An SCSI-Based Adaptive Router in Torus Network

Abstract

This paper presents the design of an adaptive router in a torus-connected computer network. The design can be divided into two parts：(1) The design of the hardware interface in the router.(2) Software support. Every node uses an SCSI interface care to connect to the neighboring nodes to transmit data, and also needs some hardware to receive data from the neighboring nodes. We have finished the design of the hardware. The router only needs 4 FPGA chips, EPF 8636A of Flex 8000 series produced by Altera, plus some SRAMs and TTL devices. All of the components are inexpensive and readily available. The adaptive router also needs software supports, such as the DMA driver, the SCSI driver and a routing algorithm. Because SCSI interface is used, the switching technique is packet-switching. In order to improve network performance, we design an adaptive routing algorithm to distribute the traffic load. Besides, we divide the bidirectional torus into 4 virtual networks, X+Y+、X+Y-、X-Y+, to decrease the complexity of the adaptive routing algorithm and increase the communication throughput. As a result, our routing algorithm is deadlock-free and minimally adaptive. The router is experimentally evaluated using different traffic patterns and message lengths. Preliminary results show that a short packet length of 128 bytes is appropriate to the torus through our design, and the saturation point is about 0.55 for random routing and 0.35 for transpose routing.