On the bunching of cell losses in ATM-based networks

The author investigates the extent to which cell losses tend to be bunched by developing a Markov model of cell losses at an output buffer in an ATM (asynchronous transfer mode) switch. The output buffer may be fed by any one of several input lines. It is completely shared among all virtual circuits passing through it. Under congestion, it is shown that successive cell losses are quite likely once an initial cell loss has occurred and that the proportion of lost cells within a frame can be quite large. The bunching of cell losses and the high proportion of cell losses within a frame suggest that a frame-based retransmission scheme is an appropriate recovery mechanism in ATM-based networks such as broadband ISDN (integrated services digital network)