Jitter and bandwidth enforcement

Cells arriving at an ATM (asynchronous transfer mode) network experience random delays due to queuing in upstream multiplexing stages. The alteration of the initial periodic nature of a constant bit rate cell stream due to such delays is the phenomenon of jitter. An assumption of Markovian dependence between the delays of successive cells makes it possible to calculate various quantities of interest for characterizing the jitter. This assumption is appropriate for two ATM multiplex models, and it was possible to investigate the effects of different source and multiplex parameters on the degree of jitter introduced. Jumping window and leaky bucket mechanisms have been dimensioned to enforce the peak rate of jittered streams. The leaky bucket is seen to be considerably more responsive than the jumping window. A synthetic characterization of jitter consists in the remote delay quantile divided by the period of the considered stream. This is sufficient to dimension the leaky bucket for one of the considered multiplex models and supports the heuristic approach of G. Niestegge (1990).<
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