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Versions: 00 01 draft-ietf-spring-sr-yang

SPRING Working Group                                        S. Litkowski
Internet-Draft                                   Orange Business Service
Intended status: Standards Track                               A. Lindem
Expires: September 6, 2015                                 Cisco Systems
                                                               P. Sarkar
                                                        Juniper Networks
                                                                 I. Chen
                                                                Ericsson
                                                          March 05, 2015


                  YANG Data Model for Segment Routing
                   draft-litkowski-spring-sr-yang-00

Abstract

   This document defines a YANG data model for segment routing
   configuration and operation.  This YANG model is intended to be used
   on network elements to configure or operate segment routing.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://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 September 6, 2015.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Tree diagram  . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Design of the Data Model  . . . . . . . . . . . . . . . . . .   3
   3.  Configuration . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Adjacency SID properties  . . . . . . . . . . . . . . . .   5
       3.1.1.  Bundling  . . . . . . . . . . . . . . . . . . . . . .   5
       3.1.2.  Protection  . . . . . . . . . . . . . . . . . . . . .   6
     3.2.  Prefix SID properties . . . . . . . . . . . . . . . . . .   6
   4.  Control plane configuration . . . . . . . . . . . . . . . . .   7
   5.  States  . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   6.  Notifications . . . . . . . . . . . . . . . . . . . . . . . .   7
   7.  YANG Module . . . . . . . . . . . . . . . . . . . . . . . . .   8
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  19
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  19
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  20
   11. Normative References  . . . . . . . . . . . . . . . . . . . .  20
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  21

1.  Introduction

   This document defines a YANG data model for segment routing
   configuration and operation.

1.1.  Tree diagram

   A simplified graphical representation of the data model is presented
   in Section 2.

   The meaning of the symbols in these diagrams is as follows:

   o  Brackets "[" and "]" enclose list keys.

   o  Curly braces "{" and "}" contain names of optional features that
      make the corresponding node conditional.





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   o  Abbreviations before data node names: "rw" means configuration
      (read-write), and "ro" state data (read-only).

   o  Symbols after data node names: "?" means an optional node and "*"
      denotes a "list" or "leaf-list".

   o  Parentheses enclose choice and case nodes, and case nodes are also
      marked with a colon (":").

   o  Ellipsis ("...") stands for contents of subtrees that are not
      shown.

2.  Design of the Data Model

   This is the initial version of this module and and its relationship
   to the protocol modules.  It is expected that there will be changes
   as the module matures.

module: ietf-segment-routing
augment /rt:routing/rt:routing-instance:
   +--rw segment-routing
      +--rw transport-type?   identityref
      +--rw bindings
      |  +--rw mapping-server {mapping-server}?
      |     +--rw ipv4
      |     |  +--rw mapping-entry* [prefix]
      |     |     +--rw prefix       inet:ipv4-prefix
      |     |     +--rw start-sid?   uint32
      |     |     +--rw range?       uint32
      |     +--rw ipv6
      |        +--rw mapping-entry* [prefix]
      |           +--rw prefix       inet:ipv6-prefix
      |           +--rw start-sid?   uint32
      |           +--rw range?       uint32
      +--rw srgb* [lower-bound upper-bound]
      |  +--rw lower-bound    uint32
      |  +--rw upper-bound    uint32
      +--rw interfaces
         +--rw interface* [name]
            +--rw name             if:interface-ref
            +--rw adjacency-sid
            |  +--rw advertise-adj-group-sid* [group-id]
            |  |  +--rw group-id    uint32
            |  +--rw advertise-protection?      enumeration
            +--rw prefix-sid
               +--rw ipv4
               |  +--rw prefix-sid* [value]
               |     +--rw value-type?          enumeration



