Rate based congestion control for multicast ABR traffic

We present an end to end rate control algorithm for multicast (point to multipoint) ABR service in ATM networks. The algorithm is the multicast extension of the SP-EPRCA unicast (point-to-point) congestion control algorithm proposed by Mascolo et al. (see Proceedings of INFOCOM'96, vo1.2, p.569-76). The goal is to control the multicast input rate in order to achieve high bandwidth utilization without overflowing any queue along the multicast tree. The straightforward approach would be to consider a multicast connection as a superposition of unicast connections, and to compute the multicast input rate as the minimum among all unicast input rates. The main problem is the congestion caused by feedback traffic from the multiple destinations. To solve this problem, we show how feedback information cells can be intelligently "merged" at each multicast tree "fork" without losing essential information needed by the control algorithm placed at the source. The algorithm proposed inherits all properties from the unicast SP-EPRCA.