Process control solutions for congestion control in computer networks

Abstract

The use of Process Control ideas for the solution of congestion control problems is discussed here. Congestion appears in modern data networks when routers receive more data than they can process. If this congestion is not properly treated congestive collapse occurs, with the router providing very low throughput, as packages have to be resent multiple times. This problem is not dissimilar to some fluid control problems in Process Control, where flows have to be controlled to avoid overflows. Thus, it can be modelled using fluid models, so it is discussed in this paper how standard process control ideas can be adapted to deal with these congestion control problems. A case study involving a set of AQM-based routers under TCP protocol is carried out, using a non-interacting PID controller previously proposed for Process Control. Equivalent fluid models are provided and its control carried out. The results show how process control ideas make possible to avoid congestion when the controller is adequately tuned, despite inherent variations.