Method and test device for performing testing in a network conveying a plurality of traffic flows. At the test device, receiving traffic flows through a first interface of the test device on a first segment and forwarding the received plurality of traffic flows towards a second segment of the network through a second interface. At the test device, receiving a test request directed to an address of a test module and, in response to the test request, causing a sequence of proprietary traffic to be injected on the second segment. A reprogrammable test device comprising a networked test module at least in part on a reprogrammable partition of a programmable logic device and a reprogramming module, on a static partition of the programmable logic device, for reprogramming at least a portion of the reprogrammable partition implementing the test module in accordance with reprogramming data received at the test device.