Internet                                                       A. Lindem
Internet-Draft                                              S. Litkowski
Intended status: Standards Track                           Cisco Systems
Expires: 25 June 7 September 2022                                          Y. Qu
                                                               Futurewei
                                                        22 December 2021
                                                            6 March 2022

   IS-IS YANG Model Augmentations for Additional Features - Version 1
              draft-ietf-lsr-isis-yang-augmentation-v1-02
              draft-ietf-lsr-isis-yang-augmentation-v1-03

Abstract

   This document defines YANG data modules augmenting the IETF IS-IS
   YANG model to provide support for IS-IS Minimum Remaining Lifetime as
   defined in RFC 7987, and IS-IS Application-Specific Link Attributes as
   defined in RFC 8919. 8919, and IS-IS Flexible Algorithm.

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 25 June 7 September 2022.

Copyright Notice

   Copyright (c) 2021 2022 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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Tree diagram  . . . . . . . . . . . . . . . . . . . . . .   3
   2.  YANG Module for IS-IS Minimum Remaining Lifetime  . . . . . .   3
   3.  YANG Module for IS-IS Application-Specific Link Attributes  .   5
   4.  YANG Module for IS-IS Flexible Algorithm  . . . . . . . . . .  14
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  25  26
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  26  27
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  27  28
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  27  28
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  27  28
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  29  30
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  29  30

1.  Overview

   YANG [RFC7950] is a data definition language used to define the
   contents of a conceptual data store that allows networked devices to
   be managed using NETCONF [RFC6241].  YANG is proving relevant beyond
   its initial confines, as bindings to other interfaces (e.g., ReST)
   and encodings other than XML (e.g., JSON) are being defined.
   Furthermore, YANG data models can be used as the basis for
   implementation of other interfaces, such as CLI and programmatic
   APIs.

   This document defines YANG data modules augmenting the IETF IS-IS
   YANG model [I-D.ietf-isis-yang-isis-cfg], which itself augments
   [RFC8349], to provide support for configuration and operational state
   for the following IS-IS features:

   RFC7987:  IS-IS Minimum Remaining Lifetime[RFC7987].

   RFC8919:  IS-IS Application-Specific Link Attributes[RFC8919].

   RFCxxxx:  IGP Flexible Algorithm [I-D.ietf-lsr-flex-algo].

   The augmentations defined in this document requires support for the
   IS-IS base model[I-D.ietf-isis-yang-isis-cfg] which defines basic IS-
   IS configuration and state.  The IS-IS YANG model augments the ietf-
   routing YANG model defined in [RFC8349].

1.1.  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.

1.2.  Tree diagram

   Tree diagrams used in this document follow the notation defined in
   [RFC8340].

2.  YANG Module for IS-IS Minimum Remaining Lifetime

   This document defines a YANG module for IS-IS Minimum Remaining
   Lifetime as defined in [RFC7987].  It is an augmentation of the IS-IS
   base model.

   module: ietf-isis-remaining-lifetime

     notifications:
       +---n corrupt-remaining-lifetime
          +--ro routing-protocol-name?   -> /rt:routing
                                            /control-plane-protocols
                                            /control-plane-protocol/name
          +--ro isis-level?              level
          +--ro lsp-id?                  isis:lsp-id

   <CODE BEGINS> file "ietf-isis-remaining-lifetime@2021-12-22.yang"
   module ietf-isis-remaining-lifetime {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-isis-remaining-lifetime";

     prefix isis-remaining-lifetime;

     import ietf-isis {
       prefix "isis";
     }

     organization
       "IETF LSR - Link State Routing Working Group";

     contact
        "WG Web:   <http://tools.ietf.org/wg/lsr>
         WG List:  <mailto:lsr@ietf.org>
         Author:   Yingzhen Qu
                   <mailto:yqu@futurewei.com>
         Author:   Acee Lindem
                   <mailto:acee@cisco.com>
         Author:   Stephane Litkowski
                   <mailto:slitkows.ietf@gmail.com>";

     description
       "This YANG module defines the configuration and operational
        state for IS-IS Minimum Remaining Lifetime feature as defined
        in RFC 7987.

        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 Revised BSD License set
        forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (http://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC XXXX;
        see the RFC itself for full legal notices.";

     reference "RFC XXXX";

     revision 2021-12-22 {
       description
         "Initial version";
       reference
         "RFC XXXX: A YANG Data Model for IS-IS Minimum Remaining Lifetime.";
     }

     notification corrupt-remaining-lifetime {
       uses isis:notification-instance-hdr;
       leaf lsp-id {
         type isis:lsp-id;
         description "LSP ID";
       }
       description
         "This notification is sent when the system
          detects corrupted lifetime of an LSP.";
       reference "RFC 7987: IS-IS Minimum Remaining Lifetime";
     }
   }
   <CODE ENDS>

3.  YANG Module for IS-IS Application-Specific Link Attributes

   This document defines a YANG module for IS-IS Application-Specific
   Link Attributes [RFC8919].  It is an augmentation of the IS-IS base
   model.

