Creates an instance of a routing circuit entity which represents
    a data link to another node, specified by the simple name
    circuit-name.

    create  [node node-id] routing circuit circuit-name -
          type circuit-type

    The Type argument is required.  Possible circuit-type values are:

    csma-cd             - a broadcast circuit
    ddcmp               - a DDCMP circuit
    fddi                - an FDDI large packet circuit
    hdlc                - an HDLC circuit
    x25 da              - a dynamically allocated X.25 circuit
    x25 permanent       - an X.25 permanent virtual circuit
    x25 static incoming - a static incoming X.25 circuit
    x25 static outgoing - a static outgoing X.25 circuit

    On OpenVMS for FDDI routing circuits, the type should only be
    fddi if large packet support is in use, otherwise the type should
    be csma-cd.

    Examples:

    create routing circuit fddi-1 type csma-cd

    create routing circuit fddi-1 type fddi ! for large packet support

    Select adjacency for information on creating routing circuit
    adjacency subentities.

    Select reachable_address for information on creating routing
    circuit reachable address subentities.

1  –  Exception Messages

 o  invalid circuit type

    The specified circuit type is invalid.

    Argument:

    reason     Reason why the circuit type is invalid.

    1          A dynamically allocated X.25 circuit type is not
               permitted for a level 1 router.

 o  maximum circuits exceeded

    An attempt has been made to create more than the maximum number
    of circuits allowed.

2  –  adjacency

    Creates an instance of a routing circuit adjacency.  An
    adjacency describes a neighboring node that is accessible
    through a particular circuit.

    This create command is allowed only if the circuit is a
    csma-cd circuit and the type is L1router or L2router.

    create  [node node-id] routing circuit circuit-name -
                   adjacency adjacency-name, -
                   endnode ids {id[,id...]}, -
                   LAN address LAN-address [,data format string]

    The required Endnode IDs argument is a set of source system
    IDs.  The required LAN Address argument is the Data Link
    address from which the adjacency receives end system hellos.
    The optional Data Format argument is the format of the reachable
    address.

3  –  reachable_address

    Creates a routing circuit reachable address entity instance
    which contains information about a manually entered address
    prefix accessible over that circuit. It exists only on L2
    routers and end nodes.

    create  [node node-id] routing circuit circuit-name -
         reachable address simple-name -
         address prefix address-prefix

    On an end system, the type may be "outbound" or (for a
    broadcast circuit only) "filter".  A reachable address of
    type outbound behaves in a way similar to that on an L2
    router except that the routing information is used to
    control the operation of the ES cache.  A reachable address
    of type filter (for the broadcast circuit only) specifies
    the permitted LAN addresses of routers on the LAN that will
    be used by the reverse path cache algorithm.  To switch
    between outbound and filter types, the reachable address
    must first be disabled.  For either outbound or filter type,
    the mapping attribute should be set to manual because the
    default is X.121.

    The address prefix argument is required.  It specifies the
    address prefix to which this reachable address corresponds.

    Example:

    create routing circuit csmacd-1 reachable address to-bulean -
           address prefix 49::4

3.1  –  Exception Messages

 o  address prefix not unique

    A reachable address already exists with the specified address
    prefix.

 o  invalid address prefix

    Specified address prefix has more than two digits, and does not
    correspond to a valid AFI.

 o  non DA circuit

    A reachable address on an endnode can only be created on a DA
    circuit.