[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-dong-idr-te-lsp-distribution) 00 01 02 03 04 05 06 07 08 09

Network Working Group                                    S. Previdi, Ed.
Internet-Draft
Intended status: Standards Track                           K. Talaulikar
Expires: December 31, 2018                           Cisco Systems, Inc.
                                                            J. Dong, Ed.
                                                                 M. Chen
                                                     Huawei Technologies
                                                              H. Gredler
                                                            RtBrick Inc.
                                                             J. Tantsura
                                                          Nuage Networks
                                                           June 29, 2018


Distribution of Traffic Engineering (TE) Policies and State using BGP-LS
                 draft-ietf-idr-te-lsp-distribution-09

Abstract

   This document describes a mechanism to collect the Traffic
   Engineering and Policy information that is locally available in a
   node and advertise it into BGP-LS updates.  Such information can be
   used by external components for path computation, re-optimization,
   service placement, network visualization, etc.

Requirements Language

   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].

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 December 31, 2018.




Previdi, et al.         Expires December 31, 2018               [Page 1]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Carrying TE Policy Information in BGP . . . . . . . . . . . .   5
   3.  TE Policy NLRI  . . . . . . . . . . . . . . . . . . . . . . .   6
   4.  TE Policy Descriptors . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Tunnel Identifier (Tunnel ID) . . . . . . . . . . . . . .   7
     4.2.  LSP Identifier (LSP ID) . . . . . . . . . . . . . . . . .   7
     4.3.  IPv4/IPv6 Tunnel Head-End Address . . . . . . . . . . . .   8
     4.4.  IPv4/IPv6 Tunnel Tail-End Address . . . . . . . . . . . .   8
     4.5.  SR Policy Candidate Path Descriptor . . . . . . . . . . .   9
     4.6.  Local MPLS Cross Connect  . . . . . . . . . . . . . . . .  11
       4.6.1.  MPLS Cross Connect Interface  . . . . . . . . . . . .  12
       4.6.2.  MPLS Cross Connect FEC  . . . . . . . . . . . . . . .  13
   5.  MPLS-TE Policy State TLV  . . . . . . . . . . . . . . . . . .  14
     5.1.  RSVP Objects  . . . . . . . . . . . . . . . . . . . . . .  15
     5.2.  PCEP Objects  . . . . . . . . . . . . . . . . . . . . . .  16
   6.  SR Policy State TLVs  . . . . . . . . . . . . . . . . . . . .  17
     6.1.  SR Binding SID  . . . . . . . . . . . . . . . . . . . . .  17
     6.2.  SR Candidate Path State . . . . . . . . . . . . . . . . .  19
     6.3.  SR Candidate Path Name  . . . . . . . . . . . . . . . . .  21
     6.4.  SR Candidate Path Constraints . . . . . . . . . . . . . .  21
       6.4.1.  SR Affinity Constraint  . . . . . . . . . . . . . . .  23
       6.4.2.  SR SRLG Constraint  . . . . . . . . . . . . . . . . .  24
       6.4.3.  SR Bandwidth Constraint . . . . . . . . . . . . . . .  24
       6.4.4.  SR Disjoint Group Constraint  . . . . . . . . . . . .  25
     6.5.  SR Segment List . . . . . . . . . . . . . . . . . . . . .  27
     6.6.  SR Segment  . . . . . . . . . . . . . . . . . . . . . . .  29
       6.6.1.  Segment Descriptors . . . . . . . . . . . . . . . . .  31
     6.7.  SR Segment List Metric  . . . . . . . . . . . . . . . . .  37
   7.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . .  39
   8.  Manageability Considerations  . . . . . . . . . . . . . . . .  40
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  40



Previdi, et al.         Expires December 31, 2018               [Page 2]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


     9.1.  BGP-LS NLRI-Types . . . . . . . . . . . . . . . . . . . .  40
     9.2.  BGP-LS Protocol-IDs . . . . . . . . . . . . . . . . . . .  40
     9.3.  BGP-LS TLVs . . . . . . . . . . . . . . . . . . . . . . .  41
     9.4.  BGP-LS SR Policy Protocol Origin  . . . . . . . . . . . .  41
     9.5.  BGP-LS TE State Path Origin . . . . . . . . . . . . . . .  42
     9.6.  BGP-LS TE State Dataplane . . . . . . . . . . . . . . . .  42
     9.7.  BGP-LS SR Segment Descriptors . . . . . . . . . . . . . .  43
     9.8.  BGP-LS Metric Type  . . . . . . . . . . . . . . . . . . .  43
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  44
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  44
   12. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  44
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  44
     13.1.  Normative References . . . . . . . . . . . . . . . . . .  44
     13.2.  Informative References . . . . . . . . . . . . . . . . .  46
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  47

1.  Introduction

   In many network environments, traffic engineering policies are
   instantiated into various forms:

   o  MPLS Traffic Engineering Label Switched Paths (TE-LSPs).

   o  IP based tunnels (IP in IP, GRE, etc).

   o  Segment Routing Policies (SR Policy) as defined in
      [I-D.ietf-spring-segment-routing-policy]

   o  Local MPLS cross-connect configuration

   All this information can be grouped into the same term: TE Policies.
   In the rest of this document we refer to TE Policies as the set of
   information related to the various instantiation of polices: MPLS TE
   LSPs, IP tunnels (IPv4 or IPv6), SR Policies, etc.

   TE Polices are generally instantiated at the head-end and are based
   on either local configuration or controller based programming of the
   node using various APIs and protocols, e.g., PCEP or BGP.

   In many network environments, the configuration and state of each TE
   Policy that is available in the network is required by a controller
   which allows the network operator to optimize several functions and
   operations through the use of a controller aware of both topology and
   state information.

   One example of a controller is the stateful Path Computation Element
   (PCE) [RFC8231], which could provide benefits in path reoptimization.
   While some extensions are proposed in Path Computation Element



Previdi, et al.         Expires December 31, 2018               [Page 3]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   Communication Protocol (PCEP) for the Path Computation Clients (PCCs)
   to report the LSP states to the PCE, this mechanism may not be
   applicable in a management-based PCE architecture as specified in
   section 5.5 of [RFC4655].  As illustrated in the figure below, the
   PCC is not an LSR in the routing domain, thus the head-end nodes of
   the TE-LSPs may not implement the PCEP protocol.  In this case a
   general mechanism to collect the TE-LSP states from the ingress LERs
   is needed.  This document proposes an TE Policy state collection
   mechanism complementary to the mechanism defined in [RFC8231].

                                   -----------
                                  |   -----   |
              Service             |  | TED |<-+----------->
              Request             |   -----   |  TED synchronization
                 |                |     |     |  mechanism (for example,
                 v                |     |     |  routing protocol)
           ------------- Request/ |     v     |
          |             | Response|   -----   |
          |     NMS     |<--------+> | PCE |  |
          |             |         |   -----   |
           -------------           -----------
         Service |
         Request |
                 v
            ----------  Signaling   ----------
           | Head-End | Protocol   | Adjacent |
           |  Node    |<---------->|   Node   |
            ----------              ----------

                 Figure 1.  Management-Based PCE Usage

   In networks with composite PCE nodes as specified in section 5.1 of
   [RFC4655], PCE is implemented on several routers in the network, and
   the PCCs in the network can use the mechanism described in [RFC8231]
   to report the TE Policy information to the PCE nodes.  An external
   component may also need to collect the TE Policy information from all
   the PCEs in the network to obtain a global view of the LSP state in
   the network.

   In multi-area or multi-AS scenarios, each area or AS can have a child
   PCE to collect the TE Policies in its own domain, in addition, a
   parent PCE needs to collect TE Policy information from multiple child
   PCEs to obtain a global view of LSPs inside and across the domains
   involved.

   In another network scenario, a centralized controller is used for
   service placement.  Obtaining the TE Policy state information is
   quite important for making appropriate service placement decisions



Previdi, et al.         Expires December 31, 2018               [Page 4]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   with the purpose to both meet the application's requirements and
   utilize network resources efficiently.

   The Network Management System (NMS) may need to provide global
   visibility of the TE Policies in the network as part of the network
   visualization function.

   BGP has been extended to distribute link-state and traffic
   engineering information to external components [RFC7752].  Using the
   same protocol to collect Traffic Engineering Policy and state
   information is desirable for these external components since this
   avoids introducing multiple protocols for network information
   collection.  This document describes a mechanism to distribute
   traffic engineering policy information (MPLS, SR, IPv4 and IPv6) to
   external components using BGP-LS.

2.  Carrying TE Policy Information in BGP

   TE Policy information is advertised in BGP UPDATE messages using the
   MP_REACH_NLRI and MP_UNREACH_NLRI attributes [RFC4760].  The "Link-
   State NLRI" defined in [RFC7752] is extended to carry the TE Policy
   information.  BGP speakers that wish to exchange TE Policy
   information MUST use the BGP Multiprotocol Extensions Capability Code
   (1) to advertise the corresponding (AFI, SAFI) pair, as specified in
   [RFC4760].  New TLVs carried in the Link_State Attribute defined in
   [RFC7752] are also defined in order to carry the attributes of a TE
   Policy in the subsequent sections.

