The optional Assistant Address argument specifies the LAN address
    of the node to be used as a loopback assistant. This argument is
    meaningful for LAN circuits only.

    The involvement of the assistant depends on the Assistance Type
    parameter. For assistance of type none (the default), no assistant
    is needed, and is ignored if specified. For other values, an
    assistant is required.

    An assistant can be specified either by including an Assistant
    Address or Assistant System argument in the command line, but not
    both.  If neither is provided, then an assistant is located by
    first sending a request to the loopback assistant multicast
    address.

    loop  [node node-id] mop client client-name -
      assistance type transmit-receive-or-full, -
      assistant address lan-address [,optional arguments...]

    Address and Circuit information loop is required for the loop mop
    client command.  If the Client cannot provide default Address and
    Circuit information, then that information must be specified in
    the command.

    loop  [node node-id] mop client client-name -
      address lan-address, -
      circuit circuit-name, -
      assistance type transmit-receive-or-full, -
      assistant address lan-address [,optional arguments...]

    Examples:

    loop mop client lamchp -   ! Client gives Address and Circuit
      assistant address aa-00-04-00-33-44, -
      assistance type transmit

    loop mop client foofoo -  ! Client gives default loop Address
      circuit fddi-1, -
      assistant address aa-00-04-00-33-44, -
      assistance type receive