On the capability of the policing function to release an ATM connection

The capability of releasing a connection has been recognized within standardization bodies as a desirable feature for the policing function in ATM networks. In this paper, we investigate how to implement this new scheme. For this purpose, we introduce a simple modification to some well known policing mechanisms, namely the Leaky Bucket, the EWMA, the Jumping and Moving Window. We first draw attention to the fact that all of them suffer from the drawback that they discard useful information which could be used to enforce tighter policing and to shut a connection off when too much excess traffic is submitted to the connection. We then propose a modification to the above mentioned schemes in which the discarded cell information is used, with almost no overhead compared to the usual ones. In the context of the Leaky Bucket, analysis using Bernoulli and On/Off MMBP input processes shows that the modified version has a behavior which differs significantly from its original counterpart. A major difference is that the new mechanism stops serving sources requiring much more resources than negotiated. It also reacts more severely to abuses of smaller magnitude and polices the sources closer to their declared resource utilization. A method is then presented to select the appropriate parameters of the modified Leaky Bucket in order to achieve a faster response time.