   The format of "Link-State NLRI" is defined in [RFC7752] as follows:

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |            NLRI Type          |     Total NLRI Length         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     //                  Link-State NLRI (variable)                 //
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   A new "NLRI Type" is defined for TE Policy Information as following:

   o  NLRI Type: TE Policy NLRI (value TBD see IANA Considerations
      Section 9.1).

   The format of this new NLRI type is defined in Section 3 below.





Previdi, et al.         Expires December 31, 2018               [Page 5]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


3.  TE Policy NLRI

   This document defines the new TE Policy NLRI-Type and its format as
   shown in the following figure:

      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
     +-+-+-+-+-+-+-+-+
     |  Protocol-ID  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                        Identifier                             |
     |                        (64 bits)                              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //                Headend (Node Descriptors)                   //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //                TE Policy Descriptors (variable)             //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     where:

   o  Protocol-ID field specifies the component that owns the TE Policy
      state in the advertising node.  The following new Protocol-IDs are
      defined (values TBD see IANA Considerations Section 9.2) and apply
      to the TE Policy NLRI:

               +-------------+----------------------------------+
               | Protocol-ID | NLRI information source protocol |
               +-------------+----------------------------------+
               |    TBD      |   RSVP-TE                        |
               |    TBD      |   Segment Routing                |
               +-------------+----------------------------------+

   o  "Identifier" is an 8 octet value as defined in [RFC7752].

   o  "Headend" consists of a Node Descriptor defined in [RFC7752].

   o  "TE Policy Descriptors" consists of (values TBD see IANA
      Considerations Section 9.3):













Previdi, et al.         Expires December 31, 2018               [Page 6]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   +-----------+----------------------------------+
   | Codepoint |       Descriptor TLVs            |
   +-----------+----------------------------------+
   |  TBD      | Tunnel ID                        |
   |  TBD      | LSP ID                           |
   |  TBD      | IPv4/6 Tunnel Head-end address   |
   |  TBD      | IPv4/6 Tunnel Tail-end address   |
   |  TBD      | SR Policy Candidate Path         |
   |  TBD      | Local MPLS Cross Connect         |
   +-----------+----------------------------------+

4.  TE Policy Descriptors

   This sections defines the TE Policy Descriptors TLVs which are used
   to describe the TE Policy being advertised by using the new BGP-LS TE
   Policy NLRI type defined in Section 3.

4.1.  Tunnel Identifier (Tunnel ID)

   The Tunnel Identifier TLV contains the Tunnel ID defined in [RFC3209]
   and is used for RSVP-TE protocol TE Policies.  It has the following
   format:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |             Type              |          Length               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Tunnel ID             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: 2 octets.

   o  Tunnel ID: 2 octets as defined in [RFC3209].

4.2.  LSP Identifier (LSP ID)

   The LSP Identifier TLV contains the LSP ID defined in [RFC3209] and
   is used for RSVP-TE protocol TE Policies.  It has the following
   format:







Previdi, et al.         Expires December 31, 2018               [Page 7]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


      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               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |            LSP ID             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: 2 octets.

   o  LSP ID: 2 octets as defined in [RFC3209].

4.3.  IPv4/IPv6 Tunnel Head-End Address

   The IPv4/IPv6 Tunnel Head-End Address TLV contains the Tunnel Head-
   End Address defined in [RFC3209] and is used for RSVP-TE protocol TE
   Policies.  It has following format:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |             Type              |          Length               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //        IPv4/IPv6 Tunnel Head-End Address (variable)         //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: 4 or 16 octets.

   When the IPv4/IPv6 Tunnel Head-end Address TLV contains an IPv4
   address, its length is 4 (octets).

   When the IPv4/IPv6 Tunnel Head-end Address TLV contains an IPv6
   address, its length is 16 (octets).

4.4.  IPv4/IPv6 Tunnel Tail-End Address

   The IPv4/IPv6 Tunnel Tail-End Address TLV contains the Tunnel Tail-
   End Address defined in [RFC3209] and is used for RSVP-TE protocol TE
   Policies.  It has following format:




Previdi, et al.         Expires December 31, 2018               [Page 8]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


      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               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //        IPv4/IPv6 Tunnel Tail-End Address (variable)         //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: 4 or 16 octets.

   When the IPv4/IPv6 Tunnel Tail-end Address TLV contains an IPv4
   address, its length is 4 (octets).

   When the IPv4/IPv6 Tunnel Tail-end Address TLV contains an IPv6
   address, its length is 16 (octets).

4.5.  SR Policy Candidate Path Descriptor

   The SR Policy Candidate Path Descriptor TLV identifies a Segment
   Routing Policy candidate path (CP) as defined in
   [I-D.ietf-spring-segment-routing-policy] and has the following
   format:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |             Type              |          Length               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |Protocol-origin|    Flags      |            RESERVED           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     Endpoint (4 or 16 octets)                //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     Policy Color (4 octets)                   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               Originator AS Number (4 octets)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |              Originator Address (4 or 16 octets)             //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                    Discriminator (4 octets)                   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     where:

   o  Type: TBD (see IANA Considerations Section 9.3)



Previdi, et al.         Expires December 31, 2018               [Page 9]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   o  Length: variable (valid values are 24, 36 or 48 octets)

   o  Protocol-Origin : 1 octet field which identifies the protocol or
      component which is responsible for the instantiation of this path.
      Following protocol-origin codepoints are defined in this document.

+------------+---------------------------------------------------------+
| Code Point |                   Protocol Origin                       |
+------------+---------------------------------------------------------+
|     1      | PCEP                                                    |
|     2      | BGP SR Policy                                           |
|     3      | Local (via CLI, Yang model through NETCONF, gRPC, etc.) |
+------------+---------------------------------------------------------+

   o  Flags: 1 octet field with following bit positions defined.  Other
      bits SHOULD be cleared by originator and MUST be ignored by
      receiver.

       0 1 2 3 4 5 6 7
      +-+-+-+-+-+-+-+-+
      |E|O|           |
      +-+-+-+-+-+-+-+-+

   where:

      *  E-Flag : Indicates the encoding of endpoint as IPv6 address
         when SET and IPv4 address when CLEAR

      *  O-Flag : Indicates the encoding of originator address as IPv6
         address when SET and IPv4 address when CLEAR

   o  Reserved : 2 octets which SHOULD be set to 0 by originator and
      MUST be ignored by receiver.

   o  Endpoint : 4 or 16 octets (as indicated by the flags) containing
      the address of the endpoint of the SR Policy

   o  Color : 4 octets that indicates the color of the SR Policy

   o  Originator ASN : 4 octets to carry the 4 byte encoding of the ASN
      of the originator.  Refer [I-D.ietf-spring-segment-routing-policy]
      Sec 2.4 for details.

   o  Originator Address : 4 or 16 octets (as indicated by the flags) to
      carry the address of the originator.  Refer
      [I-D.ietf-spring-segment-routing-policy] Sec 2.4 for details.





Previdi, et al.         Expires December 31, 2018              [Page 10]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   o  Discriminator : 4 octets to carry the discrimator of the path.
      Refer [I-D.ietf-spring-segment-routing-policy] Sec 2.5 for
      details.

4.6.  Local MPLS Cross Connect

   The Local MPLS Cross Connect TLV identifies a local MPLS state in the
   form of incoming label and interface followed by an outgoing label
   and interface.  Outgoing interface may appear multiple times (for
   multicast states).  It is used with Protocol ID set to "Static
   Configuration" value 5 as defined in [RFC7752].

   The Local MPLS Cross Connect TLV has the following format:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |             Type              |          Length               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     Incoming label (4 octets)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     Outgoing label (4 octets)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //                          Sub-TLVs (variable)                //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: variable.

   o  Incoming and Outgoing labels: 4 octets each.

   o  Sub-TLVs: following Sub-TLVs are defined:

      *  Interface Sub-TLV

      *  Forwarding Equivalent Class (FEC)

   The Local MPLS Cross Connect TLV:

      MUST have an incoming label.

      MUST have an outgoing label.

      MAY contain an Interface Sub-TLV having the I-flag set.




Previdi, et al.         Expires December 31, 2018              [Page 11]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


      MUST contain at least one Interface Sub-TLV having the I-flag
      unset.

      MAY contain multiple Interface Sub-TLV having the I-flag unset.
      This is the case of a multicast MPLS cross connect.

      MAY contain a FEC Sub-TLV.

   The following sub-TLVs are defined for the Local MPLS Cross Connect
   TLV (values TBD see IANA Considerations Section 9.3):

   +-----------+----------------------------------+
   | Codepoint |       Descriptor TLV             |
   +-----------+----------------------------------+
   |  TBD      | MPLS Cross Connect Interface     |
   |  TBD      | MPLS Cross Connect FEC           |
   +-----------+----------------------------------+

   These are defined in the following sub-sections.

4.6.1.  MPLS Cross Connect Interface

   The MPLS Cross Connect Interface sub-TLV is optional and contains the
   identifier of the interface (incoming or outgoing) in the form of an
   IPv4 address or an IPv6 address.

