Delay Analysis of Combined Input-Crosspoint Queueing Switches

The switch architecture with the combined input - crosspoint queueing (CICQ) scheme has been recognized as a practical promising solution for building cost-effective high-performance switches. In an N x N CICQ switch, the switching fabric is a nonblocking buffered crossbar, a large input buffer is provided at each input and a relatively small internal buffer is provided at each crosspoint of the buffered crossbar. Each input buffer is logically organized as N virtual output queues (VOQs). In this paper, we build the queueing model for evaluating the delay performance of a CICQ switch under i.i.d uniform 2-state Markov modulated Bernoulli process (2-MMBP) bursty traffic. The accuracy of the queuing model is examined via computer simulation, by investigating the mean cell delay in a switch as a function of the switch size, the internal buffer size, the mean offered load and the mean burst length. The numerical results show that our queueing model can well analyze the reality.