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               |     +--rw value                uint32
               |     +--rw node-flag?           boolean
               |     +--rw last-hop-behavior?   enumeration
               +--rw ipv6
                  +--rw prefix-sid* [value]
                     +--rw value-type?          enumeration
                     +--rw value                uint32
                     +--rw node-flag?           boolean
                     +--rw last-hop-behavior?   enumeration
augment /rt:routing/rt:routing-instance/rt:routing-protocols/rt:routing-protocol/isis:isis/isis:instance:
   +--rw segment-routing
      +--rw enabled?    boolean
      +--rw bindings
         +--rw advertise?   boolean
         +--rw receive?     boolean
augment /rt:routing/rt:routing-instance/rt:routing-protocols/rt:routing-protocol/ospf:ospf/ospf:instance:
   +--rw segment-routing
      +--rw enabled?    boolean
      +--rw bindings
         +--rw advertise?   boolean
         +--rw receive?     boolean
augment /rt:routing-state/rt:routing-instance:
   +--ro segment-routing
      +--ro label-blocks*
      |  +--ro lower-bound?   uint32
      |  +--ro upper-bound?   uint32
      |  +--ro size?          uint32
      |  +--ro free?          uint32
      |  +--ro used?          uint32
      +--ro global-sid-list
         +--ro sid* [target sid source source-protocol binding-type]
            +--ro target             string
            +--ro sid                uint32
            +--ro algorithm?         uint8
            +--ro source             inet:ip-address
            +--ro used?              boolean
            +--ro source-protocol    leafref
            +--ro binding-type       enumeration
notifications:
   +---n segment-routing-global-sid-collision
   |  +--ro received-target?    string
   |  +--ro original-target?    string
   |  +--ro index?              uint32
   |  +--ro routing-protocol?   leafref
   +---n segment-routing-index-out-of-range
      +--ro received-target?    string
      +--ro received-index?     uint32
      +--ro routing-protocol?   leafref



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3.  Configuration

   This module augments the "/rt:routing/rt:routing-instance:" with a
   segment-routing container.  This container defines all the
   configuration parameters related to segment-routing for this
   particular routing-instance.

   The segment-routing configuration is split in global routing-instance
   configuration and interface configuration.

   The global configuration includes :

   o  segment-routing transport type : The underlying transport type for
      segment routing.  The version of the model limits the transport
      type to an MPLS dataplane.  The transport-type is only defined
      once for a particular routing-instance and is agnostic to the
      control plane used.  Only a single transport-type is supported in
      this version of the model.

   o  bindings : Defines how external information is mapped to a segment
      ID.  The current version supports a mapping-server where static
      prefix-to-SID bindings can be defined.  Configuration of bindings
      does not allow advertisement of those bindings.  Advertisement
      must be controlled by each routing-protocol instance.

   o  SRGB (Segment Routing Global Block): Defines a list of label
      blocks represented by a pair of lower-bound/upper-bound labels.
      The SRGB is also agnostic to the control plane used.  So all
      routing-protocol instance will have to advertise the same SRGB.

   The interface configuration includes :

   o  Adjacency SID properties

   o  Prefix SID properties

3.1.  Adjacency SID properties

3.1.1.  Bundling

   This section is a first proposal on how to use S-bit in Adj-SID to
   create bundles.  Authors would like to trigger discussion based on
   this first proposal.

   In case of parallel IP links between routers, an additional Adjacency
   SID may be advertised representing more than one adjacency (i.e., a
   bundle of adjacencies).  The "advertise-adj-group-sid" configuration
   controls whether or not an additional adjacency SID is advertised.



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   The "advertise-adj-group-sid" would be a list of "group-id".  The
   "group-id" will permit to identify interfaces that must be bundled
   together.


   +-------+                 +------+
   |       | ------- L1 ---- |      |
   |   R1  | ------- L2 ---- |  R2  |
   |       | ------- L3 ---- |      |
   |       | ------- L4 ---- |      |
   +-------+                 +------+

   In the figure above, R1 and R2 are interconnected by four links.  A
   routing protocol adjacency is established on each link.  Operator
   would like to create segment-routing Adj-SID that represent some
   bundles of links.  We can imagine two different bundles : L1/L2 and
   L2/L3.  To achieve this behavior, the service provider will configure
   a "group-id" X for both interfaces L1 and L2 and a "group-id" Y for
   both interfaces L3 and L3.  This will result in R1 advertising an
   additional Adj-SID for each adjacency, for example a Adj-SID with S
   flag set and value of 400 will be added to L1 and L2.  A Adj-SID with
   S flag set and value of 500 will be added to L3 and L4.  As L1/L2 and
   L3/L4 does not share the same "group-id", a different SID value will
   be allocated.