   The MPLS Cross Connect Interface sub-TLV has the following format:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |             Type              |          Length               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     +-+-+-+-+-+-+-+-+
     |     Flags     |
     +-+-+-+-+-+-+-+-+

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Local Interface Identifier (4 octets)                |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //         Interface Address (4 or 16 octets)                  //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     where:

   o  Type: TBD (see IANA Considerations Section 9.3)




Previdi, et al.         Expires December 31, 2018              [Page 12]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   o  Length: 9 or 21.

   o  Flags: 1 octet of flags defined as follows:

                              0 1 2 3 4 5 6 7
                             +-+-+-+-+-+-+-+-+
                             |I|             |
                             +-+-+-+-+-+-+-+-+

                             where:

      *  I-Flag is the Interface flag.  When set, the Interface Sub-TLV
         describes an incoming interface.  If the I-flag is not set,
         then the Interface Sub-TLV describes an outgoing interface.

   o  Local Interface Identifier: a 4 octet identifier.

   o  Interface address: a 4 octet IPv4 address or a 16 octet IPv6
      address.

4.6.2.  MPLS Cross Connect FEC

   The MPLS Cross Connect FEC sub-TLV is optional and contains the FEC
   associated to the incoming label.

   The MPLS Cross Connect FEC sub-TLV has the following format:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |             Type              |          Length               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Flags       |  Masklength   |   Prefix (variable)          //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //                     Prefix (variable)                       //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: variable.

   o  Flags: 1 octet of flags defined as follows:







Previdi, et al.         Expires December 31, 2018              [Page 13]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


                              0 1 2 3 4 5 6 7
                             +-+-+-+-+-+-+-+-+
                             |4|             |
                             +-+-+-+-+-+-+-+-+

                             where:

      *  4-Flag is the IPv4 flag.  When set, the FEC Sub-TLV describes
         an IPv4 FEC.  If the 4-flag is not set, then the FEC Sub-TLV
         describes an IPv6 FEC.

   o  Mask Length: 1 octet of prefix length.

   o  Prefix: an IPv4 or IPv6 prefix whose mask length is given by the "
      Mask Length" field.

5.  MPLS-TE Policy State TLV

   A new TLV called "MPLS-TE Policy State TLV", is used to describe the
   characteristics of the MPLS-TE Policy and it is carried in the
   optional non-transitive BGP Attribute "LINK_STATE Attribute" defined
   in [RFC7752].  These MPLS-TE Policy characteristics include the
   characteristics and attributes of the policy, it's dataplane,
   explicit path, Quality of Service (QoS) parameters, route
   information, the protection mechanisms, etc.

   The MPLS-TE Policy State TLV has the following format:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |              Type             |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Path-origin  |   Dataplane   |            RESERVED           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //        MPLS-TE Policy State Objects (variable)              //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     where:

                         MPLS-TE Policy State TLV

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: the total length of the MPLS-TE Policy State TLV not
      including Type and Length fields.



Previdi, et al.         Expires December 31, 2018              [Page 14]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   o  Path-origin: identifies the component (or protocol) from which the
      contained object originated.  This allows for objects defined in
      different components to be collected while avoiding the possible
      codepoint collisions among these components.  Following path-
      origin codepoints are defined in this document.

               +----------+------------------+
               |  Code    |     Path         |
               |  Point   |     Origin       |
               +----------+------------------+
               |    1     | RSVP-TE          |
               |    2     | PCEP             |
               |    3     | Local/Static     |
               +----------+------------------+

   o  Dataplane: describes to which dataplane the policy is applied to.
      The following dataplane values are defined in this document:

               +----------+------------------+
               |  Code    |    Dataplane     |
               |  Point   |                  |
               +----------+------------------+
               |    1     | MPLS-IPv4        |
               |    2     | MPLS-IPv6        |
               +----------+------------------+

   o  RESERVED: 16-bit field.  SHOULD be set to 0 on transmission and
      MUST be ignored on receipt.

   o  TE Policy State Objects: Rather than replicating all these objects
      in this document, the semantics and encodings of the objects as
      defined in RSVP-TE and PCEP are reused.

   The state information is carried in the "MPLS-TE Policy State
   Objects" with the following format as described in the sub-sections
   below.

5.1.  RSVP Objects

   RSVP-TE objects are encoded in the "MPLS-TE Policy State Objects"
   field of the MPLS-TE Policy State TLV and consists of MPLS TE LSP
   objects defined in RSVP-TE [RFC3209] [RFC3473].  Rather than
   replicating all MPLS TE LSP related objects in this document, the
   semantics and encodings of the MPLS TE LSP objects are re-used.
   These MPLS TE LSP objects are carried in the MPLS-TE Policy State
   TLV.





Previdi, et al.         Expires December 31, 2018              [Page 15]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   When carrying RSVP-TE objects, the "Path-Origin" field is set to
   "RSVP-TE".

   The following RSVP-TE Objects are defined:

   o  SENDER_TSPEC and FLOW_SPEC [RFC2205]

   o  SESSION_ATTRIBUTE [RFC3209]

   o  EXPLICIT_ROUTE Object (ERO) [RFC3209]

   o  ROUTE_RECORD Object (RRO) [RFC3209]

   o  FAST_REROUTE Object [RFC4090]

   o  DETOUR Object [RFC4090]

   o  EXCLUDE_ROUTE Object (XRO) [RFC4874]

   o  SECONDARY_EXPLICIT_ROUTE Object (SERO) [RFC4873]

   o  SECONDARY_RECORD_ROUTE (SRRO) [RFC4873]

   o  LSP_ATTRIBUTES Object [RFC5420]

   o  LSP_REQUIRED_ATTRIBUTES Object [RFC5420]

   o  PROTECTION Object [RFC3473][RFC4872][RFC4873]

   o  ASSOCIATION Object [RFC4872]

   o  PRIMARY_PATH_ROUTE Object [RFC4872]

   o  ADMIN_STATUS Object [RFC3473]

   o  LABEL_REQUEST Object [RFC3209][RFC3473]

   For the MPLS TE LSP Objects listed above, the corresponding sub-
   objects are also applicable to this mechanism.  Note that this list
   is not exhaustive, other MPLS TE LSP objects which reflect specific
   characteristics of the MPLS TE LSP can also be carried in the LSP
   state TLV.

5.2.  PCEP Objects

   PCEP objects are encoded in the "MPLS-TE Policy State Objects" field
   of the MPLS-TE Policy State TLV and consists of PCEP objects defined
   in [RFC5440].  Rather than replicating all MPLS TE LSP related



Previdi, et al.         Expires December 31, 2018              [Page 16]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   objects in this document, the semantics and encodings of the MPLS TE
   LSP objects are re-used.  These MPLS TE LSP objects are carried in
   the MPLS-TE Policy State TLV.

   When carrying PCEP objects, the "Path-Origin" field is set to "PCEP".

   The following PCEP Objects are defined:

   o  METRIC Object [RFC5440]

   o  BANDWIDTH Object [RFC5440]

   For the MPLS TE LSP Objects listed above, the corresponding sub-
   objects are also applicable to this mechanism.  Note that this list
   is not exhaustive, other MPLS TE LSP objects which reflect specific
   characteristics of the MPLS TE LSP can also be carried in the TE
   Policy State TLV.

6.  SR Policy State TLVs

   Segment Routing Policy (SR Policy) architecture is specified in
   [I-D.ietf-spring-segment-routing-policy].  A SR Policy can comprise
   of one or more candidate paths (CP) of which at a given time one and
   only one may be active (i.e. installed in forwarding and usable for
   steering of traffic).  Each CP in turn may have one or more SID-List
   of which one or more may be active; when multiple are active then
   traffic is load balanced over them.

   This section defines the various TLVs which enable the headend to
   report the state of an SR Policy, its CP(s), SID-List(s) and their
   status.  These TLVs are carried in the optional non-transitive BGP
   Attribute "LINK_STATE Attribute" defined in [RFC7752] and enable the
   same consistent form of reporting for SR Policy state irrespective of
   the Protocol-Origin used to provision the policy.  Detailed procedure
   is described in Section 7 .

6.1.  SR Binding SID

   The SR Binding SID (BSID) TLV provides the BSID and its attributes
   for the SR Policy CP.  The TLV MAY also optionally contain the
   Provisioned BSID value for reporting when explicitly provisioned.

   The TLV has the following format:








Previdi, et al.         Expires December 31, 2018              [Page 17]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


    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            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           BSID Flags          |            RESERVED           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                   Binding SID (4 or 16 octets)               //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Provisioned Binding SID (optional, 4 or 16 octets)     //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: variable (valid values are 12, 16, 24 or 40 octets)

   o  BSID Flags: 2 octet field that indicates attribute and status of
      the Binding SID (BSID) associated with this CP.  The following bit
      positions are defined and the semantics are described in detail in
      [I-D.ietf-spring-segment-routing-policy].  Other bits SHOULD be
      cleared by originator and MUST be ignored by receiver.

       0                   1
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |D|B|U|S|L|F|                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

      *  D-Flag : Indicates the dataplane for the BSIDs and if they are
         16 octet SRv6 SID when SET and are 4 octet SR/MPLS label value
         when CLEAR.

