End-to-end Internet packet dynamics

Abstract

We discuss findings from a large-scale study of Internet dynamics conducted by tracing 20000 TCP bulk transfers between 35 Internet sites. Because we traced each 100-kbyte transfer at both the sender and the receiver, the measurements allow us to distinguish between the end-to-end behavior due to the different directions of the Internet paths, which often exhibit asymmetries. We: (1) characterize the prevalence of unusual network events such as out-of-order delivery and replication; (2) discuss a robust receiver-based algorithm for estimating bottleneck bandwidth that addresses deficiencies discovered in techniques based on packet pair; (3) investigate patterns of loss, finding that loss events are not well modeled as independent and, furthermore, that the distribution of the duration of loss events exhibits infinite variance; and (4) analyze variations in transit delays as indicators of congestion periods, finding that congestion periods also span a wide range of time scales.