Congestion control for multicast service in ATM networks

In recent ATM Forum activities, considerable efforts have focused on the congestion control of point-to-point available-bit-rate (ABR) service. In this paper, we present a novel approach that extends the existing point-to-point (unicast) congestion control protocol to a point-to-multipoint (multicast) environment. In particular, we establish a unified framework to derive a multicast congestion control protocol for ABR service from a given rate-based unicast protocol. We first generalize a known necessary and sufficient condition on the max-min fairness of unicast rate allocation for multicast service. Then we show that the resulting multicast protocol derived using our framework preserves fairness characteristics of the underlying unicast protocol. The practical significance of our approach is illustrated by extending a standard congestion control mechanism for ABR service to a multicast environment. The performance of the resulting multicast protocol is examined using benchmark network configurations suggested by the traffic management subworking group at the ATM Forum, and simulation results are presented to substantiate our claims