Queue-length synchronization in a communication networks

TL;DR

This paper investigates queue-length synchronization phenomena in a 2D communication network, revealing how congestion leads to synchronized queue lengths among hubs, with implications for understanding traffic dynamics and congestion control.

Contribution

It introduces a model showing queue synchronization in congested networks, including real Internet traffic, highlighting cascading relations and synchronization loss during decongestion.

Findings

Queue lengths synchronize during congestion phases.

Synchronization is observed between high betweenness centrality hubs.

Real Internet traffic exhibits phase synchronization similar to the model.

Abstract

We study synchronization in the context of network traffic on a $2-d$ communication network with local clustering and geographic separations. The network consists of nodes and randomly distributed hubs where the top five hubs ranked according to their coefficient of betweenness centrality (CBC) are connected by random assortative and gradient mechanisms. For multiple message traffic, messages can trap at the high CBC hubs, and congestion can build up on the network with long queues at the congested hubs. The queue lengths are seen to synchronize in the congested phase. Both complete and phase synchronization is seen, between pairs of hubs. In the decongested phase, the pairs start clearing, and synchronization is lost. A cascading master-slave relation is seen between the hubs, with the slower hubs (which are slow to decongest) driving the faster ones. These are usually the hubs of high CBC. Similar results are seen for traffic of constant density. Total synchronization between the hubs of high CBC is also seen in the congested regime. Similar behavior is seen for traffic on a network constructed using the Waxman random topology generator. We also demonstrate the existence of phase synchronization in real Internet traffic data.