module openconfig-if-tunnel {

    yang-version 1;

    namespace
      "http://openconfig.net/yang/interfaces/tunnel";

    prefix oc-tun;

    import openconfig-interfaces {
      prefix oc-if;
    }
    import openconfig-extensions {
      prefix oc-ext;
    }
    import openconfig-inet-types {
      prefix oc-inet;
    }
    import openconfig-if-ip {
      prefix oc-ip;
    }

    organization "OpenConfig working group";

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

    description
      "This model adds extensions to the OpenConfig interfaces
     model to configure tunnel interfaces on a network
     device.";

    revision "2018-01-05" {
      description "Initial tunnel model";
      reference
        "0.1.0";

    }

    oc-ext:openconfig-version "0.1.0";

    grouping tunnel-top {
      description
        "Top-level grouping for parameters related to
       a tunnel interface.";
      container tunnel {
        description
          "In the case that the interface is logical tunnel
         interface, the parameters for the tunnel are
         specified within this subtree. Tunnel interfaces
         have only a single logical subinterface associated
         with them.";
        container config {
          description
            "Configuration parameters associated with the
           tunnel interface";
          uses tunnel-config;
        }  // container config

        container state {
          config false;
          description
            "Operational state parameters associated with
           the tunnel interface.";
          uses tunnel-config;
        }  // container state

        uses oc-ip:ipv4-top;

        uses oc-ip:ipv6-top;
      }  // container tunnel
    }  // grouping tunnel-top

    grouping tunnel-config {
      description
        "Configuraton parameters relating to a tunnel
       interface.";
      leaf src {
        type oc-inet:ip-address;
        description
          "The source address that should be used for the
         tunnel.";
      }

      leaf dst {
        type oc-inet:ip-address;
        description
          "The destination address for the tunnel.";
      }

      leaf ttl {
        type uint8 {
          range "1..255";
        }
        description
          "The time-to-live (or hop limit) that should be utilised
         for the IP packets used for the tunnel transport.";
      }

      leaf gre-key {
        type uint32;
        description
          "The GRE key to be specified for the tunnel. The
         key is used to identify a traffic flow within
         a tunnel.";
        reference
          "RFC2890: Key and Sequence Number Extensions to GRE";

      }
    }  // grouping tunnel-config

    augment /oc-if:interfaces/oc-if:interface {
      description
        "Augment to add tunnel configuration to interfaces";
      uses tunnel-top;
    }
  }  // module openconfig-if-tunnel