Abstract: A network traffic device comprising: at least one network device adapted to receive network data packets; wherein said at least one network device filters network data packets to locate at least one identifying packet, and samples said network data packets to select at least one sample packet. The at least one network device may transfer said at least one identifying packet and said at least one sample packet to an analyser. A predetermined sample rate may determine the number of sample packets selected by said at least one network device.