Creates an X.25 protocol dte pvc entity which describes a
    permanent virtual circuit (PVC).

    create [node node-id] x25 protocol dte dte-name -
        pvc pvc-name -
        channel integer [,packet size integer] [,window size integer]

    The Channel argument is required.  It is the concatenated logical
    channel group and logical channel number for the PVC, and it
    should be a unique value among PVCs on this DTE.  These channel
    numbers must not be present in the incoming list or outgoing list
    of the parent DTE.

    Packet Size and Window Size are optional arguments.

    Example:

    create x25 protocol dte dte-0 pvc PVC-0 channel 5

1  –  packet_size

    Packet size, in octets, for the PVC. This argument determines
    the value of the packet size characteristic. This value should
    be within the maximum and minimum packet size specifier by the
    parent DTE.

2  –  window_size

    Window size for the PVC. This argument determines the value of
    the window size characteristic. This value should be within the
    maximum and minimum window size specifier by the parent DTE.

3  –  Exception Messages

 o  name not unique

    The PVC entity is not unique at the gateway system.