Fairness and Stability

Figure 12: Three independent OverQoS links compete for bandwidth on a shared bottleneck where all CLVLs are established between a university node and NBG, a node behind an access network in Oregon. To make the graph readable, the value of $b$ is averaged over every minute.

The N-TCP pipe abstraction is built using MulTCP which inherently is TCP-friendly in the aggregate with both cross traffic and other OverQoS traffic. Figure 12 illustrates this fact using a real-world experiment on a link between a university node and NBG, a node behind an access network. Three OverQoS bundles (with N=2, N=4,N=8) compete on this shared bottleneck under two different scenarios: (a) no cross-traffic, and (a) cross-traffic consisting of five long lived TCPs (wget downloading content in parallel). We make two observations. First, the three OverQoS bundles co-exist with each other and with the background traffic. Second, the ratio of throughputs of the three OverQoS bundles is preserved across both scenarios.