The paper demonstrates that the traffic of foundation fieldbus(FF) is statistically selfsimilar,that none of the commonly used traffic models is able to capture this fractal behaviour,that such behaviour has serious implications for design,control,and analysis of Infranet and Intranet,and that aggregating streams of such traffic typically intensifier the selfsimilarity instead of smoothing it.The reason why selfsimilar process is built on the superposition of AR1 processes and the superposition of other selfsimilar processes is analysed.It is concluded that the traffic has selfsimilarity in information networks based on H1 fieldbus.