Internet-Draft PCEP-SR-YANG October 2021
Li, et al. Expires 27 April 2022 [Page]
Workgroup:
PCE Working Group
Internet-Draft:
draft-li-pce-pcep-srv6-yang-05
Published:
Intended Status:
Standards Track
Expires:
Authors:
C. Li
Huawei Technologies
S. Sivabalan
Ciena Corporation
S. Peng
Huawei Technologies
M. Koldychev
Cisco Systems, Inc.
L. Ndifor
MTN Cameroon

A YANG Data Model for Segment Routing (SR) Policy and SRv6 support in Path Computation Element Communications Protocol (PCEP)

Abstract

This document augments a YANG data model for the management of Path Computation Element Communications Protocol (PCEP) for communications between a Path Computation Client (PCC) and a Path Computation Element (PCE), or between two PCEs in support for Segment Routing in IPv6 (SRv6) and SR Policy. The data model includes configuration data and state data (status information and counters for the collection of statistics).

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 27 April 2022.

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Table of Contents

1. Introduction

The Path Computation Element (PCE) defined in [RFC4655] is an entity that is capable of computing a network path or route based on a network graph, and applying computational constraints. A Path Computation Client (PCC) may make requests to a PCE for paths to be computed.

PCEP is the communication protocol between a PCC and PCE and is defined in [RFC5440]. PCEP interactions include path computation requests and path computation replies as well as notifications of specific states related to the use of a PCE in the context of Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering (TE). [RFC8231] specifies extensions to PCEP to enable stateful control of MPLS TE LSPs.

[I-D.ietf-pce-segment-routing-ipv6] extends [RFC8664] to support SR for IPv6 data plane.

[I-D.ietf-pce-pcep-yang] defines a YANG [RFC7950] data model for the management of PCEP speakers. This document contains a specification of the PCEP-SRv6 YANG module, "ietf-pcep-srv6" which provides the PCEP-SRv6 [I-D.ietf-pce-segment-routing-ipv6] data model. This document also contains the PCEP-SRPolicy YANG module, "ietf-pcep-srpolicy" which provides a reference to SR Policy [I-D.ietf-spring-segment-routing-policy].

The PCEP operational state is included in the same tree as the PCEP configuration consistent with Network Management Datastore Architecture (NMDA) [RFC8342]. The origin of the data is indicated as per the origin metadata annotation.

2. Requirements Language

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

3. Terminology and Notation

This document also uses the following terms defined in [RFC7420]:

Further, this document also uses the following terms defined in [RFC8231] :

[RFC8281] :

[RFC8408] :

[RFC8664] :

[I-D.ietf-pce-segment-routing-ipv6] :

[I-D.ietf-spring-segment-routing-policy] :

3.1. Tree Diagrams

A simplified graphical representation of the data model is used in this document. The meaning of the symbols in these diagrams is defined in [RFC8340].

3.2. Prefixes in Data Node Names

In this document, names of data nodes and other data model objects are often used without a prefix, as long as it is clear from the context in which YANG module each name is defined. Otherwise, names are prefixed using the standard prefix associated with the corresponding YANG module, as shown in Table 1.

Table 1: Prefixes and corresponding YANG modules
Prefix YANG module Reference
te-types ietf-te-types [RFC8776]
pcep ietf-pcep [I-D.ietf-pce-pcep-yang]
srv6-types ietf-srv6-types [I-D.ietf-spring-srv6-yang]
sr-policy ietf-sr-policy [I-D.ietf-spring-sr-policy-yang]
rt ietf-routing [RFC8349]

4. The Design of YANG Data Model

4.1. The Overview of PCEP SRv6 Data Model

The PCEP-SRv6 YANG module defined in this document has all the common building blocks for the PCEP-SRv6 extension.

module: ietf-pcep-srv6

  augment /pcep:pcep/pcep:entity/pcep:capability:
    +--rw srv6 {srv6}?
       +--rw enabled?     boolean
       +--rw nai?         boolean
       +--rw msd-limit?   boolean
       +--rw srv6-msd* [msd-type]
          +--rw msd-type     uint8
          +--rw msd-value?   uint8
  augment /pcep:pcep/pcep:entity/pcep:peers/pcep:peer
            /pcep:capability:
    +--rw srv6 {srv6}?
       +--rw enabled?     boolean
       +--rw nai?         boolean
       +--rw msd-limit?   boolean
       +--rw srv6-msd* [msd-type]
          +--rw msd-type     uint8
          +--rw msd-value?   uint8
  augment /pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp:
    +--ro srv6 {srv6}?
       +--ro segment-list
          +--ro segment* [index]
             +--ro index        uint32
             +--ro sid-value?   srv6-types:srv6-sid

