Due to bandwidth constraint and dynamic topology of mobile ad hoc networks, supporting Quality of Service is a challenging task. In this paper we present a solution for QoS routing based on an extension of the AODV reactive routing protocol that deals with bandwidth monitoring. The solution uses an IEEE 802.11 MAC layer as the underlying technology and the QoS routing decision is based on simple but accurate measurements, at the MAC layer, of the available bandwidth on each link of the route. In addition, to allow a QoS loss recovery, a notification mechanism is used to inform the source about bandwidth degradation on a link. This reactive solution using standard protocols is adapted to small and dynamic ad hoc networks. A complete simulation set shows that, with the proposed QoS routing protocol, bandwidth on a route is significantly improved without overhead.