On the Impact of Packet Spraying in Data Center Networks
Modern data center networks are commonly organized in multi-rooted tree topologies. They typically rely on equal-cost multipath to split flows across multiple paths, which can lead to significant load imbalance. Splitting individual flows can provide better load balance, but is not preferred because of potential packet reordering that conventional wisdom suggests may negatively interact with TCP congestion control. In this paper, the authors revisit this "myth" in the context of data center networks which have regular topologies such as multi-rooted trees. They argue that due to symmetry, the multiple equal-cost paths between two hosts are composed of links that exhibit similar queuing properties.