Efficient multicast algorithms for high-speed routers

Several types of applications, like broadcast video, interactive gaming, remote collaboration etc., require multicast distribution of content. An important problem, from the router architecture perspective, is to distribute multicast content at high-speeds and over a large number of physical or logical interfaces. In order to forward multicast packets, the system must replicate the same packet, or pointers of the packet, to multiple interfaces. This function requires significant speed-up from the memories and the forwarding engines, and has become a key bottleneck for a wide deployment of multicasting. Previous efforts in solving this problem have only led to statistical solutions, that cannot provide deterministic performance. As a result, temporary overload in multicast traffic could lead to unnecessary packet losses, even for unicast connections that share the same interfaces. In this paper, we present a novel algorithm for managing multicast sessions, that offers isolation between interfaces, deterministic performance, and flexibility in the offered delays. To the best of our knowledge, this is the first algorithm ever proposed that can provide deterministic performance for multicast sessions in highspeed switches and routers, without any speed-up requirements.