3.1.2.  Protection

   The "advertise-protection" defines how protection for an interface is
   advertised.  It does not control the activation or deactivation of
   protection.  If the "single" option is used, a single Adj-SID will be
   advertised for the interface.  If the interface is protected, the
   B-Flag for the Adj-SID advertisement will be set.  If the "dual"
   option is used and if the interface is protected, two Adj-SIDs will
   be advertised for the interface adjacencies.  One Adj-SID will always
   have the B-Flag set and the other will have the B-Flag clear.  This
   option is intended to be used in the case of traffic engineering
   where a path must use either protected segments or non-protected
   segments.

3.2.  Prefix SID properties

   An interface may have associated IP prefixes.  By default, no Prefix-
   SID will be advertised for any IP prefix associated with an
   interface.

   The operator can control the advertisement of IP prefixes by setting
   "prefix-sid" in the interface configuration.




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   The operator can control advertisement of Prefix-SID independently
   for IPv4 and IPv6.  When specified, the "prefix-sid" value must be
   included.

   The value can be expressed as an index (default), or an absolute
   value.  The operator can also control if the "node-flag" is set for
   the prefix.  As the network device owns the prefix, the default is to
   advertise the prefix with the "node-flag" set.

   The "last-hop-behavior" configuration dictates the PHP behavior:
   "explicit-null", "php", or "non-php".

4.  Control plane configuration

   Activation of segment-routing extensions for a particular control
   plane is done by augmenting routing-protocol configuration with
   segment-routing.

   The "enabled" leaf enables segment-routing extensions for the
   routing-protocol instance.

   The "bindings" container controls the routing-protocol instance's
   advertisement of local bindings and the processing of received
   bindings.

   This model supports ISIS ([I-D.ietf-isis-segment-routing-extensions])
   and OSPF as controlplane ([I-D.ietf-ospf-segment-routing-extensions]
   and [I-D.psenak-ospf-segment-routing-ospfv3-extension]) for segment-
   routing.

5.  States

   The operational states contains information reflecting the usage of
   allocated SRGB labels.

   It also includes a list of all global SIDs, their associated
   bindings, and other information such as the source protocol and
   algorithm.

6.  Notifications

   The model proposes two notifications for segment-routing.

   o  segment-routing-global-sid-collision: Raised when a control plane
      advertised index is already associated with another target (in
      this version, the only defined targets are IPv4 and IPv6
      prefixes).




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   o  segment-routing-index-out-of-range: Raised when a control plane
      advertised index fall outside the range of SRGBs configured for
      the network device.

7.  YANG Module

   <CODE BEGINS> file "ietf-segment-routing@2015-03-04.yang"

   module ietf-segment-routing {
     namespace "urn:ietf:params:xml:ns:"
             + "yang:ietf-segment-routing";
     prefix sr;

     import ietf-inet-types {
       prefix "inet";
     }

     import ietf-routing {
       prefix "rt";
     }

     import ietf-interfaces {
     prefix "if";
     }

     import ietf-isis {
     prefix "isis";
     }

     import ospf {
     prefix "ospf";
     }

     organization
      "IETF SPRING Working Group";

     contact
       "WG List:  &lt;mailto:spring@ietf.org&gt;

       Editor:    Stephane Litkowski
             &lt;mailto:stephane.litkowski@orange.com&gt;

           Acee Lindem
             &lt;mailto:acee@cisco.com&gt;
           Pushpasis Sarkar
             &lt;mailto:psarkar@juniper.net&gt;
           Ing-Wher Chen
             &lt;mailto:ing-wher.chen@ericsson.com&gt;