   module: ietf-isis-link-attr
     augment /rt:routing/rt:control-plane-protocols
             /rt:control-plane-protocol/isis:isis/isis:interfaces
             /isis:interface:
       +--rw isis-link-attr
          +--rw (link-attr-op-mode)
             +--:(legacy)
             |  +--rw legacy?         empty
             +--:(transition)
             |  +--rw transition?     empty
             +--:(app-specific)
                +--rw app-specific?   empty
     augment /rt:routing/rt:control-plane-protocols
             /rt:control-plane-protocol/isis:isis/isis:database
             /isis:levels/isis:lsp/isis:extended-is-neighbor
             /isis:neighbor/isis:instances/isis:instance:
       +--ro application-specific-link-attributes-sub-tlvs
          +--ro asla-sub-tlvs* []
             +--ro l-flag?         boolean
             +--ro sabm-length?    uint8
             +--ro r-flag?         boolean
             +--ro udabm-length?   uint8
             +--ro sabm
             |  +--ro sabm-bits*   identityref
             +--ro udabm
             +--ro unknown-tlvs
                +--ro unknown-tlv* []
                   +--ro type?     uint16
                   +--ro length?   uint16
                   +--ro value?    yang:hex-string
     augment /rt:routing/rt:control-plane-protocols
             /rt:control-plane-protocol/isis:isis/isis:database
             /isis:levels/isis:lsp/isis:mt-is-neighbor/isis:neighbor
             /isis:instances/isis:instance:
       +--ro application-specific-link-attributes-sub-tlvs
          +--ro asla-sub-tlvs* []
             +--ro l-flag?         boolean
             +--ro sabm-length?    uint8
             +--ro r-flag?         boolean
             +--ro udabm-length?   uint8
             +--ro sabm
             |  +--ro sabm-bits*   identityref
             +--ro udabm
             +--ro unknown-tlvs
                +--ro unknown-tlv* []
                   +--ro type?     uint16
                   +--ro length?   uint16
                   +--ro value?    yang:hex-string
     augment /rt:routing/rt:control-plane-protocols
             /rt:control-plane-protocol/isis:isis/isis:database
             /isis:levels/isis:lsp:
       +--ro application-specific-srlg-tlv
          +--ro as-srlg-tlvs* []
             +--ro neighbor-system-id?   isis:system-id
             +--ro pseudo-node-id?       uint8
             +--ro l-flag?               boolean
             +--ro sabm-length?          uint8
             +--ro r-flag?               boolean
             +--ro udabm-length?         uint8
             +--ro sabm
             |  +--ro sabm-bits*   identityref
             +--ro udabm
             +--ro length-of-sub-tlvs?   uint8
             +--ro link-id-sub-tlvs
             |  +--ro link-local-remote-ids
             |  |  +--ro link-local-id?    union
             |  |  +--ro link-remote-id?   union
             |  +--ro ipv4-interface-addr
             |  |  +--ro ipv4-int-addr?   inet:ipv4-address
             |  +--ro ipv4-neighbor-addr
             |  |  +--ro ipv4-neighbor-addr?   inet:ipv4-address
             |  +--ro ipv6-interface-addr
             |  |  +--ro ipv6-int-addr?   inet:ipv6-address
             |  +--ro ipv6-neighbor-addr
             |     +--ro ipv6-neighbor-addr?   inet:ipv6-address
             +--ro srlgs
                +--ro srlg*   uint32

   <CODE BEGINS> file "ietf-isis-link-attr@2021-12-22.yang" "ietf-isis-link-attr@2022-03-06.yang"
   module ietf-isis-link-attr {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-isis-link-attr";

     prefix isis-link-attr;

     import ietf-inet-types {
       prefix inet;
       reference "RFC 6991 - Common YANG Data Types";
     }
     import ietf-routing {
       prefix "rt";
     }

     import ietf-isis {
       prefix "isis";
     }

     organization
       "IETF LSR - Link State Routing Working Group";

     contact
        "WG Web:   <http://tools.ietf.org/wg/lsr>
         WG List:  <mailto:lsr@ietf.org>

         Author:   Yingzhen Qu
                   <mailto:yqu@futurewei.com>
         Author:   Acee Lindem
                   <mailto:acee@cisco.com>
         Author:   Stephane Litkowski
                   <mailto:slitkows.ietf@gmail.com>";

     description
       "This YANG module defines the configuration and operational
        state for IS-IS application specific link attributes feature as
        defined in RFC 8919.

        This YANG model conforms to the Network Management
        Datastore Architecture (NMDA) as described in RFC 8342.

        Copyright (c) 2021 2022 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 Revised BSD License set
        forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (http://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC XXXX;
        see the RFC itself for full legal notices.

