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Versions: 00 01 02 draft-ietf-idr-bgp-model

Interdomain Routing                                       A. Shaikh, Ed.
Internet-Draft                                                    Google
Intended status: Informational                            R. Shakir, Ed.
Expires: December 16, 2015                                            BT
                                                           K. Patel, Ed.
                                                                   Cisco
                                                           S. Hares, Ed.
                                                                  Huawei
                                                              K. D'Souza
                                                                    AT&T
                                                               D. Bansal
                                                               Microsoft
                                                                A. Clemm
                                                             A. Zhdankin
                                                                   Cisco
                                                         M. Jethanandani
                                                                   Ciena
                                                                  X. Liu
                                                                Ericsson
                                                           June 14, 2015


                BGP Model for Service Provider Networks
                     draft-shaikh-idr-bgp-model-02

Abstract

   This document defines a YANG data model for configuring and managing
   BGP, including protocol, policy, and operational aspects based on
   data center, carrier and content provider operational requirements.

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 December 16, 2015.




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Copyright Notice

   Copyright (c) 2015 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
   (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.

1.  Introduction

   YANG [RFC6020] is a data modeling language that was introduced 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 of
   implementation for a number of interfaces, such as CLIs and
   programmatic APIs.

   This document describes a YANG data model for the BGP [RFC4271]
   protocol, including various protocol extensions, policy
   configuration, as well as defining key operational state data.  The
   model is intended to be vendor-neutral, in order to allow operators
   to manage BGP configuration in heterogeneous environments with
   routers supplied by multiple vendors.  The model is also intended to
   be readily mapped to existing implementations to facilitate support
   from as large a set of routing hardware and software vendors as
   possible.

1.1.  Goals and approach

   The model covers the base BGP features that are deployed across major
   implementations and the common BGP configurations in use across a
   number of operator network deployments.  In particular, this model
   attempts to cover BGP features defined in [RFC4271], [RFC1997],
   [RFC4456], [RFC4760], [RFC3065], [RFC2439], [RFC4724], and [RFC6811].

   Along with configuration of base BGP features, this model also
   addresses policy configuration, by providing "hooks" for applying
   policies, and also defining BGP-specific policy features.  The BGP
   policy features are intended to be used with the general routing



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   policy model defined in [I-D.shaikh-rtgwg-policy-model].  The model
   also supports operational state data to enable a common model for
   reading BGP-related state from a BGP speaker.

   For the base BGP features, the focus of the model described in this
   document is on providing configuration and operational state
   information relating to:

   o  The global BGP instance, and neighbors whose configuration is
      specified individually, or templated with the use of peer-groups.

   o  The address families that are supported by peers, and the global
      configuration which relates to them.

   o  The policy configuration "hooks" and BGP-specific policy features
      that relate to a neighbor - controlling the import and export of
      NLRIs.

   As mentioned earlier, any configuration items that are deemed to be
   widely available in existing major BGP implementations are included
   in the model.  Additional, more esoteric, configuration items that
   are not commonly used, or only available from a single
   implementation, are omitted from the model with an expectation that
   they will be available in companion modules that augment the current
   model.  This allows clarity in identifying data that is part of the
   vendor-neutral base model.

   Where possible, naming in the model follows conventions used in
   available standards documents, and otherwise tries to be self-
   explanatory with sufficient descriptions of the intended behavior.
   Similarly, configuration data value constraints and default values,
   where used, are based on recommendations in current standards
   documentation.  Since implementations vary widely in this respect,
   this version of the model specifies only a limited set of defaults
   and ranges with the expectation of being more prescriptive in future
   versions based on actual operator use.

2.  Model overview

   The BGP model is defined across several YANG modules but at a high
   level is organized into Six elements:

   o  base protocol configuration -- configuration affecting BGP
      protocol-related operations, defined at various levels of
      hierarchy.

   o  multiprotocol configuration -- configuration affecting individual
      address-families within BGP [RFC4760].



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   o  neighbor configuration -- configuration affecting an individual
      neighbor within BGP.

   o  neighbor multiprotocol configuration -- configuration affecting
      individual address-families for a neighbor within BGP.

   o  policy configuration -- hooks for application of the policies
      defined in [I-D.shaikh-rtgwg-policy-model] that act on routes sent
      (received) to (from) peers or other routing protocols and BGP-
      specific policy features.

   o  operational state -- variables used for monitoring, management,
      etc. of BGP operations.

   These modules also make use of standard Internet types, such as IP
   addresses and prefixes, autonomous system numbers, etc., defined in
   RFC 6991 [RFC6991].

   Throughout the model, the approach described in
   [I-D.openconfig-netmod-opstate] is used to represent configuration
   (intended state), operational and derived state data.  That is to
   say, that each container holds a "config" and "state" sub-container -
   with the config container being used for configurable parameters, and
   the state container container holding representing both the
   operational state of configurable leaves, and derived counters and
   statistical information.

2.1.  BGP protocol configuration

   The BGP protocol configuration model is organized hierarchically,
   much like the majority of router implementations.  That is,
   configuration items can be specified at multiple levels, as shown
   below.

                 +--rw bgp!
                    +--rw global
                    |  +-- (global-configuration-options)
                    +--rw neighbors
                    |  +--rw neighbor* [neighbor-address]
                    |  +-- (neighbor-configuration-options)
                    +--rw peer-groups
                       +--rw peer-group* [peer-group-name]
                       +-- (neighbor-configuration-options)

   Users may specify configuration at a higher level and have it apply
   to all lower-level items, or provide overriding configuration at a
   lower level of the hierarchy.  Overriding configuration items are
   optional, with neighbor specific configuration being the most



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   specific or lowest level, followed by peer-group, and finally global.
   Global configuration options reflect a subset of the peer-group or
   neighbor specific configuration options which are relevant to the
   entire BGP instance.

   The model makes the simplifying assumption that most of the
   configuration items are available at all levels of the hierarchy.
   That is, very little configuration is specific to a particular level
   in the hierarchy, other than obvious items such as "group-name" only
   being available for the peer group-level config.  A notable exception
   is for sub-address family configuration where some items are only
   applicable for a given AFI-SAFI combination.

   In order to allow common configuration to be applied to a set of
   neighbors, all neighbor configuration options are available within a
   peer-group.  A neighbor is associated to a particular peer-group
   through the use of a peer-group leaf (which provides a reference to a
   configured item in the peer-group list).

   Address-family configuration is made available in multiple points
   within the model - primarily within the global container, where
   instance-wide configuration can be set (for example, global protocol
   parameters, the BGP best path route selection options, or global
   policies relating to the address-family); and on a per-neighbor or
   per-peer-group basis, where address-families can be enabled or
   disabled, and policy associated with the parent entity applied.
   Within the afi-safi container, generic configuration that applies to
   all address-families (e.g., whether the AFI-SAFI is enabled) is
   presented at the top-level, with address-family specific containers
   made available for options relating to only that AFI-SAFI.  Within
   the current revision of the model a generic set of address-families,
   and common configuration and state options are included - further
   work is expected to add additional parameters to this area of the
   model.

   The following address-families are currently supported by the model:















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           +--rw bgp!
             +--rw global
                +--rw afi-safis
                   +--rw afi-safi* [afi-safi-name]
                      +--rw afi-safi-name    -> ../config/afi-safi-name
                      |
                      +--rw ipv4-unicast
                      |     ...
                      +--rw ipv6-unicast
                      |     ...
                      +--rw ipv4-labelled-unicast
                      |     ...
                      +--rw ipv6-labelled-unicast
                      |     ...
                      +--rw l3vpn-ipv4-unicast
                      |     ...
                      +--rw l3vpn-ipv6-unicast
                      |     ...
                      +--rw l3vpn-ipv4-multicast
                      |     ...
                      +--rw l3vpn-ipv6-multicast
                      |     ...
                      +--rw l2vpn-vpls
                      |     ...
                      +--rw l2vpn-evpn
                      |     ...

2.2.  Policy configuration overview

   The BGP policy configuration model references the generic YANG
   routing policy model described in [I-D.shaikh-rtgwg-policy-model],
   which represents a condition-action policy framework for routing.
   This model adds BGP-specific conditions (e.g., matching on the
   community attribute), and actions (e.g., setting local preference) to
   the generic policy framework.

   Policies that are defined in the routing-policy model are referenced
   in multiple places within the model:

   o  within the global instance, where a policy applies to all address-
      families for all peers.

   o  on a global AFI-SAFI basis, where policies apply to all peers for
      a particular address-family.

   o  on a per-peer-group or per-neighbor basis - where the policy
      applies to all address-families for the particular parent entity.




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   o  on a per-afi-safi basis within a neighbor or peer-group context,
      where the policy is specific to the AFI-SAFI for a a specific
      neighbor or group.

              +--rw bgp
                 +--rw global
                 |  +--rw afi-safi
                 |  |  +--rw afi-safi* [afi-safi-name]
                 |  |     +--rw apply-policy
                 |  +--rw apply-policy
                 +--rw neighbors
                 |  +--rw neighbor* [neighbor-address]
                 |     +--rw afi-safi
                 |     |  +--rw afi-safi* [afi-safi-name]
                 |     |     +--rw apply-policy
                 |     +--rw apply-policy
                 +--rw peer-groups
                    +--rw peer-group* [peer-group-name]
                       +--rw afi-safi
                       |  +--rw afi-safi* [afi-safi-name]
                       |     +--rw apply-policy
                       +--rw apply-policy

2.3.  Operational data overview

   The BGP operational model contains a set of parameters which relate
   to the operational state of the various elements of the BGP router.
   As noted in Section 2 - the approach described in
   [I-D.openconfig-netmod-opstate] is utilized for the inclusion of
   operational and statistical data.  To this end, the "_state"
   groupings (those that contain derived operational parameters) are
   contained within the BGP operational model - and included within the
   relevant "state" containers throughout the core BGP model.  In some
   cases, operational information may be relevant to one instance of a
   common grouping, but not another - for example, the number of
   received, advertised, and installed prefixes is relevant on a per-
   neighbor-basis, but is not required (or meaningful) in the peer-group
   context.  To enable state to be added to particular contexts, the
   tree is augmented through the base BGP module to add these variables,
   without requiring separate groupings.

3.  Security Considerations

   BGP configuration has a significant impact on network operations, and
   as such any related protocol or model carries potential security
   risks.





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   YANG data models are generally designed to be used with the NETCONF
   protocol over an SSH transport.  This provides an authenticated and
   secure channel over which to transfer BGP configuration and
   operational data.  Note that use of alternate transport or data
   encoding (e.g., JSON over HTTPS) would require similar mechanisms for
   authenticating and securing access to configuration data.

   Most of the data elements in the configuration model could be
   considered sensitive from a security standpoint.  Unauthorized access
   or invalid data could cause major disruption.

4.  IANA Considerations

   This YANG data model and the component modules currently use a
   temporary ad-hoc namespace.  If and when it is redirected for the
   standards track, an appropriate namespace URI will be registered in
   the IETF XML Registry" [RFC3688].  The BGP YANG modules will be
   registered in the "YANG Module Names" registry [RFC6020].

