DiFS: Distributed Flow Scheduling for Data Center Networks

TL;DR

DiFS is a switch-only distributed flow scheduling protocol for data center networks that improves bandwidth utilization and scalability over static and centralized approaches by enabling switches to cooperatively avoid over-utilized links.

Contribution

This paper introduces DiFS, a scalable, switch-only distributed flow scheduling algorithm that enhances bandwidth utilization without centralized control or synchronization.

Findings

DiFS outperforms ECMP in aggregate bisection bandwidth across various traffic patterns.

DiFS achieves bandwidth similar to or higher than centralized scheduling algorithms.

DiFS reacts quickly to dynamic traffic conditions.

Abstract

Data center networks leverage multiple parallel paths connecting end host pairs to offer high bisection bandwidth for cluster computing applications. However, state of the art distributed multi-pathing protocols such as Equal Cost Multipath (ECMP) use static flow-to-link assignment, which is load-oblivious. They may cause bandwidth loss due to \emph{flow collisions} on a same link. Recently proposed centralized scheduling algorithm or host-based multi-pathing may suffer from scalability problems. In this paper, we present Distributed Flow Scheduling (DiFS) for data center networks, which is a switch-only distributed solution. DiFS allows switches cooperate to avoid over-utilized links and find available paths without centralized control. DiFS is scalable and can react quickly to dynamic traffic, because it is independently executed on switches and requires no synchronization. Extensive experiments show that the aggregate bisection bandwidth of DiFS using various traffic patterns is much better than that of ECMP, and is similar to or higher than that of a recent proposed centralized scheduling algorithm.