Throughput Optimal Routing in Overlay Networks

TL;DR

This paper proposes a throughput optimal dynamic routing policy for overlay networks with limited bifurcation points, improving delay performance compared to traditional backpressure policies.

Contribution

It introduces a queue-based routing policy that is maximally stable for overlay networks with non-overlapping paths and extends it heuristically to more general networks.

Findings

Policy achieves maximum throughput in restricted scenarios.

Simulation shows better delay performance than backpressure.

Heuristic extension broadens applicability to general networks.

Abstract

Maximum throughput requires path diversity enabled by bifurcating traffic at different network nodes. In this work, we consider a network where traffic bifurcation is allowed only at a subset of nodes called \emph{routers}, while the rest nodes (called \emph{forwarders}) cannot bifurcate traffic and hence only forward packets on specified paths. This implements an overlay network of routers where each overlay link corresponds to a path in the physical network. We study dynamic routing implemented at the overlay. We develop a queue-based policy, which is shown to be maximally stable (throughput optimal) for a restricted class of network scenarios where overlay links do not correspond to overlapping physical paths. Simulation results show that our policy yields better delay over dynamic policies that allow bifurcation at all nodes, such as the backpressure policy. Additionally, we provide a heuristic extension of our proposed overlay routing scheme for the unrestricted class of networks.