A Fair Leaky-bucket Traac Shaper for Atm Networks

ATM network performance hinges on user sessions, or virtual connections, adhering to the traac contracts established by the admission control policy. This paper considers eecient mechanisms for enforcing these contracts by shaping the incoming cell streams. While shaping eeectively accommodates variation in a connection's traac ow, this smoothing function introduces implementation complexity, since the shaper must buuer violating cells and schedule them for later transmission. Connicts arise when multiple cells, from diierent connections, become eligible for transmission at the same time. This paper presents a fair leaky-bucket (FLB) shaper that minimizes the traac distortions caused by these cell collisions. A theorem shows that FLB shaping, based on weighted fair queueing , closely preserves connection leaky-bucket parameters and bounds cell shaping delay. The paper also presents an eecient implementation of self-clocked fair queueing , which reduces the complexity of the FLB architecture. Finally, simulation experiments demonstrate how FLB shaping mitigates the harmful eeects of collisions between competing cells.