Improving Cross-Traffic Bounds in Feed-Forward Networks – There is a Job for Everyone

Network calculus provides a mathematical framework for deterministically bounding backlog and delay in packet-switched networks. The analysis is compositional and proceeds in several steps. In the first step, a general feed-forward network is reduced to a tandem of servers lying on the path of the flow of interest. This requires to derive bounds on the cross-traffic for that flow. Tight bounds on cross-traffic are crucial for the overall analysis to obtain tight performance bounds. In this paper, we contribute an improvement on this first bounding step in a network calculus analysis. This improvement is based on the so-called total flow analysis (TFA), which so far saw little usage as it is known to be inferior to other methods for the overall delay analysis. Yet, in this work we show that TFA actually can bring significant benefits in bounding the burstiness of cross-traffic. We investigate analytically and numerically when these benefits actually occur and show that they can be considerable with several flows’ delays being improved by more than 40 % compared to existing methods – thus giving TFA’s existence a purpose finally.