Creates the Routing entity.

    The required arguments are:

     o  Protocols

        Protocols supported by this router. The value of this argument is
        a set containing either or both of the values IP or ISO8473. This
        argument determines the value of the protocols characteristic.
        The default value of this argument depends on the value of the
        type argument.

     o  Type

        Routing type for this node. This argument determines the value
        of the type characteristic attribute.

        endnode    The node is an end system.
        L1router   The node is a level 1 router.
        L2router   The node is a level 2 router.