4.2. The Overview of PCEP SR Policy Data Model

The PCEP-SRPolicy YANG module defined in this document has all the common building blocks for the PCEP-SR Policy extension.

module: ietf-pcep-srpolicy

  augment /pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp:
    +--ro sr-policy
       +--ro color?             leafref
       +--ro endpoint?          leafref
       +--ro protocol-origin?   leafref
       +--ro originator?        leafref
       +--ro discriminator?     leafref

The sr-policy container is applicable for both SR-MPLS and SRv6.

5. The YANG Modules

5.1. ietf-pcep-srv6 module

RFC Ed.: In this section, replace all occurrences of 'XXXX' with the actual RFC number and all occurrences of the revision date below with the date of RFC publication (and remove this note).

<CODE BEGINS> file "ietf-pcep-srv6@2021-10-23.yang"

module ietf-pcep-srv6 {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-pcep-srv6";
  prefix pcep-srv6;

  import ietf-srv6-types {
    prefix srv6-types;
    reference
      "I-D.ietf-spring-srv6-yang: YANG Data Model for SRv6
       Base and Static";
  }
  import ietf-te-types {
    prefix te-types;
    reference
      "RFC 8776: Common YANG Data Types for Traffic Engineering";
  }
  import ietf-pcep {
    prefix pcep;
    reference
      "I-D.ietf-pce-pcep-yang: A YANG Data Model for Path
       Computation Element Communications Protocol (PCEP)";
  }

  organization
    "IETF PCE (Path Computation Element) Working Group";
  contact
    "WG Web:   <http://tools.ietf.org/wg/pce/>
     WG List:  <mailto:pce@ietf.org>
     Editor:   Cheng Li
               <mailto:c.l@huawei.com>
               Shuping Peng
               <mailto:pengshuping@huawei.com>";
  description
    "The YANG module augments the PCEP YANG operational
     model with SRv6.

     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Simplified BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (https://trustee.ietf.org/license-info).
     This version of this YANG module is part of RFC XXXX; see the
     RFC itself for full legal notices.";

  revision 2021-10-23 {
    description
      "Initial revision.";
    reference
      "RFC XXXX:  A YANG Data Model for Segment Routing (SR) Policy
       and SRv6 support in Path Computation Element Communications
       Protocol (PCEP)";
  }

  /* Features */

  feature srv6 {
    description
      "Support Segment Routing in IPv6 (SRv6) for PCE.";
    reference
      "I-D.ietf-pce-segment-routing-ipv6: PCEP Extensions
       for Segment Routing leveraging the IPv6 data plane";
  }

  /* Identity */

  identity path-setup-srv6 {
    if-feature "srv6";
    base te-types:path-signaling-type;
    description
      "SRv6 path setup type";
  }

  /* Groupings */

  grouping srv6-msd {
    description
      "SRv6 MSD";
    leaf msd-type {
      type uint8;
      description
        "SRv6 Maximum Segment Depth (MSD) Type";
    }
    leaf msd-value {
      type uint8;
      description
        "SRv6 MSD value for the type";
    }
    reference
      "I-D.ietf-pce-segment-routing-ipv6: PCEP Extensions
       for Segment Routing leveraging the IPv6 data plane";
  }

  grouping srv6 {
    description
      "SRv6";
    container srv6 {
      if-feature "srv6";
      description
        "If SRv6 is supported";
      leaf enabled {
        type boolean;
        description
          "Enabled or Disabled; set to true when
           Enabled";
      }
      leaf nai {
        type boolean;
        default "false";
        description
          "True indicates capability to resolve Node or
           Adjacency Identifier (NAI) to SRv6 Segment
           Identifier (SID)";
      }
      leaf msd-limit {
        type boolean;
        default "false";
        description
          "True indicates no limit on MSD, the
           list srv6-msd is ignored";
      }
      list srv6-msd {
        key "msd-type";
        description
          "list of SRv6 MSD";
        uses srv6-msd;
      }
    }
  }

  grouping segment-list {
    description
      "Segment list grouping";
    container segment-list {
      description
        "Segments for given segment list";
      list segment {
        key "index";
        description
          "Configure Segment/hop at the index";
        uses segment-properties;
      }
    }
  }

  grouping segment-properties {
    description
      "Segment properties grouping";
    leaf index {
      type uint32;
      description
        "Segment index";
    }
    leaf sid-value {
      type srv6-types:srv6-sid;
      description
        "SRv6 SID value";
    }
    /*Query: Add NAI?*/
  }

