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Versions: 00 01 02 03                                                   
Network Working Group                                    H. Bidgoli, Ed.
Internet-Draft                                                     Nokia
Intended status: Standards Track                                V. Voyer
Expires: May 3, 2021                                         Bell Canada
                                                         S. Rajarathinam
                                                                   Nokia
                                                              E. Hemmati
                                                            Cisco System
                                                                 T. Saad
                                                        Juniper Networks
                                                            S. Sivabalan
                                                                   Ciena
                                                        October 30, 2020


                   PCEP extensions for p2mp sr policy
                    draft-hsd-pce-sr-p2mp-policy-02

Abstract

   SR P2MP policies are set of policies that enable architecture for
   P2MP service delivery.  This document specifies extensions to the
   Path Computation Element Communication Protocol (PCEP) that allow a
   stateful PCE to compute and initiate P2MP paths from a Root to a set
   of Leaves.

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 May 3, 2021.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   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
   3.  Overview of PCEP Opration in SR P2MP Network  . . . . . . . .   4
     3.1.  High level view of P2MP Policy Objects  . . . . . . . . .   5
       3.1.1.  Shared Tree vs Non-Shared Replication Segment . . . .   6
     3.2.  existing drafts used for defining a P2MP Policy . . . . .   7
       3.2.1.  Existing drafts/rfcs used by this draft . . . . . . .   7
       3.2.2.  P2MP Policy Identification  . . . . . . . . . . . . .   8
       3.2.3.  Replication Segment Identificaton . . . . . . . . . .   9
     3.3.  High Level Procedures for P2MP SR LSP Instantiation . . .   9
       3.3.1.  PCE-Init Procedure  . . . . . . . . . . . . . . . . .   9
       3.3.2.  PCC-Init Procedure  . . . . . . . . . . . . . . . . .  10
       3.3.3.  Comon Procedure . . . . . . . . . . . . . . . . . . .  10
       3.3.4.  Global Optimiation of the Candidate Path  . . . . . .  12
       3.3.5.  Fast Reroute  . . . . . . . . . . . . . . . . . . . .  12
       3.3.6.  Connecting Replication Segment via Segment List . . .  13
     3.4.  SR P2MP Policy and Replication Segment TLVs and Objects .  14
       3.4.1.  SR P2MP Policy Objects  . . . . . . . . . . . . . . .  14
       3.4.2.  Replication Segment Objects . . . . . . . . . . . . .  14
       3.4.3.  P2MP Policy vs Replication Segment  . . . . . . . . .  15
       3.4.4.  P2MP Policy and Replication Segment general
               considerations  . . . . . . . . . . . . . . . . . . .  15
   4.  Object Format . . . . . . . . . . . . . . . . . . . . . . . .  15
     4.1.  Open Message and Capablity Exchange . . . . . . . . . . .  16
     4.2.  Symbolic Name in PCInit Message from PCC  . . . . . . . .  17
     4.3.  P2MP Policy Specific Objects and TLVs . . . . . . . . . .  17
       4.3.1.  P2MP Policy Association Group for P2MP Policy . . . .  17
         4.3.1.1.  P2MP SR Policy Association Group Policy
                   Identifiers TLV . . . . . . . . . . . . . . . . .  17
         4.3.1.2.  P2MP SR Policy Association Group Candidate Path
                   Identifiers TLV . . . . . . . . . . . . . . . . .  18
         4.3.1.3.  P2MP SR Policy Association Group Candidate Path
                   Attributes TLV  . . . . . . . . . . . . . . . . .  19
       4.3.2.  P2MP-END-POINTS Object  . . . . . . . . . . . . . . .  19
     4.4.  P2MP Policy and Replication Segment Identifier Object and
           TLV . . . . . . . . . . . . . . . . . . . . . . . . . . .  21



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       4.4.1.  Extension of the LSP Object, SR-P2MP-LSPID-TLV  . . .  21
     4.5.  Replication Segment . . . . . . . . . . . . . . . . . . .  22
       4.5.1.  The format of the replication segment message . . . .  23
       4.5.2.  Label action rules in replicating segment . . . . . .  23
       4.5.3.  SR-ERO Rules  . . . . . . . . . . . . . . . . . . . .  24
         4.5.3.1.  SR-ERO subobject changes  . . . . . . . . . . . .  24
   5.  Examples of PCEP messages between PCE and PCEP  . . . . . . .  25
     5.1.  PCE Initiate  . . . . . . . . . . . . . . . . . . . . . .  25
     5.2.  PCC Initiate or PCE Initiate Respond  . . . . . . . . . .  27
     5.3.  PCE P2MP Path-Instance Calculation and Replication
           Segment download  . . . . . . . . . . . . . . . . . . . .  28
     5.4.  PCC Rpt for PCE Update and Init Messages  . . . . . . . .  36
   6.  Tree Deletion . . . . . . . . . . . . . . . . . . . . . . . .  37
   7.  Fragmentation . . . . . . . . . . . . . . . . . . . . . . . .  38
   8.  Example Workflows . . . . . . . . . . . . . . . . . . . . . .  38
   9.  IANA Consideration  . . . . . . . . . . . . . . . . . . . . .  38
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  38
   11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  38
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  38
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  38
     12.2.  Informative References . . . . . . . . . . . . . . . . .  39
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  40

1.  Introduction

   The draft [draft-ietf-pim-sr-p2mp-policy] defines a variant of the SR
   Policy [draft-ietf-spring-segment-routing-policy] for constructing a
   P2MP segment to support multicast service delivery.

   A Point-to-Multipoint (P2MP) Policy connects a Root node to a set of
   Leaf nodes, optionally through a set of intermediate replication
   nodes.  We also define a Replication segment
   [draft-ietf-spring-sr-replication-segment], which corresponds to the
   state of a P2MP segment on a particular node, as an example the
   forwarding instructions for the replication SID.

   A P2MP Policy is relevant on the root of the P2MP Tree and it
   contains candidate paths.  The candidate paths are made of path-
   instances and each path-instance is constructed via replication
   segments.  These replication segments are programmed on the root,
   leaves and optionally intermediate replication nodes.

   It should be noted that two replication segments can be connected
   directly, or they can be connected or steered via unicast SR segment
   or a segment list.

   For a P2MP Tree, a controller may be used to compute paths from a
   Root node to a set of Leaf nodes, optionally via a set of replication



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   nodes.  A packet is replicated at the root node and optionally on
   Replication nodes towards each Leaf node.

   We define two types of a P2MP Tree: Spray and Replication.

   A Point-to-Multipoint service delivery could be via Ingress
   Replication (aka Spray in some SR context), i.e., the root unicast
   individual copies of traffic to each leaf.  The corresponding P2MP
   Policy consists of replication segments only for the root and the
   leaves and they are connected via a unicast SR Segment.

   A Point-to-Multipoint service delivery could also be via Downstream
   Replication (aka TreeSID in some SR context), i.e., the root and some
   downstream replication nodes replicate the traffic along the way as
   it traverses closer to the leaves.

