Load Balancing Design Question

The LTM does route, actually. You need to setup ip forwarding virtuals to accomplish this. You can do it globally by entering a forwarding virtual with 0.0.0.0/0 applied to all vlans, which will allow all packets to route (assuming the necessary routes are in the routing table). If you want to be more granular, you can apply 0.0.0.0/0 to your private DMZ network only and match it with a default route to your PIX, then setup network-specific forwarding virtuals to your internal networks and apply these where appropriate (the forwarding virtuals should be applied to the vlans where the traffic is coming from, not where it is going) Post back if you have any questions.