Buffer Sizing in a Combined Input Output Queued (CIOQ) Switch

In all internet routers buffers are needed to hold packets during times of congestion. In some recent work, the question of finding the minimum buffer size guaranteeing high throughput has been addressed [3] [6]. The answer to this question is particularly important in building all-optical routers, where the optical technology allows buffering up to a few dozen packets [7]. While in practice most high speed routers use input queued switches, the previous works have all focused on the problem of buffer sizing in output queued switches. In this work, we consider a combined input output queued switch in the core of a TCP network. Based on ns2 simulations and by adding a CIOQ switch to the simulation environment, we investigate how different parameters can affect the amount of buffering needed to have high link utilization.