A Case for Decomposition of FIFO Networks

Recent findings showing that the output of traffic flows at packet switches has similar characteristics as the corresponding input enable a decomposition analysis of a network where nodes can be studied in isolation, thus simplifying an end- to-end analysis of networks. However, network decomposition results currently available are mostly many-sources asymptotics. In this paper we explore the viability of network decomposition in a non-asymptotic regime with a finite number of flows. For traffic with Exponentially Bounded Burstiness (EBB) we derive statistical bounds for the output traffic at a FIFO buffer and compare them with bounds on the input. By evaluating the accuracy of the output bounds with exact results available for special cases and by using numerical examples we find that conditions for network decomposition appear favorable even if the number of flows is relatively small.