Packet and circuit-switched data networks
P. N. Clarke · Spiral (Imperial College London) · 1982
This thesis is concerned with packet-and circuit-switched data network performance in order to make comparisons between the two.Some data networks in current use are surveyed.Recent work on the performance of packet-switched networks is reviewed and weaknesses identified.Computer simulation models of remote data entry systems operating in the two types of network were developed.Experiments were carried out for a variety of (i) access line loading and transmission rate, (ii) trunk network loading, and (iii) trunk transmission errors.Packet switching was found to handle more traffic with higher delays.Transmission errors and the users 1 interface were found to affect throughput and delay.Two further simulation models were developed to investigate the performance of networks with terminals making calls to each other.Experiments for both networks were carried out for a variety of (i) network loading, (ii) access line rate, (iii) trunk transmission errors, (iv) network topology, (v) packet length, and (vi) signalling network structure (circuit switched).The results show that a circuit switched network needs at least twice as much transmission capacity for the same througH^as a packet switched network.Common channel signalling with circuit switching gave faster call set-up and clearing, in conditions of high error rate.The performance of packet switching of voice type traffic with respect to throughput, packet delay and inter-packet delay was investigated by simulation.Experiments were carried out for a variety of (i) network loading (talkers), (ii) packet size, and (iii) network topology.The results show that almost twice the expected number of conversations can be carried before delays become unacceptable.Finally, the conclusions of the work are summarised and suggestions made for future work.