass tunnel assignment and that triggers an RSVP Path change
   message.

   Upon receiving an RSVP Resv message with B-SFRR-Ready Extended
   ASSOCIATION object, the PLR node checks if the expected sub-objects
   from the B-SFRR-Ready Extended ASSOCIATION ID are present.  If
   present, the PLR determines if the MP has acknowledged the current
   PLR assignment.

   To be a valid acknowledgement, the received B-SFRR-Ready Extended
   ASSOCIATION ID contents within the RSVP Resv message of the protected
   LSP MUST match the latest B-SFRR-Ready Extended ASSOCIATION object
   and Association ID contents that the PLR node had sent within the
   RSVP Path message (with exception of the MESSAGE_ID).

   Note, when forwarding an RSVP Resv message upstream, the PLR node
   SHOULD remove any/all B-SFRR-Ready Extended ASSOCIATION objects whose
   Association Source matches the PLR node address.

3.3.2.  MP Signaling Procedure

   Upon receiving an RSVP Path message with a B-SFRR-Ready Extended
   ASSOCIATION object, the MP node processes all (there may be multiple
   PLRs for a single MP) B-SFRR-Ready Extended ASSOCIATION objects that
   have the MP node address as Bypass Destination address in the
   Extended Association ID.

   The MP node first ensures the existence of the bypass tunnel and that
   the Bypass_Group_Identifier is not already FRR active.  That is, an
   LSP cannot join a group that is already FRR rerouted.

   The MP node builds a mirrored Summary FRR Group database per PLR,
   which is determined using the Bypass_Source_Address field.  The
   MESSAGE_ID is extracted and recorded for the protected LSP Path
   state.  The MP node signals a B-SFRR-Ready Extended Association
   object and Extended Association ID in the RSVP Resv message of the
   protected LSP.  With the exception of the MESSAGE_ID objects, all
   other fields of the received B-SFRR-Ready Extended ASSOCIATION object
   in the RSVP Path message are copied into the B-SFRR-Ready Extended
   ASSOCIATION object to be added in the Resv message.  The MESSAGE_ID
   object is set according to [RFC2961] with the Flags being clear.

   Note, an MP may receive more than one RSVP Path message with the B-
   SFRR-Ready Extended ASSOCIATION object from different upstream PLR
   node(s).  In this case, the MP node is expected to save all the
   received MESSAGE_IDs from the different upstream PLR node(s).  After
   a failure, the MP node determines and activates the associated
   Summary Refresh ID to use once it receives and processes the RSVP
   Path message containing B-SFRR-Active Extended ASSOCIATION object
   that is signaled over the bypass tunnel from the PLR, as described
   Section 3.4

   When forwarding an RSVP Path message downstream, the MP SHOULD remove
   any/all B-SFRR-Ready Extended ASSOCIATION object(s) whose Association
   ID contains Bypass_Destination_Address matching the MP node address.

3.4.  Signaling Procedures Post Failure

   Upon detection of the fault (egress link or node failure) the PLR
   first performs the object modification procedures described by
   Section 6.4.3 of [RFC4090] for all affected protected LSPs.  For the
   Summary FRR capable LSPs that are assigned to the same bypass tunnel
   a common RSVP_HOP and SENDER_TEMPLATE MUST be used.

   The PLR MUST signal non-Summary FRR capable LSPs over the bypass
   tunnel before signaling the Summary FRR capable LSPs.  This is needed
   to allow for the case when where the PLR node has recently changed a bypass
   assignment and the MP has not processed the change yet.

   The B-SFRR-Active Extended ASSOCIATION object is sent within the RSVP
   Path message of the bypass tunnel to reroute RSVP state of Summary
   FRR capable LSPs.

3.4.1.  PLR Signaling Procedure

   After a failure event, when using the Summary FRR path signaling
   procedures, an individual RSVP Path message is not signaled for each
   Summary FRR LSP.  Instead, to reroute Summary FRR LSPs via the bypass
   tunnel, the PLR adds the B-SFRR-Active Extended Association object in
   the RSVP Path message of the RSVP session of the bypass tunnel.

   The RSVP_HOP_Object field in the B-SFRR-Active Extended ASSOCIATION
   ID is set to the common RSVP_HOP that was used by the PLR in
   Section 3.4 3.3 of this document.

   The previously received MESSAGE_ID from the MP is activated.  As a
   result, the MP may refresh the protected rerouted Resv state using
   Summary Refresh procedures.

   The PLR adds the Bypass_Group_Identifier(s) of group(s) that have
   common group attributes, including the tunnel sender address, to the
   same B-SFRR-Active Extended ASSOCIATION ID.  Note that multiple
   ASSOCIATION objects, each carrying a B-SFRR-Active Extended
   ASSOCIATION ID, can be carried within a single RSVP Path message of
   the bypass tunnel and sent towards the MP as described in [RFC6780].

3.4.2.  MP Signaling Procedure

   Upon receiving an RSVP Path message with a B-SFRR-Active Extended
   Association object, the MP performs normal merge point processing for
   each protected LSP associated with each Bypass_Group_Identifier, as
   if it received an individual RSVP Path messages for that LSP.

   For each Summary FRR capable LSP that is being merged, the MP first
   modifies the Path state as follows:

   1.  The RSVP_HOP object is copied from the B-SFRR-Active Extended
       ASSOCIATION ID.

   2.  The TIME_VALUES object is copied from the TIMES_VALUE field in
       the B-SFRR-Active Extended ASSOCIATION ID.  The TIME_VALUES
       object contains the refresh time of the PLR to generate refreshes
       and that would have exchanged in a Path message sent to the MP
       after the failure when no Summary FRR procedures are in effect.

