Abstract: A method for testing a communication network includes transmitting at least one unidirectional flow over a path through the network, and measuring arrival characteristics of the least one unidirectional flow at a receiving end of the path. The arrival characteristics include at least one of a packet throughput characteristic, a packet delay characteristic, a packet loss characteristic, a packet jitter characteristic and a packet misordering characteristic. A bidirectional flow is transmitted over the path from both ends of the path simultaneously, and the arrival characteristics of the bidirectional flow are measured at least at one of the ends. The arrival characteristics of the unidirectional and bidirectional flows are compared in order to detect a fault in the path.