5.  YANG modules

   The modules comprising the BGP configuration and operational model
   are described by the YANG modules in the sections below.  The base
   module imports the other modules to create the overall model.

5.1.  BGP base items

   <CODE BEGINS> file bgp.yang
   module bgp {

     yang-version "1";

     // namespace
     namespace "http://openconfig.net/yang/bgp";

     prefix "bgp";

     // import some basic inet types
     import ietf-inet-types { prefix inet; }
     import bgp-multiprotocol { prefix bgp-mp; }
     import routing-policy { prefix rpol; }
     import bgp-types { prefix bgp-types; }
     import bgp-operational { prefix bgp-op; }

     // meta
     organization
       "OpenConfig working group";




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     contact
       "OpenConfig working group
       netopenconfig@googlegroups.com";

     description
       "This module describes a YANG model for BGP protocol
       configuration.It is a limited subset of all of the configuration
       parameters available in the variety of vendor implementations,
       hence it is expected that it would be augmented with vendor-
       specific configuration data as needed. Additional modules or
       submodules to handle other aspects of BGP configuration,
       including policy, VRFs, VPNs, and additional address families
       are also expected.

       This model supports the following BGP configuration level
       hierarchy:

         BGP
           |
           +-> [ global BGP configuration ]
             +-> AFI / SAFI global
           +-> peer group
             +-> [ peer group config ]
             +-> AFI / SAFI [ per-AFI overrides ]
           +-> neighbor
             +-> [ neighbor config ]
             +-> [ optional pointer to peer-group ]
             +-> AFI / SAFI [ per-AFI overrides ]";

     revision "2015-05-15" {
         description
           "";
         reference "TBD";
     }

     grouping bgp-global_config {
       description
         "Global configuration options for the BGP router.";

       leaf as {
         type inet:as-number;
         mandatory "true";
         description
           "Local autonomous system number of the router.  Uses
           the 32-bit as-number type from the model in RFC 6991.";
       }
       leaf router-id {
         type inet:ipv4-address;



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         description
           "Router id of the router, expressed as an
           32-bit value, IPv4 address.";
       }
     }

     grouping bgp-default-route-distance_config {
       description
         "Configuration options relating to the administrative distance
         (or preference) assigned to routes received from different
         sources (external, internal, and local).";

       leaf external-route-distance {
         type uint8 {
           range "1..255";
         }
         description
           "Administrative distance for routes learned from external
           BGP (eBGP).";
       }
       leaf internal-route-distance {
         type uint8 {
           range "1..255";
         }
         description
           "Administrative distance for routes learned from internal
           BGP (iBGP).";
       }
     }

     grouping bgp-confederation_config {
       description
         "Configuration options specifying parameters when the local
         router is within an autonomous system which is part of a BGP
         confederation.";

       leaf enabled {
         type boolean;
         description
           "When this leaf is set to true it indicates that
           the local-AS is part of a BGP confederation";
       }

       leaf identifier {
         type inet:as-number;
         description
           "Confederation identifier for the autonomous system.";
       }



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       leaf-list member-as {
         type inet:as-number;
         description
           "Remote autonomous systems that are to be treated
           as part of the local confederation.";
       }
     }

     grouping bgp-neighbor_config {
       description
         "Neighbor level configuration items.";

       leaf peer-as {
         type inet:as-number;
         description
           "AS number of the peer.";
       }

       leaf local-as {
         type inet:as-number;
         description
           "The local autonomous system number that is to be used
           when establishing sessions with the remote peer or peer
           group, if this differs from the global BGP router
           autonomous system number.";
       }

       leaf peer-type {
           type bgp-types:peer-type;
           description
             "Explicitly designate the peer or peer group as internal
             (iBGP) or external (eBGP).";
       }

       leaf auth-password {
         type string;
         description
           "Configures an MD5 authentication password for use with
           neighboring devices.";
       }

       leaf remove-private-as {
         // could also make this a container with a flag to enable
         // remove-private and separate option.  here, option implies
         // remove-private is enabled.
         type bgp-types:remove-private-as-option;
         description
           "Remove private AS numbers from updates sent to peers.";



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       }

       leaf route-flap-damping {
         type boolean;
         default false;
         description
           "Enable route flap damping.";
       }

       leaf send-community {
         type bgp-types:community-type;
         default "NONE";
         description
           "Specify which types of community should be sent to the
           neighbor or group. The default is to not send the
           community attribute";
       }

       leaf description {
         type string;
         description
           "An optional textual description (intended primarily for use
           with a peer or group";
       }
     }

     grouping bgp-neighbor-timers_config {
       description
         "Config parameters related to timers associated with the BGP
         peer";

       leaf connect-retry {
         type decimal64 {
           fraction-digits 2;
         }
         default 30;
         description
           "Time interval in seconds between attempts to establish a
           session with the peer.";
       }

       leaf hold-time {
         type decimal64 {
           fraction-digits 2;
         }
         default 90;
         description
           "Time interval in seconds that a BGP session will be



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           considered active in the absence of keepalive or other
           messages from the peer.  The hold-time is typically
           set to 3x the keepalive-interval.";
         reference
           "RFC 4271 - A Border Gateway Protocol 4, Sec. 10";
       }

       leaf keepalive-interval {
         type decimal64 {
           fraction-digits 2;
         }
         default 30;
         description
           "Time interval in seconds between transmission of keepalive
           messages to the neighbor.  Typically set to 1/3 the
           hold-time.";
       }

       leaf minimum-advertisement-interval {
         type decimal64 {
           fraction-digits 2;
         }
         default 30;
         description
           "Minimum time which must elapse between subsequent UPDATE
           messages relating to a common set of NLRI being transmitted
           to a peer. This timer is referred to as
           MinRouteAdvertisementIntervalTimer by RFC 4721 and serves to
           reduce the number of UPDATE messages transmitted when a
           particular set of NLRI exhibit instability.";
         reference
           "RFC 4271 - A Border Gateway Protocol 4, Sec 9.2.1.1";
       }
     }

     grouping bgp-neighbor-transport_config {
       description
         "Configuration parameters relating to the transport protocol
         used by the BGP session to the peer";

       leaf tcp-mss {
         type uint16;
         description
           "Sets the max segment size for BGP TCP sessions.";
       }

       leaf mtu-discovery {
         type boolean;



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         default false;
         description
           "Turns path mtu discovery for BGP TCP sessions on (true)
           or off (false)";
       }

       leaf passive-mode {
         type boolean;
         default false;
         description
           "Wait for peers to issue requests to open a BGP session,
           rather than initiating sessions from the local router.";
       }

       leaf local-address {
         type union {
           type inet:ip-address;
           type string;
         }
         //TODO:  the string should be converted to a leafref type
         //to point to an interface when YANG 1.1 is available with
         //leafrefs in union types.
         description
           "Set the local IP (either IPv4 or IPv6) address to use
           for the session when sending BGP update messages.  This
           may be expressed as either an IP address or reference
           to the name of an interface.";
       }
     }

     grouping bgp-neighbor-error-handling_config {
       description
         "Configuration parameters relating to enhanced error handling
         behaviours for BGP";

       leaf treat-as-withdraw {
         type boolean;
         default "false";
         description
           "Specify whether erroneous UPDATE messages for which the
           NLRI can be extracted are reated as though the NLRI is
           withdrawn - avoiding session reset";
         reference "draft-ietf-idr-error-handling-16";
       }
     }

     grouping bgp-neighbor-logging-options_config {
       description



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         "Configuration parameters specifying the logging behaviour for
         BGP sessions to the peer";

       leaf log-neighbor-state-changes {
         type boolean;
         default "true";
         description
           "Configure logging of peer state changes.  Default is
           to enable logging of peer state changes.";
       }
     }

     grouping bgp-neighbor-multihop_config {
       description
         "Configuration parameters specifying the multihop behaviour for
         BGP sessions to the peer";

       leaf enabled {
         type boolean;
         default "false";
         description
           "When enabled the referenced group or neighbors are permitted
           to be indirectly connected - including cases where the TTL
           can be decremented between the BGP peers";
       }

       leaf multihop-ttl {
         type uint8;
         description
           "Time-to-live value to use when packets are sent to the
           referenced group or neighbors and ebgp-multihop is enabled";
       }
     }

     grouping bgp-neighbor-route-reflector_config {
       description
         "Configuration parameters determining whether the behaviour of
         the local system when acting as a route-reflector";

       leaf route-reflector-cluster-id {
         type bgp-types:rr-cluster-id-type;
         description
           "route-reflector cluster id to use when local router is
           configured as a route reflector.  Commonly set at the group
           level, but allows a different cluster
           id to be set for each neighbor.";
       }




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       leaf route-reflector-client {
         type boolean;
         default "false";
         description
           "Configure the neighbor as a route reflector client.";
       }
     }

     grouping bgp-neighbor-as-path-options_config {
       description
         "Configuration parameters allowing manipulation of the AS_PATH
         attribute";

       leaf allow-own-as {
         type uint8;
         default 0;
         description
           "Specify the number of occurrences of the local BGP speaker's
           AS that can occur within the AS_PATH before it is rejected.";
       }

       leaf replace-peer-as {
         type boolean;
         default "false";
         description
           "Replace occurrences of the peer's AS in the AS_PATH
           with the local autonomous system number";
       }
     }

     grouping bgp-neighbor-add-paths_config {
       description
         "Configuration parameters specfying whether the local system
         will send or receive multiple paths using ADD_PATHS";

       leaf receive {
         type boolean;
         default false;
         description
           "Enable ability to receive multiple path advertisements
           for an NLRI from the neighbor or group";
       }

       leaf send-max {
         type uint8;
         description
           "The maximum number of paths to advertise to neighbors
           for a single NLRI";



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       }
     }

     grouping bgp-neighbor-peer-group_config {
       description
         "Configuration parameters indicating whether the specified peer
         is to be considered as part of a peer-group - and therefore
         inherit its configuration";

       leaf peer-group {
         type leafref {
           // we are at /bgp/neighbors/neighbor/
           path "/bgp/peer-groups/peer-group/peer-group-name";
           require-instance true;
         }
         description
           "The peer-group with which this neighbor is associated";
       }
     }

     grouping bgp-graceful-restart {
       description
         "Configures BGP graceful restart, which is a negotiated
         option that indicates that a BGP speaker is able to retain
         forwarding state when a BGP session restarts";

       reference "RFC 4724: Graceful Restart Mechanism for BGP";
       container graceful-restart {
         description
           "Parameters relating the graceful restart mechanism for BGP";
         container config {
           description
             "Configuration parameters relating to graceful-restart";
           uses bgp-neighbor-graceful-restart_config;
         }
         container state {
           config false;
           description
             "State information associated with graceful-restart";
           uses bgp-neighbor-graceful-restart_config;
         }
       }
     }

     grouping bgp-neighbor-graceful-restart_config {
       description
         "Configuration parameters relating to BGP graceful restart.";