  /*
   * Augment modules to add SRv6
   */

  augment "/pcep:pcep/pcep:entity/pcep:capability" {
    description
      "Augmenting SRv6";
    uses srv6;
  }

  augment "/pcep:pcep/pcep:entity/pcep:peers/pcep:peer"
        + "/pcep:capability" {
    description
      "Augmenting SRv6";
    uses srv6;
  }

  augment "/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp" {
    description
      "Augmenting SRv6";
    container srv6 {
      when
        "derived-from-or-self
         (/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp/pcep:pst,
          'path-setup-srv6')" {
        description
          "For SRv6 path";
      }
      if-feature "srv6";
      uses segment-list;
      description
        "SRv6";
    }
  }
}


<CODE ENDS>

5.2. ietf-pcep-srpolicy module

RFC Ed.: In this section, replace all occurrences of 'XXXX' with the actual RFC number and all occurrences of the revision date below with the date of RFC publication (and remove this note).

<CODE BEGINS> file "ietf-pcep-srpolicy@2021-10-23.yang"

module ietf-pcep-srpolicy {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-pcep-srpolicy";
  prefix pcep-srp;

  import ietf-pcep {
    prefix pcep;
    reference
      "I-D.ietf-pce-pcep-yang: A YANG Data Model for Path
       Computation Element Communications Protocol (PCEP)";
  }
  import ietf-sr-policy {
    prefix sr-policy;
    reference
      "I-D.ietf-spring-sr-policy-yang: YANG Data Model for
       Segment Routing Policy";
  }
  import ietf-routing {
    prefix rt;
    reference
      "RFC 8349: A YANG Data Model for Routing Management";
  }

  organization
    "IETF PCE (Path Computation Element) Working Group";
  contact
    "WG Web:   <http://tools.ietf.org/wg/pce/>
     WG List:  <mailto:pce@ietf.org>
     Editor:   Cheng Li
               <mailto:c.l@huawei.com>
               Shuping Peng
               <mailto:pengshuping@huawei.com>";
  description
    "The YANG module augments the PCEP YANG model with SR Policy.

     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.
     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Simplified BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (https://trustee.ietf.org/license-info).
     This version of this YANG module is part of RFC XXXX; see the
     RFC itself for full legal notices.";

  revision 2021-10-23 {
    description
      "Initial revision.";
    reference
      "RFC XXXX:  A YANG Data Model for Segment Routing (SR) Policy
       and SRv6 support in Path Computation Element Communications
       Protocol (PCEP)";
  }

  /* Groupings */

  grouping sr-policy-cp {
    description
      "Segment Routing Policy grouping";
    // Editor's Note - headend is missig in SR Policy
    //  Yang mode
    leaf color {
      type leafref {
        path "/rt:routing/sr-policy:segment-routing/"
           + "sr-policy:traffic-engineering/sr-policy:"
           + "policies/sr-policy:policy/sr-policy:"
           + "color";
      }
      description
        "SR Policy Color";
      reference
        "I-D.ietf-spring-segment-routing-policy: Segment
         Routing Policy Architecture";
    }
    leaf endpoint {
      type leafref {
        path "/rt:routing/sr-policy:segment-routing/"
           + "sr-policy:traffic-engineering/sr-policy:"
           + "policies/sr-policy:policy/sr-policy:"
           + "endpoint";
      }
      description
        "SR Policy Endpoint";
      reference
        "I-D.ietf-spring-segment-routing-policy: Segment
         Routing Policy Architecture";
    }
    leaf protocol-origin {
      type leafref {
        path "/rt:routing/sr-policy:segment-routing/"
           + "sr-policy:traffic-engineering/sr-policy:"
           + "policies/sr-policy:policy/sr-policy:"
           + "candidate-paths/sr-policy:"
           + "candidate-path/sr-policy:protocol-origin";
      }
      must '(. = "pcep")' {
        error-message "The protocol origin must be PCEP";
      }
      description
        "SR Policy Candidate Path Protocol";
      reference
        "I-D.ietf-spring-segment-routing-policy: Segment
         Routing Policy Architecture";
    }
    leaf originator {
      type leafref {
        path "/rt:routing/sr-policy:segment-routing/"
           + "sr-policy:traffic-engineering/sr-policy:"
           + "policies/sr-policy:policy/sr-policy:"
           + "candidate-paths/sr-policy:"
           + "candidate-path/sr-policy:originator";
      }
      description
        "SR Policy Candidate Path Originator";
      reference
        "I-D.ietf-spring-segment-routing-policy: Segment
         Routing Policy Architecture";
    }
    leaf discriminator {
      type leafref {
        path "/rt:routing/sr-policy:segment-routing/"
           + "sr-policy:traffic-engineering/sr-policy:"
           + "policies/sr-policy:policy/sr-policy:"
           + "candidate-paths/sr-policy:"
           + "candidate-path/sr-policy:discriminator";
      }
      description
        "SR Policy Candidate Path Discriminator";
      reference
        "I-D.ietf-spring-segment-routing-policy: Segment
         Routing Policy Architecture";
    }
  }

