draft-dhody-pce-pcep-srv6-yang-00.txt

PCE Working Group                                          D. Dhody, Ed.
Internet-Draft                                       Huawei Technologies
Intended status: Standards Track                            S. Sivabalan
Expires: April 22, 2019                              Cisco Systems, Inc.
                                                        October 19, 2018


  A YANG Data Model for Segment Routing in IPv6 (SRv6) support in Path
           Computation Element Communications Protocol (PCEP)
                   draft-dhody-pce-pcep-srv6-yang-00

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.  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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 22, 2019.

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



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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Terminology and Notation  . . . . . . . . . . . . . . . . . .   3
     3.1.  Tree Diagrams . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Prefixes in Data Node Names . . . . . . . . . . . . . . .   4
   4.  The Design of PCEP-SRv6 Data Model  . . . . . . . . . . . . .   4
     4.1.  The Overview of PCEP SRv6 Data Model  . . . . . . . . . .   4
   5.  PCEP-SRv6 YANG Modules  . . . . . . . . . . . . . . . . . . .   5
     5.1.  ietf-pcep-srv6 module . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

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.negi-pce-segment-routing-ipv6] extends
   [I-D.ietf-pce-segment-routing] 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.negi-pce-segment-routing-ipv6] data model.





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   The PCEP operational state is included in the same tree as the PCEP
   configuration consistent with Network Management Datastore
   Architecture [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]:

   o  PCEP entity: a local PCEP speaker.

   o  PCEP peer: to refer to a remote PCEP speaker.

   o  PCEP speaker: where it is not necessary to distinguish between
      local and remote.

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

   o  Stateful PCE, Passive Stateful PCE, Active Stateful PCE

   o  Delegation, Revocation, Redelegation

   o  LSP State Report, Path Computation Report message (PCRpt).

   o  LSP State Update, Path Computation Update message (PCUpd).

   [RFC8281] :

   o  PCE-initiated LSP, Path Computation LSP Initiate Message
      (PCInitiate).

   [RFC8408] :

   o  Path Setup Type (PST).

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

   o  Segment Routing (SR).




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

   o  Segment Routing in IPv6 (SRv6).

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.

       +----------+-----------------+-----------------------------+
       | Prefix   | YANG module     | Reference                   |
       +----------+-----------------+-----------------------------+
       | te-types | ietf-te-types   | [I-D.ietf-teas-yang-te]     |
       | p        | ietf-pcep       | [I-D.ietf-pce-pcep-yang]    |
       | st       | ietf-srv6-types | [I-D.raza-spring-srv6-yang] |
       +----------+-----------------+-----------------------------+

             Table 1: Prefixes and corresponding YANG modules

4.  The Design of PCEP-SRv6 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 extention.

















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   module: ietf-pcep-srv6
     augment /p:pcep/p:entity/p:capability:
       +--rw srv6 {srv6}?
          +--rw enabled?    boolean
          +--rw max-sl?     uint8
          +--rw sl-limit?   boolean
     augment /p:pcep/p:entity/p:peers/p:peer/p:capability:
       +--rw srv6 {srv6}?
          +--rw enabled?    boolean
          +--rw max-sl?     uint8
          +--rw sl-limit?   boolean
     augment /p:pcep/p:entity/p:lsp-db/p:lsp:
       +--ro srv6 {srv6}?
          +--ro segment-list
             +--ro segment* [index]
                +--ro index        uint32
                +--ro sid-value?   st:srv6-sid
     groupings:
     segment-list
         +---- segment-list
            +---- segment* [index]
               +---- index?       uint32
               +---- sid-value?   st:srv6-sid

     segment-properties
         +---- index?       uint32
         +---- sid-value?   st:srv6-sid

     srv6
         +---- srv6 {srv6}?
            +---- enabled?    boolean
            +---- max-sl?     uint8
            +---- sl-limit?   boolean


5.  PCEP-SRv6 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@2018-10-19.yang"
   module ietf-pcep-srv6 {

       yang-version 1.1;



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       namespace "urn:ietf:params:xml:ns:yang:ietf-pcep-srv6";
       prefix ps;


       import ietf-srv6-types {
           prefix "st";
           reference "RFC XXXX";
       }

       import ietf-te-types {
          prefix "te-types";
          reference "RFC XXXX";
       }

       import ietf-pcep {
          prefix "p";
          reference "RFC XXXX";
       }


       organization
           "IETF PCE (Path Computation Element) Working Group";

       contact
           "WG Web:   <http://tools.ietf.org/wg/pce/>
            WG List:  <mailto:pce@ietf.org>
            Editor:   Dhruv Dhody
                      <mailto:dhruv.ietf@gmail.com>";
       description
           "The YANG module augments the PCEP yang operational
           model with SRv6";


       revision 2018-10-19 {
           description "Initial revision.";
           reference
               "RFC XXXX:  A YANG Data Model for Path Computation
                           Element Communications Protocol
                           (PCEP) - Segement Routing in IPv6
                           (SRv6)";
       }

