On-line estimating skew in one-way delay measurement

Delay metrics of Internet play an important role in evaluating the network performance. They are also the foundation for other metrics measuring, such as bandwidth, jitter and loss. One-way delay (OWD) measurement has been getting much attention in recent years. IP Performance Metrics Working Group of IETF has made great efforts on one-way related metrics measurement and brought several RFCs[G. Almes et al., (1999), R. Koodli et al., (2001)]. A key issue for one-way related metrics measurement is the clock skew, especially in the situation of without external clock synchronization mechanism. Many researches have been done on removing clock skew in OWD. A real time skew estimation algorithm named RTSE is proposed to estimate the online skew. We prove that it is not only as efficient as other static algorithms but also could provide an online insight view of the OWD dynamics of monitored networks with a month experiments on an operating network. RTSE has been integrated into our OWD measurement tool capOWD.