        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 (RFC 2119) (RFC 8174) when, and only when,
        they appear in all capitals, as shown here.";

     reference "RFC XXXX";

     revision 2021-12-22 2022-03-06 {
       description
         "Initial version";
       reference
         "RFC XXXX: A YANG Data Model for IS-IS Application-Specific Link
          Attributes.";
     }

     identity sabm-bit {
       description
         "Base identity for sabm bits.";
       reference "RFC 8919: IS-IS Application-Specific Link Attributes";
     }

     identity rsvp-te-bit {
       base sabm-bit;
       description
         "R bit, RSVP-TE.";
     }

     identity sr-policy-bit {
       base sabm-bit;
       description
         "S bit, Segment Routing Policy.";
     }

     identity lfa-bit {
       base sabm-bit;
       description
         "F bit, Loop Free Alternate (LFA). Includes all LFA types.";
     }

     grouping application-identifier-bit-mask {
       description
         "Identification of the set of applications associated with link
          attribute advertisements";

       leaf l-flag {
         type boolean;
         description
           "Legacy Flag. When set, all of the applications
            specified in the bit mask MUST use the legacy
            advertisements.";
       }
       leaf sabm-length {
         type uint8;
         description
           "Standard Application Identifier Bit Mask Length in
            octets.";
       }
       leaf r-flag {
         type boolean;
         default false;
         description
           "Reserved.";
       }
       leaf udabm-length {
         type uint8;
         description
         "User Defined Application Identifier Bit Mask Length
         in octets.";
       }
       container sabm {
         leaf-list sabm-bits {
           type identityref {
             base sabm-bit;
           }
           description
             "SABM bits list. This list will contain
              identities for the bits which are set in the
              SABA bits.";
         }
         description
           "Standard Application Identifier Bit Mask.";
       }
       container udabm {
         description
           "User Defined Application Identifier Bit Mask.
            This container is to be augmented by user defined
            applications.";
       }
     }

     grouping application-specific-link-attributes-sub-tlv {
       description
         "Grouping for specification of the applications and
          application-specific attribute values.";

       container application-specific-link-attributes-sub-tlvs {
         list asla-sub-tlvs {
           uses application-identifier-bit-mask;
           uses isis:unknown-tlvs;
           description
             "List of application specific link attributes sub-tlvs.";

         }
         description
           "Application specific link attributes sub-tlv.";
       }
     }

     grouping application-specific-srlg-tlv {
       description
         "Grouping of a TLV to advertise application-specific
          SRLGs for a given link.";
       container application-specific-srlg-tlv {
         list as-srlg-tlvs {
           leaf neighbor-system-id {
             type isis:system-id;
             description
               "Neighbor System-ID.";
           }
           leaf pseudo-node-id {
             type uint8;
             description
               "Pseudo-node ID.";
           }
           uses application-identifier-bit-mask;
           leaf length-of-sub-tlvs {
             type uint8;
             description
               "Length of sub-tlvs.";
           }

           container link-id-sub-tlvs {
             description
               "Link Identifier sub-TLVs.";
             container link-local-remote-ids {
               description
                 "Link local/remote identifier sub-tlv.";
               leaf link-local-id {
                 type union {
                   type inet:ipv4-address;
                   type uint32;
                 }
                 description
                   "Local identifier of the link.
                    It could be an IPv4 address or a local identifier.";
               }
               leaf link-remote-id {
                 type union {
                   type inet:ipv4-address;
                   type uint32;

                 }
                 description
                   "Remote identifier of the link.
                   It could be an IPv4 address or a remotely learned
                   identifier.";
               }
             }
             container ipv4-interface-addr {
               leaf ipv4-int-addr {
                 type inet:ipv4-address;
                 description
                   "IPv4 address for the interface.";
               }
               description
                 "IPv4 interface address sub-tlv.";
             }
             container ipv4-neighbor-addr {
               leaf ipv4-neighbor-addr {
                 type inet:ipv4-address;
                 description
                   "IPv4 address for a neighboring router
                   on this link.";
               }
               description
                 "IPv4 neighbor address sub-tlv.";
             }
             container ipv6-interface-addr {
               leaf ipv6-int-addr {
                 type inet:ipv6-address;
                 description
                   "IPv6 address for the interface.";
               }
               description
                 "IPv6 interface address sub-tlv.";
             }
             container ipv6-neighbor-addr {
               leaf ipv6-neighbor-addr {
                 type inet:ipv6-address;
                 description
                   "IPv6 address for a neighboring router
                   on this link.";
               }
               description
                 "IPv6 neighbor address sub-tlv.";
             }
           }

           container srlgs {
             description "List of SRLGs.";
             leaf-list srlg {
               type uint32;
               description
                 "SRLG value of the link.";
             }
           }

           description
             "List of application specific SRLG tlvs.";
         }
         description
           "Application specific SRLG tlv.";
       }
     }

     augment "/rt:routing/" +
             "rt:control-plane-protocols/rt:control-plane-protocol"+
             "/isis:isis/isis:interfaces/isis:interface" {
       when "/rt:routing/rt:control-plane-protocols/"+
                        "rt:control-plane-protocol/rt:type = 'isis:isis'" {
         description
           "This augment ISIS routing protocol when used.";
       }
       description
         "This augments ISIS protocol configuration
          with TE attributes per application.";

       container isis-link-attr {
         choice link-attr-op-mode {
           mandatory "true";
           leaf legacy {
             type empty;
             description
               "Only send legacy advertisements.";
           }
           leaf transition {
             type empty;
             description
               "Send both application-specific and legacy advertisements.";
           }
           leaf app-specific{
             type empty;
             description
               "Only send application-specific advertisements.";
           }
           description
             "Link attributes mode";

