Improved VCP: Fast convergence to max-min fair bandwidth allocation

Abstract

As the product of bandwidth and latency increases, TCP becomes inefficient and prone to instability. The Variable structure congestion Control Protocol (VCP) uses the load factor as a signal of congestion and sends two bits of explicit feedback to the sources. VCP is a novel and promising congestion control protocol that outperforms TCP in terms of efficiency, fairness, persistent queue length, and packet loss rate. However, the usage of a single, fixed Multiplicative Decrease (MD) parameter in VCP causes slow convergence to fairness and reduces responsiveness to congestion. In this paper, we propose iVCP, an improved version of VCP, to overcome the weakness of VCP. iVCP estimates the fair bandwidth allocation using the precise load factor, and then, exponentially converges to the fair bandwidth allocation. Extensive simulations have shown that iVCP is better than VCP in terms of the convergence speed. Simulations also have shown that iVCP preserves the good properties of VCP, including high efficiency, reasonable fairness, low persistent queue length, and negligible packet loss rate.