Characterizing End-to-End Packet Reordering with UDP Traffic

Packet reordering is an Internet event that degrades the performance of both TCP and UDP-based applications. In this paper, we present an end-to-end measurement study of packet reordering of UDP traffic. The goal of the measurement study, performed on PlanetLab, was to answer four main questions: how prevalent is reordering across end-to-end paths, what are the time scales of reordered packets, how correlated is reordering with traffic load, and does the size of a transmitted packet affect the likelihood of reordering? Overall, our analysis shows that current UDP traffic reordering is consistent to prior 1990's studies on TCP traffic, despite increased Internet load and technology advancements, and it adds to the previous results by identifying additional reordering characteristics. More specifically, we show that packet reordering is asymmetric as well as temporal and site-dependent, packet size does influence the likelihood of reordering, that there exists a time-of-the-day dependency, and reordering primarily exists at two time-scales (a few milliseconds or multiple tens of milliseconds.)

• Networking