   The leaves and the root can be explicitly configured on the PCE or
   PCC can update the PCE with the information of the discovered root
   and leaves.  As an example Multicast protocols like mvpn procedures
   [RFC6513] or pim can be used to discovery the leaves and roots on the
   PCC and update the PCE with these relevant information.  The
   controller can calculate the P2MP Policy based on these info.

   In all of above cases a set of new PCEP object and TLVs are needed to
   update and instantiate the P2MP tree.  This draft explains the
   procedure needed to instantiate a P2MP TreeSID.

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 [RFC2119].

3.  Overview of PCEP Opration in SR P2MP Network

   After discovering the root and the leaves on the PCE (via different
   mechanism mentioned in previous sections) computes the P2MP Tree and
   identifying the relevant Replication routers, the PCE programs the
   PCCs with relevant information needed to create a P2MP Tree.

   As per draft [draft-ietf-pim-sr-p2mp-policy] a P2MP Policy is defined
   by Root-ID, Tree-ID and a set of leaves.  A P2MP policy is a variant
   of SR policy as such it uses the same concept as draft
   [draft-ietf-pce-segment-routing-policy-cp].  In short a P2MP policy
   uses a collection of SR P2MP Candidate paths.  Candidate paths are
   computed by the PCE and can be used for P2MP Tree redundancy, only a
   single candidate path is active at each time.  Each candidate paths
   can be globally optimized and is consists of multiple path-instances.



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   A path-instance can be thought of as a P2MP LSP.  If a candidate path
   needs to be globally optimized two path-instances can be programmed
   on the root node and via make before procedures the candidate path
   can be switched from path-instance 1 to the 2nd path-instance.  The
   forwarding states of these path-instances are build via replication
   segments, in short each path-instance initiated on the root has its
   own set of replication segments on the Root, Transit and Leaf nodes.

   A replication segment is set of forwarding instructions on a specific
   node.  As an example the push information on the Root node or swap
   and outgoing interface information on the transit nodes or pop
   information on the bud and leaves nodes.

   PCE could also calculate and download additional information for the
   replication segments, such as protections next-hops for link
   protection (FRR).

3.1.  High level view of P2MP Policy Objects

   o  SR P2MP Policy

      *  Is only relevant on the Root of the P2MP path and is a policy
         on PCE which contains information about:

         +  Root node of the P2MP Segment

         +  Leaf nodes of the P2MP Segment

         +  Tree-ID, which is a unique identifier of the P2MP tree on
            the Root

         +  It also contains a set of Candidate paths and their path-
            instances for P2MP tree redundancy and global optimization

         +  Optional Constrains used to build these candidate paths

         +  P2MP policy information is downloaded only on the Root node
            and is identified via <Root-ID, Tree-ID>

   o  Candidate Path:

      *  Is used for P2MP Tree redundancy where the candidate path with
         the highest preference is the active path.

      *  It can contain up to two path-instance for global optimization
         procedures (i.e. make before break), each identified with their
         own path-instance ID




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      *  Contains information about protocol-id, originator,
         discriminator, preference, path-instances

   o  Replication Segment:

      *  Is the forwarding information needed on each node for building
         the forwarding path for each path-instance of the P2MP
         Candidate path.

      *  As it will be explained in upcoming sections there are 2 ways
         to identify the replication segment, shared and non-shared

         +  It is identified via Tree-ID and Root-ID and path-instance
            for non-shared replication segment.

         +  It is identified via Node-ID, Replication-ID, for shared
            replication segment

         +  Contains forwarding instructions for the path-instances

         +  On the forwarding plane the Replication Segment is
            identified via the incoming Replication SID.

         +  Replication segment information is downloaded on Root,
            Transit and Leaf nodes respectively.

3.1.1.  Shared Tree vs Non-Shared Replication Segment

   A non-shared Replication Segment is used when the label field of the
   PMSI Tunnel Attribute (PTA) is set to zero as per
   [draft-parekh-bess-mvpn-sr-p2mp].  In short this is used when there
   is no upstream assigned label in the PTA (provider tunnel attribute)
   and aggregate of MVPNs into a single P-Tunnel is not desired.

   On other hand shared Replication Segment is used when the label field
   of the PTA is not set to Zero and there is an upstream assigned label
   in the PTA.  In this case multiple MVPNs (VRFs) can be aggregate into
   a single Provider Tunnel and the upstream assigned label
   distinguishes the MVPNs context.

   It should be noted that the shared Replication Segment can also be
   used to build a bypass tunnel for the purpose of FRR.  This might be
   desirable if the bypass tunnel is build via the PCE and downloaded to
   the PCC for link protection.  In this case multiple non-shared
   Replication Segments can use the shared replication segment as their
   bypass tunnel for link protection.  This replication segments used in
   this bypass tunnel should only create a unicast bypass tunnel to




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   protect the link between two replication segments on the primary
   path.

3.2.  existing drafts used for defining a P2MP Policy

   P2MP Policy reuses current drafts and PCEP objects to update the PCE
   with Root and Leaves information when PCC Initiated method is used.
   Also current drafts are used as much as possible to update the PCC
   with relevant information to build the P2MP Policy and its
   Replication Segments.

   In addition this draft will introduced new TLVs and Objects specific
   to a programing P2MP policy and its replication segment.

3.2.1.  Existing drafts/rfcs used by this draft

   o  [RFC8231] The bases for a stateful PCE, and reuses the following
      objects or a variant of them

      *  <SRP Object>

      *  <LSP Object>

      *  A variation of the LSP identifier TLV is defined in this draft,
         to support P2MP LSP Identifier

   o  [RFC8236] P2MP capabilities advertisement

   o  [draft-ietf-pce-segment-routing-policy-cp] Candidate paths for
      P2MP Policy is used for Tree Redundancy.  As an example a P2MP
      Policy can have multiple candidate paths.  Each protecting the
      primary candidate path.  The active path is chosen via the
      preference of the candidate path.

   o  [RFC3209] Defines the instance-ID, instance-ID is used for global
      optimization of a candidate path with in a P2MP policy.  Each
      Candidate path can have 2 path-instances.  These path-instances
      are equivalent to sub-lsps (instance-IDs).  There are used for MBB
      and global optimization procedures.  instance-ID is equivalent to
      LSP ID

   o  [draft-ietf-spring-segment-routing-policy] Segment-list, used for
      connecting two non-adjacent replication policy via a unicast
      binding SID or Segment-list.

   o  [RFC8306] P2MP End Point objects, used for the PCC to update the
      PCE with discovered Leaves.




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   o  [draft-sivabalan-pce-binding-label-sid] Section 3; Path binding
      TLV is used to indicate the incoming replication SID

   o  [draft-koldychev-pce-multipath] Forwarding instruction for a P2MP
      LSP is defined by a set of SR-ERO sub-objects in the ERO object,
      ERO-ATTRIBUTES object and MULTIPATH-BACKUP TLV as defined in this
      draft.

   o  [RFC8664] SR-ERO Sub Object used in the multipath.

   It should be noted that the [draft-dhs-spring-sr-p2mp-policy-yang]
   can provide further details of the high level P2MP Policy Model.