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       leaf enabled {
         type boolean;
         description
           "Enable or disable the graceful-restart capability.";
       }

       leaf restart-time {
         type uint16 {
           range 0..4096;
         }
         description
           "Estimated time (in seconds) for the local BGP speaker to
           restart a session. This value is advertise in the graceful
           restart BGP capability.  This is a 12-bit value, referred to
           as Restart Time in RFC4724.  Per RFC4724, the suggested
           default value is <= the hold-time value.";
       }

       leaf stale-routes-time {
         type decimal64 {
           fraction-digits 2;
         }
         description
           "An upper-bound on the time thate stale routes will be
           retained by a router after a session is restarted. If an
           End-of-RIB (EOR) marker is received prior to this timer
           expiring stale-routes will be flushed upon its receipt - if
           no EOR is received, then when this timer expires stale paths
           will be purged. This timer is referred to as the
           Selection_Deferral_Timer in RFC4724";
       }

       leaf helper-only {
         type boolean;
         description
           "Enable graceful-restart in helper mode only. When this
           leaf is set, the local system does not retain forwarding
           its own state during a restart, but supports procedures
           for the receiving speaker, as defined in RFC4724.";
       }
     }

     // ************************************************************
     // *              configuration context containers            *
     // ************************************************************

     grouping bgp-global-base {
       description



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         "Global configuration parameters for the BGP router";

       container config {
         description
           "Configuration parameters relating to the global BGP router";
         uses bgp-global_config;
       }
       container state {
         config false;
         description
           "State information relating to the global BGP router";
         uses bgp-global_config;
         uses bgp-op:bgp-global_state;
       }

       uses bgp-mp:bgp-route-selection-options;

       container default-route-distance {
         description
           "Administrative distance (or preference) assigned to
           routes received from different sources
           (external, internal, and local).";

         container config {
           description
             "Configuration parameters relating to the default route
             distance";
           uses bgp-default-route-distance_config;
         }
         container state {
           config false;
           description
             "State information relating to the default route distance";
           uses bgp-default-route-distance_config;
         }
       }

       container confederation {
         description
           "Parameters indicating whether the local system acts as part
           of a BGP confederation";

         container config {
           description
             "Configuration parameters relating to BGP confederations";
           uses bgp-confederation_config;
         }
         container state {



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           config false;
           description
             "State information relating to the BGP confederations";
           uses bgp-confederation_config;
         }
       }

       uses bgp-mp:bgp-use-multiple-paths;

       uses bgp-graceful-restart;

       container afi-safis {
         description
           "Address family specific configuration";
         uses bgp-mp:bgp-common-afi-safi-list;
       }
     }

     grouping bgp-neighbors {
       description
         "BGP neighbors configured on the local system";
       list neighbor {
         key "neighbor-address";
         description
           "List of BGP neighbors configured on the local system,
           uniquely identified by peer IPv[46] address";

         leaf neighbor-address {
           type leafref {
             path "../config/neighbor-address";
           }
           description
             "Reference to the address of the BGP neighbor used as
             a key in the neighbor list";
         }

         uses bgp-neighbor-group;
       }
     }

     grouping bgp-peer-group {
       description
         "BGP peer-groups configured on the local system";
       list peer-group {
         key "peer-group-name";
         description
           "List of BGP peer-groups configured on the local system -
           uniquely identified by peer-group name";



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       leaf peer-group-name {
         type leafref {
           path "../config/peer-group-name";
         }
         description
           "Reference to the name of the BGP peer-group used as a
           key in the peer-group list";
         }

         uses bgp-neighbor-group;
       }
     }

     grouping bgp-neighbor-group {
       description
         "Parameters related to a BGP neighbor or group";

       container config {
         description
           "Configuration parameters relating to the BGP neighbor or
           group";
         uses bgp-neighbor_config;
       }
       container state {
         config false;
         description
           "State information relating to the BGP neighbor or group";
         uses bgp-neighbor_config;
       }

       container timers {
         description
           "Timers related to a BGP neighbor or group";
         container config {
           description
             "Configuration parameters relating to timers used for the
             BGP neighbor or group";
           uses bgp-neighbor-timers_config;
         }
         container state {
           config false;
           description
             "State information relating to the timers used for the BGP
             neighbor or group";
           uses bgp-neighbor-timers_config;
         }
       }




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       container transport {
         description
           "Transport session parameters for the BGP neighbor or group";
         container config {
           description
             "Configuration parameters relating to the transport
             session(s) used for the BGP neighbor or group";
           uses bgp-neighbor-transport_config;
         }
         container state {
           config false;
           description
             "State information relating to the transport session(s)
             used for the BGP neighbor or group";
           uses bgp-neighbor-transport_config;
         }
       }

       container error-handling {
         description
           "Error handling parameters used for the BGP neighbor or
           group";
         container config {
           description
             "Configuration parameters enabling or modifying the
             behavior or enhanced error handling mechanisms for the BGP
             neighbor or group";
           uses bgp-neighbor-error-handling_config;
         }
         container state {
           config false;
           description
             "State information relating to enhanced error handling
             mechanisms for the BGP neighbor or group";
           uses bgp-neighbor-error-handling_config;
         }
       }

       container logging-options {
         description
           "Logging options for events related to the BGP neighbor or
           group";
         container config {
           description
             "Configuration parameters enabling or modifying logging
             for events relating to the BGP neighbor or group";
           uses bgp-neighbor-logging-options_config;
         }



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         container state {
           config false;
           description
             "State information relating to logging for the BGP neighbor
             or group";
           uses bgp-neighbor-logging-options_config;
         }
       }

       container ebgp-multihop {
         description
           "eBGP multi-hop parameters for the BGP neighbor or group";
         container config {
           description
             "Configuration parameters relating to eBGP multihop for the
             BGP neighbor or group";
           uses bgp-neighbor-multihop_config;
         }
         container state {
           config false;
           description
             "State information for eBGP multihop, for the BGP neighbor
             or group";
           uses bgp-neighbor-multihop_config;
         }
       }

       container route-reflector {
         description
           "Route reflector parameters for the BGP neighbor or group";
         container config {
           description
             "Configuraton parameters relating to route reflection
             for the BGP neighbor or group";
           uses bgp-neighbor-route-reflector_config;
         }
         container state {
           config false;
           description
             "State information relating to route reflection for the
             BGP neighbor or group";
           uses bgp-neighbor-route-reflector_config;
         }
       }

       container as-path-options {
         description
           "AS_PATH manipulation parameters for the BGP neighbor or



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           group";
         container config {
           description
             "Configuration parameters relating to AS_PATH manipulation
             for the BGP peer or group";
           uses bgp-neighbor-as-path-options_config;
         }
         container state {
           config false;
           description
             "State information relating to the AS_PATH manipulation
             mechanisms for the BGP peer or group";
           uses bgp-neighbor-as-path-options_config;
         }
       }

       container add-paths {
         description
           "Parameters relating to the advertisement and receipt of
           multiple paths for a single NLRI (add-paths)";
         container config {
           description
             "Configuration parameters relating to ADD_PATHS";
           uses bgp-neighbor-add-paths_config;
         }
         container state {
           config false;
           description
             "State information associated with ADD_PATHS";
           uses bgp-neighbor-add-paths_config;
         }
       }

       container afi-safis {
         description
           "Per-address-family configuration parameters associated with
           the neighbor or group";
         uses bgp-mp:bgp-common-afi-safi-list;
       }

       uses bgp-graceful-restart;

       uses rpol:apply-policy-group;
     }

     grouping bgp-neighbor-neighbor-address_config {
       description
         "Configuration options relating to the BGP neighbor address";



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       leaf neighbor-address {
           type inet:ip-address;
           description
             "Address of the BGP peer, either in IPv4 or IPv6";
       }
     }

     grouping bgp-peer-group-peer-group-name_config {
       description
         "Configuration options relating to the BGP peer-group name";

       leaf peer-group-name {
         type string;
         description
           "Name of the BGP peer-group";
       }
     }

     // add peer-group pointer only for the neighbor list
     augment /bgp/neighbors/neighbor/config {
       description
         "Augmentation to allow association of a neighbor with a
         peer-group";
       uses bgp-neighbor-peer-group_config;
     }

     augment /bgp/neighbors/neighbor/state {
       description
         "Augmentation to reflect the association of a neighbor with a
         peer-group";
       uses bgp-neighbor-peer-group_config;
     }

     augment /bgp/peer-groups/peer-group {
       description
         "Augmentation to add multipath configuration to a peer-group";
       uses bgp-mp:bgp-use-multiple-paths;
     }

     augment /bgp/neighbors/neighbor {
       description
         "Augmentation to add the multipath configuration to a
         neighbor";
       uses bgp-mp:bgp-use-multiple-paths-neighbor;
     }

     augment /bgp/peer-groups/peer-group/afi-safis/afi-safi {
       description



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         "Augmentation to add multipath configuration to a peer-group
         on a per-AFI-SAFI basis";
       uses bgp-mp:bgp-use-multiple-paths;
     }

     augment /bgp/neighbors/neighbor/afi-safis/afi-safi {
       description
         "Augmentation to add multipath configuration to a neighbor
         on a per-AFI-SAFI basis";
       uses bgp-mp:bgp-use-multiple-paths-neighbor;
     }

     augment /bgp/global/afi-safis/afi-safi {
       description
         "Augmentation to add global instance specific AFI-SAFI
         configuration information";
       uses bgp-mp:bgp-global-afi-safi;
       uses bgp-mp:bgp-use-multiple-paths;
     }

     augment /bgp/peer-groups/peer-group/afi-safis/afi-safi {
       description
         "Augmentation that adds peer-group instance specific
         AFI-SAFI configuration information";
       uses bgp-mp:bgp-group-afi-safi;
     }

     augment /bgp/neighbors/neighbor/config {
       description
         "Augmentation adding the neighbor address to the
         neighbor configuration container";
       uses bgp-neighbor-neighbor-address_config;
     }

     augment /bgp/neighbors/neighbor/state {
       description
         "Augmentation adding the neighbor address to the
         neighbor state container";
       uses bgp-neighbor-neighbor-address_config;
     }

     augment /bgp/peer-groups/peer-group/config {
       description
         "Augmentation adding the peer-group name to the
         peer-group configuration container";
       uses bgp-peer-group-peer-group-name_config;
     }




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     augment /bgp/peer-groups/peer-group/state {
       description
         "Augmentation adding the peer-group name to the
         peer-group state container";
       uses bgp-peer-group-peer-group-name_config;
     }

     // ************************************************************
     // *              Augmentations to add state                  *
     // *  (rjs: cleaner to have these in the base module to avoid *
     //     needing to specify which module - e.g. augment of      *
     //     /bgp:bgp/bgp:neighbors/bgp:neighbor...)                *
     // ************************************************************
     augment /bgp/neighbors/neighbor/state {
       description
         "Augmentation to add operational state related to a particular
         BGP neighbor";
       uses bgp-op:bgp-neighbor_state;
     }

     augment /bgp/neighbors/bgp:neighbor/state {
       description
         "Augmentation to add operational state related to a particular
         BGP neighbor";

       container messages {
         description
           "Counters for BGP messages sent and received from the
           neighbor";
         container sent {
           description
             "Counters relating to BGP messages sent to the neighbor";
           uses bgp-op:bgp-neighbor-message-counters-sent_state;
           }

         container received {
           description
             "Counters for BGP messages received from the neighbor";
           uses bgp-op:bgp-neighbor-message-counters-received_state;
         }
       }

       container queues {
         description
           "Counters related to queued messages associated with the
           BGP neighbor";
         uses bgp-op:bgp-neighbor-queue-counters_state;
       }



