CALM: congestion-aware layered multicast

Abstract

This paper demonstrates the flexibility and utility of two lightweight, general-purpose network services (Emphemeral State Processing and LightWeight Processing modules) by showing how end-systems can use these services to obtain timely and accurate information about the location of congested links and their level of congestion. Although accurate congestion information is useful to a wide range of network services, here we illustrate its benefits to layered multicast systems. In particular, we show how these services can be used to overcome well-known problems with layered multicast, including the desire to reduce router state, the need to drop layers quickly (i.e., within one RTT), the problem of coordinating receivers, and the desire to support fine-grained layering without thrashing between layers-even in the face of join experiments.