3.2.2.  P2MP Policy Identification

   A P2MP Policy and its candidate path can be identified on the root
   via the P2MP LSP Object.  This Object is a variation of the LSP ID
   Object defined in [RFC8231] and is as follow:

   o  PLSP-ID: [RFC8231], is assigned by PCC and is unique per candidate
      path.  It is constant for the lifetime of a PCEP session.  Stand-
      by candidate paths will be assigned a new PLSP-ID by PCC.  Stand-
      by candidate paths can co-exist with the active candidate path.

      *  Note: Every candidate path in the SR-P2MP Policy is unique with
         its own unique PLSP-ID and Instance-ID.  But the same Tree-ID
         is used for all candidate paths as they are part of the same
         P2MP Tree.

   o  Root-ID: is equivalent to the first node on the P2MP path, as per
      [RFC3209], Section 4.6.2.1

   o  Tree-ID: is equivalent to Tunnel Identifier color which identifies
      a unique P2MP Policy at a ROOT and is advertised via the PTA in
      the BGP AD route or can be assigned manually on the root.  Tree-ID
      needs to be unique on the root.

   o  Instance-ID: LSP ID Identifier as defined in RFC 3209, is the
      path-instance identifier and is assigned by the PCC.  As it was
      mentioned the candidate path can have up to two path-instance for
      global optimization.  Note that the Root-ID, Tree-ID and Instance-
      ID are part of a new SR- P2MP-LSP-IDENTIFIER TLV which will be
      identified in this draft.

      *  Note: each Path-instance on the Root node is assigned a unique
         Instance-ID





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3.2.3.  Replication Segment Identificaton

   The key to identify a replication segment is also a P2MP LSP Object.
   That said there are different rules for coding the SR-P2MP-LSP-
   IDENTIFIER TLV which will be explained in later sections.  In short
   for replication segment the P2MP LSP Object does not have the
   association object.

3.3.  High Level Procedures for P2MP SR LSP Instantiation

   A P2MP policy can be instantiated via the PCC or the PCE depending on
   how the root and the leaves are discovered.  In theory there is two
   way to discover the root and the leaves:

   o  They can be configured and identified on the controller, PCE
      initiated.

   o  They can be discovered on the PCC via MVPN procedures [RFC6513] or
      legacy multicast protocols like PIM or IGMP etc... PCC initiated.

3.3.1.  PCE-Init Procedure

   o  PCE is informed of the P2MP request through it's API or
      configuration mechanism to instantiate a P2MP tunnel.

   o  PCE will initiate the P2MP Policy for the request, by sending a
      PCInitiate message to the Root.  This PCInitiation message will
      have the association object to identify the Candidate Path

      *  Optionally the EROs can be added to the PCInitiate message to
         construct the replication segment on the root.

   o  Root in response to the PCInitiate message.  It will generate
      PLSP-ID for the candidate paths and an Instance-ID for the Path-
      Instance (LSP-ID) contained with in a candidate path.  The tree-id
      for the P2MP Policy is also filled.  PCC will reports back the
      PLSP-ID, Instance-ID and tree-id via PCRpt message

      *  Optionally, the Root can add any additional leaves that were
         discovered by multicast procedures in this PCRpt message.

   o  PCE based on any update to the configured leaves or if any new
      discovered leaves, can re-compute the P2MP Policy and its
      replication segments from the Root to the leaves.

      *  Any new EROs are send via PCInitiate message, without the
         association object




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      *  Any update to the existing EROs are send via PCUpd message,
         without the association object

   o  PCE will also sends a PCInitiate message to the Transit and the
      leaves for the Replication Segment.

3.3.2.  PCC-Init Procedure

   After Root (PCC) discovers the leaves (as an example via MVPN
   Procedures or other mechanism), the following communication happens
   between the PCE and PCCs

   o  Root sends a PCRpt message for P2MP policy to PCE including the
      Root-ID, Tree-ID, PLSP-ID, Instance-ID, symbolic-path-name, and
      any leaves discovered until then.

   o  PCE on receiving of this report, will compute the P2MP Policy and
      its replication segments.

      *  The PCE will send a PCUpd message to Root for P2MP policy with
         the Tree-ID, PLSP-ID and the Instance-ID assigned by the PCC.
         It should be noted the replication segment for root is also
         downloaded via this update message.  In short a single update
         message that includes the association object will create the
         P2MP Policy and its replication segment on the Root

         +  Note: in this scenario no PCInitiate message was send from
            the PCE to the PCC to instantiate the P2MP Policy and its
            Replication segment.  This is because for an PCInitiate
            message a brand new PLSP-ID and Instance-ID is assigned by
            PCC which is undesirable, since they are already assigned on
            the first step of this procedure.

      *  PCE will also sends a PCInitiate message to the Transit and the
         leaves for the Replication Segment.

3.3.3.  Comon Procedure

   Beyond this, the following procedures are the same for PCE or PCC
   Init.

   o  PCE will download the replication segments for the Candidate-
      path's path-instances to all the leaves and transit nodes using
      PCInitiate message with PLSP-ID = 0, Instance-ID =0, symbolic path
      name, Root-address, Tree-id(assigned by the root).  This
      PCInitiate message includes the EROs needed for the replication
      segments.




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   o  Any new candidate path for the P2MP Policy is downloaded by PCE to
      its connected Root by sending a PCInitiate message

      *  it should be noted, PLSP-ID, Path-Instance ID and the Tree-ID
         are generated by the PCC for these new candidate paths and
         their Path-instances

      *  The ERO objects can be included in this Initiate message

      *  The PCC will reply with a PCRpt message

      *  Any update to the Candidate Paths or Replication Segments is
         done via the PCUpd message.  Association object need to be
         present for Candidate Path updates.

   o  The PCE will also download the necessary replication segment for
      the candidate path and its path-instances to the leaves and the
      transit nodes via a PCInit message

   o  New leaves can be discovered via Multicast procedures, and new
      replication segments can be instantiated or existing one updated
      to reach these leaves

      *  If these leaves reside on routers that are part of the P2MP LSP
         path, then PCUpd is sent from PCE to necessary PCCs (LEAVES,
         TRANSIT or ROOT) with the correct PLSP-ID, Instance-ID and
         Tree-ID

      *  If the new leaves are residing on routers that are not part of
         the P2MP Tree yet, then a PCInitiate message is sent down with
         PLSP- ID=0 and Instance-ID=0 on the corresponding routers.

   o  The active candidate-path is indicated by the PCC through the
      operational bits(Up/Active) of the LSP object in the PCRpt
      message.  If a candidate path needs to be removed, PCE sends PC
      Initiate message, setting the R-flag in the LSP object and R bit
      in the SRP-object.

   o  To remove the entire P2MP-LSP, PCE needs to send PC Initiate
      remove messages for every candidate path of the P2MP POLICY to all
      the PCCs on the P2MP Tree.  The R bit in the LSP Object as defined
      in [RFC8231], refers to the removal of the LSP as identified by
      the SR-P2MP-POLICY-ID-TLV (defined in this document).  An all zero
      (SR-P2MP-LSP-ID-TLV defines to remove all the state of the
      corresponding PLSP-ID.

   o  A candidate path is made active based on the preference of the
      path.  If the Root is programed with multiple candidate paths from



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      different sources, as an example PCE and CLI, based on its tie-
      breaking rules, if it selects the CLI path, it will send a report
      to PCE for the PCE path indicating the status of label-download
      and sets operational bit of the LSP object to UP and Not Active .
      At any instance, only one path will be active

3.3.4.  Global Optimiation of the Candidate Path

   When a P2MP LSP needs to be optimized for any reason (i.e. it is
   taking a FRR tunnel or new routers are added to the network) a global
   optimization of the candidate path is possible.