      *  B-Flag : Indicates the allocation of the value in the BSID
         field when SET and indicates that BSID is not allocated when
         CLEAR.

      *  U-Flag : Indicates the provisioned BSID value is unavailable
         when SET.

      *  S-Flag : Indicates the BSID value in use is specified or
         provisioned value when SET and dynamically allocated value when
         CLEAR.





Previdi, et al.         Expires December 31, 2018              [Page 18]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


      *  L-Flag : Indicates the BSID value is from the Segment Routing
         Local Block (SRLB) of the headend node when SET and is from the
         local label pool when CLEAR

      *  F-Flag : Indicates the BSID value is one allocated from dynamic
         range due to fallback (e.g. when specified BSID is unavailable)
         when SET.

   o  RESERVED: 2 octets.  SHOULD be set to 0 by originator and MUST be
      ignored by receiver.

   o  Binding SID: It indicates the operational or allocated BSID value
      for the CP based on the status flags.

   o  Provisioned BSID: Optional field used to report the explicitly
      provisioned BSID value as indicated by the S-Flag being SET.

   The BSID fields above are 4 octet carrying the MPLS Label or 16
   octets carrying the SRv6 SID based on the BSID D-flag.  When carrying
   the MPLS Label, as shown in the figure below, the TC, S and TTL
   (total of 12 bits) are RESERVED and SHOULD be set to 0 by originator
   and MUST be ignored by the receiver.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Label                        | TC  |S|       TTL     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


6.2.  SR Candidate Path State

   The SR Candidate Path (CP) State TLV provides the operational status
   and attributes of the SR Policy at the CP level.  The TLV has the
   following format:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              Type             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Priority    |   RESERVED    |              Flags            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Preference (4 octets)                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:




Previdi, et al.         Expires December 31, 2018              [Page 19]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: 12 octets

   o  Priority : 1 octet value which indicates the priority of the CP

   o  RESERVED: 1 octet.  SHOULD be set to 0 by originator and MUST be
      ignored by receiver.

   o  Flags: 2 octet field that indicates attribute and status of the
      CP.  The following bit positions are defined and the semantics are
      described in detail in [I-D.ietf-spring-segment-routing-policy].
      Other bits SHOULD be cleared by originator and MUST be ignored by
      receiver.

       0                   1
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |S|A|B|E|V|O|D|C|I|T|           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

      *  S-Flag : Indicates the CP is in administrative shut state when
         SET

      *  A-Flag : Indicates the CP is the active path (i.e. one
         provisioned in the forwarding plane) for the SR Policy when SET

      *  B-Flag : Indicates the CP is the backup path (i.e. one
         identified for path protection of the active path) for the SR
         Policy when SET

      *  E-Flag : Indicates that the CP has been evaluated for validity
         (e.g. headend may evaluate CPs based on their preferences) when
         SET

      *  V-Flag : Indicates the CP has at least one valid SID-List when
         SET

      *  O-Flag : Indicates the CP was instantiated by the headend due
         to an on-demand-nexthop trigger based on local template when
         SET

      *  D-Flag : Indicates the CP was delegated for computation to a
         PCE/controller when SET





Previdi, et al.         Expires December 31, 2018              [Page 20]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


      *  C-Flag : Indicates the CP was provisioned by a PCE/controller
         when SET

      *  I-Flag : Indicates the CP will perform the "drop upon invalid"
         behavior when no other active path is available for this SR
         Policy and this path is the one with best preference amongst
         the available CPs.

      *  T-Flag : Indicates the CP has been marked as eligible for use
         as Transit Policy on the headend when SET

   o  Preference : 4 octet value which indicates the preference of the
      CP

6.3.  SR Candidate Path Name

   The SR Candidate Path Name TLV is an optional TLV that is used to
   carry the symbolic name associated with the candidate path.  The TLV
   has the following format:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               Type            |              Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Candidate Path Symbolic Name (variable)             //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: variable

   o  CP Name : Symbolic name for the CP.  It is a string of printable
      ASCII characters without a NULL terminator.

6.4.  SR Candidate Path Constraints

   The SR Candidate Path Constraints TLV is an optional TLV that is used
   to report the contraints associated with the candidate path.  The
   constraints are generally applied to a dynamic candidate path which
   is computed by the headend.  The constraints may also be applied to
   an explicit path where the headend is expected to validate that the
   path expresses satisfies the specified constraints and the path is to
   be invalidated by the headend when the constraints are no longer met
   (e.g. due to topology changes).




Previdi, et al.         Expires December 31, 2018              [Page 21]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   The TLV has the following format:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               Type            |              Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              Flags            |   Algorithm   |    RESERVED   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   sub-TLVs (variable)                                        //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: variable

   o  Flags: 2 octet field that indicates the constraints that are being
      applied to the CP.  The following bit positions are defined and
      the other bits SHOULD be cleared by originator and MUST be ignored
      by receiver.

       0                   1
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |D|P|U|A|                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

      *  A-Flag : Indicates that the CP needs to use SRv6 dataplane when
         SET and SR/MPLS dataplane when CLEAR

      *  P-Flag : Indicates that the CP needs to use only protected SIDs
         when SET

      *  U-Flag : Indicates that the CP needs to use only unprotected
         SIDs when SET

      *  A-Flag : Indicates that the CP needs to use the SIDs belonging
         to the specified SR Algorithm only when SET

   o  Algorithm : Indicates the algorithm that is preferred to be used
      when the path is setup.  When the A-flag is SET then the path is
      strictly using the specified algorithm SIDs only.





Previdi, et al.         Expires December 31, 2018              [Page 22]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   o  RESERVED: 1 octet.  SHOULD be set to 0 by originator and MUST be
      ignored by receiver.

   o  sub-TLVs: optional sub-TLVs MAY be included in this TLV to
      describe other constraints.

   The following constraint sub-TLVs are defined for the SR CP
   Constraints TLV.

6.4.1.  SR Affinity Constraint

   The SR Affinity Constraint sub-TLV is an optional sub-TLV that is
   used to carry the affinity constraints [RFC2702] associated with the
   candidate path.  The affinity is expressed in terms of Extended Admin
   Group (EAG) as defined in [RFC7308].  The TLV has the following
   format:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               Type            |              Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Excl-Any-Size | Incl-Any-Size | Incl-All-Size |    RESERVED   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Exclude-Any EAG (optional, variable)             //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Include-Any EAG (optional, variable)             //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Include-All EAG (optional, variable)             //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: variable, dependent on the size of the Extended Admin
      Group.  MUST be a multiple of 4 octets.

   o  Exclude-Any-Size : one octet to indicate the size of Exclude-Any
      EAG bitmask size in multiples of 4 octets. (e.g.  value 0
      indicates the Exclude-Any EAG field is skipped, value 1 indicates
      that 4 octets of Exclude-Any EAG is included)

   o  Include-Any-Size : one octet to indicate the size of Include-Any
      EAG bitmask size in multiples of 4 octets. (e.g.  value 0
      indicates the Include-Any EAG field is skipped, value 1 indicates
      that 4 octets of Include-Any EAG is included)




Previdi, et al.         Expires December 31, 2018              [Page 23]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   o  Include-All-Size : one octet to indicate the size of Include-All
      EAG bitmask size in multiples of 4 octets. (e.g.  value 0
      indicates the Include-All EAG field is skipped, value 1 indicates
      that 4 octets of Include-All EAG is included)

   o  RESERVED: 1 octet.  SHOULD be set to 0 by originator and MUST be
      ignored by receiver.

   o  Exclude-Any EAG : the bitmask used to represent the affinities to
      be excluded from the path.

   o  Include-Any EAG : the bitmask used to represent the affinities to
      be included in the path.

   o  Include-All EAG : the bitmask used to represent the all affinities
      to be included in the path.

6.4.2.  SR SRLG Constraint

   The SR SRLG Constraint sub-TLV is an optional sub-TLV that is used to
   carry the Shared Risk Link Group (SRLG) values [RFC4202] that are to
   be excluded from the candidate path.  The TLV has the following
   format:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               Type            |              Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         SRLG Values (variable, multiples of 4 octets)        //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: variable, dependent on the number of SRLGs encoded.  MUST
      be a multiple of 4 octets.

   o  SRLG Values : One or more SRLG values (each of 4 octets).

6.4.3.  SR Bandwidth Constraint

   The SR Bandwidth Constraint sub-TLV is an optional sub-TLV that is
   used to indicate the desired bandwidth availability that needs to be
   ensured for the candidate path.  The TLV has the following format:





Previdi, et al.         Expires December 31, 2018              [Page 24]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


    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           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Bandwidth                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: 8 octects

   o  Bandwidth : 4 octets which specify the desired bandwidth in unit
      of bytes per second in IEEE floating point format.

6.4.4.  SR Disjoint Group Constraint

   The SR Disjoint Group Constraint sub-TLV is an optional sub-TLV that
   is used to carry the disjointness constraint associated with the
   candidate path.  The disjointness between two SR Policy Candidate
   Paths is expressed by associating them with the same disjoint group
   identifier and then specifying the type of disjointness required
   between their paths.  The computation is expected to achieve the
   highest level of disjointness requested and when that is not possible
   then fallback to a lesser level progressively based on the levels
   indicated.

