The performance of an Ethernet, measured by the throughput achieved and delay suffered by packets, is a function of both the nature of the traffic and of several parameters of the protocol and network. Published analytical studies have shown that the Ethernet protocol, carrier sense multiple access with collision detection (CSMA/CD), achieves the desired performance with data traffic over a range of conditions. In the Ethernet the following parameters are not easily amenable to analytical models: (1) the retransmission algorithm, (2) the number of stations, (3) the topology; and (4) the distribution of stations along the network. This makes simulation modeling an attractive approach for detailed performance evaluation of Ethernet networks. In the present work, a new model has been developed with a general form that can replace the measurement tools to evaluate the performance of Ethernet networks. The present model has been given the acronym ESIM for Ethernet Simulation Model. The present work implements ESIM in the fields of evaluation of the throughput and delay characteristics for both network, and individual stations. A systematic approach is followed while constructing ESIM. This approach separates the station part from the protocol part. This approach gives a complete flexibility for modification to accommodate the different configurations of Ethernet networks. ESIM gives more reliable results than the measurement studies under low loads and short packet length conditions.ESIM utilizes the linear bus topology and a protocol identical to the Ethernet CSMA/CD protocol. ESIM is subjected to extensive validations with the results obtained by measurements related to throughput and delay. ESIM exhibits good agreement with negligible error ratios. This approach represents a new method for constructing more developed models to characterize the performance of Ethernet networks, while maintaining ESIM as a benchmark for credibility for the new models instead of the measurement.