   Each Candidate Path can contain two Path-Instances.  The current
   unoptimized Path-Instance is the active instance and its replication
   segments are forwarding the multicast PDUs from the root to the
   leaves.  How ever the second optimized Path-Instance will be setup
   with its own unique replication segments throughout the network, from
   the Root to the leaves.  These two Path-Instances can co-exist.  The
   two Path-Instances are uniquely identified by their Instance-ID in
   the SR-P2MP-POLICY-ID-TLV (defined in this document).  After the
   optimized LSP has been downloaded successfully PCC MUST send two
   reports, reporting UP of the new path indicating the new LSP-ID, and
   a second reporting the tear down of the old path with the R bit of
   the LSP Object SET with the old Instance-ID in the SR-P2MP-POLICY-ID-
   TLV.  This MBB procedure will move the multicast PDUs to the
   optimized Path-Instance.

   The leaf should be able to accept traffic from both Path-Instances to
   minimize the traffic outage by the Make Before Break process.

3.3.5.  Fast Reroute

   Currently this draft identifies the Facility FRR procedures.  In
   addition, only LINK Protection procedures are defined.  How the
   Facility Path is built and instantiated is beyond the scope of this
   document.















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            R
            | |
             T
             |
            ---
           |   |
           L1 L2

           Figure 1



             R---F1
             |    |
             T---F2
             |
            ---
           |   |
           L1 L2

           Figure 2

   As an example, the bypass path (unicast bypass) between the PLR and
   MP can be constructed via SR or even via a shared tree (replication
   segment).

   As an example, in figure 1 the detour path between R and T is the 2nd
   fiber between these nodes.  As such the bypass path could be setup on
   the 2nd fiber.  That said in figure 2 the bypass path is traversing
   multiple nodes and this example a unicast SR path might be ideal for
   setting up the detour path.

   In addition, PHP procedure and implicit null label on the bypass path
   can be implemented to reduce the PCE programming on the MP PCC.

   Optional shared replication segments can be used in networks that do
   not have unicast SR turned on.  These shared replication segments can
   be programmed on the bypass nodes without a P2MP Policy.  The
   replication segments on primary path can use these shared replication
   segments as a protection tunnel to protect links.

3.3.6.  Connecting Replication Segment via Segment List

   There could be nodes between two replication segment that do not
   understand P2MP Policy or Replication segment.  It is possible to
   connect two non-adjacent Replication segment via a unicast binding
   SID or segment-list.




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   Replication segment does support the concept of a segment-list.  A
   list of unicast SIDs (Binding SID, Adjacency SIDs or Node SIDs) can
   be programmed on a Replication segment via the SR-ERO sub-objects and
   ERO-attributes object.

   How ever it should be noted that there needs to be a Replication SID
   as the bottom of the stack in all cases.

3.4.  SR P2MP Policy and Replication Segment TLVs and Objects

3.4.1.  SR P2MP Policy Objects

   SR P2MP Policy can be constructed via the following objects

   <Common Header>

   [<SRP>]

   <LSP>

   [<association-list>]

   optionally if the root is updating the PCE with end point list the
   end-point-list object can be added.

   [<end-points-list>]

3.4.2.  Replication Segment Objects

   Replication segment can be constructed via the following objects

   <Common Header>

   [<SRP>]

   <LSP>

   [<replication-sid>]

   as described in [draft-sivabalan-pce-binding-label-sid]

   [<ERO-Attributes Object>]

   as per [draft-koldychev-pce-multipath]







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3.4.3.  P2MP Policy vs Replication Segment

   Note on the root the P2MP Policy and Replication Segment can be
   downloaded via the same message that includes the association object.
   That said on the transit or leaf nodes the replication segment needs
   to be downloaded individually as P2MP Policy is only relevant to the
   Root node.  P2MP Policy and Replication segments objects have a very
   close definition, they can be told apart via the following abstracts:

   o  The P2MP Policy will always have an association list object for
      the Candidate Paths in its PCInitiate message.  While the
      replication segment does not have the association list object.
      That said they can be downloaded simultaneously by inserting the
      association list object and the ERO object in the same PCInitiate
      or PCUdp message.

   o  Both P2MP Policy and Replication segment have the PLSP-ID and it
      is set to 0 in the PCInitiate message.  For both Objects the PLSP-
      ID is set via the PCC.

3.4.4.  P2MP Policy and Replication Segment general considerations

   The above new objects and TLV's defined in this document can be
   included in PCRpt, PcInitiate and PcUpd messages.

   It should be noted that every PcRpt, PcInitiate and PCUpd messages
   will contain full list of the Leaves and labels and forwarding
   information that is needed to build the Candidate path and its
   Replication segments.  They will never send the delta information
   related to the new leaves or forwarding information that need to be
   added or updated.  This is necessary to ensure that PCE or any new
   PCE is in sync with the PCC.

   As such when a PcRpt, PcInitiate and PCUpd messages is send via PCEP
   it maintains the previous ERO Path IDs and generates new Path IDs for
   new instructions, as per [draft-koldychev-pce-multipath].  This means
   the PATH IDs are maintained for each specific forwarding instructions
   until these instructions are deleted.  For example: When the first
   leaf is added the PCE will be update with PathI ID 1 to the PCC.
   When the second leaf is add, according to the path calculated, PCE
   might just append the existing instruction Path ID 1 with a new Path
   ID 2 to construct the new PCUpd message.

4.  Object Format







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4.1.  Open Message and Capablity Exchange

   Format of the open Object:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Ver |   Flags |   Keepalive   |  DeadTimer    |      SID      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      //                        Optional TLVs                        //
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   All the nodes need to establish a PCEP connection with the PCE.

   During PCEP Initialization Phase, PCEP Speakers need to set flags N,
   M, P in the STATEFUL-PCE-CAPABILITY TLV as defined in
   [draft-ietf-pce-stateful-pce-p2mp] section-5.2

   This draft extends the PCEP OPEN object by defining an optional TLV
   to indicate the PCE's capability to perform SR-P2MP path computations
   with a new IANA capability type.

   The inclusion of this TLV in an OPEN object indicates that the sender
   can perform SR-P2MP path computations.  This will be similar to the
   P2MP-CAPABILITY defined in [RFC8306] section-3.1.2 and a new value
   needs to be defined for SR-P2MP.

