A Comparative Analysis of Packet Reordering Metrics

* This research was supported in part by NSF ITR Grant No. 0121546, Ixia University Partners Program and Agilent Technologies. Nischal Piratla was with Colorado State University during this research; Email: {Nischal.Piratla, Anura.Jayasumana)@colostate.edu, [email protected] Abstract – Packet reordering is an inevitable phenomenon on the Internet. Reorder Density, Reorder Buffer-occupancy Density, Reorder Extent, and n-Reordering are metrics that have been proposed to measure packet reordering; they overcome to various degrees the deficiencies of percentage reordering in capturing the nature and extent of reordering. These metrics vary widely in areas such as evaluation complexity, measurement technique, usage, and in the definition used for packet reordering itself. An ideal metric for packet reordering will capture reordering accurately, provides insight into nature of reordering, and helps in analysis of reordering leading to mitigation of its adverse effects. Metrics for reordering are evaluated using a framework developed for their comparison and analysis. The framework consists of both essential and desirable attributes of reorder metrics that include capturing reordering, low sensitivity to lost and duplicate packets in reorder measurements, usefulness, simplicity, evaluation complexity, etc. Finally, the characterization of packet reordering using these metrics is discussed, using sets of measurements carried over the Internet.