SPACE PRIORITY MECHANISMS WITH BURSTY TRAFFIC

The introduction of a special class of priorities called space priorities, enables the Asynchronous Transfer Mode (ATM) layer to adapt the quality of the cell transfer to the quality of service requirements of the specific Broadband ISDN services and to improve the utilization of the networks resources. This is done by a selective discarding of cells according to the class they belong to. This paper evaluates two space priority mechanisms previously proposed: the Push-Out scheme and the Partial Buffer Sharing when the input traffic is bursty. The performance study is done by using a two-state Markov-modulated Poisson process which models the bursty arrival processes commonly arising in communication applications. The analytical models we have developed use a more general arrival process: the Markovian arrival process (MAP) which has as a particular case the Markov-modulated Poisson process. The derived values are used to see the benefits of using priorities in an ATM network when the traffic is bursty and to make a comparative study of the buffer mechanisms. These results extend the previously developed models which were limited to Poisson arrivals.