module ietf-interfaces {
    namespace "urn:ietf:params:xml:ns:yang:ietf-interfaces";
    prefix if;
    typedef interface-state-ref {
        type leafref {
            path "/if:interfaces-state/if:interface/if:name";
        }
        description
            "This type is used by data models that need to reference
            the operationally present interfaces";
    }
    /*
     * Operational state data nodes
     */
    container interfaces-state {
        config false;
        description
            "Data nodes for the operational state of interfaces.";
        list interface {
            key "name";
            description
                "The list of interfaces on the device.
                System-controlled interfaces created by the system are
                always present in this list, whether they are configured or
                not.";
            leaf name {
                type string;
                description
                    "The name of the interface.
                    A server implementation MAY map this leaf to the ifName
                    MIB object.  Such an implementation needs to use some
                    mechanism to handle the differences in size and characters
                    allowed between this leaf and ifName.  The definition of
                    such a mechanism is outside the scope of this document.";
                    reference "RFC 2863: The Interfaces Group MIB - ifName";
            }
            leaf-list higher-layer-if {
                type interface-state-ref;
                description
                    "A list of references to interfaces layered on top of this
                    interface.";
                reference
                    "RFC 2863: The Interfaces Group MIB - ifStackTable";
            }
            leaf-list lower-layer-if {
                type interface-state-ref;
                description
                    "A list of references to interfaces layered underneath this
                    interface.";
                reference
                    "RFC 2863: The Interfaces Group MIB - ifStackTable";
            }
        }
    }
}