  augment "/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp" {
    description
      "Augmenting SR Policy";
    container sr-policy {
      when
        "derived-from-or-self
         (/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp/pcep:pst,
          'path-setup-sr') or
         derived-from-or-self
         (/pcep:pcep/pcep:entity/pcep:lsp-db/pcep:lsp/pcep:pst,
          'path-setup-srv6')" {
        description
          "Applicable for SR or SRv6";
      }
      uses sr-policy-cp;
      description
        "SR Policy Candidate Path";
    }
  }
}


<CODE ENDS>

6. Security Considerations

The YANG module defined in this document is designed to be accessed via network management protocol such as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer and the mandatory-to-implement secure transport is SSH [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446]

The NETCONF access control model [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a pre-configured subset of all available NETCONF or RESTCONF protocol operations and content.

There are a number of data nodes defined in the YANG module which are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., <edit-config>) to these data nodes without proper protection can have a negative effect on network operations. These are the subtrees and data nodes and their sensitivity/vulnerability:

Unauthorized access to above list can adversely affect the PCEP session between the local entity and the peers. This may lead to inability to compute new paths, stateful operations on the delegated as well as PCE-initiated LSPs.

Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes and their sensitivity/vulnerability:

7. IANA Considerations

This document registers a URI in the "IETF XML Registry" [RFC3688]. Following the format in RFC 3688, the following registration has been made.

URI:
urn:ietf:params:xml:ns:yang:ietf-pcep-srv6
Registrant Contact:
The PCE WG of the IETF.
XML:
N/A; the requested URI is an XML namespace.
URI:
urn:ietf:params:xml:ns:yang:ietf-pcep-srpolicy
Registrant Contact:
The PCE WG of the IETF.
XML:
N/A; the requested URI is an XML namespace.

This document registers a YANG module in the "YANG Module Names" registry [RFC6020].

    Name:         ietf-pcep-srv6
    Namespace:    urn:ietf:params:xml:ns:yang:ietf-pcep-srv6
    Prefix:       pcep-srv6
    Reference:    This I-D

    Name:         ietf-pcep-srpolicy
    Namespace:    urn:ietf:params:xml:ns:yang:ietf-pcep-srpolicy
    Prefix:       pcep-srp
    Reference:    This I-D

8. Acknowledgements

The authors would like to thank Dhruv Dhody for the initial YANG model.

