Effects of buffer and node size on packet switch performance

Performance in packet switch with arbitrary buffer space and the switch size in three different buffer allocation schemes, OQ, VOQ and FPCF, are analyzed. The performance measures are mean and maximum packet delay and packet loss probability. For the analysis ns2, simulation environment is applied, where the VOQ and FPCF nodes are newly implemented. The results show that the node architecture itself determines the relations between size and buffer space on one hand and the node performance on the other. In all the architectures, packet loss probability decreases and mean queuing delay increases with increased buffer size. The switch size has no effect on the performance in OQ and causes slight increase of packet loss probability in FPCF due to its specific classification algorithm. In VOQ, N and B are strongly related because of the separation of total buffer space in N virtual queues and both substantially influence the performance. Changes in packet loss probability related to the switch size in FPCF can be compensated with additional buffer space without influencing the queuing delay. In VOQ, the additional buffer space required is much larger and well-planned buffer allocation is required.