The solution has been designed with cost being a major limitation so I only have two F5 Big-IP GTM and I don't have the scope for buying any additional equipment such as the LTM or the LinkContoller. From what I've read so far having the LinkController would help to monitor the lease line?
The web servers use Windows clustering (urgh I know, not my implementation).
I'm glad you mentioned the DNS nameservers because this is exactly how I assumed the devices should work but then read about the network based failover and wondered if that implied that the GTM had to be setup as a redundant pair.
Do you need to use both of the default VLANs? I was thinking of dumping the GTM in the DMZ, pointing the web servers default gateway at the GTM and in bound traffic to be routed to the GTM.
Cheers,
Dc.