PERFORMANCE ANALYSIS OF TIMELY-TOKEN PROTOCOL WITH VARIABLE LOAD OF SYNCHRONOUS TRAFFIC

Abstract

Timely-Token protocol solved the problems of token-lateness in FDDI and starvation of asynchronous traffic in FDDI-M. Jorge and Miaohua proposed the Timely-Token protocol and presented its timing analysis. In this paper, we presented the performance analysis of the Timely-Token protocol with variable load of synchronous traffic but with heavy load of asynchronous traffic. The essence of such analysis is to determine how variations in the load level of the synchronous traffic affect the bandwidth allocated to the asynchronous traffic. Specifically, we derived the expressions for the Maximum Cycle Length, the Average Cycle Length and the Upper Bound on the Average Bandwidth allocated to the asynchronous traffic. Secondly, we developed mathematical expressions for relating the simulation results of the Timely-Token algorithm to the analytical results. Thirdly, we used a program written in Visual Basic for Applications (VBA) to run the simulation of the Timely-Token algorithm and also perform the computations of the performance parameters using the expressions derived from our analytical approach.

The simulation results of the Timely-Token algorithm corresponded with the analytical results for various network configurations. Finally, we believe that the ideas presented in this paper will be relevant to network designers and researchers, especially those wishing to develop improved versions of the timed-token algorithm. The expressions will enable researchers to make comparative studies of the performance of the Timely-Token protocol and other timed-token protocols. Also, the expressions for relating the simulation results to the analytical results are easy-to-use tools for validating the values obtained from the analytical computations.