         }
         description
           "Link attributes operation mode.";
       }
     }

     /* TLV 22 */
     augment "/rt:routing/" +
             "rt:control-plane-protocols/rt:control-plane-protocol"+
             "/isis:isis/isis:database/isis:levels/isis:lsp"+
             "/isis:extended-is-neighbor/isis:neighbor"+
             "/isis:instances/isis:instance" {
       when "/rt:routing/rt:control-plane-protocols/"+
            "rt:control-plane-protocol/rt:type = 'isis:isis'" {
         description
           "This augment ISIS routing protocol when used";
       }
       description
         "This augments ISIS protocol LSDB TLV22.";

          uses application-specific-link-attributes-sub-tlv;
     }

     /* TLV 223 */
     augment "/rt:routing/" +
             "rt:control-plane-protocols/rt:control-plane-protocol"+
             "/isis:isis/isis:database/isis:levels/isis:lsp"+
             "/isis:mt-is-neighbor/isis:neighbor"+
             "/isis:instances/isis:instance" {
       when "/rt:routing/rt:control-plane-protocols/"+
            "rt:control-plane-protocol/rt:type = 'isis:isis'" {
         description
           "This augment ISIS routing protocol when used";
       }
       description
         "This augments ISIS protocol LSDB TLV22."; TLV223.";

          uses application-specific-link-attributes-sub-tlv;
     }

     /* application-specific SRLG TLV 238 */
     augment "/rt:routing/" +
             "rt:control-plane-protocols/rt:control-plane-protocol"+
             "/isis:isis/isis:database/isis:levels/isis:lsp" {
       when "/rt:routing/rt:control-plane-protocols/"+
            "rt:control-plane-protocol/rt:type = 'isis:isis'" {
         description
           "This augment ISIS routing protocol when used";

       }
       description
         "This augments ISIS protocol LSDB router capability."; LSDB.";

       uses application-specific-srlg-tlv;
     }

   }
   <CODE ENDS>

4.  YANG Module for IS-IS Flexible Algorithm

   This document defines a YANG module for IS-IS Flexible Algorithm
   [I-D.ietf-lsr-flex-algo].  It is an augmentation of the IS-IS base
   model.

   module: ietf-isis-flex-algo
     augment /rt:routing/rt:control-plane-protocols
             /rt:control-plane-protocol/isis:isis:
       +--rw isis-flex-algo
          +--rw flex-algo* [algo-number]
             +--rw algo-number             uint8
             +--rw advertise-definition?   boolean
             +--rw admin-groups {te-types:extended-admin-groups,
                                 te-types:named-extended-admin-groups}?
             |  +--rw exclude-admin-groups*   -> /te:te/globals
                                                 /named-admin-groups
                                                 /named-admin-group/name
             |  +--rw include-any-admin-groups*   -> /te:te/globals
                                                 /named-admin-groups
                                                 /named-admin-group/name
             |  +--rw include-all-admin-groups*   -> /te:te/globals
                                                 /named-admin-groups
                                                 /named-admin-group/name
             +--rw exclude-srlgs*   -> /te:te/globals
                                       /named-srlgs/named-srlg/name
                                       {te-types:named-srlg-groups}?
             +--rw fast-reroute?           boolean
             +--rw metric-type?            identityref
             +--rw microloop-avoidance?    boolean
             +--rw prefix-metric!
             +--rw priority?               uint8
     augment /rt:routing/rt:control-plane-protocols
             /rt:control-plane-protocol/isis:isis/isis:database
             /isis:levels/isis:lsp/isis:router-capabilities:
       +--ro fad-tlvs
          +--ro fad-tlv* []
             +--ro flex-algo?              uint8
             +--ro metric-type?            identityref
             +--ro calc-type?              uint8
             +--ro priority?               uint8
             +--ro fa-ex-ag-sub-tlv
             |  +--ro extended-admin-groups*   uint64
             +--ro fa-in-any-ag-sub-tlv
             |  +--ro extended-admin-groups*   uint64
             +--ro fa-in-all-ag-sub-tlv
             |  +--ro extended-admin-groups*   uint64
             +--ro fad-flags-sub-tlv
             |  +--ro fad-flags*   identityref
             +--ro fa-ex-srlg-sub-tlv
             |  +--ro srlgs*   uint32
             +--ro unknown-tlvs
                +--ro unknown-tlv* []
                   +--ro type?     uint16
                   +--ro length?   uint16
                   +--ro value?    yang:hex-string
     augment /rt:routing/rt:control-plane-protocols
             /rt:control-plane-protocol/isis:isis/isis:database
             /isis:levels/isis:lsp/isis:extended-ipv4-reachability
             /isis:prefixes:
       +--ro fapm-sub-tlvs
          +--ro fapm-sub-tlv* []
             +--ro flex-algo?   uint8
             +--ro metric?      uint32
     augment /rt:routing/rt:control-plane-protocols
             /rt:control-plane-protocol/isis:isis/isis:database
             /isis:levels/isis:lsp/isis:mt-extended-ipv4-reachability
             /isis:prefixes:
       +--ro fapm-sub-tlvs
          +--ro fapm-sub-tlv* []
             +--ro flex-algo?   uint8
             +--ro metric?      uint32
     augment /rt:routing/rt:control-plane-protocols
             /rt:control-plane-protocol/isis:isis/isis:database
             /isis:levels/isis:lsp/isis:ipv6-reachability/isis:prefixes:
       +--ro fapm-sub-tlvs
          +--ro fapm-sub-tlv* []
             +--ro flex-algo?   uint8
             +--ro metric?      uint32
     augment /rt:routing/rt:control-plane-protocols
             /rt:control-plane-protocol/isis:isis/isis:database
             /isis:levels/isis:lsp/isis:mt-ipv6-reachability
             /isis:prefixes:
       +--ro fapm-sub-tlvs
          +--ro fapm-sub-tlv* []
             +--ro flex-algo?   uint8
             +--ro metric?      uint32

