EVALUATION OF THE EFFECTS OF PROTOCOL PROCESSING OVERHEAD IN ERROR RECOVERY SCHEMES FOR A HIGH-SPEED PACKET SWITCHED NETWORK - LINK-BY-LINK VERSUS EDGE-TO-EDGE SCHEMES

This paper investigates the effects of protocol processing overhead on the performance of error recovery schemes in high-speed network environments. The investigated error recovery schemes are: . an edge-to-edge error recovery scheme, where retransmission of erred packets only take place between source and destination nodes, and . a link-by-link error recovery scheme, where retransmissions only take place between adjacent switching nodes. For retransmission of erred packets, we consider both Go-back-N and Selective-Repeat procedures in the analysis. The performance measures we obtain are the distribution of transfer delays and the loss probability of packets across a network. To obtain these measures, this paper takes a vertical view of the layers and develops a tandem queueing network model with feedbacks where each queue represents a protocol layer within a switching node, rather than a switching node as a whole. The effects of propagation delay on a transmission link and the timeout mechanism are also considered in the model. Numerical results show that for a network with very-high-speed/low-error-rate channels, an edge-to-edge scheme gives the smaller packet transmission delay than a link-by-link scheme for both Go-back-N and Selective-Repeat retransmission procedures, while keeping the packet loss probability sufficiently small.