I've added two airport extreme 802.11n base stations to my WDS network. Mostly this was straightforward. The basic procedure is just as described earlier for the previous Airport models. The UI of the new Airport Utility app is clearer than the previous version.
However, I found the two Airport Extreme base stations got confused when I used DHCP to link them into the network. Instead, I've given them manually assigned IP addresses - in the same 10.0.0.xxx range as I use for DHCP. My Alcatel Speedtouch DSL modem acts as a DHCP server, and I've set it to distribute addresses above 10.0.0.16 — which leaves me plenty of addresses below this to allocate manually.
The network is now something like this (with some base stations running the full range of protocols, 802.11b,g,n, and othersonly one of these, as shown):
airport(b) express(g) = speakers \ / disk = extreme(b,g,n) - airport(g) - express(g) / \ = extreme(b,g,n) = printer express(g) = speakers | router | = airport(b,g)
Here, "airport" means an old conical airport extreme; express is the small block airtunes gizmo; extreme is the new 802.11n-capable mini-sized device.
To insert a new base station into my existing network, I first set its MAC address (aka airport ID) as the WDS main value for each of its children; then I configured the new base station with the children's MAC addresses in the WDS remotes list.
To configure the new devices I found it easiest to switch off the other base stations, and connect wirelessly to the new device. If you click on the name of a setting shown under the Summary tab, you are taken directly to the tab where you can edit the value. You want Wireless Mode: Participate in a WDS network. You should also set the Channel: and Network Name: to match the other base stations. Then you can set IP Address:. (As described above, DHCP confuses my two new Express base stations, so I set Configure IPv4: Manually. You can find the subnet mask and router address from the configuration of another base station. You may want to try Configure IPv4: Use DHCP first, as this is simpler.) For WDS relay and remotes you want Connection Sharing: Off (Bridge Mode). This is also correct for the WDS root if your modem acts as a DHCP server; otherwise you may need the WDS root to act as DHCP server (Distribute a range of IP addresses).