freebsd 6.0 network card / route fail over question

[Matthew Lineen]

Hello,

I'm trying to workout the specifics of NIC/route fail over on FreeBSD 
6.0 and hoped someone here could point me in the right direction.

We have 2 ServerIron load balancers and each of our application servers 
is plugged into both LBs.

So, for example, an app server would have the following...

  bge0 IP of x.y.z.61 netmask 255.255.255.128
  bge1 IP of x.y.z.63 netmask 255.255.255.128

In /etc/rc.conf the default route is x.y.z.1

In the routing table, the default route uses Netif bge0.  So, when we 
turn off the first load balancer, bge0 goes down, but the default route 
never "moves" from bge0.

I assume this is because ...

#1 - FreeBSD doesn't like having two interfaces bound to the same 
x.y.z/25 network (we get plenty of the "arp: x.y.z.123 is on bge0 but 
got reply from ... on bge1" messages)

#2 - The default route is bound to bge0 because bge0 is the first 
interface that contains an IP in the same network as the default route's.

So, my question is: what approaches do people take to solve this 
problem?  I've come across  forwarding and carp, but I thought I'd ask 
the list to see if there is something simple I'm missing, other ways of 
handling this, etc...

Thanks,
Matthew