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       ";

     description
       "The YANG module defines a generic configuration model for
       Segment routing common across all of the vendor
       implementations.";

     revision 2015-02-27 {
       description "Initial";
       reference "draft-litkowski-spring-sr-yang-00";
     }

     /* Identities */
     identity segment-routing-transport {
       description
       "Base identity for segment routing transport.";
     }
     identity segment-routing-transport-mpls {
       base segment-routing-transport;
       description
       "This identity represents MPLS transport for segment
       routing.";
     }

     /* Features */

     feature mapping-server {
       description
        "Support of SRMS.";
     }

     /* Groupings */

     grouping controlplane-cfg {
       container segment-routing {
         leaf enabled {
           type boolean;
           default false;
           description
            "Enables segment-routing
            protocol extensions.";
         }
         container bindings {
           leaf advertise {
             type boolean;
             default true;
             description
             "Authorize the advertise



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             of local mappings in binding TLV.";
           }
           leaf receive {
             type boolean;
             default true;
             description
             "Authorize the reception and usage
             of binding TLV.";
           }
           description
            "Control of binding advertisement
            and reception.";
         }

         description
         "segment routing global config.";
       }
       description
        "Defines protocol configuration.";
     }

     grouping prefix-sid-cfg {
       list prefix-sid {
         key value;
         leaf value-type {
           type enumeration {
             enum index {
               description
                  "The value will be
                  interpreted as an index.";

             }
             enum absolute {

               description
                  "The value will become
                  interpreted as an absolute
                  value.";
             }
           }
           default index;
           description
             "This leaf defines how value
              must be interpreted.";
         }

         leaf value {
           type uint32;



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           mandatory true;
           description
           "Value associated with
           prefix. The value must
           be interpreted in the
           context of value-type.";
         }
         leaf node-flag {
           type boolean;
           default true;
           description
           "Set prefix as a node
            representative prefix.";
         }
         leaf last-hop-behavior {
           type enumeration {
             enum explicit-null {
               description
                "Use explicit-null for the SID.";
             }
             enum no-php {
               description
                "Do no use PHP for the SID.";
             }
             enum php {
               description
                "Use PHP for the SID.";
             }
           }
           description
            "Configure last hop behavior.";
         }
         description
          "List of prefix SID.";
       }
       description
        "This grouping defines cfg of prefix SID.";
     }

     /* Cfg */

     augment "/rt:routing/rt:routing-instance" {
       description
        "This augments routing-instance
        configuration with segment-routing.";
       container segment-routing {
         leaf transport-type {
           type identityref {



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             base segment-routing-transport;
           }
           default "segment-routing-transport-mpls";
           description "Dataplane to be used.";
         }
         container bindings {
           container mapping-server {
             if-feature mapping-server;
             container ipv4 {
               list mapping-entry {
                 key prefix;

                 leaf prefix {
                   type inet:ipv4-prefix;
                   description
                    "Base prefix used for mapping.";
                 }
                 leaf start-sid {
                   type uint32;
                   description
                    "Starting SID value to be associated
                    with prefix.";
                 }
                 leaf range {
                   type uint32;
                   description
                    "Describes how many SIDs could be
                    allocated.";
                 }
                 description
                  "Mapping entries.";
               }
               description
                "IPv4 mapping entries.";
             }
             container ipv6 {
               list mapping-entry {
                 key prefix;

                 leaf prefix {
                   type inet:ipv6-prefix;
                   description
                    "Base prefix used for mapping.";
                 }
                 leaf start-sid {
                   type uint32;
                   description
                    "Starting SID value to be associated



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                    with prefix.";
                 }
                 leaf range {
                   type uint32;
                   description
                    "Describes how many SIDs could be
                    allocated.";
                 }
                 description
                  "Mapping entries.";
               }
               description
                "IPv6 mapping entries.";
             }
             description
              "Configuration of mapping-server
               local entries.";
           }
           description
            "List of bindings.";
         }
         list srgb {
           key "lower-bound upper-bound";
           ordered-by user;
           leaf lower-bound {
             type uint32;
             description
             "Lower value in the block.";
           }
           leaf upper-bound {
             type uint32;
             description
             "Upper value in the block.";
           }
           description
             "List of global blocks to be
                advertised.";
         }

         container interfaces {
           list interface {
             key "name";
             leaf name {
               type if:interface-ref;

               description
                "Reference to the interface within
                 the routing-instance.";



