Optimal buffer control during congestion in an ATM network node

The problem of optimal buffer space priority control in an asynchronous transfer mode (ATM) network node is studied. 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 exceed the available buffer space, certain cells have to be dropped. Different traffic classes have different sensitivities to cell losses. By appropriate selection of the classes of cells that are dropped in case of overflow, the more sensitive classes can be made to suffer smaller cell losses. Arriving cells might be blocked from entering the system or they may be dropped after they are already in the buffer. Depending on the control that is on the system, three classes of policies are distinguished. In each one, policies that schedule the buffer allocation in some optimal manner are identified