   In addition a Assoc-Type-List TlV as per [RFC8697] section 3.4 should
   be send via PCEP open object with following association type

   +-------------------+----------------------------+------------------+
   | Association Type  | Association Name           | Reference        |
   | Value             |                            |                  |
   +-------------------+----------------------------+------------------+
   | TBD1              | P2MP SR Policy Association | This document    |
   +-------------------+----------------------------+------------------+

   OP-CONF-Assoc-RANGE (Operator-configured Association Range)should not
   be set for this association type and must be ignored.

   Finally the open message needs to include the MULTIPATH CAPABILITY
   TLV as defined in [draft-koldychev-pce-multipath]








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4.2.  Symbolic Name in PCInit Message from PCC

   As per [RFC8231] section 7.3.2. a Symbolic Path Name TLV should
   uniquely identify the P2MP path on the PCC.  This symbolic path name
   is a human-readable string that identifies an P2MP LSP in the
   network.  It needs to be constant through the life time of the P2MP
   path.

   As an example in the case of P2MP LSP the symbolic name can be p2mp
   policy name + candidate path name of the LSP.

4.3.  P2MP Policy Specific Objects and TLVs

4.3.1.  P2MP Policy Association Group for P2MP Policy

   Two ASSOCIATION object types for IPv4 and IPv6 are defined in
   [RFC8697].  The ASSOCIATION object includes "Association type"
   indicating the type of the association group.  This document adds a
   new Association type.  Association type = TBD1 "P2MP SR Policy
   Association Type" for SR Policy Association Group (P2MP SRPAG).  As
   per [draft-barth-pce-segment-routing-policy-cp] section 5, three new
   TLVs are identified to carry association information: P2MP-SRPAG-
   POL-ID-TLV, P2MP-SRPAG-CPATH-ID-TLV, P2MP-SRPAG-CPATH-ATTR-TLV

4.3.1.1.  P2MP SR Policy Association Group Policy Identifiers TLV

   The P2MP-SRPOLICY-POL-ID TLV is a mandatory TLV for the P2MP-SRPAG
   Association.  Only one P2MP-SRPOLICY-POL-ID TLV can be carried and
   only the first occurrence is processed and any others MUST be
   ignored.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Root                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          TREE-ID                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type: TBD2 for "P2MP-SRPOLICY-POL-ID" TLV.

   Length: 8 or 20, depending on length of End-point (IPv4 or IPv6)

   Tunnel Sender Address : Can be either IPv4 or IPv6, this value is the
   value of the root loopback IP.




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   Tree-ID: Tree ID that the replication segment is part of as per
   draft-ietf-spring-sr-p2mp-policy

4.3.1.2.  P2MP SR Policy Association Group Candidate Path Identifiers
          TLV

   The P2MP-SRPOLICY-CPATH-ID TLV is a mandatory TLV for the P2MPSRPAG
   Association.  Only one P2MP-SRPOLICY-CPATH-ID TLV can be carried and
   only the first occurrence is processed and any others MUST be
   ignored.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Proto. Origin |Flags        |A|    Reserved                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Originator ASN                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                       Originator Address                      |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Discriminator                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type: TBD3 for "P2MP-SRPOLICY-CPATH-ID" TLV.

   Length: 28.

   Protocol Origin: 8-bit value that encodes the protocol origin, as
   specified in [I-D.ietf-spring-segment-routing-policy] Section 2.3.

   Flags : A: This candidate path is active.  At any instance only one
   candidate path can be active.  PCC indicates the active candidate
   path to PCE through this bit.  Reserved: MUST be set to zero on
   transmission and ignored on receipt.

   Originator ASN: Represented as 4 byte number, part of the originator
   identifier, as specified in
   [draft-ietf-spring-segment-routing-policy] Section 2.4.

   Originator Address: Represented as 128 bit value where IPv4 address
   are encoded in lowest 32 bits, part of the originator identifier, as
   specified in [draft-ietf-spring-segment-routing-policy] Section 2.4.




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   Discriminator: 32-bit value that encodes the Discriminator of the
   candidate path.

4.3.1.3.  P2MP SR Policy Association Group Candidate Path Attributes TLV

   The P2MP-SRPOLICY-CPATH-ATTR TLV is an optional TLV for the SRPAG
   Association.  Only one P2MP-SRPOLICY-CPATH-ATTR TLV can be carried
   and only the first occurrence is processed and any others MUST be
   ignored.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           Preference                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type: TBD4 for "P2MP-SRPOLICY-CPATH-ATTR" TLV.

   Length: 4.  Preference: Numerical preference of the candidate path,
   as specified in [draft-ietf-spring-segment-routing-policy]
   Section 2.7.

   If the TLV is missing, a default preference of 100 as specified in
   [draft-ietf-spring-segment-routing-policy] is used.

4.3.2.  P2MP-END-POINTS Object

   In order for the Root to indicate operations of its
   leaves(Add/Remove/Modify/DoNotModify), the PC Report message is
   extended to include P2MP End Point <P2MP End-points> Object which is
   defined in [RFC8306]

   The format of the PC Report message is as follow:

   <Common Header>

   [<SRP>]

   <LSP>

   [<association-list>]

   [<end-points-list>]






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      IPV4-P2MP END-POINTS:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Leaf type                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Source IPv4 address                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Destination IPv4 address                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                           ...                                 ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Destination IPv4 address                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


      IPV6-P2MP END-POINTS:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Leaf type                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                Source IPv6 address (16 bytes)                 |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |              Destination IPv6 address (16 bytes)              |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                           ...                                 ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |              Destination IPv6 address (16 bytes)              |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Leaf Types (derived from [RFC8306] section 3.3.2) :

   1.  New leaves to add (leaf type = 1)

   2.  Old leaves to remove (leaf type = 2)

   3.  Old leaves whose path can be modified/reoptimized (leaf type =
       3), Future reserved not used for tree SID as of now.

   4.  Old leaves whose path must be left unchanged (leaf type = 4)




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   A given P2MP END-POINTS object gathers the leaves of a given type.
   Note that a P2MP report can mix the different types of leaves by
   including several P2MP END-POINTS objects.  The END-POINTS object
   body has a variable length.  These are multiples of 4 bytes for IPv4,
   multiples of 16 bytes, plus 4 bytes, for IPv6.

4.4.  P2MP Policy and Replication Segment Identifier Object and TLV

   As it was mentioned previously both P2MP Policy and Replication
   Segment are identified via the LSP object and more precisely via the
   SR-P2MP-LSPID-TLV

   The P2MP Policy uses the PLSP-ID to identify the Candidate Paths and
   the Instance-ID to identify a Path-Instance with in the Candidate
   path.

   On other hand the Replication Segment uses the SR-P2MP-LSPID-TLV to
   identify and correlate a Replication Segment to a P2MP Policy

   As it was noted previously on the Root, the P2MP Policy and the
   Replication Segment is downloaded via the same PCUpd message.

