Thanks to the tremendous advances in wireless network and mobile ad hoc network new applications are now possible: inter vehicle communication, telemedicine etc. However many problems such as quality of service and security are still unsolved. Our work is focused on the implementation of a MANET bandwidth estimator enables to improve routing protocol and by the way the quality of service. In fact, two types of techniques exist to estimate network bandwidth: invasive and non invasive. In this paper, we present a non-invasive technique based on Round Trip Time or One-Way Trip Time. The performance of our estimator will be presented and discussed.