Exploiting Path Diversity in Datacenters using MPTCP-aware SDN

TL;DR

This paper proposes an SDN controller that intelligently assigns MPTCP subflows to different paths in datacenter networks, improving performance and resilience over traditional random hashing methods.

Contribution

It introduces an MPTCP-aware SDN controller with deterministic subflow routing and demonstrates performance gains, especially with multi-interface hosts, compared to standard approaches.

Findings

Deterministic subflow assignment improves throughput and resilience.

Using multiple interfaces at hosts enhances performance in multi-path scenarios.

Modified MPTCP Linux Kernel supports multiple subflows per interface pair.

Abstract

Recently, Multipath TCP (MPTCP) has been proposed as an alternative transport approach for datacenter networks. MPTCP provides the ability to split a flow into multiple paths thus providing better performance and resilience to failures. Usually, MPTCP is combined with flow-based Equal-Cost Multi-Path Routing (ECMP), which uses random hashing to split the MPTCP subflows over different paths. However, random hashing can be suboptimal as distinct subflows may end up using the same paths, while other available paths remain unutilized. In this paper, we explore an MPTCP-aware SDN controller that facilitates an alternative routing mechanism for the MPTCP subflows. The controller uses packet inspection to provide deterministic subflow assignment to paths. Using the controller, we show that MPTCP can deliver significantly improved performance when connections are not limited by the access links of hosts. To lessen the effect of throughput limitation due to access links, we also investigate the usage of multiple interfaces at the hosts. We demonstrate, using our modification of the MPTCP Linux Kernel, that using multiple subflows per pair of IP addresses can yield improved performance in multi-interface settings.