Pathological Behaviors for RLM and RLC

RLM [4] and RLC [7] are two well known receiver-driven cumulative layered multicast congestion control protocols. They both represent an indisputable advance in the area of congestion control for multimedia applications. However, there are very few studies that evaluate these protocols, and most of the time, these studies conclude that RLM and RLC perform reasonably well over a broad range of conditions. In this paper, we evaluate both RLM and RLC and show that they exhibit fundamental pathological behaviors. We explain in which context these pathological behaviors happen, why they are harmful, and why they are inherent to the protocols themselves and cannot be easily corrected. Our aim is to shed some light on the fundamental problems with these protocols.