Performance evaluation of a new CSMA/CD protocol based on the SRPT principle

The SRPT (shortest remaining processing time first) principle is applied to the Ethernet LAN (local area network) using the CSMA/CD (carrier sense multiple access with collision detection) access protocol. A short description of the new CSMA/CD/SRPT protocol is given, and detailed simulation results are presented for a typical user scenario. The comparison with other strategies shows that the performance gain is considerable and that the new protocol is near optimal. Under realistic conditions with a high coefficient of variation of the message length, it is shown that the new CSMA/CD/SRPT protocol with the SRPT principle applied to the output queue and to the network as a whole considerably reduces the mean transfer time, especially under a high traffic load. Short messages, e.g. terminal traffic or protocol packets, are favored similar to the way the hyperchannel protocol gives priority to certain station numbers. This means that the total delay, including higher protocol layers, is also reduced. Implementing the new protocol allows the network throughput to be raised, without increasing the mean transfer time for the users