4.4.1.  Extension of the LSP Object, SR-P2MP-LSPID-TLV

   The LSP Object is defined in Section 7.3 of [RFC8231].  It specifies
   the PLSP-ID to uniquely identify an LSP that is constant for the life
   time of a PCEP session.  Similarly for a P2MP tunnel, the PLSP-ID
   identify a Candidate Path uniquely with in the P2MP policy.

   The LSP Object MUST include the new SR-P2MP-POLICY-ID-TLV (IPV4/IpV6)
   defined in this document below.  This is a variation to the P2MP
   object defined in [draft-ietf-pce-stateful-pce-p2mp]



















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 SR-IPV4-P2MP-POLICY-ID TLV:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           Type=TBD            |           Length=10           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   Root                                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                  Tree-ID                                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            Path-Instance-ID   |       Reserved                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


    SR-IPV6-P2MP-POLICY-ID TLV :

         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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           Type=TBD            |           Length=22           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                  Root                                         |
       +                          (16 octets)                          +
       |                                                               |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                             Tree-ID                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |             Path-Instance-ID  |       Reserved                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The type (16-bit) of the TLV is TBD (need allocation by IANA).

   Root: Source Router IP Address

   Tree-ID: Unique Identifier of this P2MP LSP on the Root.

   Instance-ID : Contains 16 Bit instance ID.

4.5.  Replication Segment

   As per [draft-ietf-spring-sr-replication-segment] a replication
   segment has a next-hop-group which MAY contain a single outgoing
   replication sid OR a list of SIDs (sr-policy-sid-list) In either case
   there needs to be a replication SID at the bottom of the stack.  This




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   means two replication segments can be directly connected or connected
   via a SR domain.

4.5.1.  The format of the replication segment message

   As it was mentioned in previous chapters the format of the
   replication segment message is close to P2MP Policy.  That said the
   P2MP Policy contains the association object and the replication
   segment message does not contain the association object.  The
   replication segment may be downloaded individually on transit and
   leaf nodes without the P2MP Policy.  The P2MP Policy is a Root
   Concept.  The replication segment uses SR-P2MP-LSPID-TLV as its
   identifier.  That said this TLV is coded differently for shared and
   on shared case.

   o  In the case of a replication segment being shared, the Tree-ID in
      the SR-P2MP-POLICY Identifier TLV is the replication-id of the
      replication segment and Root = 0, Instance-Id = 0.  When
      downloading a shared replication segment from PCE through a
      PcInitiate message, the SR-P2MP-POLICY Identifier TLV is all 0,
      and on the report back from PCC, PCC generates PLSP-ID,
      Replication-id (Tree-id field will be populated with replication-
      id).  Instance-id will be 0.

4.5.2.  Label action rules in replicating segment

   The node action, ingress, transit, leaf or Bud, is indicated via a
   new Node Role TLV.  This document introduces a new SR-P2MP-NODE-ROLE
   TLV (Type To be assigned by IANA) that will be present in the PATH-
   ATTRIB object.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           Type=TBD            |           Length=4            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Role Type   |                 Reserved                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   o  ingress, role type = 1

   o  transit, role type = 2

   o  leaf, role type = 3

   o  bud, role type = 4






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4.5.3.  SR-ERO Rules

   Forwarding information of a replication segment can be configured and
   steered via many different mechanisms.

   As an example a replication SID can be steered via:

   1.  Replication SID steered with an IPv4/IPv6 directly connected
       nexthop

       *  In this case there will two SR-ERO in the ERO Object, with the
          Replication SID SR-ERO at the bottom and the IPv4/IPv6 SR-ERO
          on the top.

   2.  Replication SID steered with an IPv4/IPv6 loopback address that
       reside on the directly connected router.

       *  In this case there will two SR-ERO in the ERO Object, with the
          Replication SID SR-ERO at the bottom and the IPv4/IPv6 SR-ERO
          on the top.

       *  In addition a new flag D is added to the SR-ERO to signal that
          the Loopback nexthop is connected to the directly attached
          router.

   3.  Replication SID steered with unnumbered IPv4/IPv6 directly
       connected Interface

   4.  Replication SID steered via a SR adjacency or node SID

       *  In this case even a sid-list can be used to traffic engineer
          the path between two Replication SID

       *  The Replication SID SR-ERO is at the bottom while all other
          SR-EROs are on the top in order.

4.5.3.1.  SR-ERO subobject changes

   SR-ERO from RFC 8664 is used to construct the forwarding information
   needed for Replication Segment.

   A new D flag was added to indicate a loopback nexthop that is
   residing on the directly attached router.  It should be noted that
   this flag should be set only for the loopback case and not for a
   local interface as a nexthop.






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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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |L|   Type=36   |     Length    |  NT   |     Flags   |D|F|S|C|M|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         SID (optional)                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       //                   NAI (variable, optional)                  //
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Flags : F, S, C, M are already defined in rfc8664.

   This document defines a new flag D: If the next-hop in NAI field is
   system IP or loopback, this bit indicates whether the system IP /
   loopback is directly connected router or not.  If set indicates
   directly connected address.  When this bit is set, F bit should be 0
   (meaning NAI should be present)

5.  Examples of PCEP messages between PCE and PCEP

                                   +-------+
                                   |       |
                        +-------+  |LEAF D |                   +-------+
                        |Rep    |  |       |                   |  PCE  |
                        |Transit|  +-------+                   +-------+
                 +------|C      |
                 | Non  |       |  +-------+
                 | Rep  +-------+  |       |
                 | Transit|        |LEAF E |
          +------| B      |        |       |
          |Rep   +--------+        +-------+
          |ROOT    |
          |A       |
          +--------+

5.1.  PCE Initiate

   For a PCE Initiate P2MP Policy a sample PC Initiate message from the
   PCE to the root is provided below.  This is on reception of a P2MP
   Policy creation on the PCE:

       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
                                 <SRP OBJECT>
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Flags = 0                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        SRP-ID-number  = 1                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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      |  TLV Type = 28 (PathSetupType)| TLV Len = 4                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                             | PST = TBD       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             <LSP OBJECT>

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                PLSP-ID = 0            |     A:1,D:1,N:1,C:1   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Type=17             |           Length=<var>        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            symbolic path name                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type=TBD          |  Length                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Root   = A                                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Tree-ID = 0                                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Instance-id = 0       |         Reserved              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                            <ASSOCIATION OBJECT>
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Reserved              |            Flags            |0|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Association type= SR-P2MP-PAG |      Association ID = z       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |              IPv4 Association Source = <pce-address>          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |             Type              |             Length            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Root  = A                             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                           TREE-ID = 0                         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |             Type              |             Length            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |ProtOrigin 10  |    Reserved                                   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Originator ASN                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       |                       Originator Address = <pce-address>      |
       |                                                               |
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Discriminator = 1                     |



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       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |             Type              |             Length            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                           Preference = 100 <default>          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Presence of an association object with Tree-ID = 0 in the Initiate
   message, is an indication to the node to create a P2MP policy and
   associated candidate path.  An initiate message without an
   association object, is an indication to PCC that a Replication
   Segment (forwarding instructions) is being instantiated.

