Så här skriver Apple:
"The base station that connects to your Internet service provider is the main base station. A remote base station connects wirelessly to the main station and extends (or "rebroadcasts") the wireless network to clients that are not in range of the main. A relay base station is like a remote, but it has the additional function of extending the wireless network to a remote which isn't within range of the main. There can be only one relay between a remote and a main.
AirPort Express and all AirPort Extreme base stations can use WDS. Earlier AirPort base stations can't."
A WDS network with one main, two remotes, a relay, and an AirTunes stream might look like this:
http://docs.info.apple.com/article.html?artnum=107454
Detta kräver dock att din andra basstation kan agera "master" och den kanske inte har WDS möjligheter?