LOOK-AHEAD RESERVATION-BASED SCHEDULING FOR INPUT-OUTPUT BUFFERED ATMSWITCH

The authors present a decentralised scheduling approach for an input-o utput buffered ATM switch based on look-ahead reservation that minimis es head-of-line blocking. Cells in an input port are queued separately according to their destined output port. To schedule the transmission time of cells in the input buffer, the input port may send requests t o output ports to reserve bandwidth and buffer space at most omega cel l times in advance. The reservation request carries with it the state information of the input port which allows the output port to compute a conflict-free schedule. Co-ordination among input/output ports are n ot required. This approach effectively minimises head-of-line blocking . A simulation study reveals that the performance of the proposed meth od, in terms of throughput and cell delay, is substantially better tha n the windowing approach and is close to that of the optimal schedulin g method using exhaustive search.