On Minimizing the Completion Times of Long Flows over Inter-Datacenter WAN

TL;DR

This paper introduces BWRH, a heuristic routing method that minimizes long flow completion times over inter-datacenter WANs by considering ongoing flows, significantly improving performance compared to existing heuristics.

Contribution

The paper presents BWRH, a novel heuristic for routing long flows that accounts for current network conditions, achieving near-optimal solutions efficiently.

Findings

BWRH achieves less than 0.25% optimality gap.

BWRH reduces mean FCT by up to 1.46 times.

BWRH reduces tail FCT by up to 1.53 times.

Abstract

Long flows contribute huge volumes of traffic over inter-datacenter WAN. The Flow Completion Time (FCT) is a vital network performance metric that affects the running time of distributed applications and the users' quality of experience. Flow routing techniques based on propagation or queuing latency or instantaneous link utilization are insufficient for minimization of the long flows' FCT. We propose a routing approach that uses the remaining sizes and paths of all ongoing flows to minimize the worst-case completion time of incoming flows assuming no knowledge of future flow arrivals. Our approach can be formulated as an NP-Hard graph optimization problem. We propose BWRH, a heuristic to quickly generate an approximate solution. We evaluate BWRH against several real WAN topologies and two different traffic patterns. We see that BWRH provides solutions with an average optimality gap of less than $0.25\%$. Furthermore, we show that compared to other popular routing heuristics, BWRH reduces the mean and tail FCT by up to $1.46\times$ and $1.53\times$, respectively.