Optimal Buffer Control During Congestion in an ATM Network Node

In this paper we study the problem of optimal buffer space priority control in an ATM network node. The buffer of a transmission link is shared among the cells of several traffic classes waiting for transmission through the link. When the number of cells to be stored in the buffer exceeds the available buffer space, certain cells have to be dropped. Different traffic classes have different sensitivities to cell losses. By appropriately selecting the classes of cells which are dropped or blocked in case of overflow, we can have the more sensitive classes suffer smaller cell losses. Depending on the control that we have on the system, three classes of policies are distinguished. In each one, policies that schedule the buffer allocation in some optimal manner are identified.