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     }

     augment /bgp:bgp/bgp:neighbors/neighbor/timers/state {
       description
         "Augmentation to add the operational state of timers associated
         with the BGP neighbor";
       uses bgp-op:bgp-neighbor-timers_state;
     }

     augment /bgp/neighbors/neighbor/transport/state {
       description
         "Augmentation to add the operational state of the transport
         session associated with the BGP neighbor";
       uses bgp-op:bgp-neighbor-transport_state;
     }

     augment /bgp/neighbors/neighbor/error-handling/state {
       description
         "Augmentation to add the operational state of the error
         handling associated with the BGP neighbor";
       uses bgp-op:bgp-neighbor-error-handling_state;
     }

     augment /bgp/neighbors/neighbor/graceful-restart/state {
       description
         "Augmentation to add the operational state of graceful-restart
         associated with a BGP neighbor";
       uses bgp-op:bgp-afi-safi-graceful-restart_state;
     }

     augment /bgp/peer-groups/peer-group/state {
       description
         "Augmentation to add the operational state and counters
         relating to a BGP peer-group";
       uses bgp-op:bgp-peer-group_state;
     }

     augment /bgp/global/afi-safis/afi-safi/state {
       description
         "Augmentation to add operational state and counters
         on a per-AFI-SAFI basis to the global BGP router";
       uses bgp-op:bgp-global-afi-safi_state;
     }

     augment /bgp/neighbors/neighbor/afi-safis/afi-safi/state {
       description
         "Augmentation to add per-AFI-SAFI operational state
         and counters to the BGP neighbor";



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       uses bgp-op:bgp-neighbor-afi-safi_state;
     }

     augment "/bgp/neighbors/neighbor/afi-safis/afi-safi/" +
       "graceful-restart/state" {
       description
         "Augmentation to add per-AFI-SAFI operational state for BGP
         graceful-restart";
       uses bgp-op:bgp-neighbor-afi-safi-graceful-restart_state;
     }

     // ************************************************************
     // *              module structure containers                 *
     // ************************************************************

     container bgp {
       presence "Container for BGP protocol hierarchy";
       description
         "Top-level configuration and state for the BGP router";

       container global {
         description
           "Global configuration for the BGP router";
           uses bgp-global-base;
           uses rpol:apply-policy-group;
       }

       container neighbors {
         description
           "Configuration for BGP neighbors";
         uses bgp-neighbors;
       }

       container peer-groups {
         description
           "Configuration for BGP peer-groups";
         uses bgp-peer-group;
       }
     }
   }
   <CODE ENDS>


5.2.  BGP base types

   <CODE BEGINS> file bgp-types.yang
   module bgp-types {
       yang-version "1";



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       namespace "http://openconfig.net/yang/bgp-types";

       prefix "bgp-types";

       import ietf-inet-types { prefix inet; }

       // meta
       organization
       "OpenConfig working group";

     contact
       "OpenConfig working group
       netopenconfig@googlegroups.com";

     description
       "This module contains general data definitions for use in BGP
       policy. It can be imported by modules that make use of BGP
       attributes";

     revision "2015-05-15" {
       description "Initial revision";
       reference "TBD";
     }


     identity bgp-capability {
       description "Base identity for a BGP capability";
     }

     identity MPBGP {
       base "bgp-capability";
       description
         "Multi-protocol extensions to BGP";
       reference "RFC2858";
     }

     identity ROUTE-REFRESH {
       base "bgp-capability";
       description
         "The BGP route-refresh functionality";
       reference "RFC2918";
     }

     identity ASN32 {
       base "bgp-capability";
       description
         "4-byte (32-bit) AS number functionality";
       reference "RFC6793";



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     }

     identity GRACEFUL-RESTART {
       base "bgp-capability";
       description
         "Graceful restart functionality";
       reference "RFC4724";
     }

     identity ADD-PATHS {
       base "bgp-capability";
       description
         "BGP add-paths";
       reference "draft-ietf-idr-add-paths";
     }

     identity afi-safi-type {
       description
         "Base identity type for AFI,SAFI tuples for BGP-4";
       reference "RFC4760 - multiprotocol extensions for BGP-4";
     }

     identity ipv4-unicast {
       base afi-safi-type;
       description
         "IPv4 unicast (AFI,SAFI = 1,1)";
       reference "RFC4760";
     }

     identity ipv6-unicast {
       base afi-safi-type;
       description
         "IPv6 unicast (AFI,SAFI = 2,1)";
       reference "RFC4760";
     }

     identity ipv4-labelled-unicast {
       base afi-safi-type;
       description
         "Labelled IPv4 unicast (AFI,SAFI = 1,4)";
       reference "RFC3107";
     }

     identity ipv6-labelled-unicast {
       base afi-safi-type;
       description
         "Labelled IPv6 unicast (AFI,SAFI = 2,4)";
       reference "RFC3107";



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     }

     identity l3vpn-ipv4-unicast {
       base afi-safi-type;
       description
         "Unicast IPv4 MPLS L3VPN (AFI,SAFI = 1,128)";
       reference "RFC4364";
     }

     identity l3vpn-ipv6-unicast {
       base afi-safi-type;
       description
         "Unicast IPv6 MPLS L3VPN (AFI,SAFI = 2,128)";
       reference "RFC4659";
     }

     identity l3vpn-ipv4-multicast {
       base afi-safi-type;
       description
         "Multicast IPv4 MPLS L3VPN (AFI,SAFI = 1,129)";
       reference "RFC6514";
     }

     identity l3vpn-ipv6-multicast {
       base afi-safi-type;
       description
         "Multicast IPv6 MPLS L3VPN (AFI,SAFI = 2,129)";
       reference "RFC6514";
     }

     identity l2vpn-vpls {
       base afi-safi-type;
       description
         "BGP-signalled VPLS (AFI,SAFI = 25,65)";
       reference "RFC4761";
     }

     identity l2vpn-evpn {
       base afi-safi-type;
       description
         "BGP MPLS Based Ethernet VPN (AFI,SAFI = 25,70)";
     }

     identity bgp-well-known-std-community {
       description
         "Reserved communities within the standard community space
         defined by RFC1997. These communities must fall within the
         range 0x00000000 to 0xFFFFFFFF";



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       reference "RFC1997";
     }

     identity NO_EXPORT {
       base bgp-well-known-std-community;
       description
         "Do not export NLRI received carrying this community outside
         the bounds of this autonomous system, or this confederation if
         the local autonomous system is a confederation member AS. This
         community has a value of 0xFFFFFF01.";
       reference "RFC1997";
     }

     identity NO_ADVERTISE {
       base bgp-well-known-std-community;
       description
         "All NLRI received carrying this community must not be
         advertised to other BGP peers. This community has a value of
         0xFFFFFF02.";
       reference "RFC1997";
     }

     identity NO_EXPORT_SUBCONFED {
       base bgp-well-known-std-community;
       description
         "All NLRI received carrying this community must not be
         advertised to external BGP peers - including over confederation
         sub-AS boundaries. This community has a value of 0xFFFFFF03.";
       reference "RFC1997";
     }

     identity NOPEER {
       base bgp-well-known-std-community;
       description
         "An autonomous system receiving NLRI tagged with this community
         is advised not to readvertise the NLRI to external bi-lateral
         peer autonomous systems. An AS may also filter received NLRI
         from bilateral peer sessions when they are tagged with this
         community value";
       reference "RFC3765";
     }

     identity INTERNET {
       base bgp-well-known-std-community;
       description
         "A community used by some implementations with the value 0:0
         which represents all possible community values.";
     }



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     typedef bgp-session-direction {
       type enumeration {
         enum INBOUND {
           description
             "Refers to all NLRI received from the BGP peer";
         }
         enum OUTBOUND {
           description
             "Refers to all NLRI advertised to the BGP peer";
         }
       }
       description
         "Type to describe the direction of NLRI transmission";
     }

     typedef bgp-well-known-community-type {
       type identityref {
         base bgp-well-known-std-community;
       }
       description
         "Type definition for well-known IETF community attribute
         values";
       reference
         "IANA Border Gateway Protocol (BGP) Well Known Communities";
     }


     typedef bgp-std-community-type {
       // TODO: further refine restrictions and allowed patterns
       // 4-octet value:
       //  <as number> 2 octets
       //  <community value> 2 octets
       type union {
         type uint32 {
         // per RFC 1997, 0x00000000 - 0x0000FFFF and 0xFFFF0000 -
         // 0xFFFFFFFF are reserved
           range "65536..4294901759"; // 0x00010000..0xFFFEFFFF
         }
         type string {
           pattern '([0-9]+:[0-9]+)';
         }
       }
       description
         "Type definition for standard commmunity attributes";
       reference "RFC 1997 - BGP Communities Attribute";
     }

     typedef bgp-ext-community-type {



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       // TODO: needs more work to make this more precise given the
       // variability of extended community attribute specifications
       // 8-octet value:
       //  <type> 2 octects
       //  <value> 6 octets
       type string {
         pattern '([0-9\.]+(:[0-9]+)?:[0-9]+)';
       }
       description
         "Type definition for extended community attributes";
       reference "RFC 4360 - BGP Extended Communities Attribute";
     }

     typedef bgp-community-regexp-type {
       // TODO: needs more work to decide what format these regexps can
       // take.
       type string;
       description
         "Type definition for communities specified as regular
         expression patterns";
     }

     typedef bgp-origin-attr-type {
       type enumeration {
         enum IGP {
           description "Origin of the NLRI is internal";
         }
         enum EGP {
           description "Origin of the NLRI is EGP";
         }
         enum INCOMPLETE {
           description "Origin of the NLRI is neither IGP or EGP";
         }
       }
       description
         "Type definition for standard BGP origin attribute";
       reference "RFC 4271 - A Border Gateway Protocol 4 (BGP-4),
         Sec 4.3";
     }

     typedef peer-type {
       type enumeration {
         enum INTERNAL {
           description "internal (iBGP) peer";
         }
         enum EXTERNAL {
           description "external (eBGP) peer";
         }



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       }
       description
         "labels a peer or peer group as explicitly internal or
         external";
     }


     typedef remove-private-as-option {
       type enumeration {
         enum ALL {
           description "remove all private ASes in the path";
         }
         enum REPLACE {
           description "replace private ASes with local AS";
         }
       }
       description
         "set of options for configuring how private AS path numbers
         are removed from advertisements";
     }

     typedef percentage {
       type uint8 {
         range "0..100";
       }
       description
         "Integer indicating a percentage value";
     }

     typedef rr-cluster-id-type {
       type union {
         type uint32;
         type inet:ipv4-address;
       }
       description
         "union type for route reflector cluster ids:
         option 1: 4-byte number
         option 2: IP address";
     }

     typedef community-type {
       type enumeration {
         enum STANDARD {
           description "send only standard communities";
         }
         enum EXTENDED {
           description "send only extended communities";
         }



