Measuring IP and TCP behavior on edge nodes

Tstat is a new tool for the collection and statistical analysis of TCP/IP traffic, able to infer TCP connection status from traces. Discussing its use, we present some of the performance figures that can be obtained and the insight that such figures can give on TCP/IP protocols and the Internet. While standard performance measure, such as flow dimensions, traffic distribution, etc., remain at the base of traffic evaluation, more sophisticated indices, like the out-of-order probability and gap dimension in TCP connections, obtained through data correlation between the incoming and outgoing traffic, give reliable estimates of the network performance also from the user perspective. Several of these indices are discussed on traffic measures performed for more than 2 months on the access link of our institution.