In packet-switching networks, many performance characteristics can be estimated by sending probe packets. In this paper, we discuss the end-to-end packet delay and the bandwidth of the links in the network path. There are dierent techniques to estimate these performance parameters. Nevertheless they do not always give accurate results, only work well under limited conditions and have disadvantages, for example, some of them have to send massive amount of data across the network and some of them are not based on wellunderstood properties. We summarize these limitations and disadvantages based on several research works [Pax98, Don99, LB99]... In this paper the relative oset is taken into account because there is a close relation between relative oset and end-to-end delay. We develop a rened algorithm to estimate relative clock oset for the case of asymmetric links. We propose partial methods to measure bandwidth and relative oset. In this paper new necessary services are..