     notifications:
       +---n flex-algo-not-supported
          +--ro routing-protocol-name?   -> /rt:routing
                                            /control-plane-protocols
                                            /control-plane-protocol/name
          +--ro isis-level?              level
          +--ro flex-algo-number?        uint8

   <CODE BEGINS> file "ietf-isis-flex-algo@2021-12-22.yang" "ietf-isis-flex-algo@2022-03-06.yang"
   module ietf-isis-flex-algo {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-isis-flex-algo";
     prefix isis-flex-algo;

     import ietf-routing {
       prefix rt;
       reference "RFC 8349: A YANG Data Model for Routing
                  Management (NMDA Version)";
     }

     import ietf-te-types {
       prefix te-types;
       reference
         "RFC8776: Common YANG Data Types for Traffic Engineering.";
     }

     import ietf-isis {
       prefix "isis";
     }

     import ietf-te {
       prefix "te";
     }

     import ietf-isis-link-attr {
       prefix "isis-link-attr";
     }

     organization
       "IETF LSR - Link State Routing Working Group";
     contact
       "WG Web:   <https://tools.ietf.org/wg/spring/>
        WG List:  <mailto:spring@ietf.org>
        Author:    Yingzhen Qu
                  <mailto:yingzhen.qu@futurewei.com>
        Author:    Acee Lindem
                  <mailto:acee@cisco.com>
        Author:    Stephane Litkowski
                  <mailto:slitkows.ietf@gmail.com>
       ";

     description
       "The YANG module defines the configuration and operational
        state for ISIS Flexible Algorithm as defined in RFC xxxx.

        This YANG model conforms to the Network Management
        Datastore Architecture (NMDA) as described in RFC 8342.

        Copyright (c) 2021 2022 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 Revised 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.

        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 (RFC 2119) (RFC 8174) when, and only when,
        they appear in all capitals, as shown here.";

     reference "RFC XXXX: YANG Data Model for ISIS Flexible Algorithm.";

     revision 2021-12-22 2022-03-06 {
       description
         "Initial Version";
       reference "RFC XXXX: YANG Data Model for ISIS Flexible Algorithm.";
     }

     /* Identities */

     identity metric-type {
       description
         "Base identity for route metric types.";

     }

     identity igp-metric {
       base metric-type;
       description
         "Identity for the IGP metric type.";
     }

     identity min-uni-delay {
       base metric-type;
       description
         "Min unidirectional link delay metric type.";
       reference
         "RFC 8570 - IS-IS Traffic Engineering (TE) Metric Extensions";
     }

     identity te-metric {
       base metric-type;
       description
         "Traffic engineering metric type.";
       reference
         "RFC 5305 - IS-IS Extensions for Traffic Engineering (TE)";
     }

     identity fad-flags {
       description
         "Base identity for ISIS FAD flags.";
     }

     identity m-bit {
       base fad-flags;
       description
         "M bit, when set, the fex-algo flex-algo specific prefix and ASBR
          metric MUST be used for inter-area and external prefix
          calculation.";
     }

     /* Identity augmentation */
     identity flex-algo-bit {
       base isis-link-attr:sabm-bit;
       description
         "X bit, flexible algorithm.";
     }

