Evaluation of an admission control scheme for an ATM network considering fluctuations in cell loss rate

The authors investigate an admission-flow-control scheme for an ATM (asynchronous transfer mode) network and analytically obtain the cell loss rate considering fluctuations in the number of active calls on a network. A queuing model is developed for an ATM switch where a number of bursty calls are multiplexed onto an output port of a switch. To make the analysis tractable, it is assumed that the number of active calls changes slowly relative to the cell transmission time (quasi-stationary approximation). It is shown that the fluctuation of the cell loss rate is larger when high-speed calls (e.g. 10 Mb/sec) are multiplexed than when low-speed calls (e.g. 64 kb/sec) are multiplexed. Furthermore, it is observed that congestion may last for more than several hundred milliseconds, which is comparable to or even longer than one talkspurt (burst). Thus, it is shown that bursty cell loss is a serious problem