TCP SIAD: Congestion Control supporting High Speed and Low Latency

Abstract

Congestion control has been an open research issue for more than two decades. More and more applications with narrow latency requirements are emerging which are not well addressed by existing proposals. In this paper we present TCP Scalable Increase Adaptive Decrease (SIAD), a new congestion control scheme supporting both high speed and low latency. More precisely, our algorithm aims to provide high utilization under various networking conditions, and therefore would allow operators to configure small buffers for low latency support. To provide full scalability with high speed networks, we designed TCP SIAD based on a new approach that aims for a fixed feedback rate independent of the available bandwidth. Further, our approach provides a configuration knob for the feedback rate. This can be used by a higher layer control loop to impact the capacity share, potentially at the cost of higher congestion, e.g. for applications that need a minimum rate. We evaluated TCP SIAD against well-known high-speed congestion control schemes, such as Scalable TCP and High Speed TCP, as well as H-TCP that among other goals targets small buffers. We show that only SIAD is able to utilize the bottleneck with arbitrary buffer sizes while avoiding a standing queue. Moreover, we demonstrate the capacity sharing of SIAD depending on the configured feedback rate and a high robustness of TCP SIAD to non-congestion related loss.