Factors in the Performance of the AN1 Computer Network

AN1 (formerly known as Autonet) is a local area network composedof crossbar switches interconnected by 100Mbit/second, full-duplex links. In this paper, we evaluate the performance impact of certain choices in the AN1 design. These include the use of FIFO input buffering in the crossbar switch, the deadlockavoidance mechanism, cut-through routing, back-pressure for flow control, and multi-path routing. AN1's performance goals were to provide low latency and high bandwidth in a lightly loaded network. In this it is successful. Under heavy load, the most serious impediment to good performance is the use of FIFO input buffers. The deadlock-avoidance technique has an adverse effect on the performance of some topologies, but it seems to be the best alternative, given the goals and constraints of the AN1 design. Cut-through switching performs well relative to store-and-forward switching, even under heavy load. Back-pressure deals adequately with congestion in a lightly-loaded network; under ..