With increasing link speeds and increased parallelism within routers, packet reordering will be more widespread over the Internet. The definition of "percentage out-of-order" metric is vague and ambiguous and in addition, the measure is incapable of characterizing and evaluating the packet-reordering problem. At CNRL, we have proposed two metrics for reordering, "Reorder Density" (RD) and "Reorder Buffer-occupancy Density" (RBD). In addition, we also characterize reordering introduced by a network in the form of "Reorder Response."
For complete description of RD and RBD and other useful details, follow these links:
N. Piratla, A. P. Jayasumana, and A. Bare "A Comparative
Analysis of Packet Reordering Metrics," Presented at First
International Conference on Communication System Software
and Middleware (COMSWARE 2006), New Delhi, India, Jan. 2006.