Load Balancing Firewalls

[Nathaniel Hall]

I am looking to load balance two or three linux servers running
iptables.  Each of these firewalls will separate another network segment
and will perform load balancing to the servers behind them.  My biggest
problem with this setup is the possibility of the firewall going down,
causing the entire system to stop.  Does anybody have a good idea for
this?  Here is an idea of how I would like to make the system:

Internet
    |
    |
 FW1                   |--Server1
    |--------FW2--|--Server2
    |--------FW3--|--Server3
    |--------FW4--|--Server4
                            |--Server5

I want to be able to use each firewall to load balance between
Server1-5, but I also want to be able to load balance between FW2-4. 
Any ideas?

--
Nathaniel Hall, GSEC