Toward Coexistence of Different Congestion Control Mechanisms

Interactive and delay-sensitive applications constitute an important and growing part of the Internet. Today, low delays can only be achieved if there are no congested links along the path. At a bottleneck, the commonly used congestion control mechanisms induce high queuing delay and packet loss. Specialized congestion control mechanisms achieving a low queuing delay in an otherwise congested network exist. However, if their flows share a bottleneck with traditionally congestion controlled flows, they get suppressed or loose their low-delay property. This paper presents three approaches - Separate Paths, Separate Queues and Limited Queue - that enable coexistence of congestion control mechanisms that are optimized for different goals, e.g., interactive applications and bulk transfers. The measurement results show that concurrent operation of different congestion control mechanisms can be successfully implemented this way.