     /* Groupings */
     grouping fa-ex-ag-sub-tlv {
       container fa-ex-ag-sub-tlv {
         leaf-list extended-admin-groups {
           type uint64;
           description
             "Extended administrative group as defined in RFC 7308.";
         }
         description
           "The flex-algo exclude admin group sub-tlv.";
       }
       description
         "The flex-algo exclude admin group sub-tlv.";
     }

     grouping fa-in-any-ag-sub-tlv {
       container fa-in-any-ag-sub-tlv {
         leaf-list extended-admin-groups {
           type uint64;
           description
             "Extended administrative group as defined in RFC 7308.";
         }
         description
           "The flex-algo include-any admin group sub-tlv.";
       }
       description
         "The flex-algo include-any admin group sub-tlv.";
     }

     grouping fa-in-all-ag-sub-tlv {
       container fa-in-all-ag-sub-tlv {
         leaf-list extended-admin-groups {
           type uint64;
           description
             "Extended administrative group as defined in RFC 7308.";
         }
         description
           "The flex-algo include-all admin group sub-tlv.";
       }
       description
         "The flex-algo include-all admin group sub-tlv.";
     }

     grouping fad-flags-sub-tlv {
       container fad-flags-sub-tlv {
         leaf-list fad-flags {
           type identityref {
             base fad-flags;
           }
           description
             "Flex-algo definition flags list.";
         }
         description
           "ISIS flex-algo definition flags.";
       }
       description
         "The flex-algo definition flags sub-tlv.";
     }

     grouping fa-ex-srlg-sub-tlv {
       container fa-ex-srlg-sub-tlv {
         leaf-list srlgs {
           type uint32;
           description
             "SRLG value as defined in RFC 4203.";
         }
         description
           "The flex-algo exclude SRLG sub-tlv.";
       }
       description
         "The flex-algo exclude SRLG sub-tlv.";
     }

     grouping fad-tlvs {
       container fad-tlvs {
         list fad-tlv {
           leaf flex-algo {
             type uint8;
             description
               "Flex-algo number, value between 128 and 255 inclusive.";
           }
           leaf metric-type {
             type identityref {
               base metric-type;
             }
               description
                 "Type of metric to be used during the calculation.";
           }
           leaf calc-type {
             type uint8 {
               range "0..127";
             }
             description
               "IGP algorithm types, value from 0 to 127 as
               defined under 'Interior Gateway Protocol (IGP)
               Parameter' by IANA.";
           }
           leaf priority {
             type uint8;
               description
                 "Priority of the advertisement.";
           }

           uses fa-ex-ag-sub-tlv;
           uses fa-in-any-ag-sub-tlv;
           uses fa-in-all-ag-sub-tlv;
           uses fad-flags-sub-tlv;
           uses fa-ex-srlg-sub-tlv;
           uses isis:unknown-tlvs;

           description
             "List of flex-algo definition TLVs.";
         }
         description
           "ISIS Flexible Algorithm Definition TLV.";
       }
       description
         "ISIS Flexible Algorithm Definition (FAD) TLV.";
     }

     grouping fapm-sub-tlvs {
       container fapm-sub-tlvs {
         list fapm-sub-tlv {
           leaf flex-algo {
             type uint8;
             description
               "Flex-algo number, value between 128 and 255
                inclusive.";
           }
           leaf metric {
             type uint32;
             description
               "Prefix metric.";
           }
           description
             "List of flex-algo prefix sub-tlvs.";
         }
         description
           "Flex-algo prefix metric sub-tlvs.";
       }
       description
         "Flexible Algorithm Prefix Metric (FAPM) sub TLVs.";
     }

     /* Configurations */

     augment "/rt:routing/" +
             "rt:control-plane-protocols/rt:control-plane-protocol"+
             "/isis:isis" {
       when "/rt:routing/rt:control-plane-protocols/"+
                    "rt:control-plane-protocol/rt:type = 'isis:isis'" {
         description
           "This augment ISIS routing protocol when used";
       }
       description
         "This augments ISIS protocol configuration
          with flexible algorithm.";

       container isis-flex-algo {
         list flex-algo {
           key "algo-number";

           leaf algo-number {
             type uint8 {
               range "128..255";
             }
             description
               "An identifier in the range 128-255 that's associated
               with the Flexible Algorithm Definition.";
           }

           leaf advertise-definition {
             type boolean;
             default true;
             description
               "Enable to advertise the flex-algo definition.";
           }

           container admin-groups {
             if-feature "te-types:extended-admin-groups";
             if-feature "te-types:named-extended-admin-groups";
             leaf-list exclude-admin-groups {
               type leafref {
                 path "/te:te/te:globals/te:named-admin-groups/"
                    + "te:named-admin-group/te:name";
               }
               description
                 "Exclude rule used during the flex-algo
                 path computation.";
             }
             leaf-list include-any-admin-groups {
               type leafref {
                 path "/te:te/te:globals/te:named-admin-groups/"
                    + "te:named-admin-group/te:name";
               }
               description
                 "Include-any rule used during the flex-algo
                 path computation.";
             }
             leaf-list include-all-admin-groups {
               type leafref {
                 path "/te:te/te:globals/te:named-admin-groups/"
                    + "te:named-admin-group/te:name";
               }
               description
                 "Include-all rule used during the flex-algo
                 path computation.";
             }
             description
               "Specify links for the flex-algo path computation.";
           }

