AirPort-equipped computers connected to two or more different AirPort Base Stations can communicate with each other when the base stations are joined by a wired Ethernet network. Each base station may offer its own wireless network to clients, or the base stations may be set up for "active roaming," a configuration in which two or more base stations appear as one wireless network to client computers.
Note: Though an AirPort Base Station communicates wirelessly with AirPort-equipped computers, it cannot do so with other base stations. This means you must have Ethernet to connect LAN users across multiple base stations.
Active roaming and its advantages
Active roaming allows computers on one AirPort network to move throughout a coverage area greater than the 50 m radius provided by a single base station. An AirPort user with an iBook, for example, can log on to the network once then move into the coverage area of a different base station without having to log on again. By placing base stations strategically, you may also work around obstructions such as structural concrete or steel.
Setting up active roaming
To use active roaming, you must have AirPort 1.1 or later software. You may download AirPort 1.3 from Apple Software Updates (
http://www.apple.com/swupdates/). These steps are performed using the AirPort Admin Utility.
1. Connect all the AirPort Base Stations to the same subnet on your Ethernet network.
2. Give the same network name and password to each base station.
3. Be sure that all base stations have the checkbox for "Enable AirPort to Ethernet bridging" checked.
Setting up DHCP with active roaming (optional)
These steps are performed using the Network pane of the AirPort Admin Utility.
1. Set one base station to act as a DHCP server by clicking the checkbox to "Distribute IP addresses."
2. For the same base station, click the radio button to "Share a range of IP addresses (using only DHCP)." In the corresponding fields, add a range of real IP addresses for client computers.
Important: You should not use network address translation (NAT) with active roaming. Client computers on an active roaming network should receive real IP addresses via DHCP or manually.
3. Be sure that all base stations have the checkbox for "Enable AirPort to Ethernet bridging" checked.
4. Be sure that all base stations other than the one selected as DHCP server are acting as bridges only and do not have the checkbox checked for "Distribute IP addresses."
Learning more
AirPort 1.3 introduces new features including Base Station Density and Multicast Rate. For information on these and other considerations of setting up a network with multiple base stations, please see the document "Designing AirPort Networks." This document may have been installed on your computer by the AirPort Installer. It is also found at Apple Software Updates (
http://www.apple.com/swupdates/).
Note: Wireless Internet access requires an AirPort Card, AirPort Base Station, and an Internet service provider, for which fees may apply. Some ISPs are not compatible with AirPort. For more information, see technical document 106590: "
AirPort: Requirements for Wireless Internet Access."