Multimodal Congestion Control for Low Stable-State Queuing

To discover an efficient fair sending rate for a flow, Transmission Control Protocol (TCP) saturates the bottleneck link and its buffer until the router discards a packet. Such TCP-caused queuing is detrimental for interactive and other delay-sensitive applications. In this paper, we present Multimodal Control Protocol (MCP) which strives to maintain low queues and avoid congestion losses at network links. The multimodal MCP engages routers and hosts in limited explicit communication. A distinguishing property of MCP is stable transmission after converging to efficient fair states. To ensure convergence to fairness, MCP incorporates an innovative mechanism that enables a flow to urge all flows sharing its bottleneck links to operate in a fairing mode, dedicated to fairness improvement. To make the stable fair rates independent of round-trip times and packet sizes, MCP employs rate-based control and uniform timing of adjustments.