A basic requirement for the policing function in ATM networks

Abstract

Since ATM networks will have to cope with a wide range of applications, some of them producing highly variable traffic, congestion control plays a crucial role for such networks. The policing function has been introduced to monitor some traffic characteristics of any connection, and several policing mechanisms have been proposed in the literature. They will be called pick-up policing mechanisms because either cells pass transparently through or else they are picked up—either discarded or tagged. In this paper, we draw attention to the fact that cell clusters of a given connectioncan pass transparently at the multiplex rate through such a mechanism, giving rise to a bursty component entering the network. The impact of this bursty component on network performance is analyzed in a possible ATM network configuration, involving a switch based upon an output queueing architecture. It appears that even slightly bursty traffic can induce severe degradation. Consequently, a suitable policing function must strictly avoid cell clusters entering the network.