A computer network including: at least one switch connecting at least one edge device to the remainder of the network, said at least one switch including: snooping apparatus using DHCP to monitor the signal traffic through the switch to or from the each edge device to determine, without changing the traffic signals, for each edge device, the MAC address, the IP address, and the port of the switch to which it is connected, and a dynamic table within said switch of, for each edge device, the MAC address, the IP address, and the port which it is connected, the contents of the table being provided by said snooping apparatus.