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         enum BOTH {
           description "send both standard and extended communities";
         }
         enum NONE {
           description "do not send any community attribute";
         }
       }
       description
         "type describing variations of community attributes:
         STANDARD: standard BGP community [rfc1997]
         EXTENDED: extended BGP community [rfc4360]
         BOTH: both standard and extended community";
     }


   }
   <CODE ENDS>


5.3.  BGP policy items

   <CODE BEGINS> file bgp-policy.yang
   module bgp-policy {

     yang-version "1";

     // namespace
     namespace "http://openconfig.net/yang/bgp-policy";

     prefix "bgp-pol";

     // import some basic types
     import ietf-inet-types { prefix inet; }
     import routing-policy {prefix rpol; }
     import policy-types { prefix pt; }
     import bgp-types { prefix bgp-types; }



     // meta
     organization
       "OpenConfig working group";

     contact
       "OpenConfig working group
       netopenconfig@googlegroups.com";

     description



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       "This module contains data definitions for BGP routing policy.
       It augments the base routing-policy module with BGP-specific
       options for conditions and actions.";

     revision "2015-05-15" {
       description
         "Updated model to augment base routing-policy module";
       reference "TBD";
     }

     // extension statements

     // feature statements

     // identity statements

     // typedef statements

     typedef bgp-as-path-prepend-repeat {
       type uint8;
       description
         "Option for the BGP as-prepend policy action.  Prepends the
         local AS number repeated n times";
     }

     typedef bgp-set-community-option-type {
       type enumeration {
         enum ADD {
           description
             "add the specified communities to the existing
             community attribute";
         }
         enum REMOVE {
           description
             "remove the specified communities from the
             existing community attribute";
         }
         enum REPLACE {
           description
             "replace the existing community attribute with
             the specified communities. If an empty set is
             specified, this removes the community attribute
             from the route.";
         }
       }
       description
         "Type definition for options when setting the community
         attribute in a policy action";



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     }

     typedef bgp-next-hop-type {
       type union {
         type inet:ip-address;
         type enumeration {
           enum SELF {
             description "special designation for local router's own
             address, i.e., next-hop-self";
           }
         }
       }
       description
         "type definition for specifying next-hop in policy actions";
     }

     typedef bgp-set-med-type {
       type union {
         type uint32;
         type string {
           pattern "^[+-][0-9]+";
         }
         type enumeration {
           enum IGP {
             description "set the MED value to the IGP cost toward the
             next hop for the route";
           }
         }
       }
       description
         "Type definition for specifying how the BGP MED can
         be set in BGP policy actions. The three choices are to set
         the MED directly, increment/decrement using +/- notation,
         and setting it to the IGP cost (predefined value).";
     }

     // grouping statements

     grouping bgp-match-conditions {
       description
         "Condition statement definitions for checking membership in a
         defined set";

       container match-community-set {
         presence
           "The presence of this container indicates that the routes
           should match the referenced community-set";




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         description
           "Match a referenced community-set according to the logic
           defined in the match-set-options leaf";

         leaf community-set {
           type leafref {
             path "/rpol:routing-policy/rpol:defined-sets/" +
               "bgp-pol:bgp-defined-sets/bgp-pol:community-sets/" +
               "bgp-pol:community-set/bgp-pol:community-set-name";
             require-instance true;
           }
           description
             "References a defined community set";
         }
         uses rpol:match-set-options-group;
       }

       container match-ext-community-set {
         presence
           "The presence of this container indicates that the routes
           should match the referenced extended community set";

         description
           "Match a referenced extended community-set according to the
           logic defined in the match-set-options leaf";

         leaf ext-community-set {
           type leafref {
             path "/rpol:routing-policy/rpol:defined-sets/" +
               "bgp-pol:bgp-defined-sets/bgp-pol:ext-community-sets/" +
               "bgp-pol:ext-community-set/" +
               "bgp-pol:ext-community-set-name";
             require-instance true;
           }
           description "References a defined extended community set";
         }
         uses rpol:match-set-options-group;
       }

       container match-as-path-set {
         presence
           "The presence of this container indicates that the route
           should match the referenced as-path set";

         description
           "Match a referenced as-path set according to the logic
           defined in the match-set-options leaf";




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         leaf as-path-set {
           type leafref {
             path "/rpol:routing-policy/rpol:defined-sets/" +
               "bgp-pol:bgp-defined-sets/bgp-pol:as-path-sets/" +
               "bgp-pol:as-path-set/bgp-pol:as-path-set-name";
             require-instance true;
           }
           description "References a defined AS path set";
         }
         uses rpol:match-set-options-group;
       }
     }

     grouping bgp-attribute-conditions {
       description
         "Condition statement definitions for comparing a BGP route
         attribute to a specified value";

       leaf med-eq {
         type uint32;
         description
           "Condition to check if the received MED value is equal to
           the specified value";
       }

       leaf origin-eq {
         type bgp-types:bgp-origin-attr-type;
         description
           "Condition to check if the route origin is equal to the
           specified value";
       }

       leaf-list next-hop-in {
         type inet:ip-address;
         description
           "List of next hop addresses to check for in the route
           update";
       }

       leaf local-pref-eq {
         type uint32;
         // TODO: add support for other comparisons if needed
         description
           "Condition to check if the local pref attribute is equal to
           the specified value";
       }

       container community-count {



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         presence "node is present in the config data to indicate a
         community-count condition";

         description
           "Value and comparison operations for conditions based on the
           number of communities in the route update";

         uses pt:attribute-compare-operators;

       }

       container as-path-length {

         presence "node is present in the config data to indicate a
         as-path-length condition";

         description
           "Value and comparison operations for conditions based on the
           length of the AS path in the route update";

         uses pt:attribute-compare-operators;
       }

       leaf route-type {
         // TODO: verify extent of vendor support for this comparison
         type enumeration {
           enum INTERNAL {
             description "route type is internal";
           }
           enum EXTERNAL {
             description "route type is external";
           }
         }
         description
           "Condition to check the route type in the route update";
       }
     }


     // augment statements

     augment "/rpol:routing-policy/rpol:defined-sets" {
       description "adds BGP defined sets container to routing policy
       model";

       container bgp-defined-sets {
         description
           "BGP-related set definitions for policy match conditions";



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         container community-sets {
           description
             "Enclosing container for community sets";

           list community-set {
             key community-set-name;
             description
                 "Definitions for community sets";

             leaf community-set-name {
               type string;
               mandatory true;
               description
                 "name / label of the community set -- this is used to
                 reference the set in match conditions";
             }

             leaf-list community-member {
               type union {
                 type bgp-types:bgp-std-community-type;
                 type bgp-types:bgp-community-regexp-type;
                 type bgp-types:bgp-well-known-community-type;
               }
               description
                 "members of the community set";
             }
           }
         }

         container ext-community-sets {
           description
             "Enclosing container for extended community sets";

           list ext-community-set {
             key ext-community-set-name;
             description
                 "Definitions for extended community sets";

             leaf ext-community-set-name {
               type string;
               description
                 "name / label of the extended community set -- this is
                 used to reference the set in match conditions";
             }

             leaf-list ext-community-member {
               type union {
                 type bgp-types:bgp-ext-community-type;



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                 // TODO: is regexp support needed for extended
                 // communities?
                 type bgp-types:bgp-community-regexp-type;
               }
               description
                   "members of the extended community set";
             }
           }
         }

         container as-path-sets {
           description
             "Enclosing container for AS path sets";

           list as-path-set {
             key as-path-set-name;
             description
                 "Definitions for AS path sets";

             leaf as-path-set-name {
               type string;
               description
                 "name of the AS path set -- this is used to reference
                 the set in match conditions";
             }

             leaf-list as-path-set-member {
               // TODO: need to refine typedef for AS path expressions
               type string;
               description
                   "AS path expression -- list of ASes in the set";
             }
           }
         }
       }
     }

     augment "/rpol:routing-policy/rpol:policy-definitions/" +
       "rpol:policy-definition/rpol:statements/rpol:statement/" +
       "rpol:conditions" {
       description "BGP policy conditions added to routing policy
       module";

       container bgp-conditions {
         description "Policy conditions for matching
         BGP-specific defined sets or comparing BGP-specific
         attributes";




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         uses bgp-match-conditions;
         uses bgp-attribute-conditions;
       }
     }

     augment "/rpol:routing-policy/rpol:policy-definitions/" +
       "rpol:policy-definition/rpol:statements/rpol:statement/" +
       "rpol:actions" {
       description "BGP policy actions added to routing policy
       module";

       container bgp-actions {
         description
           "Definitions for policy action statements that
           change BGP-specific attributes of the route";

         container set-as-path-prepend {

           presence "node is present in the config data to use the AS
         prepend action";
           description
               "action to prepend local AS number to the AS-path a
           specified number of times";

           leaf repeat-n {
             type uint8;
             description "number of times to prepend the local AS
             number";
           }
         }

         container set-community {
           presence "node is present in the config data when
           set-community action is used";
           description
             "action to set the community attributes of the route, along
             with options to modify how the community is modified";

           choice set-community-method {
             description
               "Option to set communities using an inline list or
               reference to an existing defined set.";

             case inline {
               leaf-list communities {
                 type union {
                   type bgp-types:bgp-std-community-type;
                   type bgp-types:bgp-well-known-community-type;



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                 }
                 description
                   "Set the community values for the update inline with
                   a list.";
               }
             }
             case reference {
               leaf community-set-ref {
                 type leafref {
                   path "/rpol:routing-policy/rpol:defined-sets/" +
                     "bgp-pol:bgp-defined-sets/" +
                     "bgp-pol:community-sets/bgp-pol:community-set/" +
                     "bgp-pol:community-set-name";
                   require-instance true;
                 }
                 description
                   "References a defined community set by name";
               }
             }
           }
           leaf options {
             type bgp-set-community-option-type;
             description
               "Options for modifying the community attribute with
               the specified values.  These options apply to both
               methods of setting the community attribute.";
           }
         }

         container set-ext-community {

           presence "node is present in the config data when
           set-community action is used";
           description
             "Action to set the extended community attributes of the
             route, along with options to modify how the community is
             modified";

           choice set-ext-community-method {
             description
               "Option to set communities using an inline list or
               reference to an existing defined set.";

             case inline {
               leaf-list communities {
                 type union {
                   type bgp-types:bgp-ext-community-type;
                   type bgp-types:bgp-well-known-community-type;



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                 }
                 description
                   "Set the community values for the update inline with
                   a list.";
               }
             }
             case reference {
               leaf ext-community-set-ref {
                 type leafref {
                   path "/rpol:routing-policy/rpol:defined-sets/" +
                     "bgp-pol:bgp-defined-sets/" +
                     "bgp-pol:ext-community-sets/" +
                     "bgp-pol:ext-community-set/" +
                     "bgp-pol:ext-community-set-name";
                   require-instance true;
                 }
                 description
                   "References a defined extended community set by
                   name";
               }
             }
           }
           leaf options {
             type bgp-set-community-option-type;
             description
               "options for modifying the extended community
               attribute with the specified values. These options
               apply to both methods of setting the community
               attribute.";
           }
         }

         leaf set-route-origin {
           type bgp-types:bgp-origin-attr-type;
           description "set the origin attribute to the specified
           value";
         }

         leaf set-local-pref {
           type uint32;
           description "set the local pref attribute on the route
           update";
         }

         leaf set-next-hop {
           type bgp-next-hop-type;
           description "set the next-hop attribute in the route update";
         }



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         leaf set-med {
           type bgp-set-med-type;
           description "set the med metric attribute in the route
           update";
         }
       }
     }

     // rpc statements

     // notification statements
   }
   <CODE ENDS>


5.4.  BGP multiprotocol items

   <CODE BEGINS> file bgp-multiprotocol.yang
   module bgp-multiprotocol {

     yang-version "1";

     // namespace
     namespace "http://openconfig.net/yang/bgp-multiprotocol";

     prefix "bgp-mp";

     // import some basic inet types
     import routing-policy { prefix rpol; }
     import bgp-types { prefix bgp-types; }
     import bgp-operational { prefix bgp-op; }

     // meta
     organization
       "OpenConfig working group";

     contact
       "OpenConfig working group
       netopenconfig@googlegroups.com";

     description
       "This module is part of a YANG model for BGP protocol
       configuration, focusing on configuration of multiprotocol
       BGP, in particular various relevant address families (AFI) and
       sub-address families (SAFI).