5.2.  PCC Initiate or PCE Initiate Respond

   For PCC initiated P2MP Policy, the Root will send a P2MP request to
   the PCE, this is achieved through Root sending a PCRpt to PCE with
   the Tree-ID, PLSP-ID and Instance-ID Set. Below is a sample Report
   generated by the Root (PCC) to the PCE

   In addition for the PCE Initiated case the same PCRpt message can be
   send from Root (PCC) to the PCE.  The Root will generate the Tree-ID,
   PLSP-ID, Instance-ID for the candidate path identified by the
   candidate path identifier TLV and sends a report back to PCE.  Note,
   in this case the End point object is optional.  The end point object
   (optionally) is added if the root has discovered any new leaves on
   the PCC.

























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   Sample Report generated by the Root to the PCE for Leaf Add

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Flags = 0                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        SRP-ID-number  = 1                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  TLV Type = 28 (PathSetupType)| TLV Len = 4                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                             | PST = TBD       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                               <LSP OBJECT>
      |                PLSP-ID = 1            |     A:1,D:1,N:1       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Type=17             |           Length=<var>        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            symbolic path name                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type=TBD          |  Length                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Root = A                                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Tree-ID = Y                                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Instance-ID =L1            |      Reserved                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                              <END POINT OBJECT>
      |                          Leaf type =1                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Source IPv4 address = A                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Destination IPv4 address = D                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Destination IPv4 address = E                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

5.3.  PCE P2MP Path-Instance Calculation and Replication Segment
      download

   Once the PCRpt message including the endpoints (optional in case of
   PCE Initiated) is sent to the PCE, PCE computes the path from root to
   the leaves and would send a PCInitiate to the transit and leaf nodes
   for instantiating the replication segment for the Path-Instance.

   In addition a PCUpd is send to the Root node to construct the
   replication segment.



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   The forwarding information is downloaded via the ERO object, ERO-
   attribute object and SR-ERO sub-objects.  For example, say PCE
   computed 2 candidate paths <cp1 and cp2> that needs to be downloaded
   on the root and their corresponding Replication Segment download to
   the root, transit and leaf nodes.  The sample messages are explained
   below.

   For cp1:

   o  For PCC initiate case, the PCE will send a PCUpd message to
      download the Candidate Paths and the replication segment.  Note on
      the root a single message with association object will achieve
      this.

   o  For PCE initiate case, the PCE optionally sends a PCUpd message to
      instantiate the replication segment that were newly discovered by
      the PCC and send to the PCE via the PCRpt message.. Note for this
      case the association object might not be needed is there is no
      update to the P2MP Policy.

   For cp2:

   o  For both PCC/PCE initiate, a PCInitiate messages sent from PCE,
      initiating the new Candidate Path and its associated Replication
      Segments.

   For both CP1 and CP2 on the transit and leaves, since PCE is
   initiating newly Replication Segments, PCE will send one PCInitiate
   message with two LSP objects and no association object, defining the
   Replication Semgnets on each candidate path.  On other hand, PCE can
   send separate PCInitiate message for every Replication Segment.  As
   defined in [draft-barth-pce-segment-routing-policy-cp]

   A sample PCUpd message sent to the Root for cp1 is as follows, NOTE
   in the below example the Node B is not Replication Segment Capable as
   such there is a sid-list programmed on A with node SID B as steering
   followed by node SID of C and finally the Replication SID C at the
   bottom :

   Note:

   1.  Root is connected to the next replication Segment C via non
       replication segment B.  Hence a segment List is used.

   2.  The following PCUpd message send to the root is for PCC Initiated
       case as such it has the association object to instantiate the
       Candidate Path and the Replication Segment via a single message
       on the root.



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   3.  For PCE Initiate message the association object can be omitted
       sense it is only used for instantiating or updating the
       Replication Segment only.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Flags = 0                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        SRP-ID-number  = 2                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  TLV Type = 28 (PathSetupType)| TLV Len = 4                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                             | PST = TBD       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             <LSP OBJECT>
      |                PLSP-ID = 1            |     A:1,D:1,N:1,C:0   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Type=17             |           Length=<var>        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            symbolic path name                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type=TBD          |  Length                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Root =A                                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Tree-ID = Y                                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Instance-ID = L1        |         Reserved              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      BT= 0    |                 Reserved                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Binding value = incoming replication SID           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                            <ASSOCIATION OBJECT>
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Reserved              |            Flags            |0|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Association type= SR-P2MP-PAG |      Association ID = z       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              IPv4 Association Source = <pce-address>          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Root  = A                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           TREE-ID = 0                         |



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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |ProtOrigin 10  |    Reserved                                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Originator ASN                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                       Originator Address = <pce-address>      |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Discriminator = 1                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           Preference = 100 <default>          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                       <ERO-ATTRIBUTES OBJECT>
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Flags                           | Oper|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|0|0|                 Reserved                                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ERO-path Id = 1                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            Back-up ero path id = 0            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |L|   Type=36   |     Length    |  NT= 1|     Flags     |0|0|0|0|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         SID = node sid b                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |L|   Type=36   |     Length    |  NT= 1|     Flags     |0|0|0|0|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         SID = node sid c                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |L|   Type=36   |     Length    |  NT= 1|     Flags     |0|0|0|0|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         SID = RSID C                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   A sample PC Initiate message to the Root for cp2 is as follows: Note
   cp2 can be either on the same path as cp1 or on a separate path,
   assuming that there is a 2nd path connecting A to B to C.  In this
   example a 2nd interface is used on A and B, hence the adjacency SIDs
   are programmed



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       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Flags = 0                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        SRP-ID-number  = 3                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  TLV Type = 28 (PathSetupType)| TLV Len = 4                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                             | PST = TBD       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             <LSP OBJECT>
      |                PLSP-ID = 0            |     A:1,D:1,N:1,C:1   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Type=17             |           Length=<var>        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            symbolic path name                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type=TBD          |  Length                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Root = A                                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Tree-ID = Y                                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Instance-ID = 0     |   reserved                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      BT       |                 Reserved                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Binding Value= incoming replication sid            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                           <ASSOCIATION OBJECT>
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Reserved              |            Flags            |0|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Association type= SR-P2MP-PAG |      Association ID = z       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              IPv4 Association Source = <pce-address>          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Root = A                                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           TREE-ID = Y                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |ProtOrigin 10  |    Reserved                   |



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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Originator ASN                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                       Originator Address = <pce-address>      |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Discriminator = 2                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           Preference = 50 <Lower Pref>        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             <ERO-ATTRIBUTES OBJECT>
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Flags                           | Oper|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|0|0|                 Reserved                                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ERO-path Id = 2                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            Back-up ero path id = 0            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |L|   Type=36   |     Length    |  NT= 1|     Flags     |0|0|0|0|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               SID = adjacency sid a-b-int2                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |L|   Type=36   |     Length    |  NT= 1|     Flags     |0|0|0|0|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                SID = adjacency sid b-c-int2                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |L|   Type=36   |     Length    |  NT= 1|     Flags     |0|0|0|0|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         SID = RSID C                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   A sample PC Initiate message to the transit Replication Segment C for
   cp1 Lets assume C is connected to D and E via 2 fiber hence Fast
   Reroute is possible.  Below example sets up the forwarding plane fro
   C to Leaves D and E

