Oscillations with TCP-like Flow Control in Networks of Queues

TL;DR

This paper analyzes a network of queues with TCP-like flow control, demonstrating that such systems can oscillate under certain congestion conditions, contrasting with prior models that predict convergence to a steady state.

Contribution

It introduces a new model where congestion depends on actual traffic, revealing oscillatory behavior not seen in traditional flow control models.

Findings

System can oscillate under certain congestion rules

Contrasts with models predicting convergence to equilibrium

Highlights importance of congestion modeling assumptions

Abstract

We consider a set of flows passing through a set of servers. The injection rate into each flow is governed by a flow control that increases the injection rate when all the servers on the flow's path are empty and decreases the injection rate when some server is congested. We show that if each server's congestion is governed by the arriving traffic at the server then the system can *oscillate*. This is in contrast to previous work on flow control where congestion was modeled as a function of the flow injection rates and the system was shown to converge to a steady state that maximizes an overall network utility.