A PIPELINED, MULTIPROCESSOR ARCHITECTURE FOR A CONNECTIONLESS SERVER FOR BROAD-BAND ISDN

The Direct Provision of Connectionless Service in BISDN calls for Serv ers that are connected to or are part of an ATM network to provide the routing function at input speeds up to 622 Mb/s. Routing is achieved in such a server by changing the VCI/VPI headers in the ATM cells; act ual switching is done by existing switches in the ATM network. The pap er presents an architecture capable of executing all the functions of a server at input speeds up to 622 Mb/s, scalable to multiple inputs a t that speed, making use of processors and special hardware that are a vailable today. To avoid storing large quantities of data, the archite cture routes data packets by examining routing information in the init ial cell of the packet and routing subsequent cells as they arrive rat her than waiting until the complete packet has arrived. It is capable of handling packets that have been multiplexed at the SAR sublayer usi ng AAL Type 3/4 and, with minor modifications, could also handle Type 5 traffic. Arguments are also presented for the use of AAL Type 5 for the Direct Connectionless Service.