MAINTAINING HIGH THROUGHPUTDURING OVERLOAD IN ATM SWITCHESJonathan

This report analyzes two popular heuristics for ensuring packet integrity in ATM switching systems. In particular, we analyze the behavior of packet tail discarding, in order to understand how the packet level link eeciency is dependent on the rates of individual virtual circuits and the degree of the imposed overload. In addition, we study early packet discard and show that the queue capacity needed to achieve high eeciency under worst-case conditions grows with the number of virtual circuits and we determine the eeciency obtainable with more limited queue capacities. Using the insights from these analyses, extensions to early packet discard are proposed which achieve high eeciency with dramatically smaller queue capacities (independent of the number of virtual circuits).