The available bandwidth measurement is important for many Internet applications, such as network behavior analysis, quality of service (QoS) verification, and so on. Existing available bandwidth measurement toolsmainly measure the available bandwidth for a whole network path, and provide information about the tight link(s)other than vital links. Therefore, this paper presents a novel algorithm called LinkPPQ (trains of pairs of packet-quartets used to measure available bandwidth of arbitrary links), which uses trains of pairs of packet-quartets to measure the available bandwidth of any link along the path, and track the variety of the cross-traffic on it. This paper studies the performance of LinkPPQ in both simulation circumstances and the laboratorial network.Simulation results show that LinkPPQ can accurately measure the available bandwidth of each link on the paths thathave one narrow link or multiple narrow links, under different cross-traffic loads. Most measurement errors are under 30%, and the results are stable. The laboratorial experimental results show that LinkPPQ can accuratelymeasure the available bandwidth in the following situations: a) measuring a link with capacity 100Mbps from a link with capacity 10Mbps; b) monitoring the link with capacity that is ten times of the narrow link next to it on the path;c) estimating the available bandwidth of the narrow links on a path having multiple narrow links.