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Flags = 0                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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      |                        SRP-ID-number  = 4                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  TLV Type = 28 (PathSetupType)| TLV Len = 4                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                             | PST = TBD       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             <LSP OBJECT>
      |                PLSP-ID = 0            |     A:1,D:1,N:1,C:1   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Type=17             |           Length=<var>        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            symbolic path name                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type=TBD          |  Length                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Root=A                                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Tree-ID = Y                                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Instance-ID =L1     |        Reserved               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      BT       |                 Reserved                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Binding Value= incoming replication sid = c1       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                             <With FRR over NHD2>
                            <ERO-ATTRIBUTES OBJECT>
                            <incoming label c1 swap with D1>
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Flags                           | Oper|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|0|1|                 Reserved                                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ERO-path Id = 3                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            Back-up ero path id = 4            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |L|   Type=36   |     Length    |  NT= 1|     Flags     |0|0|0|0|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         SID = d1                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                ipv4-address  = NHD1           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                            <ERO-ATTRIBUTES OBJECT>



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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Flags                           | Oper|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|1|0|                 Reserved                                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ERO-path Id = 4                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            Back-up ero path id = 0            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |L|   Type=36   |     Length    |  NT= 1|     Flags     |0|0|0|0|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         SID = d protect                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                ipv4-address  = NHD2           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     <incoming label c1 swap with E1>
                        <ERO-ATTRIBUTES OBJECT>
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Flags                           | Oper|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|0|1|                 Reserved                                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ERO-path Id = 5                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            Back-up ero path id = 6            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |L|   Type=36   |     Length    |  NT= 1|     Flags     |0|0|0|0|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         SID = e1                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                ipv4-address  = NHE1           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                            <ERO-ATTRIBUTES OBJECT>
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Flags                           | Oper|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|1|0|                 Reserved                                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ERO-path Id = 6                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            Back-up ero path id = 0            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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      |L|   Type=36   |     Length    |  NT= 1|     Flags     |0|0|0|0|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         SID = e protect                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                ipv4-address  = NHE2           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

5.4.  PCC Rpt for PCE Update and Init Messages

   In response to the PC Initiate message / PC Update message , PCC will
   send PC Reports to PCE indicating the state of the label download for
   that particular candidate path.  PCC's will generate PLSP-ID for
   newly initiated candidate path.  Here is an PC Report Message send
   for the root PCE Init message with cp2 on the root.





































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       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Flags = 0                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        SRP-ID-number  = 2                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  TLV Type = 28 (PathSetupType)| TLV Len = 4                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                             | PST = TBD       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                               <LSP OBJECT>
      |                PLSP-ID = 1            |    O:1,A:1,D:1,N:1,C:1|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Type=17             |           Length=<var>        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            symbolic path name                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type=TBD          |  Length                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Root                                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Tree-ID                                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Instance-ID = L1    |          Reserved             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                               <ERO-ATTRIBUTE OBJECT>
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Flags                           |O =Up|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|0|1|                 Reserved                                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ERO-path Id = 5                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            Back-up ero path id = 6            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

6.  Tree Deletion

   To delete the entire tree (P2MP LSP) , Root send a PCRpt message with
   the R bit of the LSP object set and all the fields of the SR-P2MP-
   LSP-ID TLV set to 0(indicating to remove all state associated with
   this P2MP tunnel).  The controller in response sends a PCInitiate
   message with R bit in the SRP object SET to all nodes along the path
   to indicate deletion of a label entry.





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7.  Fragmentation

   The Fragmentation bit in the LSP object (F bit) can be used to
   indicate a fragmented PCEP message

8.  Example Workflows

   As per slides submitted in IETF 105.

9.  IANA Consideration

   1.  This draft extends the PCEP OPEN object by defining an optional
       TLV to indicate the PCE's capability to perform SR-P2MP path
       computations with a new IANA capability type (TBD).

   2.  PCEP open object with a new association type " P2MP SR Policy
       Association " value (TBD).

   3.  A new Association type.  Association type = TBD1 "P2MP SR Policy
       Association Type" for SR Policy Association Group (P2MP SRPAG)

       1.  three new TLVs are identified to carry association
           information: P2MP-SRPAG- POL-ID-TLV, P2MP-SRPAG-CPATH-ID-TLV,
           P2MP-SRPAG-CPATH-ATTR-TLV

   4.  Two new TLVs for Identifying the P2MP Policy and the Replication
       segment SR-IPV4-P2MP-POLICY-ID TLV and SR-IPV6-P2MP-POLICY-ID TLV

   5.  A new SR-P2MP-NODE-ROLE TLV (Type To be assigned by IANA) that
       will be present in the PATH-ATTRIB object

10.  Security Considerations

   TBD

11.  Acknowledgments

   The authors would like to thank Tanmoy Kundu and Stone Andrew at
   Nokia for their feedback and major contribution to this draft.

12.  References

12.1.  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>.



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12.2.  Informative References

   [draft-barth-pce-segment-routing-policy-cp]
              .

   [draft-dhs-spring-sr-p2mp-policy-yang]
              .

   [draft-ietf-pce-segment-routing-policy-cp]
              .

   [draft-ietf-pce-stateful-pce-p2mp]
              .

   [draft-ietf-pim-sr-p2mp-policy]
              "D. Yoyer, C. Filsfils, R.Prekh, H.bidgoli, Z. Zhang,
              "draft-voyer-pim-sr-p2mp-policy"", October 2019.

   [draft-ietf-spring-segment-routing-policy]
              .

   [draft-ietf-spring-sr-replication-segment]
              "D. Yoyer, C. Filsfils, R.Prekh, H.bidgoli, Z. Zhang,
              "draft-voyer-pim-sr-p2mp-policy "draft-voyer-spring-sr-
              replication-segment"", July 2020.

   [draft-koldychev-pce-multipath]
              .

   [draft-parekh-bess-mvpn-sr-p2mp]
              .

   [draft-sivabalan-pce-binding-label-sid]
              .

   [RFC3209]  .

   [RFC6513]  .

   [RFC8231]  .

   [RFC8236]  .

   [RFC8306]  .

   [RFC8664]  .

   [RFC8697]  .



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Authors' Addresses

   Hooman Bidgoli (editor)
   Nokia
   Ottawa
   Canada

   Email: hooman.bidgoli@nokia.com


   Daniel Voyer
   Bell Canada
   Montreal
   Canada

   Email: daniel.yover@bell.ca


   Saranya Rajarathinam
   Nokia
   Mountain View
   US

   Email: saranya.Rajarathinam@nokia.com


   Ehsan Hemmati
   Cisco System
   San Jose
   USA

   Email: ehemmati@cisco.com


   Tarek Saad
   Juniper Networks
   Ottawa
   Canada

   Email: tsaad@juniper.com


   Siva Sivabalan
   Ciena
   Ottawa
   Canada

   Email: ssivabal@ciena.com



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