           leaf-list exclude-srlgs {
             if-feature "te-types:named-srlg-groups";
             type leafref {
               path "/te:te/te:globals/te:named-srlgs/te:named-srlg/"
                  + "te:name";
             }
             description
               "Shared Risk Link Groups (SRLGs) to be excluded during
               the flex-algo path computation.";
           }

           leaf fast-reroute {
             type boolean;
             default true;
             description
               "Enable fast reroute.";
           }

           leaf metric-type {
             type identityref {
               base metric-type;
             }
             description
               "Type of metric to be used during the calculation.";
           }

           leaf microloop-avoidance {
             type boolean;
             default true;
             description
               "Enable microloop avoidance.";

           }

           container prefix-metric {
             presence
               "Use flex-algo specific prefix metric.";
             description
               "Use flex-algo prefix metric.";
           }

           leaf priority {
             type uint8;
             description
               "Priority of the advertisement.";
           }

           description
             "List of flex-algo configurations.";
         }
         description
           "Flexible Algorithm configuration.";
       }
     }

     /* Database */

     augment "/rt:routing/" +
             "rt:control-plane-protocols/rt:control-plane-protocol"+
             "/isis:isis/isis:database/isis:levels/isis:lsp"+
                         "/isis:router-capabilities" {
             when "/rt:routing/rt:control-plane-protocols/"+
                        "rt:control-plane-protocol/rt:type = 'isis:isis'" {
         description
           "This augment ISIS routing protocol when used";
       }
             description
               "This augments ISIS protocol LSDB router capability.";

             uses fad-tlvs;
     }

     augment "/rt:routing/" +
             "rt:control-plane-protocols/rt:control-plane-protocol"+
             "/isis:isis/isis:database/isis:levels/isis:lsp"+
                         "/isis:extended-ipv4-reachability/isis:prefixes" {
                   when "/rt:routing/rt:control-plane-protocols/"+
                        "rt:control-plane-protocol/rt:type = 'isis:isis'" {
         description
           "This augment ISIS routing protocol when used";

       }
                   description
               "This augments ISIS protocol LSDB prefix.";
                uses fapm-sub-tlvs;
     }

     augment "/rt:routing/" +
             "rt:control-plane-protocols/rt:control-plane-protocol"+
             "/isis:isis/isis:database/isis:levels/isis:lsp"+
                   "/isis:mt-extended-ipv4-reachability/isis:prefixes" {
                   when "/rt:routing/rt:control-plane-protocols/"+
                        "rt:control-plane-protocol/rt:type = 'isis:isis'" {
         description
           "This augment ISIS routing protocol when used";
       }
                   description
               "This augments ISIS protocol LSDB prefix.";
             uses fapm-sub-tlvs;
     }

     augment "/rt:routing/" +
             "rt:control-plane-protocols/rt:control-plane-protocol"+
             "/isis:isis/isis:database/isis:levels/isis:lsp"+
                         "/isis:ipv6-reachability/isis:prefixes" {
                   when "/rt:routing/rt:control-plane-protocols/"+
                        "rt:control-plane-protocol/rt:type = 'isis:isis'" {
         description
           "This augment ISIS routing protocol when used";
       }
                   description
               "This augments ISIS protocol LSDB prefix.";
             uses fapm-sub-tlvs;
     }

     augment "/rt:routing/" +
             "rt:control-plane-protocols/rt:control-plane-protocol"+
             "/isis:isis/isis:database/isis:levels/isis:lsp"+
                         "/isis:mt-ipv6-reachability/isis:prefixes" {
                   when "/rt:routing/rt:control-plane-protocols/"+
                        "rt:control-plane-protocol/rt:type = 'isis:isis'" {
         description
           "This augment ISIS routing protocol when used";
       }
                   description
               "This augments ISIS protocol LSDB prefix.";
           uses fapm-sub-tlvs;
     }
     /* notification */

     notification flex-algo-not-supported {
       uses isis:notification-instance-hdr;
       leaf flex-algo-number {
         type uint8 {
           range "128..255";
         }
         description
           "Flex-algo identifier which is not supported by the IS-IS
            instance.";
       }
       description
         "This notification is sent when an IS-IS instance does not
          support this flex-algo.";
     }
   }
   <CODE ENDS>

5.  Security Considerations

   The YANG modules specified in this document define a schema for data
   that is designed to be accessed via network management protocols such
   as NETCONF [RFC6241] or RESTCONF [RFC8040].  The lowest NETCONF layer
   is the secure transport layer, and the mandatory-to-implement secure
   transport is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
   is HTTPS, and the mandatory-to-implement secure transport is TLS
   [RFC5246].

   The NETCONF access control model [RFC6536] 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 modules that 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 correspond to the following
   schema nodes:

      /isis:isis/isis:interfaces/isis:interface/isis-link-attr -
      Modification of link attributes operation mode could result in
      traffic being redirected or DoS attack.

