Impact of router buffer size on TCP/UDP performance

In data communication when there are too many packets contending for the limited shared resources, such as the queue buffer in the router at bottleneck link, it may result in congestion. During congestion, large amount of packets experience delay or even be dropped due to the queue overflow. Severe congestion problems result in degradation of the throughput and large packet loss rate. In this paper, analysis of throughput and packet loss rate for different buffer sizes is presented; taking into account two popular queue management methods, Random Early Detection (RED) and Drop Tail, for different TCP and UDP streams coming to a common router buffer. The results indicate that the throughput and efficiency of TCP increases with increase in buffer size for RED. Moreover, UDP packet loss decreases with an increase in buffer size while the buffer size has no key impact on UDP packet delays. Simulation has been done by using Network Simulator (NS2-2.37) and the graphs are plotted using GNU plot.