Dynamic VLAN - limiting switchs VLANs?

[Robert]

Hello all,

I currently have FR running and happily doing MAC authentication against
a MYSQL DB. 

I can plug a computer into the switch, have the switch grab the MAC
addy, pass it to FR, hit the DB and return what VLAN that MAC belongs
to, and then have the switch configure to port to the correct VLAN.

Now the complication that I'm facing is that in our environment, a MAC
might be assigned to multiple VLANs and our switches only have a
fraction of the total number VLANs trunked to them.

What I need is a way FR can not only match the MAC to a VLAN, but also
to cross reference that result to the VLANs that are available from the
requesting switch. 

Anyone know how to do this? Or at least a good place that I can start?

I'll admit that I'm very noob-ish about all this and it's is my first
time trying to setup FR so I apologize if this is a really simple or
conversely an impossible task. I just can not get Google to give me any
love on this. 

Thanks,
Rob