Over the years, different techniques have been proposed to detect bottleneck bandwidth and available bandwidth of an end-to-end path. However, to the author's knowledge, no work has been conducted on detecting which link or node on the path could be the narrow link. In this paper, we present a novel technique based on packet pairs dispersion analysis, whose objective is twofold: first, it allows to estimate the narrow link capacity using a new approach which takes into account both inter-packet time and packet propagation delay. Its second objective is to induce the specific hop in the end-to-end path which represents the narrow link. This is achieved by injecting packets trains with intermediate TTL-expiring packets which decrease the train rate when they cross the narrow link (red-shift effect). We validate our approach in simulations showing the tool robustness in very complex scenarios.