An access network is built using Ethernet or IEEE 802.3 technology. The network comprises a plurality of terminals, a hierarchy of concentrator stages and a DHCP server. On startup of the terminals, DHCP discover messages are sent to the server which include the terminals' MAC addresses. These addresses are cached at the concentrators against the ports on which they are received. Thus unknown MAC addresses are only sent upstream. To avoid the network being flooded with broadcast messages any time a client PC uses ARP to find the MAC address of any other client, the central server provides a proxy ARP function.
