Here is a picture of my current setup. The primary AEBS Dual Band is in the basement along with the other AE's shown below it. I've noted the ones on the first and second floor. The G5 desktop has an airport card with the old antenna and it pretty much sucks for reception even though it's only 25' away on the same level.
These devices are all hooked up through a wireless network and all of the AE's except for the printer are newer AE "N". The AEBS Gen 1 N is the previous model to the dual band. Right now the performance is slow but it works. I can hardwire the primary AEBS dual band to the stereo AE and Playstation in the basement and the stereo AE and Apple TV on the first floor. But as you know there are limited ports on the AEBS. I'll put my flame suit on and let you have at it. Thanks.
Looking at your diagram makes my head explode, just thinking of the strain your primary AEBS is under!
The question is - which base stations do you want to hard-wire together in order to create your roaming network? I have 2 Time Capsules (AEBS)[original 802.11n/b/g - not dual-band] and 2 Airport Express devices. With them, I have set up a dual-band Wifi network:
AEBS 1) is 802.11n 5.0GHZ extended via ethernet (powerline adapter) and a
Roaming network to an Airport Express (AE).
AEBS 2) is 802.11 n/b/g extended wirelessly to the second AE.
Here is a diagram of my setup:
The AEBS on the lower left, called "STUDY n/b/g" is the primary device, connected to the Modem.
What I am thinking, is that you have the newer dual-band AEBS in the basement as your primary unit, and the older AEBS hard-wired to that (with the powerline adapters) on the 1st floor. There is one really BIG "but" to this setup. The 2 powerline adapters (the first being plugged into the primary, the 2nd into the unit upstairs), HAVE to be on the same electrical circuit, otherwise this setup is NOT possible. This can be the situation in some older houses with multiple electrical circuits. You can see this the first time you plug the powerline adapters into their electrical outlets. If the indicator lights show red, you are out of luck, and means they are on different circuits. The color green depicts the optimum connection between the 2 units for the best data transfer between them. An amber light is still okay, but not the best. I found I had to try several outlets for the secondary adapter before it gave me the "green light".
You would then have the choice of extending both of these networks, the "n" and the "b/g" (or "n/b/g") yet again via the roaming setup to the AE's, or wirelessly. Obviously if you do not want to suffer bandwidth degradation, you would not select the latter. I am not sure of the exact number of devices you can use in a roaming network, but I would see 3 units is a very safe bet.
Hope what I am saying is clear....if not fire away, and I'll also don my Flame Suite.
NOTE: if you elect to do the above with your newer, dual-band AEBS, make sure to give each network a different name (SSID). So say for example, the 802.11n 5.0GHz SSID is "Speedy n", and the 2.4GHz is called "Crawler n/b/g" -on the older AEBS (upstairs), extending the "n" network, you would have the identical setup, same network name - "Speedy n", same password, security, BUT you would set them on DIFFERENT channels. See pic below:
edit: open each of the above attachments on a separate page, that way the detail will be clear.
