A Study of Internet Packet Reordering

Packet reordering is a well-known phenomenon that the order of packets is inverted in the Internet. Previous studies indicates reordering can affect the performance of both the network and the packets receiver. Nevertheless, they get different results about the prevalence of reordering in the Internet. In this paper, we firstly present a methodology for single-point reordering measurement at a TCP receiver, including the algorithm and its implementation. Then we show the results of our threeweek observation of reordering from a set of 10,647 Internet Web sites in China. In addition, we discuss a method to distinguish reordering and loss by making use of the distribution of their time lag and packet lag. Finally, we study the pertinence of sites experiencing reordering according to the network topology and propose a novel and relatively reliable approach to infer reorder-generating spots in the Internet.