Performances analysis of Ethernet networks in the process control

The main obstacle to using Ethernet in real-time communications is the fact that these systems require network behaviour to be as deterministic as possible, while Ethernet, cannot provide connected stations with deterministic channel access times and therefore guarantee that data delivery deadlines will be met. Traffic smoothing can be a good solution to this problem. In this paper we introduce Dynamic Traffic Smoothing, which consists of dynamically assigning each station a portion of bandwidth according to the current workload on the network. Whereas in static smoothing the available bandwidth is shared equally between the various stations, in dynamic smoothing it is entirely available only for stations that are actually transmitting, thus optimising its use. In the paper, the results of a series of simulations made to compare the performance obtained without smoothing, with static smoothing, and with dynamic smoothing respectively are presented and discussed.