Per-packet load balancing in data center networks

In this paper, we evaluate the performance of per-packet load balancing in data center networks (DCNs). Throughput and flow completion time are considered among the main metrics to evaluate the performance of the transport of flows over the presence of long flows in a DCN. Load balancing in a DCN may benefit those performance metrics but also it may generate out-of-order packet delivery. We investigate the impact of out-of-order packet delivery on the throughput and flow completion time of long and short flows, respectively, in a DCN. Our simulations confirm the presence of out-of-order packet delivery in a DCN using per-packet load balancing. Simulation results also reveal that per-packet load balancing may yield smaller average flow completion time for short flows and larger average throughput for long flows than the single-path transport model used by TCP despite the presence of out-of-order packet delivery. As the delay difference between alternative paths decreases, the occurrence of out-of-order packet delivery in per-packet load balancing also decreases. Therefore, under the studied scenarios, the benefits of the per-packet load balancing prevail.