   The TLV has the following format:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               Type            |              Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Request-Flags |  Status-Flags |            RESERVED           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Disjoint Group Identifier                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: 12 octets





Previdi, et al.         Expires December 31, 2018              [Page 25]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   o  Request Flags : one octet to indicate the level of disjointness
      requested as specified in the form of flags.  The following flags
      are defined and the other bits SHOULD be cleared by originator and
      MUST be ignored by receiver.

       0 1 2 3 4 5 6 7
      +-+-+-+-+-+-+-+-+
      |S|N|L|F|I|     |
      +-+-+-+-+-+-+-+-+

   where:

      *  S-Flag : Indicates that SRLG disjointness is requested

      *  N-Flag : Indicates that node disjointness is requested when

      *  L-Flag : Indicates that link disjointness is requested when

      *  F-Flag : Indicates that the computation may fallback to a lower
         level of disjointness amongst the ones requested when all
         cannot be achieved

      *  I-Flag : Indicates that the computation may fallback to the
         default best path (e.g.  IGP path) in case of none of the
         desired disjointness can be achieved.

   o  Status Flags : one octet to indicate the level of disjointness
      that has been achieved by the computation as specified in the form
      of flags.  The following flags are defined and the other bits
      SHOULD be cleared by originator and MUST be ignored by receiver.

       0 1 2 3 4 5 6 7
      +-+-+-+-+-+-+-+-+
      |S|N|L|F|I|X|   |
      +-+-+-+-+-+-+-+-+

   where:

      *  S-Flag : Indicates that SRLG disjointness is achieved

      *  N-Flag : Indicates that node disjointness is achieved

      *  L-Flag : Indicates that link disjointness is achieved

      *  F-Flag : Indicates that the computation has fallen back to a
         lower level of disjointness that requested.





Previdi, et al.         Expires December 31, 2018              [Page 26]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


      *  I-Flag : Indicates that the computation has fallen back to the
         best path (e.g.  IGP path) and disjointness has not been
         achieved

      *  X-Flag : Indicates that the disjointness constraint could not
         be achieved and hence path has been invalidated

   o  RESERVED: 2 octets.  SHOULD be set to 0 by originator and MUST be
      ignored by receiver.

   o  Disjointness Group Identifier : 4 octet value that is the group
      identifier for a set of disjoint paths

6.5.  SR Segment List

   The SR Segment List TLV is used to report the SID-List(s) of a
   candidate path.  The TLV has following format:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              Type             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              Flags            |   Algorithm   |    RESERVED   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Weight (4 octets)                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   sub-TLVs (variable)                                        //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: variable

   o  Flags: 1 octet field that indicates attribute and status of the
      SID-List.The following bit positions are defined and the semantics
      are described in detail in
      [I-D.ietf-spring-segment-routing-policy].  Other bits SHOULD be
      cleared by originator and MUST be ignored by receiver.










Previdi, et al.         Expires December 31, 2018              [Page 27]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


       0                   1
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |D|E|C|V|R|C|A|                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

      *  D-Flag : Indicates the SID-List is comprised of SRv6 SIDs when
         SET and indicates it is comprised of SR/MPLS labels when CLEAR.

      *  E-Flag : Indicates that SID-List is an explicit path when SET
         and indicates dynamic path when CLEAR.

      *  C-Flag : Indicates that SID-List has been computed for a
         dynamic path when SET.  It is always reported as SET for
         explicit paths.

      *  V-Flag : Indicates the SID-List has passed verification or its
         verification was not required when SET and failed verification
         when CLEAR.

      *  R-Flag : Indicates that the first Segment has been resolved
         when SET and failed resolution when CLEAR.

      *  C-Flag : Indicates that the computation for the dynamic path
         failed when SET and succeeded (or not required in case of
         explicit path) when CLEAR

      *  A-Flag : Indicates that all the SIDs in the SID-List belong to
         the specified algorithm when SET.

   o  RESERVED: 1 octet.  SHOULD be set to 0 by originator and MUST be
      ignored by receiver.

   o  Algorithm: 1 octet that indicates the algorithm of the SIDs used
      in the SID-List when the A-flag is SET.

   o  Weight: 4 octet field that indicates the weight associated with
      the SID-List for weighted load-balancing

   o  Sub-TLVs : variable and contains the ordered set of Segments and
      any other optional attributes associated with the specific SID-
      List.

   The SR Segment sub-TLV (defined in Section 6.6) is the only currently
   defined sub-TLV for use with the SR Segment List TLV and it MUST be
   included as an ordered set of sub-TLVs within the SR Segment List TLV



Previdi, et al.         Expires December 31, 2018              [Page 28]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   when the SID-List is not empty.  A SID-List may be empty in certain
   cases (e.g. for a dynamic path) where the headend has not yet
   performed the computation and hence not derived the segments required
   for the path; in such cases, the SR Segment List TLV SHOULD NOT
   include any SR Segment sub-TLVs.

6.6.  SR Segment

   The SR Segment sub-TLV describes a single segment in a SID-List.  One
   or more instances of this sub-TLV in an ordered manner constitute a
   SID-List for a SR Policy candidate path.  It is a sub-TLV of the SR
   Segment List TLV and has following format:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              Type             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Segment Type  |    RESERVED   |             Flags             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                   SID (4 or 16 octets)                       //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   //                   SID Descriptor (variable)                 //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   //   Sub-TLVs (variable)                                       //
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: variable

   o  Segment Type : 1 octet which indicates the type of segment (refer
      Section 6.6.1 for details)

   o  RESERVED: 1 octet.  SHOULD be set to 0 by originator and MUST be
      ignored by receiver.

   o  Flags: 2 octet field that indicates attribute and status of the
      Segment and its SID.  The following bit positions are defined and
      the semantics are described in detail in
      [I-D.ietf-spring-segment-routing-policy].  Other bits SHOULD be
      cleared by originator and MUST be ignored by receiver.







Previdi, et al.         Expires December 31, 2018              [Page 29]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


       0                   1
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |S|E|V|R|A|                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

      *  S-Flag : Indicates the presence of SID value in the SID field
         when SET and that no value is indicated when CLEAR.

      *  E-Flag : Indicates the SID value is explicitly provisioned
         value (locally on headend or via controller/PCE) when SET and
         is a dynamically resolved value by headend when CLEAR

      *  V-Flag : Indicates the SID has passed verification or did not
         require verification when SET and failed verification when
         CLEAR.

      *  R-Flag : Indicates the SID has been resolved or did not require
         resolution (e.g. because it is not the first SID) when SET and
         failed resolution when CLEAR.

      *  A-Flag : Indicates that the Algorithm indicated in the Segment
         descriptor is valid when SET.  When CLEAR, it indicates that
         the headend is unable to determine the algorithm of the SID.

   o  SID : 4 octet carrying the MPLS Label or 16 octets carrying the
      SRv6 SID based on the F-flag.  When carrying the MPLS Label, as
      shown in the figure below, the TC, S and TTL (total of 12 bits)
      are RESERVED and SHOULD be set to 0 by originator and MUST be
      ignored by the receiver.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Label                        | TC  |S|       TTL     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   o  SID Descriptor : variable size SID descriptor based on the type of
      segment (refer Section 6.6.1 for details)

   o  Sub-Sub-TLVs : variable and contains any other optional attributes
      associated with the specific SID-List.

   Currently no Sub-Sub-TLV of the SR Segment sub-TLV is defined.




Previdi, et al.         Expires December 31, 2018              [Page 30]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


6.6.1.  Segment Descriptors

   [I-D.ietf-spring-segment-routing-policy] section 4 defines multiple
   types of segments and their description.  This section defines the
   encoding of the Segment Descriptors for each of those Segment types
   to be used in the Segment sub-TLV describes previously in
   Section 6.6.

   The following types are currently defined (suggested values, to be
   assigned by IANA):

+-------+--------------------------------------------------------------+
| Type  |   Segment Description                                        |
+-------+--------------------------------------------------------------+
|   0   | Invalid                                                      |
|   1   | SR-MPLS Label                                                |
|   2   | SRv6 SID as IPv6 address                                     |
|   3   | SR-MPLS Prefix SID as IPv4 Node Address                      |
|   4   | SR-MPLS Prefix SID as IPv6 Node Global Address               |
|   5   | SR-MPLS Adjacency SID as IPv4 Node Address & Local           |
|       | Interface ID                                                 |
|   6   | SR-MPLS Adjacency SID as IPv4 Local & Remote Interface       |
|       | Addresses                                                    |
|   7   | SR-MPLS Adjacency SID as pair of IPv6 Global Address &       |
|       | Interface ID for Local & Remote nodes                        |
|   8   | SR-MPLS Adjacency SID as pair of IPv6 Global Addresses for   |
|       | the Local & Remote Interface                                 |
|   9   | SRv6 END SID as IPv6 Node Global Address                     |
|  10   | SRv6 END.X SID as pair of IPv6 Global Address & Interface ID |
|       | for Local & Remote nodes                                     |
|  11   | SRv6 END.X SID as pair of IPv6 Global Addresses for the      |
|       | Local & Remote Interface                                     |
+-------+--------------------------------------------------------------+


6.6.1.1.  Type 1: SR-MPLS Label

   The Segment is SR-MPLS type and is specified simply as the label.
   The format of its Segment Descriptor is as follows:

    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
   +-+-+-+-+-+-+-+-+
   |   Algorithm   |
   +-+-+-+-+-+-+-+-+

   Where:




Previdi, et al.         Expires December 31, 2018              [Page 31]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   o  Algorithm: 1 octet value that indicates the algorithm used for
      picking the SID.  This is valid only when the A-flag has been SET
      in the Segment TLV.

