Abstract: The prototype high performance switching system will connect several different types of machines with widely varying clock and internal bus speeds. At one end of the range we have a CRAY YMP and a CRAY XMP with a high performance parallel interface (HIPPI). At the other end there are many SUN 3/260 VME bus machines. In between there are various flavors of MAC IIs. This presents a substantial speed matching problem. The CRAY HIPPI channel speed is 100 MB/s. The SUN VME bus speed is approximately 1 MB/s with bursts to 13 MB/s, the MAC II NU-BUS obtains about the same speed. So what do you do when the network is 2 to 3 orders of magnitude faster than the internal bus? The short answer is use big packets and even bigger buffers. This paper expands on that theme and describes the approach LLNL and Ancor Communications took in the case of the SUN VMEbus machine. !14
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