VLANs onto existing subnets
I'm trying to build a seperate VLAN for our wireless system so we can add a guest vlan. Now the problem is we have a network system that is not best designed for this. Basically we have a large network with switch cabinets across the school, all the cabinets meet at one central cabinet in the server room where there are plugged into a L3 switch. On that switch each port is configured as a seperate subnet (192 ranges ) and routing is configured between them all. This was originally done so we could easily switch from the LEA's IP addressing to our own private ranges and effectively only had to change the firewall.
This all works fine, 9 seperate subnets with 100's device on each all communicating happily. Each cabinet (effectively we have 'geographic' subnets) is is connected to the main one via fibre.
The issue comes now with ruckus - we have AP's all over the school, all ultimately connected to local switches with the zone director in the main cabinet. Again this works fine but the problem is if I now want to add a guest WLAN to the APs using a seperate VLAN I can't see how to do it! If I assign a vlan to the AP's then they are plugged in the local switch which has no vlans assigned. If I assign a vlan to the main network (i.e VLAN 1) and add a new one to the AP's switch port then they effectively have 2 vlans on the same port - which will defeat the purpose of seperating the network - plus at the core switch each subnet will be carrying traffic for 2 vlans and I then need to route the WLAN guest VLAN off to a smoothwall box for internet access.
Basically what I'm asking (badly!) is how do you deal with adding a WLAN with that is tagged with a VLAN to an existing system with no VLANs? Is this even going to be possible as the AP's are used on our main network so they also need to be accessible for the 'proper' networked devices.