6.6.1.2.  Type 2: SRv6 SID

   The Segment is SRv6 type and is specified simply as the SRv6 SID
   address.  The format of its Segment Descriptor is as follows:

    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
   +-+-+-+-+-+-+-+-+
   |   Algorithm   |
   +-+-+-+-+-+-+-+-+

   Where:

   o  Algorithm: 1 octet value that indicates the algorithm used for
      picking the SID.  This is valid only when the A-flag has been SET
      in the Segment TLV.

6.6.1.3.  Type 3: SR-MPLS Prefix SID for IPv4

   The Segment is SR-MPLS Prefix SID type and is specified as an IPv4
   node address.  The format of its Segment Descriptor is as follows:

    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
   +-+-+-+-+-+-+-+-+
   |   Algorithm   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 IPv4 Node Address (4 octets)                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   o  Algorithm: 1 octet value that indicates the algorithm used for
      picking the SID

   o  IPv4 Node Address: 4 octet value which carries the IPv4 address
      associated with the node

6.6.1.4.  Type 4: SR-MPLS Prefix SID for IPv6

   The Segment is SR-MPLS Prefix SID type and is specified as an IPv6
   global address.  The format of its Segment Descriptor is as follows:





Previdi, et al.         Expires December 31, 2018              [Page 32]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


    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
   +-+-+-+-+-+-+-+-+
   |   Algorithm   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          IPv6 Node Global Address (16 octets)                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   o  Algorithm: 1 octet value that indicates the algorithm used for
      picking the SID

   o  IPv6 Node Global Address: 16 octet value which carries the IPv6
      global address associated with the node

6.6.1.5.  Type 5: SR-MPLS Adjacency SID for IPv4 with Interface ID

   The Segment is SR-MPLS Adjacency SID type and is specified as an IPv4
   node address along with the local interface ID on that node.  The
   format of its Segment Descriptor is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 IPv4 Node Address (4 octets)                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                Local Interface ID (4 octets)                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   o  IPv4 Node Address: 4 octet value which carries the IPv4 address
      associated with the node

   o  Local Interface ID : 4 octet value which carries the local
      interface ID of the node identified by the Node Address

6.6.1.6.  Type 6: SR-MPLS Adjacency SID for IPv4 with Interface Address

   The Segment is SR-MPLS Adjacency SID type and is specified as a pair
   of IPv4 local and remote addresses.  The format of its Segment
   Descriptor is as follows:








Previdi, et al.         Expires December 31, 2018              [Page 33]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                IPv4 Local Address (4 octets)                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               IPv4 Remote Address (4 octets)                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   o  IPv4 Local Address: 4 octet value which carries the local IPv4
      address associated with the node

   o  IPv4 Remote Address: 4 octet value which carries the remote IPv4
      address associated with the node's neighbor.  This is optional and
      MAY be set to 0 when not used (e.g. when identifying point-to-
      point links).

6.6.1.7.  Type 7: SR-MPLS Adjacency SID for IPv6 with interface ID

   The Segment is SR-MPLS Adjacency SID type and is specified as a pair
   of IPv6 global address and interface ID for local and remote nodes.
   The format of its Segment Descriptor is as follows:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          IPv6 Local Node Global Address (16 octets)           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Local Node Interface ID (4 octets)                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          IPv6 Remote Node Global Address (16 octets)          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Remote Node Interface ID (4 octets)                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   o  IPv6 Local Node Global Address: 16 octet value which carries the
      IPv6 global address associated with the local node

   o  Local Node Interface ID : 4 octet value which carries the
      interface ID of the local node identified by the Local Node
      Address

   o  IPv6 Remote Node Global Address: 16 octet value which carries the
      IPv6 global address associated with the remote node.  This is




Previdi, et al.         Expires December 31, 2018              [Page 34]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


      optional and MAY be set to 0 when not used (e.g.  when identifying
      point-to-point links).

   o  Remote Node Interface ID : 4 octet value which carries the
      interface ID of the remote node identified by the Remote Node
      Address.  This is optional and MAY be set to 0 when not used (e.g.
      when identifying point-to-point links).

6.6.1.8.  Type 8: SR-MPLS Adjacency SID for IPv6 with interface address

   The Segment is SR-MPLS Adjacency SID type and is specified as a pair
   of IPv6 Global addresses for local and remote interface addresses.
   The format of its Segment Descriptor is as follows:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Global IPv6 Local Interface Address (16 octets)        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Global IPv6 Remote Interface Address (16 octets)       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   o  IPv6 Local Address: 16 octet value which carries the local IPv6
      address associated with the node

   o  IPv6 Remote Address: 16 octet value which carries the remote IPv6
      address associated with the node's neighbor

6.6.1.9.  Type 9: SRv6 END SID as IPv6 Node Address

   The Segment is SRv6 END SID type and is specified as an IPv6 global
   address.  The format of its Segment Descriptor is as follows:

    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
   +-+-+-+-+-+-+-+-+
   |   Algorithm   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          IPv6 Node Global Address (16 octets)                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   o  Algorithm: 1 octet value that indicates the algorithm used for
      picking the SID




Previdi, et al.         Expires December 31, 2018              [Page 35]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   o  IPv6 Node Global Address: 16 octet value which carries the IPv6
      global address associated with the node

6.6.1.10.  Type 10: SRv6 END.X SID as interface ID

   The Segment is SRv6 END.X SID type and is specified as a pair of IPv6
   global address and interface ID for local and remote nodes.  The
   format of its Segment Descriptor is as follows:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          IPv6 Local Node Global Address (16 octets)           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Local Node Interface ID (4 octets)                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          IPv6 Remote Node Global Address (16 octets)          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Remote Node Interface ID (4 octets)                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   o  IPv6 Local Node Global Address: 16 octet value which carries the
      IPv6 global address associated with the local node

   o  Local Node Interface ID : 4 octet value which carries the
      interface ID of the local node identified by the Local Node
      Address

   o  IPv6 Remote Node Global Address: 16 octet value which carries the
      IPv6 global address associated with the remote node.  This is
      optional and MAY be set to 0 when not used (e.g.  when identifying
      point-to-point links).

   o  Remote Node Interface ID : 4 octet value which carries the
      interface ID of the remote node identified by the Remote Node
      Address.  This is optional and MAY be set to 0 when not used (e.g.
      when identifying point-to-point links).

6.6.1.11.  Type 11: SRv6 END.X SID as interface address

   The Segment is SRv6 END.X SID type and is specified as a pair of IPv6
   Global addresses for local and remote interface addresses.  The
   format of its Segment Descriptor is as follows:






Previdi, et al.         Expires December 31, 2018              [Page 36]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Global IPv6 Local Interface Address (16 octets)        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Global IPv6 Remote Interface Address (16 octets)       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   o  IPv6 Local Address: 16 octet value which carries the local IPv6
      address associated with the node

   o  IPv6 Remote Address: 16 octet value which carries the remote IPv6
      address associated with the node's neighbor

6.7.  SR Segment List Metric

   The SR Segment List Metric sub-TLV describes the metric used for
   computation of the SID-List.  It is used to report the type of metric
   used in the computation of a dynamic path either on the headend or
   when the path computation is delegated to a PCE/controller.  When the
   path computation is done on the headend, it is also used to report
   the calculated metric for the path.

   It is a sub-TLV of the SR Segment List TLV and has following format:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              Type             |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Metric Type  |      Flags    |          RESERVED             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Metric Margin                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Metric Bound                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Metric Value                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where:

   o  Type: TBD (see IANA Considerations Section 9.3)

   o  Length: variable





Previdi, et al.         Expires December 31, 2018              [Page 37]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   o  Metric Type : 1 octet field which identifies the type of metric
      used for path computation.  Following metric type codepoints are
      defined in this document.

   +------------+-----------------------------------------+
   | Code Point |         Metric Type                     |
   +------------+-----------------------------------------+
   |     0      | IGP Metric                              |
   |     1      | Min Unidirectional Link Delay [RFC7471] |
   |     2      | TE Metric [RFC3630]                     |
   +------------+-----------------------------------------+

   o  Flags: 1 octet field that indicates the validity of the metric
      fields and their semantics.  The following bit positions are
      defined and the other bits SHOULD be cleared by originator and
      MUST be ignored by receiver.

