RTCP - Reduce Delay Variability with an End-to-end Approach

Many important applications in modern network systems are sensitive to delay and delay variability. To ensure good performance on both metrics, in this paper, we propose a novel transport protocol called Regulated TCP (RTCP), whose design is inspired by the use of auxiliary variables in optimization theory. RTCP is a light-weight protocol and it uses counters in end devices and end-to-end delay measurements for rate adaptation (via window adjustment). We implement RTCP in both ns-3 and a network testbed under two workload types, i.e., web search and data mining. Our testbed experiments show that compared to existing congestion control schemes such as BBR [1] and PCC [2], RTCP guarantees a better delay performance for urgent flows, while keeping a competitive goodput. Our ns-3 simulation results also demonstrate that RTCP performs well in a wide range of scenarios. In particular, RTCP achieves a 9.78% throughput increase over BBR, and a 64.22% delay reduction of DCTCP [3] in a random sending scenario. It also reduces the 99th packet delay to less than 56% of other end-to-end TCP versions, including LEDBAT [4], TIMELY [5] and Vegas [6], in the large-scale incast scenario.