       /* Identity */
       identity path-setup-srv6 {
           base te-types:path-signaling-type;
           description
             "SRv6 path setup type";
       }



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       /* Features */
       feature srv6 {
           description
               "Support Segment Routing in IPv6 (SRv6) for PCE.";
       }

       /* Groupings */
       grouping srv6 {
           description
               "SRv6";
           container srv6 {
               if-feature srv6;
               description
                   "If SRv6 is supported";
               leaf enabled{
                   type boolean;
                   description
                       "Enabled or Disabled";
               }
               leaf max-sl {
                   type uint8;
                   description
                       "Max value of the segment left field in SRH";
               }
               leaf sl-limit{
                   type boolean;
                   default false;
                   description
                       "True indicates no limit on SL, the
                       leaf max-sl is ignored";
               }
           }
       }

       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;
               }
           }
       }



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       grouping segment-properties {
           description "Segment properties grouping";
           leaf index {
               type uint32;
               description "Segment index";
           }
           leaf sid-value {
               type st:srv6-sid;
               description "SRv6 SID value";
           }
       }


       /*
        * Augment modules to add SRv6
        */
       augment "/p:pcep/p:entity/p:capability"{
           description
               "Augmenting SRv6";
           uses srv6;
       }
       augment "/p:pcep/p:entity/p:peers/p:peer/p:capability"{
           description
               "Augmenting SRv6";
           uses srv6;
       }
       augment "/p:pcep/p:entity/p:lsp-db/p:lsp"{
           description
               "Augmenting SRv6";
           container srv6 {
               when "/p:pcep/p:entity/p:lsp-db/p:lsp/p:pst
                     = 'path-setup-srv6'" {
                   description
                       "For SRv6 path";
               }
               if-feature srv6;
               uses segment-list;
               description
                   "SRv6";
           }
       }

   }//module

   <CODE ENDS>






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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:

      /p:pcep/p:entity/p:capability/ps:srv6 - configure local SRv6
      capability and parameters.

      /p:pcep/p:entity/p:peers/p:peer/p:capability/ps:srv6 - configure
      peer's SRv6 capability and parameters.

   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:

      /p:pcep/p:entity/p:lsp-db/p:lsp/ps:srv6 - The SRv6 SID in the
      network.  Unauthorized access to this could provide the all path
      and network usage information.

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.



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   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.

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

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

8.  Acknowledgements

9.  References

9.1.  Normative References

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

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <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, March 2009,
              <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, October 2010,
              <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, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.




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   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <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,
              May 2017, <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, September 2017,
              <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, December 2017,
              <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, March 2018,
              <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, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [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,
              July 2018, <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, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

   [I-D.ietf-teas-yang-te]
              Saad, T., Gandhi, R., Liu, X., Beeram, V., Shah, H., and
              I. Bryskin, "A YANG Data Model for Traffic Engineering
              Tunnels and Interfaces", draft-ietf-teas-yang-te-16 (work
              in progress), July 2018.




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   [I-D.ietf-pce-segment-routing]
              Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
              and J. Hardwick, "PCEP Extensions for Segment Routing",
              draft-ietf-pce-segment-routing-14 (work in progress),
              October 2018.

   [I-D.raza-spring-srv6-yang]
              Raza, K., Rajamanickam, J., Liu, X., Hu, Z., Hussain, I.,
              Shah, H., daniel.voyer@bell.ca, d., Elmalky, H.,
              Matsushima, S., Horiba, K., and A. Abdelsalam, "YANG Data
              Model for SRv6 Base and Static", draft-raza-spring-
              srv6-yang-01 (work in progress), March 2018.

   [I-D.ietf-pce-pcep-yang]
              Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A
              YANG Data Model for Path Computation Element
              Communications Protocol (PCEP)", draft-ietf-pce-pcep-
              yang-09 (work in progress), October 2018.

   [I-D.negi-pce-segment-routing-ipv6]
              Negi, M., Kaladharan, P., Dhody, D., and S. Sivabalan,
              "PCEP Extensions for Segment Routing leveraging the IPv6
              data plane", draft-negi-pce-segment-routing-ipv6-02 (work
              in progress), June 2018.

9.2.  Informative References

   [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>.

   [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, December 2014,
              <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, March 2018,
              <https://www.rfc-editor.org/info/rfc8342>.

Authors' Addresses







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   Dhruv Dhody (editor)
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore, Karnataka  560066
   India

   EMail: dhruv.ietf@gmail.com


   Siva Sivabalan
   Cisco Systems, Inc.
   2000 Innovation Drive
   Kanata, Ontario  K2K 3E8
   Canada

   EMail: msiva@cisco.com



































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