Abstract: Provided are methods of estimating an available bandwidth and a delay in a multi-channel multi-interface based wireless ad-hoc network, and a method of relaying a route request message using the methods. The method of relaying a route request message includes (a) receiving a first route request message including information on a required bandwidth, (b) determining whether or not a condition that a link from a node transmitting the first route request message to the intermediate node and a link from the intermediate node to one of one or more neighboring nodes both have an available bandwidth equal to or larger than the required bandwidth, is satisfied, and (c) when it is determined that the condition is satisfied, broadcasting a second route request message including the information on the required bandwidth. According to the methods, it is possible to efficiently configure a route guaranteeing Quality of Service (QoS) required for a call.