Congestion Control Mechanisms for Inter-Datacenter Networks

TL;DR

This paper introduces GEMINI and FlashPass, two novel congestion control mechanisms tailored for inter-datacenter networks, effectively managing heterogeneous congestion scenarios and shallow buffers to improve performance and reduce packet loss.

Contribution

The paper presents GEMINI and FlashPass, innovative congestion control solutions specifically designed for the complex, heterogeneous environment of inter-datacenter networks.

Findings

GEMINI effectively manages congestion in both DCN and WAN environments.

FlashPass achieves near-zero packet loss with shallow buffers.

Both mechanisms outperform existing congestion control methods.

Abstract

Applications running in geographically distributed setting are becoming prevalent. Large-scale online services often share or replicate their data into multiple data centers (DCs) in different geographic regions. Driven by the data communication need of these applications, inter-datacenter network (IDN) is getting increasingly important. However, we find congestion control for inter-datacenter networks quite challenging. Firstly, the inter-datacenter communication involves both data center networks (DCNs) and wide-area networks (WANs) connecting multiple data centers. Such a network environment presents quite heterogeneous characteristics (e.g., buffer depths, RTTs). Existing congestion control mechanisms consider either DCN or WAN congestion, while not simultaneously capturing the degree of congestion for both. Secondly, to reduce evolution cost and improve flexibility, large enterprises have been building and deploying their wide-area routers based on shallow-buffered switching chips. However, with legacy congestion control mechanisms (e.g., TCP Cubic), shallow buffer can easily get overwhelmed by large BDP (bandwidth-delay product) wide-area traffic, leading to high packet losses and degraded throughput. This thesis describes my research efforts on optimizing congestion control mechanisms for the inter-datacenter networks. First, we design GEMINI - a practical congestion control mechanism that simultaneously handles congestions both in DCN andWAN. Second, we present FlashPass - a proactive congestion control mechanism that achieves near zero loss without degrading throughput under the shallow-buffered WAN. Extensive evaluation shows their superior performance over existing congestion control mechanisms.