Abstract

We present two algorithms, IRRM and SLIP-IRRM, for scheduling cells in an input-queued cell switch. Both algorithms exhibit asymptotically 100% utilisation under high load; SLIP-IRRM within a single iteration. 1 Introduction The major problem with input-queued switches is head-of-line blocking which can limit the maximum throughput asymptotically to 58% [1]. Previous algorithms have improved upon the 58% utilisation [2, 3, 4, 5, 6] using non-FIFO input queues and state-dependent scheduling. In each case, if the traffic is not uniformly distributed over outputs, or if the arrival process is not Bernoulli then the asymptotic utilisation decreases from its maximum. In particular, Parallel Iterative Matching (PIM) [6] will tend towards 100% utilisation if a sufficiently large number of iterations are used. The proposed scheduling algorithm called Iterative Round Robin Matching (IRRM) is a simplified version of PIM [6]. The maximum achievable utilisation of IRRM is always asymptotic to...

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