Abstract— Interactive and other delay-sensitive applications are interested in keeping end-to-end delays of their packets minimal. Unfortunately, congestion control offered by Transmission Control Protocol (TCP) and other existing protocols inflates the end-to-end delays by building up queues at bottleneck links. In this paper, we investigate Multimodal Control Protocol (MCP) designed to maintain low queues after converging to the stable state where MCP flows utilize shared bottleneck links efficiently and fairly. To achieve this goal, MCP incorporates multiple modes of operation and allocates few bits in each packet header for explicit communication between hosts and routers. An innovative aspect of the explicit communication mechanism is an ability of a flow to urge all flows on its bottleneck links to switch temporarily into a fairing mode and thereby improve fairness of the bottleneck sharing. To make the fair sharing independent of round-trip times and packet sizes, MCP use...