I've got a situation where I need to connect two switches, a 4507R (our core switch) to a 3560, using two devices which are functioning as transparent bridges, connected in parallel. The devices are actually content filters (they're Lightspeed Rocket appliances if that makes any difference), and we'd like to have one online as a standby unit in case the first one fails. The only other thing connected to the 3560 is two PIX firewalls (active/standby) which are in a vlan from the core network. The two switch are EIGRP neighbors.
I was hoping that spanning-tree would take care of selecting one device for production use and the other as a standby. When we tried it, there was no connectivity at all. It seemed like the switches were not agreeing on which device to use. Is there any way to maybe have the 4507R take care of the forwarding/blocking decisions and turn off spanning-tree on the 3560?