Distributed Processing Within an Integrated Circuit/Packet-Switching Node

Based on the premise that flexibility is a primary objective for future data networks, it is proposed to integrate circuit switching (CS) and packet switching (PS) in a single network. This paper addresses the switching node in such a network. A novel node concept is presented, imposing PS on a CS structure. Connection management and node control functions on the one hand and packet processing/storing on the other are performed by two groups of modules. The modularity requirement leads to very small, simple processors built into storage modules for packet handling. Considering the high throughput requirement of about 1200 packets/s/node, configurations may exceed 30 packet-handling modules. The wellknown saturation effect of multiprocessor systems, i.e., decreasing incremental throughput with increasing number of processor modules, is overcome by a new concept of intermodule communications, taking advantage of the particular data-communications environment. Intermodule communications-and therefore overhead-have been significantly reduced. As a result, systems throughput for fixed processor module utilization is nearly a linear function of the number of modules, the deviation from linearity being less than 10 percent over the range considered.