FAST PACKET SWITCH ARCHITECTURES FOR BROAD-BAND INTEGRATED SERVICES DIGITAL NETWORKS

Traditionally, the scarce and expensive resource in communications networks has been the bandwidth of transmission facilities; accordingly, the techniques used for networking and switching have been chosen so as to optimize the efficient use of that resource. These techniques have differed according to the type of information carried (circuit switching for voice, packet switching for data) and the environment served (local area, metropolitan area, or wide area). Today, two new characteristics mark the design of telecommunications networks. One is the desire to support many new (high bandwidth) applications (such as digitized video and image communication), made possible by the high capacity of fiber optics transmission systems; the second is the desire to design a single communications system which supports all services in an integrated and unified fashion. In response to these needs, the switching technique emerging to be the most appropriate is packet switching. It is clearly the appropriate technique to use for data applications with bursty traffic; it also offers greater flexibility than circuit switching in handling the wide diversity of data rates and latency requirements resulting from the integration of services. One main challenge therefore has been to design and build packet switches capable of switching relatively small packets at extremely high rates (say WO 000 to 1 000 000 packets per second per line). The various architectures proposed for such fast packet switches are surveyed, and performance and implementation issues underlying such architectures are discussed. © 1990 IEEE