Performance evaluation of an IEEE 802.4 LAN

An IEEE 802.4 local area network (LAN) can be analyzed by two different approaches. The first approach focuses on aspects of the network, or protocol, which affect performance. In the IEEE 802.4 token bus protocol, the key performance measurements of token rotation time and network efficiency can be altered by defining several parameters. Experiments on a real token bus network showed that by carefully selecting these parameters to match characteristics of the given application, the tradeoff between token rotation time and efficiency can be optimized. The second approach emphasizes the performance level of the individual station provided by VLSI integrated circuits. The relevant measures of performance, which were analyzed for the MC68824 Token Bus Controller (TBC), include percentage of bus bandwidth, the contribution of the TBC to station delay, and the ability of the TBC to avoid the transmit underrun and receive overrun error conditions