       Identities (rather than enumerated types) are used to identify
       each AFI / SAFI type to make it easier for users to extend to



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       pre-standard or custom AFI/SAFI types.  This module is only
       intended to capture the most";


     revision "2015-05-15" {
       description
         "Refactored multiprotocol module";
       reference "TBD";
     }

     grouping ipv4-unicast-group {
       description
         "Group for IPv4 Unicast configuration options";

       container ipv4-unicast {
         when "../afi-safi-name = 'bgp-mp:ipv4-unicast'" {
           description
             "Include this container for IPv4 Unicast specific
             configuration";
         }

         description "IPv4 unicast configuration options";

         // include common IPv[46] unicast options
         uses ipv4-ipv6-unicast-common;

         // placeholder for IPv4 unicast  specific configuration
       }
     }

     grouping ipv6-unicast-group {
       description
         "Group for IPv6 Unicast configuration options";

       container ipv6-unicast {
         when "../afi-safi-name = 'bgp-mp:ipv6-unicast'" {
           description
             "Include this container for IPv6 Unicast specific
             configuration";
         }

         description "IPv6 unicast configuration options";

         // include common IPv[46] unicast options
         uses ipv4-ipv6-unicast-common;

         // placeholder for IPv6 unicast specific configuration
         // options



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       }
     }

     grouping ipv4-labelled-unicast-group {
       description
         "Group for IPv4 Labelled Unicast configuration options";

       container ipv4-labelled-unicast {
         when "../afi-safi-name = 'bgp-mp:ipv4-labelled-unicast'" {
           description
             "Include this container for IPv4 Labelled Unicast specific
             configuration";
         }

         description "IPv4 Labelled Unicast configuration options";

         uses all-afi-safi-common;

         // placeholder for IPv4 Labelled Unicast specific config
         // options
       }
     }

     grouping ipv6-labelled-unicast-group {
       description
         "Group for IPv6 Labelled Unicast configuration options";

       container ipv6-labelled-unicast {
         when "../afi-safi-name = 'bgp-mp:ipv6-labelled-unicast'" {
           description
             "Include this container for IPv6 Labelled Unicast specific
             configuration";
         }

         description "IPv6 Labelled Unicast configuration options";

         uses all-afi-safi-common;

         // placeholder for IPv6 Labelled Unicast specific config
         // options.
       }
     }

     grouping l3vpn-ipv4-unicast-group {
       description
         "Group for IPv4 Unicast L3VPN configuration options";

       container l3vpn-ipv4-unicast {



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         when "../afi-safi-name = 'bgp-mp:l3vpn-ipv4-unicast'" {
           description
             "Include this container for IPv4 Unicast L3VPN specific
             configuration";
         }

         description "Unicast IPv4 L3VPN configuration options";

         // include common L3VPN configuration options
         uses l3vpn-ipv4-ipv6-unicast-common;

         // placeholder for IPv4 Unicast L3VPN specific config options.
       }
     }

     grouping l3vpn-ipv6-unicast-group {
       description
         "Group for IPv6 Unicast L3VPN configuration options";

       container l3vpn-ipv6-unicast {
         when "../afi-safi-name = 'bgp-mp:l3vpn-ipv6-unicast'" {
           description
             "Include this container for unicast IPv6 L3VPN specific
             configuration";
         }

         description "Unicast IPv6 L3VPN configuration options";

         // include common L3VPN configuration options
         uses l3vpn-ipv4-ipv6-unicast-common;

         // placeholder for IPv6 Unicast L3VPN specific configuration
         // options
       }
     }

     grouping l3vpn-ipv4-multicast-group {
       description
         "Group for IPv4 L3VPN multicast configuration options";

       container l3vpn-ipv4-multicast {
         when "../afi-safi-name = 'bgp-mp:l3vpn-ipv4-multicast'" {
           description
             "Include this container for multicast IPv6 L3VPN specific
             configuration";
         }

         description "Multicast IPv4 L3VPN configuration options";



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         // include common L3VPN multicast options
         uses l3vpn-ipv4-ipv6-multicast-common;

         // placeholder for IPv4 Multicast L3VPN specific configuration
         // options
       }
     }

     grouping l3vpn-ipv6-multicast-group {
       description
         "Group for IPv6 L3VPN multicast configuration options";

       container l3vpn-ipv6-multicast {
         when "../afi-safi-name = 'bgp-mp:l3vpn-ipv6-multicast'" {
           description
             "Include this container for multicast IPv6 L3VPN specific
             configuration";
         }

         description "Multicast IPv6 L3VPN configuration options";

         // include common L3VPN multicast options
         uses l3vpn-ipv4-ipv6-multicast-common;

         // placeholder for IPv6 Multicast L3VPN specific configuration
         // options
       }
     }

     grouping l2vpn-vpls-group {
       description
         "Group for BGP-signalled VPLS configuration options";

       container l2vpn-vpls {
         when "../afi-safi-name = 'bgp-mp:l2vpn-vpls'" {
           description
             "Include this container for BGP-signalled VPLS specific
             configuration";
         }

         description "BGP-signalled VPLS configuration options";

         // include common L2VPN options
         uses l2vpn-common;

         // placeholder for BGP-signalled VPLS specific configuration
         // options
       }



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     }

     grouping l2vpn-evpn-group {
       description
         "Group for BGP EVPN configuration options";

       container l2vpn-evpn {
         when "../afi-safi-name = 'bgp-mp:l2vpn-evpn'" {
           description
             "Include this container for BGP EVPN specific
             configuration";
         }

         description "BGP EVPN configuration options";

         // include common L2VPN options
         uses l2vpn-common;

         // placeholder for BGP EVPN specific configuration options
       }
     }



     grouping bgp-route-selection-options_config {
       description
         "Set of configuration options that govern best
          path selection.";

       leaf always-compare-med {
         type boolean;
         default "false";
         description
           "Compare multi-exit discriminator (MED) value from
           different ASes when selecting the best route.  The
           default behavior is to only compare MEDs for paths
           received from the same AS.";
       }

       leaf ignore-as-path-length {
         type boolean;
         default "false";
         description
           "Ignore the AS path length when selecting the best path.
           The default is to use the AS path length and prefer paths
           with shorter length.";
       }




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       leaf external-compare-router-id {
         type boolean;
         default "true";
         description
           "When comparing similar routes received from external
           BGP peers, use the router-id as a criterion to select
           the active path.";
       }

       leaf advertise-inactive-routes {
         type boolean;
         default "false";
         description
           "Advertise inactive routes to external peers.  The
           default is to only advertise active routes.";
       }

       leaf enable-aigp {
         type boolean;
         default false;
         description
           "Flag to enable sending / receiving accumulated IGP
           attribute in routing updates";
       }

       leaf ignore-next-hop-igp-metric {
         type boolean;
         default "false";
         description
           "Ignore the IGP metric to the next-hop when calculating
           BGP best-path. The default is to select the route for
           which the metric to the next-hop is lowest";
       }
     }

     grouping bgp-use-multiple-paths-ebgp-as-options_config {
       description
         "Configuration parameters specific to eBGP multipath applicable
         to all contexts";

       leaf allow-multiple-as {
        type boolean;
        default "false";
        description
         "Allow multipath to use paths from different neighbouring
         ASes.  The default is to only consider multiple paths from
         the same neighbouring AS.";
       }



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     }

     grouping bgp-use-multiple-paths-ebgp_config {
       description
         "Configuration parameters relating to multipath for eBGP";

       uses bgp-use-multiple-paths-ebgp-as-options_config;

       leaf maximum-paths {
        type uint32;
        default 1;
        description
         "Maximum number of parallel paths to consider when using
         BGP multipath. The default is use a single path.";
       }
     }

     grouping bgp-use-multiple-paths-ibgp_config {
       description
         "Configuration parmaeters relating to multipath for iBGP";

       leaf maximum-paths {
         type uint32;
         default 1;
         description
           "Maximum number of parallel paths to consider when using
           iBGP multipath. The default is to use a single path";
       }
     }

     grouping bgp-use-multiple-paths {
       description
         "Configuration parameters relating to multipath for BGP - both
         iBGP and eBGP";

       container use-multiple-paths {
         description
           "Parameters related to the use of multiple paths for the
           same NLRI";

         container config {
           description
             "Configuration parameters relating to multipath";
           uses bgp-use-multiple-paths_config;
         }
         container state {
           description
             "State parameters relating to multipath";