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             }
             container adjacency-sid {
               list advertise-adj-group-sid {
                 key group-id;

                 leaf group-id {
                   type uint32;
                   description

                    "The value is an internal value to identify
                    a group-ID. Interfaces with the same
                    group-ID will be bundled together.
                    ";
                 }
                 description
                  "Control advertisement of S flag.
                    Enable to advertise a common Adj-SID
                    for parallel links.";
               }
               leaf advertise-protection {
                 type enumeration {
                   enum "single" {
                     description
                      "A single Adj-SID is associated
                      with the adjacency and reflects
                      the protection configuration.";
                   }
                   enum "dual" {
                     description
                      "Two Adj-SIDs will be associated
                      with the adjacency if interface
                      is protected. In this case
                      one will be enforced with
                      backup flag set, the other
                      will be enforced to backup flag unset.
                      In case, protection is not configured,
                      a single Adj-SID will be advertised
                      with backup flag unset.";
                   }
                 }
                 description
                  "If set, the Adj-SID refers to an
                 adjacency being protected.";
               }
               description
                "Defines the adjacency SID properties.";
             }
             container prefix-sid {



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               container ipv4 {
                 uses prefix-sid-cfg;
                 description
                  "Parameters associated with IPv4 prefix SID";
               }
               container ipv6 {
                 uses prefix-sid-cfg;
                 description
                  "Parameters associated with IPv6 prefix SID";
               }
               description
                "Prefix SID configuration.";
             }
             description
              "List of interfaces.";
           }
           description
            "Interface configuration.";
         }
         description
         "segment routing global config.";
       }
     }


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

       uses controlplane-cfg;
     }

     augment "/rt:routing/rt:routing-instance/rt:routing-protocols" +
           "/rt:routing-protocol/ospf:ospf/ospf:instance" {
       when "rt:type = 'ospf:ospfv2' or rt:type = 'ospf:ospfv3'" {
         description
         "This augment ISIS routing protocol when used";
       }
       description
        "This augments ISIS protocol configuration
         with segment routing.";



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       uses controlplane-cfg;
     }


     /* Operational states */

     augment "/rt:routing-state/rt:routing-instance" {
       description
        "This augments the operational states
         with segment-routing.";
       container segment-routing {
         list label-blocks {
           leaf lower-bound {
             type uint32;
             description
              "Lower bound of the label block.";
           }
           leaf upper-bound {
             type uint32;
             description
              "Upper bound of the label block.";
           }
           leaf size {
             type uint32;
             description
              "Number of indexes in the block.";
           }
           leaf free {
             type uint32;
             description
              "Number of indexes free in the block.";
           }
           leaf used {
             type uint32;
             description
              "Number of indexes used in the block.";
           }
           description
            "List of labels blocks currently
            in use.";
         }

         container global-sid-list {
           list sid {
             key "target sid source source-protocol binding-type";
             ordered-by system;

             leaf target {



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               type string;
               description
                "Defines the target of the binding.
                It can be a prefix or something else.";
             }
             leaf sid {
               type uint32;
               description
                "Index associated with the prefix.";
             }
             leaf algorithm {
               type uint8;
               description
                "Algorithm to be used for the prefix
                SID.";
             }
             leaf source {
               type inet:ip-address;
               description
                "IP address of the router than own
                 the binding.";
             }
             leaf used {
               type boolean;
               description
                "Defines if the binding is used
                 in forwarding plane.";
             }
             leaf source-protocol {
               type leafref {
                 path "/rt:routing-state/rt:routing-instance/" +
                 "rt:routing-protocols/rt:routing-protocol/rt:name";
               }
               description
                "Rtg protocol that owns the binding";
             }
             leaf binding-type {
               type enumeration {
                 enum prefix-sid {
                   description
                    "Binding is learned from
                    a prefix SID.";
                 }
                 enum binding-tlv {
                   description
                    "Binding is learned from
                    a binding TLV.";
                 }



