Load balanced Birkhoff–von Neumann switches, part II: multi-stage buffering

Abstract

The main objective of this sequel is to solve the out-of-sequence problem that occurs in the load balanced Birkhoff–von Neumann switch with one-stage buffering. We do this by adding a load-balancing buffer in front of the first stage and a resequencing-and-output buffer after the second stage. Moreover, packets are distributed at the first stage according to their flows, instead of their arrival times in part I. In this paper, we consider multicasting flows with two types of scheduling policies: the first come first served (FCFS) policy and the earliest deadline first (EDF) policy. The FCFS policy requires a jitter control mechanism in front of the second stage to ensure proper ordering of the traffic entering the second stage. For the EDF scheme, there is no need for jitter control. It uses the departure times of the corresponding FCFS output-buffered switch as deadlines and schedules packets according to their deadlines. For both policies, we show that the end-to-end delay through our multi-stage switch is bounded above by the sum of the delay from the corresponding FCFS output-buffered switch and a constant that only depends on the size of the switch and the number of multicasting flows supported by the switch.