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           uses bgp-use-multiple-paths_config;
         }

         container ebgp {
           description
             "Multipath parameters for eBGP";
           container config {
             description
               "Configuration parameters relating to eBGP multipath";
             uses bgp-use-multiple-paths-ebgp_config;
           }
           container state {
             config false;
             description
               "State information relating to eBGP multipath";
             uses bgp-use-multiple-paths-ebgp_config;
           }
         }

         container ibgp {
           description
             "Multipath parameters for iBGP";
           container config {
             description
               "Configuration parameters relating to iBGP multipath";
             uses bgp-use-multiple-paths-ibgp_config;
           }
           container state {
             config false;
             description
               "State information relating to iBGP multipath";
             uses bgp-use-multiple-paths-ibgp_config;
           }
         }
       }
     }

     grouping bgp-use-multiple-paths-neighbor {
       description
         "Per-neighbor configuration for multipath for BGP";

       container use-multiple-paths {
         description
           "Parameters related to the use of multiple-paths for the same
           NLRI when they are received only from this neighbor";

         container config {
           description



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             "Configuration parameters relating to multipath";
           uses bgp-use-multiple-paths_config;
         }
         container state {
           description
             "State parameters relating to multipath";
           uses bgp-use-multiple-paths_config;
         }

         container ebgp {
           description
             "Multipath configuration for eBGP";
           container config {
             description
               "Configuration parameters relating to eBGP multipath";
             uses bgp-use-multiple-paths-ebgp-as-options_config;
           }
           container state {
             config false;
             description
               "State information relating to eBGP multipath";
             uses bgp-use-multiple-paths-ebgp-as-options_config;
           }
         }
       }
     }

     grouping bgp-use-multiple-paths_config {
       description
         "Generic configuration options relating to use of multiple
         paths for a referenced AFI-SAFI, group or neighbor";

       leaf enabled {
         type boolean;
         default false;
         description
           "Whether the use of multiple paths for the same NLRI is
           enabled for the neighbor. This value is overridden by
           any more specific configuration value.";
       }
     }

     grouping bgp-afi-safi-graceful-restart_config {
       description
         "BGP graceful restart parameters that apply on a per-AFI-SAFI
         basis";

       leaf enabled {



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         type boolean;
         default false;
         description
           "This leaf indicates whether graceful-restart is enabled for
           this AFI-SAFI";
       }
     }

     grouping bgp-afi-safi_config {
       description
         "Configuration parameters used for all BGP AFI-SAFIs";

       leaf afi-safi-name {
         type identityref {
           base bgp-types:afi-safi-type;
         }
         description "AFI,SAFI";
       }

       leaf enabled {
         type boolean;
         default false;
         description
           "This leaf indicates whether the IPv4 Unicast AFI,SAFI is
           enabled for the neighbour or group";
       }
     }

     grouping all-afi-safi-common-prefix-limit_config {
       description
         "Configuration parameters relating to prefix-limits for an
         AFI-SAFI";

       leaf max-prefixes {
         type uint32;
         description
           "Maximum number of prefixes that will be accepted
           from the neighbour";
       }

       leaf shutdown-threshold-pct {
         type bgp-types:percentage;
         description
           "Threshold on number of prefixes that can be received
           from a neighbour before generation of warning messages
           or log entries. Expressed as a percentage of
           max-prefixes";
       }



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       leaf restart-timer {
         type decimal64 {
           fraction-digits 2;
         }
         units "seconds";
         description
           "Time interval in seconds after which the BGP session
           is re-established after being torn down due to exceeding
           the max-prefix limit.";
       }
     }

     grouping ipv4-ipv6-unicast-common_config {
       description
         "Common configuration parameters for IPv4 and IPv6 Unicast
         address families";

       leaf send-default-route {
         type boolean;
         default "false";
         description
           "If set to true, send the default-route to the neighbour(s)";
       }
     }

     grouping all-afi-safi-common {
       description
         "Grouping for configuration common to all AFI,SAFI";

       container prefix-limit {
         description
           "Configure the maximum number of prefixes that will be
           accepted from a peer";

         container config {
           description
             "Configuration parameters relating to the prefix
             limit for the AFI-SAFI";
           uses all-afi-safi-common-prefix-limit_config;
         }
         container state {
           config false;
           description
             "State information relating to the prefix-limit for the
             AFI-SAFI";
           uses all-afi-safi-common-prefix-limit_config;
         }
       }



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     }

     grouping ipv4-ipv6-unicast-common {
       description
         "Common configuration that is applicable for IPv4 and IPv6
         unicast";

       // include common afi-safi options.
       uses all-afi-safi-common;

       // configuration options that are specific to IPv[46] unicast
       container config {
         description
           "Configuration parameters for common IPv4 and IPv6 unicast
           AFI-SAFI options";
         uses ipv4-ipv6-unicast-common_config;
       }
       container state {
         config false;
         description
           "State information for common IPv4 and IPv6 unicast
           parameters";
         uses ipv4-ipv6-unicast-common_config;
       }
     }

     grouping l3vpn-ipv4-ipv6-unicast-common {
       description
         "Common configuration applied across L3VPN for IPv4
          and IPv6";

       // placeholder -- specific configuration options that are generic
       // across IPv[46] unicast address families.
       uses all-afi-safi-common;
     }

     grouping l3vpn-ipv4-ipv6-multicast-common {
       description
         "Common configuration applied across L3VPN for IPv4
         and IPv6";

       // placeholder -- specific configuration options that are
       // generic across IPv[46] multicast address families.
       uses all-afi-safi-common;
     }

     grouping l2vpn-common {
       description



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         "Common configuration applied across L2VPN address
         families";

       // placeholder -- specific configuration options that are
       // generic across L2VPN address families
       uses all-afi-safi-common;
     }

     grouping bgp-route-selection-options {
       description
         "Parameters relating to the BGP route selection process";

       container route-selection-options {
         description
           "Parameters relating to options for route selection";
         container config {
           description
             "Configuration parameters relating to route selection
             options";
           uses bgp-route-selection-options_config;
         }
         container state {
           config false;
           description
             "State information for the route selection options";
           uses bgp-route-selection-options_config;
         }
       }
     }

     // *********** STRUCTURE GROUPINGS **********************

     grouping bgp-global-afi-safi {
       description
         "Parameters and route selection options for MP-BGP
         specific to the Global AFI-SAFI";
       uses bgp-route-selection-options;
     }

     grouping bgp-group-afi-safi {
       description
         "Parameters and route selection options for MP-BGP
         specific to peer groups";
       uses bgp-route-selection-options;
     }

     grouping bgp-common-afi-safi-list {
       description



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         "List of address-families associated with the BGP instance,
         a peer-group or neighbor";

       list afi-safi {
         key "afi-safi-name";

         description
           "AFI,SAFI configuration available for the
           neighbour or group";


         leaf afi-safi-name {
           type leafref {
             path "../config/afi-safi-name";
           }
           description
             "Reference to the AFI-SAFI name used as a key
             for the AFI-SAFI list";
         }

         container graceful-restart {
           description
             "Parameters relating to BGP graceful-restart";
           container config {
             description
               "Configuration options for BGP graceful-restart";
             uses bgp-afi-safi-graceful-restart_config;
           }
           container state {
             config false;
             description
               "State information for BGP graceful-restart";
             uses bgp-afi-safi-graceful-restart_config;
           }
         }

         container config {
           description
             "Configuration parameters for the AFI-SAFI";
           uses bgp-afi-safi_config;
         }
         container state {
           config false;
           description
             "State information relating to the AFI-SAFI";
           uses bgp-afi-safi_config;
           uses bgp-op:bgp-afi-safi_state;
         }



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         // import and export policy included for the afi/safi
         uses rpol:apply-policy-group;

         uses ipv4-unicast-group;
         uses ipv6-unicast-group;
         uses ipv4-labelled-unicast-group;
         uses ipv6-labelled-unicast-group;
         uses l3vpn-ipv4-unicast-group;
         uses l3vpn-ipv6-unicast-group;
         uses l3vpn-ipv4-multicast-group;
         uses l3vpn-ipv6-multicast-group;
         uses l2vpn-vpls-group;
         uses l2vpn-evpn-group;
       }
     }
   }
   <CODE ENDS>


5.5.  BGP operational data items

   <CODE BEGINS> file bgp-operational.yang
   module bgp-operational {

     yang-version "1";

     // namespace
     // TODO: change to an ietf or other more generic namespace
     namespace "http://openconfig.net/yang/bgp-operational";

     prefix "bgp-op";

     // import some basic inet types
     import ietf-inet-types { prefix inet; }
     import ietf-yang-types { prefix yang; }
     import bgp-types { prefix bgp-types; }

     // meta

     organization
       "OpenConfig working group";

     contact
       "OpenConfig working group
       netopenconfig@googlegroups.com";

     description
       "This module is part of a YANG model for BGP protocol



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       configuration, focusing on operational data (i.e., state
       variables) related to BGP operations";


     revision "2015-05-15" {
       description
         "Initial revision";
       reference "TBD";
     }

     // extension statements

     // feature statements

     // identity statements

     // typedef statements

     // grouping statements

     grouping bgp-counters-message-types_common {
       description
         "Grouping of BGP message types, included for re-use
         across counters";

       leaf UPDATE {
         type uint64;
         description
           "Number of BGP UPDATE messages announcing, withdrawing
           or modifying paths exchanged.";
       }

       leaf NOTIFICATION {
         type uint64;
         description
           "Number of BGP NOTIFICATION messages indicating an
           error condition has occurred exchanged.";
       }
     }


     grouping bgp-context-pfx-path-counters_common {
       description
         "Grouping containing common counters relating to prefixes and
         paths";

       leaf total-paths {
         type uint32;



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         description
           "Total number of BGP paths within the context";
       }

       leaf total-prefixes {
         type uint32;
         description
           "";
       }
     }

     grouping bgp-global_state {
       description
         "Grouping containing operational parameters relating to the
         global BGP instance";
       uses bgp-context-pfx-path-counters_common;
     }

     grouping bgp-global-afi-safi_state {
       description
         "Grouping containing operational parameters relating to each
         AFI-SAFI within the BGP global instance";
       uses bgp-context-pfx-path-counters_common;
     }

     grouping bgp-peer-group_state {
       description
         "Grouping containing operational parameters relating to a BGP
         peer group";
       uses bgp-context-pfx-path-counters_common;
     }

     grouping bgp-neighbor_state {
       description
         "Grouping containing operational state variables relating to a
         BGP neighbor";

       leaf session-state {
         type enumeration {
             enum IDLE {
               description
                 "neighbor is down, and in the Idle state of the
                 FSM";
             }
             enum CONNECT {
               description
                 "neighbor is down, and the session is waiting for
                 the underlying transport session to be established";



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             }
             enum ACTIVE {
               description
                 "neighbor is down, and the local system is awaiting
                 a conncetion from the remote peer";
             }
             enum OPENSENT {
               description
                 "neighbor is in the process of being established.
                 The local system has sent an OPEN message";
             }
             enum OPENCONFIRM {
               description
                 "neighbor is in the process of being established.
                 The local system is awaiting a NOTIFICATION or
                 KEEPALIVE message";
             }
             enum ESTABLISHED {
               description
                 "neighbor is up - the BGP session with the peer is
                 established";
             }
           }
         description
           "Operational state of the BGP peer";
       }

       leaf-list supported-capabilities {
         type identityref {
           base bgp-types:bgp-capability;
         }
         description
           "BGP capabilities negotiated as supported with the peer";
       }
     }

     grouping bgp-neighbor-afi-safi_state {
       description
         "Operational state on a per-AFI-SAFI basis for a BGP
         neighbor";

       leaf active {
         type boolean;
         description
           "This value indicates whether a particular AFI-SAFI has
           been succesfully negotiated with the peer. An AFI-SAFI
           may be enabled in the current running configuration, but a
           session restart may be required in order to negotiate the new