   Some of the readable data nodes in the modules 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.  The exposure of the Link State
   Database (LSDB) will expose the detailed topology of the network.
   This may be undesirable since both due to the fact that exposure may
   facilitate other attacks.  Additionally, network operators may
   consider their topologies to be sensitive confidential data.These
   correspond to the following schema nodes:

      /isis:isis/isis:database/isis:levels/isis:lsp/isis:mt-is-
      neighbor/isis:neighbor/isis:instances/isis:instance/application-
      specific-link-attributes-sub-tlvs

      /isis:isis/isis:database/isis:levels/isis:lsp/application-
      specific-srlg-tlv

6.  IANA Considerations

   This document registers URIs in the IETF XML registry [RFC3688].
   Following the format in [RFC3688], the following registrations is
   requested to be made:

      URI: urn:ietf:params:xml:ns:yang:ietf-isis-remaining-lifetime
      Registrant Contact: The IESG.
      XML: N/A, the requested URI is an XML namespace.

      URI: urn:ietf:params:xml:ns:yang:ietf-isis-link-attr
      Registrant Contact: The IESG.
      XML: N/A, the requested URI is an XML namespace.

      URI: urn:ietf:params:xml:ns:yang:ietf-isis-flex-algo
      Registrant Contact: The IESG.
      XML: N/A, the requested URI is an XML namespace.

   This document registers the YANG modules in the YANG Module Names
   registry [RFC6020].

     name: ietf-isis-remaining-lifetime
     namespace: urn:ietf:params:xml:ns:yang:ietf-isis-remaining-lifetime
     prefix: isis-remaining-lifetime
     reference: RFC XXXX
      name: ietf-isis-link-attr
      namespace: urn:ietf:params:xml:ns:yang:ietf-isis-link-attr
      prefix: isis-link-attr
      reference: RFC XXXX

      name: ietf-isis-flex-algo
      namespace: urn:ietf:params:xml:ns:yang:ietf-isis-flex-algo
      prefix: isis-flex-algo
      reference: RFC XXXX

7.  Acknowledgements

   This document was produced using Marshall Rose's xml2rfc tool.

   The YANG model was developed using the suite of YANG tools written
   and maintained by numerous authors.

8.  References

8.1.  Normative References

   [I-D.ietf-isis-yang-isis-cfg]
              Litkowski, S., Yeung, D., Lindem, A., Zhang, J., and L.
              Lhotka, "YANG Data Model for IS-IS Protocol", Work in
              Progress, Internet-Draft, draft-ietf-isis-yang-isis-cfg-
              42, 15 October 2019, <https://www.ietf.org/archive/id/
              draft-ietf-isis-yang-isis-cfg-42.txt>.

   [I-D.ietf-lsr-flex-algo]
              Psenak, P., Hegde, S., Filsfils, C., Talaulikar, K., and
              A. Gulko, "IGP Flexible Algorithm", Work in Progress,
              Internet-Draft, draft-ietf-lsr-flex-algo-18, 25 October
              2021, <https://www.ietf.org/archive/id/draft-ietf-lsr-
              flex-algo-18.txt>.

   [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>.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,
              <https://www.rfc-editor.org/info/rfc5246>.

   [RFC5329]  Ishiguro, K., Manral, V., Davey, A., and A. Lindem, Ed.,
              "Traffic Engineering Extensions to OSPF Version 3",
              RFC 5329, DOI 10.17487/RFC5329, September 2008,
              <https://www.rfc-editor.org/info/rfc5329>.

   [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>.

   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
              Protocol (NETCONF) Access Control Model", RFC 6536,
              DOI 10.17487/RFC6536, March 2012,
              <https://www.rfc-editor.org/info/rfc6536>.

   [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>.

   [RFC7987]  Ginsberg, L., Wells, P., Decraene, B., Przygienda, T., and
              H. Gredler, "IS-IS Minimum Remaining Lifetime", RFC 7987,
              DOI 10.17487/RFC7987, October 2016,
              <https://www.rfc-editor.org/info/rfc7987>.

   [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>.

   [RFC8349]  Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for
              Routing Management (NMDA Version)", RFC 8349,
              DOI 10.17487/RFC8349, March 2018,
              <https://www.rfc-editor.org/info/rfc8349>.

   [RFC8919]  Ginsberg, L., Psenak, P., Previdi, S., Henderickx, W., and
              J. Drake, "IS-IS Application-Specific Link Attributes",
              RFC 8919, DOI 10.17487/RFC8919, October 2020,
              <https://www.rfc-editor.org/info/rfc8919>.

8.2.  Informative References

   [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>.

Authors' Addresses

   Acee Lindem
   Cisco Systems
   301 Midenhall Way
   Cary, NC 27513
   Email: acee@cisco.com

   Stephane Litkowski
   Cisco Systems
   Email: slitkows.ietf@gmail.com

   Yingzhen Qu
   Futurewei
   2330 Central Expressway
   Santa Clara, CA 95050
   United States of America
   Email: yingzhen.qu@futurewei.com