9. References

9.1. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC3688]
Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, , <https://www.rfc-editor.org/info/rfc3688>.
[RFC5440]
Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, DOI 10.17487/RFC5440, , <https://www.rfc-editor.org/info/rfc5440>.
[RFC6020]
Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, , <https://www.rfc-editor.org/info/rfc6020>.
[RFC6241]
Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, , <https://www.rfc-editor.org/info/rfc6241>.
[RFC6242]
Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, , <https://www.rfc-editor.org/info/rfc6242>.
[RFC7950]
Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, , <https://www.rfc-editor.org/info/rfc7950>.
[RFC8040]
Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, , <https://www.rfc-editor.org/info/rfc8040>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
[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, , <https://www.rfc-editor.org/info/rfc8231>.
[RFC8281]
Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path Computation Element Communication Protocol (PCEP) Extensions for PCE-Initiated LSP Setup in a Stateful PCE Model", RFC 8281, DOI 10.17487/RFC8281, , <https://www.rfc-editor.org/info/rfc8281>.
[RFC8340]
Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, , <https://www.rfc-editor.org/info/rfc8340>.
[RFC8341]
Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, , <https://www.rfc-editor.org/info/rfc8341>.
[RFC8349]
Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for Routing Management (NMDA Version)", RFC 8349, DOI 10.17487/RFC8349, , <https://www.rfc-editor.org/info/rfc8349>.
[RFC8408]
Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J. Hardwick, "Conveying Path Setup Type in PCE Communication Protocol (PCEP) Messages", RFC 8408, DOI 10.17487/RFC8408, , <https://www.rfc-editor.org/info/rfc8408>.
[RFC8446]
Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, , <https://www.rfc-editor.org/info/rfc8446>.
[RFC8664]
Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., and J. Hardwick, "Path Computation Element Communication Protocol (PCEP) Extensions for Segment Routing", RFC 8664, DOI 10.17487/RFC8664, , <https://www.rfc-editor.org/info/rfc8664>.
[RFC8776]
Saad, T., Gandhi, R., Liu, X., Beeram, V., and I. Bryskin, "Common YANG Data Types for Traffic Engineering", RFC 8776, DOI 10.17487/RFC8776, , <https://www.rfc-editor.org/info/rfc8776>.
[I-D.ietf-spring-srv6-yang]
Raza, K., Agarwal, S., Liu, X., Hu, Z., Hussain, I., Shah, H., Voyer, D., Matsushima, S., Horiba, K., AbdelSalam, A., and J. Rajamanickam, "YANG Data Model for SRv6 Base and Static", Work in Progress, Internet-Draft, draft-ietf-spring-srv6-yang-00, , <https://www.ietf.org/archive/id/draft-ietf-spring-srv6-yang-00.txt>.
[I-D.ietf-pce-pcep-yang]
Dhody, D., Hardwick, J., Beeram, V. P., and J. Tantsura, "A YANG Data Model for Path Computation Element Communications Protocol (PCEP)", Work in Progress, Internet-Draft, draft-ietf-pce-pcep-yang-16, , <https://www.ietf.org/archive/id/draft-ietf-pce-pcep-yang-16.txt>.
[I-D.ietf-pce-segment-routing-ipv6]
Li, C., Negi, M., Sivabalan, S., Koldychev, M., Kaladharan, P., and Y. Zhu, "PCEP Extensions for Segment Routing leveraging the IPv6 data plane", Work in Progress, Internet-Draft, draft-ietf-pce-segment-routing-ipv6-09, , <https://www.ietf.org/internet-drafts/draft-ietf-pce-segment-routing-ipv6-09.txt>.
[I-D.ietf-spring-sr-policy-yang]
Raza, K., Sawaya, R., Shunwan, Z., Voyer, D., Durrani, M., Matsushima, S., and V. P. Beeram, "YANG Data Model for Segment Routing Policy", Work in Progress, Internet-Draft, draft-ietf-spring-sr-policy-yang-01, , <https://www.ietf.org/archive/id/draft-ietf-spring-sr-policy-yang-01.txt>.

9.2. Informative References

[RFC4655]
Farrel, A., Vasseur, J.-P., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC 4655, DOI 10.17487/RFC4655, , <https://www.rfc-editor.org/info/rfc4655>.
[RFC7420]
Koushik, A., Stephan, E., Zhao, Q., King, D., and J. Hardwick, "Path Computation Element Communication Protocol (PCEP) Management Information Base (MIB) Module", RFC 7420, DOI 10.17487/RFC7420, , <https://www.rfc-editor.org/info/rfc7420>.
[RFC8342]
Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, , <https://www.rfc-editor.org/info/rfc8342>.
[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and P. Mattes, "Segment Routing Policy Architecture", Work in Progress, Internet-Draft, draft-ietf-spring-segment-routing-policy-13, , <https://www.ietf.org/archive/id/draft-ietf-spring-segment-routing-policy-13.txt>.

Authors' Addresses

Cheng Li
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing
100095
China
Siva Sivabalan
Ciena Corporation
Shuping Peng
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing
100095
China
Mike Koldychev
Cisco Systems, Inc.
Luc-Fabrice Ndifor
MTN Cameroon
Cameroon