module ex-vlan {
  namespace "http://example.com/vlan";
  prefix "vlan";
  
  import ietf-interfaces {
    prefix if;
  }
  
  revision 2013-10-22 {
    description
      "Initial revision.";
    reference
      "RFC A YANG Data Model for Interface Management draft-ietf-netmod-interfaces-cfg-12 - Appendix C";
  }

  augment "/if:interfaces/if:interface" {
    when "if:type = 'ethernetCsmacd' or
          if:type = 'ieee8023adLag'";
    leaf vlan-tagging {
      type boolean;
      default false;
    }
  }

  augment "/if:interfaces/if:interface" {
    when "if:type = 'l2vlan'";

    leaf base-interface {
      type if:interface-ref;
      must "/if:interfaces/if:interface[if:name = current()]"
         + "/vlan:vlan-tagging = 'true'" {
        description
          "The base interface must have vlan tagging enabled.";
      }
    }
    leaf vlan-id {
      type uint16 {
        range "1..4094";
      }
      must "../base-interface" {
        description
          "If a vlan-id is defined, a base-interface must
           be specified.";
      }
    }
  }
}