Data Traffic, Topology and Congestion

Abstract

We consider the interaction between the topology of a network and the tra.c carried along its channels. The binding elements between the topology and the traffic dynamics are the routing mechanisms. In a packet-based network, like the Internet, the transmission of information is carried out in discrete packets. The path that a packet follows when travelling the network is determined by the routing algorithm. Usually, from the topological properties of the network and statistical properties of the traffic, the routing algorithm tries to minimise the packet delivery time and maximise the throughput; this implies that packet flow affects the behaviour of the routers which in return regulate the flow. The dynamics of a packet network can also be regulated by controlling the packet production at the various packet sources and varying the server capacities. An example is Transmission Control Protocol or TCP, where the source of traffic adjusts its rate of packet transmission as a function of the round trip delay time.