New methods for passive estimation of TCP round-trip times

Abstract

We propose two methods to passively measure and monitor changes in round-trip times (RTTs) throughout the lifetime of a TCP connection. Our first method associates data segments with the acknowledgments (ACKs) that trigger them by leveraging the TCP timestamp option. Our second method infers TCP RTT by observing the repeating patterns of segment clusters where the pattern is caused by TCP self-clocking. We evaluate the two methods using both emulated and real Internet tests. © Springer-Verlag Berlin Heidelberg 2005.