Document Type


Date of Award


Degree Name

Master of Science in Electrical Engineering - (M.S.)


Electrical and Computer Engineering

First Advisor

Irving Y. Wang

Second Advisor

John D. Carpinelli

Third Advisor

Edwin Hou


The purpose of this work was to investigate the performance of two interconnected X.25 networks via CCITT internet protocol X.75. Since internet protocol X.75 follow the same flow approach as X.25, we are allowed to model the acknowledgement queue in such a way that this queue provides a feed back path from destination to the source queue. Thus we are able to model our interconnected network as a closed queueing network with limited number of packets in transit within the network. Mean Value Analysis with Blocking (MVA) algorithm was applied to obtain the performance characteristics as the resources available were considered to have limited capacity. Our objective was to study the variation in throughputs of the network in terms of number of packets with the variation of capacities and service rates.

We first modify the queue capacity keeping the service rate fixed and then keeping the queue capacity fixed, we modify the service rates of the signalling terminals. We observed that throughputs improves with increasing queue capacity and service rates. As the number of packets in the network increases the throughput varies. With queue capacity fixed, networks with higher service rate gives maximum throughput at lower number of packets in transit within the network. At some maximum number of packets in the network the throughput of higher service rate network fall far beyond that of lower service rate networks. By fixing the service rate and increasing queue capacities of stations in the network, the throughput increases as the number of packets in the network increases. Thus a trade off must be taken into account between the service rate and the queue capacity to accommodate the maximum number of packets in the network.



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