       0 1 2 3 4 5 6 7
      +-+-+-+-+-+-+-+-+
      |M|A|B|V|       |
      +-+-+-+-+-+-+-+-+

   where:

      *  M-Flag : Indicates that the metric margin allowed for path
         computation is specified when SET

      *  A-Flag : Indicates that the metric margin is specified as an
         absolute value when SET and is expressed as a percentage of the
         minimum metric when CLEAR.

      *  B-Flag : Indicates that the metric bound allowed for the path
         is specified when SET.

      *  V-Flag : Indicates that the metric value computed is being
         reported when SET.

   o  RESERVED: 2 octets.  SHOULD be set to 0 by originator and MUST be
      ignored by receiver.

   o  Metric Margin : 4 octets which indicate the metric margin value
      when M-flag is SET.  The metric margin is specified as either an
      absolute value or as a percentage of the minimum computed path
      metric based on the A-flag.  The metric margin loosens the
      criteria for minimum metric path calculation up to the specified
      metric to accomodate for other factors such as bandwidth
      availability, minimal SID stack depth and maximizing of ECMP for
      the SR path computed.



Previdi, et al.         Expires December 31, 2018              [Page 38]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   o  Metric Bound : 4 octects which indicate the maximum metric value
      that is allowed when B-flag is SET.  If the computed path metric
      crosses the specified bound value then the path is considered as
      invalid.

   o  Metric Value : 4 octets which indicate the metric value of the
      computed path when V-flag is SET.  This value is available and
      reported when the computation is successful and a valid path is
      available.

7.  Procedures

   The BGP-LS advertisements for the TE Policy NLRI are originated by
   the headend node for the TE Policies that are instantiated on its
   local node.

   For MPLS TE LSPs signaled via RSVP-TE, the NLRI descriptor TLVs as
   specified in Section 4.1, Section 4.2, Section 4.3 and Section 4.4
   are used.  Then the TE LSP state is encoded in the BGP-LS Attribute
   field as MPLS-TE Policy State TLV as described in Section 5.  The
   RSVP-TE objects that reflect the state of the LSP are included as
   defined in Section 5.1.  When the TE LSP is setup with the help of
   PCEP signaling then another MPLS-TE Policy State TLV SHOULD be used
   to to encode the related PCEP objects corresponding to the LSP as
   defined in Section 5.2.

   For SR Policies, the NLRI descriptor TLV as specified in Section 4.5
   is used.  An SR Policy candidate path (CP) may be instantiated on the
   headend node via a local configuration, PCEP or BGP SR Policy
   signaling and this is indicated via the SR Protocol Origin.  Then the
   SR Policy Candidate Path's attribute and state is encoded in the BGP-
   LS Attribute field as SR Policy State TLVs and sub-TLVs as described
   in Section 6.  The SR Candidate Path State TLV as defined in
   Section 6.2 is included to report the state of the CP.  The SR BSID
   TLV as defined in Section 6.1 is included to report the BSID of the
   CP when one is either provisioned or allocated by the headend.  The
   constraints for the SR Policy Candidate Path are reported using the
   SR Candidate Path Constraints TLV as described in Section 6.4.The SR
   Segment List TLV is included for each of the SID-List(s) associated
   with the CP.  Each SR Segment List TLV in turn includes SR Segment
   sub-TLV(s) to report the segment(s) and their status.  The SR Segment
   List Metric sub-TLV is used to report the metric values and
   constraints for the specific SID List.

   When the SR Policy CP is setup with the help of PCEP signaling then
   another MPLS-TE Policy State TLV MAY be used to to encode the related
   PCEP objects corresponding to the LSP as defined in Section 5.2
   specifically to report information and status that is not covered by



Previdi, et al.         Expires December 31, 2018              [Page 39]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   the defined TLVs under Section 6.  In the event of a conflict of
   information, the receiver MUST prefer the information originated via
   TLVs defined in Section 6 over the PCEP objects reported via the TE
   Policy State TLV.

8.  Manageability Considerations

   The Existing BGP operational and management procedures apply to this
   document.  No new procedures are defined in this document.  The
   considerations as specified in [RFC7752] apply to this document.

   In general, it is assumed that the TE Policy head-end nodes are
   responsible for the distribution of TE Policy state information,
   while other nodes, e.g. the nodes in the path of a policy, MAY report
   the TE Policy information (if available) when needed.  For example,
   the border routers in the inter-domain case will also distribute LSP
   state information since the ingress node may not have the complete
   information for the end-to-end path.

9.  IANA Considerations

   This document requires new IANA assigned codepoints.

9.1.  BGP-LS NLRI-Types

   IANA maintains a registry called "Border Gateway Protocol - Link
   State (BGP-LS) Parameters" with a sub-registry called "BGP-LS NLRI-
   Types".

   The following codepoints is suggested (to be assigned by IANA):

    +------+----------------------------+---------------+
    | Type | NLRI Type                  |   Reference   |
    +------+----------------------------+---------------+
    |  5   | TE Policy NLRI type        | this document |
    +------+----------------------------+---------------+

9.2.  BGP-LS Protocol-IDs

   IANA maintains a registry called "Border Gateway Protocol - Link
   State (BGP-LS) Parameters" with a sub-registry called "BGP-LS
   Protocol-IDs".

   The following Protocol-ID codepoints are suggested (to be assigned by
   IANA):






Previdi, et al.         Expires December 31, 2018              [Page 40]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


    +-------------+----------------------------------+---------------+
    | Protocol-ID | NLRI information source protocol |   Reference   |
    +-------------+----------------------------------+---------------+
    |     8       |          RSVP-TE                 | this document |
    |     9       |       Segment Routing            | this document |
    +-------------+----------------------------------+---------------+

9.3.  BGP-LS TLVs

   IANA maintains a registry called "Border Gateway Protocol - Link
   State (BGP-LS) Parameters" with a sub-registry called "Node Anchor,
   Link Descriptor and Link Attribute TLVs".

   The following TLV codepoints are suggested (to be assigned by IANA):

   +----------+----------------------------------------+---------------+
   | TLV Code |             Description                | Value defined |
   |  Point   |                                        |       in      |
   +----------+----------------------------------------+---------------+
   |   TBD    |   Tunnel ID TLV                        | this document |
   |   TBD    |   LSP ID TLV                           | this document |
   |   TBD    |   IPv4/6 Tunnel Head-end address TLV   | this document |
   |   TBD    |   IPv4/6 Tunnel Tail-end address TLV   | this document |
   |   TBD    |   SR Policy CP Descriptor TLV          | this document |
   |   TBD    |   MPLS Local Cross Connect TLV         | this document |
   |   TBD    |   MPLS Cross Connect Interface TLV     | this document |
   |   TBD    |   MPLS Cross Connect FEC TLV           | this document |
   |   TBD    |   MPLS-TE Policy State TLV             | this document |
   |   TBD    |   SR BSID TLV                          | this document |
   |   TBD    |   SR CP State TLV                      | this document |
   |   TBD    |   SR CP Name TLV                       | this document |
   |   TBD    |   SR CP Constraints TLV                | this document |
   |   TBD    |   SR Segment List TLV                  | this document |
   |   TBD    |   SR Segment sub-TLV                   | this document |
   |   TBD    |   SR Segment List Metric sub-TLV       | this document |
   |   TBD    |   SR Affinity Constraint sub-TLV       | this document |
   |   TBD    |   SR SRLG Constraint sub-TLV           | this document |
   |   TBD    |   SR Bandwidth Constraint sub-TLV      | this document |
   |   TBD    |   SR Disjoint Group Constraint sub-TLV | this document |
   +----------+----------------------------------------+---------------+

9.4.  BGP-LS SR Policy Protocol Origin

   This document requests IANA to maintain a new sub-registry under
   "Border Gateway Protocol - Link State (BGP-LS) Parameters".  The new
   registry is called "SR Policy Protocol Origin" and contains the
   codepoints allocated to the "Protocol Origin" field defined in




Previdi, et al.         Expires December 31, 2018              [Page 41]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   Section 4.5.  The registry contains the following codepoints
   (suggested values, to be assigned by IANA):

+------------+---------------------------------------------------------+
| Code Point |                   Protocol Origin                       |
+------------+---------------------------------------------------------+
|     1      | PCEP                                                    |
|     2      | BGP SR Policy                                           |
|     3      | Local (via CLI, Yang model through NETCONF, gRPC, etc.) |
+------------+---------------------------------------------------------+

9.5.  BGP-LS TE State Path Origin

   This document requests IANA to maintain a new sub-registry under
   "Border Gateway Protocol - Link State (BGP-LS) Parameters".  The new
   registry is called "TE State Path Origin" and contains the codepoints
   allocated to the "Path Origin" field defined in Section 5.  The
   registry contains the following codepoints (suggested values, to be
   assigned by IANA):

               +----------+------------------+
               |  Code    |     Path         |
               |  Point   |     Origin       |
               +----------+------------------+
               |    1     | RSVP-TE          |
               |    2     | PCEP             |
               |    3     | Local/Static     |
               +----------+------------------+