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           capability.";
       }

       uses bgp-neighbor-prefix-counters_state;
     }

     grouping bgp-neighbor-prefix-counters_state {
       description
         "Counters for BGP neighbor sessions";

       container prefixes {
         description "Prefix counters for the BGP session";
         leaf received {
           type uint32;
           description
             "The number of prefixes received from the neighbor";
         }

         leaf sent {
           type uint32;
           description
             "The number of prefixes advertised to the neighbor";
         }

         leaf installed {
           type uint32;
           description
             "The number of advertised prefixes installed in the
             Loc-RIB";
         }
       }
     }

     grouping bgp-neighbor-message-counters-sent_state {
       description
         "Counters relating to messages sent to a BGP neighbor";
       uses bgp-counters-message-types_common;
     }

     grouping bgp-neighbor-message-counters-received_state {
       description
         "Counters relating to the mesages received from a BGP
         neighbor";
       uses bgp-counters-message-types_common;
     }

     grouping bgp-neighbor-queue-counters_state {
       description



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         "Counters relating to the message queues associated with the
         BGP peer";
       leaf input {
         type uint32;
         description
           "The number of messages received from the peer currently
           queued";
       }

       leaf output {
         type uint32;
         description
           "The number of messages queued to be sent to the peer";
       }
     }

     grouping bgp-neighbor-transport_state {
       description
         "Operational state parameters relating to the transport session
         used for the BGP session";

       leaf local-port {
         type inet:port-number;
         description
           "Local TCP port being used for the TCP session supporting
           the BGP session";
       }

       leaf remote-address {
         type inet:ip-address;
         description
           "Remote port being used by the peer for the TCP session
           supporting the BGP session";
       }

       leaf remote-port {
         type inet:port-number;
         description
           "Remote address to which the BGP session has been
           established";
       }
     }

     grouping bgp-neighbor-error-handling_state {
       description
         "Operational state parameters relating to enhanced error
         error handling for BGP";




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       leaf erroneous-update-messages {
         type uint32;
         description
           "The number of BGP UPDATE messages for which the
           treat-as-withdraw mechanism has been applied based
           on erroneous message contents";
       }
     }

     grouping bgp-neighbor-timers_state {
       description
         "Operational state parameters relating to BGP timers associated
         with the BGP session";

       leaf uptime {
         type yang:timeticks;
         description
           "This timer determines the amount of time since the
           BGP last transitioned in or out of the Established
           state";
       }

       leaf negotiated-hold-time {
         type decimal64 {
           fraction-digits 2;
         }
         description
           "The negotiated hold-time for the BGP session";
       }
     }

     grouping bgp-afi-safi_state {
       description
         "Operational state information relevant to all address
         families that may be carried by the BGP session";

       // placeholder - options in this container are
       // valid in both the global and per-neighbor
       // paths

     }

     grouping bgp-afi-safi-graceful-restart_state {
       description
         "Operational state information relevant to graceful restart
         for BGP";

       leaf peer-restart-time {



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         type uint16 {
           range 0..4096;
         }
         description
           "The period of time (advertised by the peer) that
           the peer expects a restart of a BGP session to
           take";
       }

       leaf peer-restarting {
         type boolean;
         description
           "This flag indicates whether the remote neighbor is currently
           in the process of restarting, and hence received routes are
           currently stale";
       }

       leaf local-restarting {
         type boolean;
         description
           "This flag indicates whether the local neighbor is currently
           restarting. The flag is unset after all NLRI have been
           advertised to the peer, and the End-of-RIB (EOR) marker has
           been unset";
       }

       leaf mode {
         type enumeration {
           enum HELPER-ONLY {
             description
               "The local router is operating in helper-only mode, and
               hence will not retain forwarding state during a local
               session restart, but will do so during a restart of the
               remote peer";
           }
           enum BILATERAL {
             description
               "The local router is operating in both helper mode, and
               hence retains forwarding state during a remote restart,
               and also maintains forwarding state during local session
               restart";
           }
           enum REMOTE-HELPER {
             description
               "The local system is able to retain routes during restart
               but the remote system is only able to act as a helper";
           }
         }



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         description
           "Ths leaf indicates the mode of operation of BGP graceful
           restart with the peer";
       }
     }

     grouping bgp-neighbor-afi-safi-graceful-restart_state {
       description
         "Operational state variables relating to the graceful-restart
         mechanism on a per-AFI-SAFI basis";

       leaf received {
         type boolean;
         description
           "This leaf indicates whether the neighbor advertised the
           ability to support graceful-restart for this AFI-SAFI";
       }

       leaf advertised {
         type boolean;
         description
           "This leaf indicates whether the ability to support
           graceful-restart has been advertised to the peer";
       }
     }


   }


   <CODE ENDS>


6.  References

6.1.  Normative references

   [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.

   [RFC4271]  Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
              Protocol 4 (BGP-4)", RFC 4271, January 2006.




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   [RFC1997]  Chandrasekeran, R., Traina, P., and T. Li, "BGP
              Communities Attribute", RFC 1997, August 1996.

   [RFC4456]  Bates, T., Chen, E., and R. Chandra, "BGP Route
              Reflection: An Alternative to Full Mesh Internal BGP
              (IBGP)", RFC 4456, April 2006.

   [RFC3065]  Traina, P., McPherson, D., and J. Scudder, "Autonomous
              System Confederations for BGP", RFC 3065, February 2001.

   [RFC2439]  Villamizar, C., Chandra, R., and R. Govindan, "BGP Route
              Flap Damping", RFC 2439, November 1998.

   [RFC4724]  Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y.
              Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724,
              January 2007.

   [RFC6811]  Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R.
              Austein, "BGP Prefix Origin Validation", RFC 6811, January
              2013.

   [RFC4760]  Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
              "Multiprotocol Extensions for BGP-4", RFC 4760, January
              2007.

   [RFC6991]  Schoenwaelder, J., "Common YANG Data Types", RFC 6991,
              July 2013.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              January 2004.

6.2.  Informative references

   [I-D.openconfig-netmod-opstate]
              Shakir, R., Shaikh, A., and M. Hines, "Consistent Modeling
              of Operational State Data in YANG", draft-openconfig-
              netmod-opstate-00 (work in progress), March 2015.

   [I-D.shaikh-rtgwg-policy-model]
              Shaikh, A., Shakir, R., D'Souza, K., and C. Chase,
              "Routing Policy Configuration Model for Service Provider
              Networks", draft-shaikh-rtgwg-policy-model-00 (work in
              progress), January 2015.








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Appendix A.  Acknowledgements

   The authors are grateful for valuable contributions to this document
   and the associated models from: Ebben Aires, Pavan Beeram, Chris
   Chase, Ed Crabbe, Luyuan Fang, Bill Fenner, Akshay Gattani, Josh
   George, Vijay Gill, Jeff Haas, Dhanendra Jain, Ina Minei, Carl
   Moberg, Ashok Narayanan, Einar Nilsen-Nygaard, Adam Simpson, Puneet
   Sood, Jason Sterne, Jim Uttaro, and Gunter Vandevelde.

Appendix B.  Change summary

B.1.  Changes between revisions -01 and -02

   The -02 revision generally does not affect the structure of the
   model, but there are a number of changes that improve clarity, or
   simplify mappings to implementations.

   o  Reorganized modules to move BGP-specific types, including policy-
      related types, to the bgp-types module.

   o  Added ability to configure route selection options at the global
      level.  Removed route selection options from per-neighbor AFI-SAFI
      since it is not widely implemented.

   o  Removed a number of presence containers (e.g., in AFI-SAFI,
      graceful-restart, and multipath).  Presence has been replaced with
      an explicit 'enabled' leaf to simplify semantics of inheritance
      and override in other parts of the BGP hieararchy.

   o  Fixed inconsistencies with use-multiple-paths config.  Added
      'enabled' leaves with default false.

   o  Updated top level list key to be a leafref in most lists for
      consistency with the operational state modeling approach outlined
      in [I-D.openconfig-netmod-opstate].

   o  Some minor renaming / restructuring of routing policy defined-sets
      and apply-policy container.

   o  Added ability to increment/decrement MED value in BGP policy
      statement actions.

   o  Changed local-address leaf to be a union which can specify either
      an IP address, or be a reference to an interface.

   o  Changed ebgp-multihop to add 'enabled' leaf and TTL behavior.





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   o  Changed BGP well-known communities from a enumeration to a
      identity.  Also made consistent with IANA-defined standard well-
      known communities.

   o  Remove enumeration values from BGP origin type given the
      disagreement in RFC 4271 and RFC 4273.

   o  Added an additional match-options enumerated type for sets that
      only support ANY | INVERT, but not ALL behavior.

   o  Modified prefix-sets to use inet:ip-prefix type and removed range
      checking on masklength-range (also added 'exact' specifier for
      masklength range).

   o  Removed send-update-delay timer leaf.  Desired behavior is
      reflected by minimum-advertisement-interval, i.e., MRAI.

   o  Changed allow-own-as leaf to allow specification of a number of
      occurrences -- some implementations only support 0 or 1, i.e.,
      equivalent of a boolean but several others support multiple
      occurrences.

B.2.  Changes between revisions -00 and -01

   The -01 revision reflects a number of changes, many based on feedback
   from implementors of the model on various routing platforms.

   o  Refactored model to explicitly provide 'config' and 'state'
      containers at each leaf node to enable consistent and predictable
      access to operational state data corresponding to configuration
      data.  This is based on the model design in
      [I-D.openconfig-netmod-opstate].

   o  Refactored multiprotocol module with explicit set of supported
      AFI-SAFI combinations (using YANG identities) in a flattened list.
      Focus was on common config with more AFI-SAFI specific
      configuration forthcoming in future revisions.

   o  Refactored BGP policy module to work with a new general routing
      policy model [I-D.shaikh-rtgwg-policy-model] by augmenting it with
      BGP-specific policy options (conditions, actions, and defined
      sets).

   o  Added enclosing containers to lists (e.g., neighbors, peer-groups,
      and AFI-SAFI)






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   o  Removed neighbor configuration from the peer-group hierarchy.
      Neighbor configuration now has a peer-group leaf which references
      the peer group to which the neighbor belongs.

   o  Several new configuration items added to base bgp module,
      including adding some configuration items to the global hierarchy
      level.

Authors' Addresses

   Anees Shaikh (editor)
   Google
   1600 Amphitheatre Pkwy
   Mountain View, CA  94043
   US

   Email: aashaikh@google.com


   Rob Shakir (editor)
   BT
   pp. C3L, BT Centre
   81, Newgate Street
   London  EC1A 7AJ
   UK

   Email: rob.shakir@bt.com
   URI:   http://www.bt.com/


   Keyur Patel (editor)
   Cisco
   170 W. Tasman Drive
   San Jose, CA  95134
   USA

   Email: keyupate@cisco.com


   Susan Hares (editor)
   Huawei
   7453 Hickory Hill
   Saline, MI  48176
   USA

   Email: shares@ndzh.com





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   Kevin D'Souza
   AT&T
   200 S. Laurel Ave
   Middletown, NJ
   US

   Email: kd6913@att.com


   Deepak Bansal
   Microsoft
   205 108th Ave. NE, Suite 400
   Bellevue, WA
   US

   Email: dbansal@microsoft.com


   Alexander Clemm
   Cisco
   170 W. Tasman Drive
   San Jose, CA  95134
   USA

   Email: alex@cisco.com


   Aleksandr Zhdankin
   Cisco
   170 W. Tasman Drive
   San Jose, CA  95134
   USA

   Email: azhdanki@cisco.com


   Mahesh Jethanandani
   Ciena
   1741 Technology Drive
   San Jose, CA  95110
   USA

   Email: mjethanandani@gmail.com








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   Xyfeng Liu
   Ericsson
   1595 Spring Hill Road, Suite 500
   Vienna, VA  22182
   USA

   Email: xufeng.liu@ericsson.com












































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