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               }
               description
                "Type of binding.";
             }
             description
               "Binding.";

           }
           description
            "List of prefix and SID associations.";
         }
         description
          "Segment routing operational states.";
       }
     }


     /* Notifications */

     notification segment-routing-global-sid-collision {
       leaf received-target {
         type string;
         description
         "Target received in the controlplane that
                caused SID collision.";
       }
       leaf original-target {
         type string;
         description
         "Target already available in database that have the same SID
         as the received target.";
       }
       leaf index {
         type uint32;
         description
         "Value of the index used by two different prefixes.";
       }
       leaf routing-protocol {
         type leafref {
           path "/rt:routing-state/rt:routing-instance/" +
           "rt:routing-protocols/rt:routing-protocol/rt:name";
         }
         description
          "Routing protocol reference that received the event.";
       }
       description
         "This notification is sent when a new mapping is learned
         , containing mapping



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         where the SID is already used.
         The notification generation must be throttled with at least
          a 5 second gap. ";
     }
     notification segment-routing-index-out-of-range {
       leaf received-target {
         type string;
         description
         "Target received in the controlplane
               that caused SID collision.";
       }
       leaf received-index {
         type uint32;
         description
         "Value of the index received.";
       }
       leaf routing-protocol {
         type leafref {
           path "/rt:routing-state/rt:routing-instance/" +
           "rt:routing-protocols/rt:routing-protocol/rt:name";
         }
         description
          "Routing protocol reference that received the event.";
       }
       description
         "This notification is sent when a binding
         is received, containing a segment index
         which is out of the local configured ranges.
         The notification generation must be throttled with at least
          a 5 second gap. ";
     }

   }

   <CODE ENDS>

8.  Security Considerations

   TBD.

9.  Acknowledgements

   TBD.








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10.  IANA Considerations

   TBD.

11.  Normative References

   [I-D.ietf-isis-segment-routing-extensions]
              Previdi, S., Filsfils, C., Bashandy, A., Gredler, H.,
              Litkowski, S., Decraene, B., and J. Tantsura, "IS-IS
              Extensions for Segment Routing", draft-ietf-isis-segment-
              routing-extensions-03 (work in progress), October 2014.

   [I-D.ietf-ospf-segment-routing-extensions]
              Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
              Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
              Extensions for Segment Routing", draft-ietf-ospf-segment-
              routing-extensions-04 (work in progress), February 2015.

   [I-D.ietf-spring-segment-routing]
              Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
              Litkowski, S., Horneffer, M., Shakir, R., Tantsura, J.,
              and E. Crabbe, "Segment Routing Architecture", draft-ietf-
              spring-segment-routing-01 (work in progress), February
              2015.

   [I-D.psenak-ospf-segment-routing-ospfv3-extension]
              Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
              Shakir, R., Henderickx, W., and J. Tantsura, "OSPFv3
              Extensions for Segment Routing", draft-psenak-ospf-
              segment-routing-ospfv3-extension-02 (work in progress),
              July 2014.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC6020]  Bjorklund, M., "YANG - A Data Modeling Language for the
              Network Configuration Protocol (NETCONF)", RFC 6020,
              October 2010.

   [RFC6241]  Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
              Bierman, "Network Configuration Protocol (NETCONF)", RFC
              6241, June 2011.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, June 2011.






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   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
              Protocol (NETCONF) Access Control Model", RFC 6536, March
              2012.

Authors' Addresses

   Stephane Litkowski
   Orange Business Service

   Email: stephane.litkowski@orange.com


   Acee Lindem
   Cisco Systems

   Email: acee@cisco.com


   Pushpasis Sarkar
   Juniper Networks

   Email: psarkar@juniper.net


   Ing-Wher Chen
   Ericsson

   Email: ing-wher.chen@ericsson.com























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