9.6.  BGP-LS TE State Dataplane

   This document requests IANA to maintain a new sub-registry under
   "Border Gateway Protocol - Link State (BGP-LS) Parameters".  The new
   registry is called "TE State Dataplane" and contains the codepoints
   allocated to the "dataplane" field defined in Section 5.  The
   registry contains the following codepoints (suggested values, to be
   assigned by IANA):

               +----------+------------------+
               |  Code    |   Dataplane      |
               |  Point   |                  |
               +----------+------------------+
               |    1     | MPLS-IPv4        |
               |    2     | MPLS-IPv6        |
               +----------+------------------+






Previdi, et al.         Expires December 31, 2018              [Page 42]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


9.7.  BGP-LS SR Segment Descriptors

   This document requests IANA to maintain a new sub-registry under
   "Border Gateway Protocol - Link State (BGP-LS) Parameters".  The new
   registry is called "SR Segment Descriptor Types" and contains the
   codepoints allocated to the "Segment Type" field defined in
   Section 6.6 and described in Section 6.6.1.  The registry contains
   the following codepoints (suggested values, to be assigned by IANA):

+-------+--------------------------------------------------------------+
| Code  |   Segment Description                                        |
| Point |                                                              |
+-------+--------------------------------------------------------------+
|   0   | Invalid                                                      |
|   1   | SR-MPLS Label                                                |
|   2   | SRv6 SID as IPv6 address                                     |
|   3   | SR-MPLS Prefix SID as IPv4 Node Address                      |
|   4   | SR-MPLS Prefix SID as IPv6 Node Global Address               |
|   5   | SR-MPLS Adjacency SID as IPv4 Node Address & Local           |
|       | Interface ID                                                 |
|   6   | SR-MPLS Adjacency SID as IPv4 Local & Remote Interface       |
|       | Addresses                                                    |
|   7   | SR-MPLS Adjacency SID as pair of IPv6 Global Address &       |
|       | Interface ID for Local & Remote nodes                        |
|   8   | SR-MPLS Adjacency SID as pair of IPv6 Global Addresses for   |
|       | the Local & Remote Interface                                 |
|   9   | SRv6 END SID as IPv6 Node Global Address                     |
|  10   | SRv6 END.X SID as pair of IPv6 Global Address & Interface ID |
|       | for Local & Remote nodes                                     |
|  11   | SRv6 END.X SID as pair of IPv6 Global Addresses for the      |
|       | Local & Remote Interface                                     |
+-------+--------------------------------------------------------------+

9.8.  BGP-LS Metric Type

   This document requests IANA to maintain a new sub-registry under
   "Border Gateway Protocol - Link State (BGP-LS) Parameters".  The new
   registry is called "Metric Type" and contains the codepoints
   allocated to the "metric type" field defined in Section 6.7.  The
   registry contains the following codepoints (suggested values, to be
   assigned by IANA):










Previdi, et al.         Expires December 31, 2018              [Page 43]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   +------------+-----------------------------------------+
   | Code Point |         Metric Type                     |
   +------------+-----------------------------------------+
   |     0      | IGP Metric                              |
   |     1      | Min Unidirectional Link Delay [RFC7471] |
   |     2      | TE Metric [RFC3630]                     |
   +------------+-----------------------------------------+


10.  Security Considerations

   Procedures and protocol extensions defined in this document do not
   affect the BGP security model.  See [RFC6952] for details.

11.  Acknowledgements

   The authors would like to thank Dhruv Dhody, Mohammed Abdul Aziz
   Khalid, Lou Berger, Acee Lindem, Siva Sivabalan, Arjun Sreekantiah,
   and Dhanendra Jain for their review and valuable comments.

12.  Contributors

   The following people have substantially contributed to the editing of
   this document:

   Clarence Filsfils
   Cisco Systems
   Email: cfilsfil@cisco.com

13.  References

13.1.  Normative References

   [I-D.ietf-spring-segment-routing-policy]
              Filsfils, C., Sivabalan, S., daniel.voyer@bell.ca, d.,
              bogdanov@google.com, b., and P. Mattes, "Segment Routing
              Policy Architecture", draft-ietf-spring-segment-routing-
              policy-01 (work in progress), June 2018.

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

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



Previdi, et al.         Expires December 31, 2018              [Page 44]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


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

   [RFC3473]  Berger, L., Ed., "Generalized Multi-Protocol Label
              Switching (GMPLS) Signaling Resource ReserVation Protocol-
              Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
              DOI 10.17487/RFC3473, January 2003,
              <https://www.rfc-editor.org/info/rfc3473>.

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

   [RFC4760]  Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
              "Multiprotocol Extensions for BGP-4", RFC 4760,
              DOI 10.17487/RFC4760, January 2007,
              <https://www.rfc-editor.org/info/rfc4760>.

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

   [RFC4873]  Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel,
              "GMPLS Segment Recovery", RFC 4873, DOI 10.17487/RFC4873,
              May 2007, <https://www.rfc-editor.org/info/rfc4873>.

   [RFC4874]  Lee, CY., Farrel, A., and S. De Cnodder, "Exclude Routes -
              Extension to Resource ReserVation Protocol-Traffic
              Engineering (RSVP-TE)", RFC 4874, DOI 10.17487/RFC4874,
              April 2007, <https://www.rfc-editor.org/info/rfc4874>.

   [RFC5420]  Farrel, A., Ed., Papadimitriou, D., Vasseur, JP., and A.
              Ayyangarps, "Encoding of Attributes for MPLS LSP
              Establishment Using Resource Reservation Protocol Traffic
              Engineering (RSVP-TE)", RFC 5420, DOI 10.17487/RFC5420,
              February 2009, <https://www.rfc-editor.org/info/rfc5420>.

   [RFC5440]  Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
              Element (PCE) Communication Protocol (PCEP)", RFC 5440,
              DOI 10.17487/RFC5440, March 2009,
              <https://www.rfc-editor.org/info/rfc5440>.





Previdi, et al.         Expires December 31, 2018              [Page 45]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   [RFC7752]  Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
              S. Ray, "North-Bound Distribution of Link-State and
              Traffic Engineering (TE) Information Using BGP", RFC 7752,
              DOI 10.17487/RFC7752, March 2016,
              <https://www.rfc-editor.org/info/rfc7752>.

13.2.  Informative References

   [RFC2702]  Awduche, D., Malcolm, J., Agogbua, J., O'Dell, M., and J.
              McManus, "Requirements for Traffic Engineering Over MPLS",
              RFC 2702, DOI 10.17487/RFC2702, September 1999,
              <https://www.rfc-editor.org/info/rfc2702>.

   [RFC3630]  Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
              (TE) Extensions to OSPF Version 2", RFC 3630,
              DOI 10.17487/RFC3630, September 2003,
              <https://www.rfc-editor.org/info/rfc3630>.

   [RFC4202]  Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions
              in Support of Generalized Multi-Protocol Label Switching
              (GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005,
              <https://www.rfc-editor.org/info/rfc4202>.

   [RFC4655]  Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
              Element (PCE)-Based Architecture", RFC 4655,
              DOI 10.17487/RFC4655, August 2006,
              <https://www.rfc-editor.org/info/rfc4655>.

   [RFC6952]  Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
              BGP, LDP, PCEP, and MSDP Issues According to the Keying
              and Authentication for Routing Protocols (KARP) Design
              Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013,
              <https://www.rfc-editor.org/info/rfc6952>.

   [RFC7308]  Osborne, E., "Extended Administrative Groups in MPLS
              Traffic Engineering (MPLS-TE)", RFC 7308,
              DOI 10.17487/RFC7308, July 2014,
              <https://www.rfc-editor.org/info/rfc7308>.

   [RFC7471]  Giacalone, S., Ward, D., Drake, J., Atlas, A., and S.
              Previdi, "OSPF Traffic Engineering (TE) Metric
              Extensions", RFC 7471, DOI 10.17487/RFC7471, March 2015,
              <https://www.rfc-editor.org/info/rfc7471>.








Previdi, et al.         Expires December 31, 2018              [Page 46]


Internet-Draft  TE Policy State Distribution using BGP-LS      June 2018


   [RFC8231]  Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
              Computation Element Communication Protocol (PCEP)
              Extensions for Stateful PCE", RFC 8231,
              DOI 10.17487/RFC8231, September 2017,
              <https://www.rfc-editor.org/info/rfc8231>.

Authors' Addresses

   Stefano Previdi (editor)

   Email: stefano@previdi.net


   Ketan Talaulikar
   Cisco Systems, Inc.

   Email: ketant@cisco.com


   Jie Dong (editor)
   Huawei Technologies
   Huawei Campus, No. 156 Beiqing Rd.
   Beijing  100095
   China

   Email: jie.dong@huawei.com


   Mach(Guoyi) Chen
   Huawei Technologies
   Huawei Campus, No. 156 Beiqing Rd.
   Beijing  100095
   China

   Email: mach.chen@huawei.com


   Hannes Gredler
   RtBrick Inc.

   Email: hannes@rtbrick.com


   Jeff Tantsura
   Nuage Networks

   Email: jefftant.ietf@gmail.com




Previdi, et al.         Expires December 31, 2018              [Page 47]


Html markup produced by rfcmarkup 1.127, available from https://tools.ietf.org/tools/rfcmarkup/