Cell scheduling for ATM switch with two priority classes

The flexibility of ATM allows it to support various types of applications with diversified quality of service (QoS) requirements. We broadly classified these services into the delay sensitive (DS) class and the loss sensitive (LS) class. The scheduling problem for two priority classes is much more complex than the single priority class counterpart. The scheduling algorithm is required to satisfy two conflicting requirements (i) maintain the cell delay of DS traffic within an acceptable range by giving it a higher transmission priority; and (ii) minimize the cell loss probability of LS traffic. A good scheduling algorithm for a single priority class may not perform well when applied to two priority classes scheduling. We present a reservation based scheduling approach that can handle the QoS requirements of both the DS class and LS class effectively.