   3.  The tunnel sender address field in the SENDER_TEMPLATE object is
       copied from the tunnel sender address of the B-SFRR-Active
       Extended ASSOCIATION ID.

   4.  The ERO object is modified as per Section 6.4.4 of [RFC4090].
       Once the above modifications are completed, the MP node performs
       the merge processing as per [RFC4090].

   5.  The previously received MESSAGE_ID from the PLR is activated,
       meaning that the PLR may now refresh the protected rerouted Path
       state using Summary Refresh procedures.

   A failure during merge processing of any individual rerouted LSP MUST
   result in an RSVP Path Error message.

   An individual RSVP Resv message for each successfully merged Summary
   FRR LSP is not signaled.  The MP node SHOULD immediately use Summary
   Refresh procedures to refresh the protected LSP Resv state.

3.5.  Refreshing Summary FRR Active LSPs

   Refreshing of Summary FRR active LSPs is performed using Summary
   Refresh as defined by [RFC2961].

4.  Backwards Compatibility

   The (Extended) ASSOCIATION object is defined in [RFC4872] with a
   class number in the form 11bbbbbb, which ensures compatibility with
   non-supporting node(s).  Such nodes will ignore the object and
   forward it without modification.

5.  Security Considerations

   This document updates an existing RSVP object.  Thus, in the event of
   the interception of a signaling message, slightly more information
   could be deduced about the state of the network than was previously
   the case.

   When using procedures defined in this document, FRR (or the reroute
   of protected LSP(s) on to the bypass tunnel) can be activated on per
   group of protected LSP(s).  This allows an intruder to potentially
   impact and manipulate a set of protected LSP that are assigned to the
   same bypass tunnel group.

   Existing mechanisms for maintaining the integrity and authenticity of
   RSVP protocol messages [RFC2747] can be applied.  Other
   considerations mentioned in [RFC4090] and [RFC5920] also apply.

6.  IANA Considerations

   IANA maintains the "Generalized Multi-Protocol Label Switching
   (GMPLS) Signaling Parameters" registry.  The "Association Type" sub-
   registry is included in this registry.

   This registry has been updated by new Association Type for Extended
   ASSOCIATION Object defined in this document as follows:

      Value  Name                         Reference
      -----  ----                         ---------
      TBD-1  B-SFRR-Ready Association     Section 3.1
      TBD-2  B-SFRR-Active Association    Section 3.2

7.  Acknowledgments

   The authors would like to thank Alexander Okonnikov, Loa Andersson,
   Lou Berger, Eric Osborne, Gregory Mirsky, Mach Chen for reviewing and
   providing valuable comments to this document.

8.  Contributors

      Nicholas Tan
      Arista Networks

      Email: ntan@arista.com

9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC2205]  Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
              Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
              Functional Specification", RFC 2205, DOI 10.17487/RFC2205,
              September 1997, <https://www.rfc-editor.org/info/rfc2205>.

   [RFC2747]  Baker, F., Lindell, B., and M. Talwar, "RSVP Cryptographic
              Authentication", RFC 2747, DOI 10.17487/RFC2747, January
              2000, <https://www.rfc-editor.org/info/rfc2747>.

   [RFC2961]  Berger, L., Gan, D., Swallow, G., Pan, P., Tommasi, F.,
              and S. Molendini, "RSVP Refresh Overhead Reduction
              Extensions", RFC 2961, DOI 10.17487/RFC2961, April 2001,
              <https://www.rfc-editor.org/info/rfc2961>.

   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
              <https://www.rfc-editor.org/info/rfc3209>.

   [RFC4090]  Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast
              Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
              DOI 10.17487/RFC4090, May 2005,
              <https://www.rfc-editor.org/info/rfc4090>.

   [RFC4872]  Lang, J., Ed., Rekhter, Y., Ed., and D. Papadimitriou,
              Ed., "RSVP-TE Extensions in Support of End-to-End
              Generalized Multi-Protocol Label Switching (GMPLS)
              Recovery", RFC 4872, DOI 10.17487/RFC4872, May 2007,
              <https://www.rfc-editor.org/info/rfc4872>.

   [RFC6780]  Berger, L., Le Faucheur, F., and A. Narayanan, "RSVP
              ASSOCIATION Object Extensions", RFC 6780,
              DOI 10.17487/RFC6780, October 2012,
              <https://www.rfc-editor.org/info/rfc6780>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

9.2.  Informative References

   [RFC5920]  Fang, L., Ed., "Security Framework for MPLS and GMPLS
              Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010,
              <https://www.rfc-editor.org/info/rfc5920>.

Authors' Addresses

   Mike Taillon
   Cisco Systems, Inc.

   Email: mtaillon@cisco.com

   Tarek Saad (editor)
   Juniper Networks

   Email: tsaad@juniper.net

   Rakesh Gandhi
   Cisco Systems, Inc.

   Email: rgandhi@cisco.com

   Abhishek Deshmukh
   Juniper Networks

   Email: adeshmukh@juniper.net
   Markus Jork
   128 Technology

   Email: mjork@128technology.com

   Vishnu Pavan Beeram
   Juniper Networks

   Email: vbeeram@juniper.net