A network device with integrated topology discovery functions adapted to virtual local area networks (VLANs). VLAN segments are mapped on a network system formed from multiple network devices. One network device creates and broadcasts a query packet for topology discovery in each VLAN, in response to a command from a management console linked to that network device. At each receiving network device, a query packet receiver receives the query packet, and a reply packet is produced by a reply packet generator. A reply packet transmitter sends the produced reply packet back to the requesting network device. A query packet transmitter forwards the received query packet to neighboring subordinate network devices.