MAN/WAN integration-The ATM-to-DQDB case

The interworking modes for the interconnection of metropolitan area networks (MANs) and asynchronous transfer mode (ATM)-based broadband-integrated services digital network (ISDN) are studied. The modes considered are "cell-to-slot interworking" and "frame interworking." The cell-to-slot mode modifies ATM cells to distributed queue dual bus (DQDB) slots and vice versa. The frame mode reassembles cells/slots and modifies AAL frames to DQDB IMPDUs and vice versa. Cell/segment delays for both modes in an interworking unit (IWU) receiving aggregated traffic from B-ISDN and using high priority transmission controlled by the guaranteed bandwidth (GBW) protocol for access to DQDB are compared. The performance results show the advantages of the cell-to-slot mode.