gateway failover.

[spam () eek org]

i've a situation where the network we're building is 
very low-traffic, but requires maximum uptime. the 
budget is for all components to be duplicated to
allow for failover. 

i've figured out various ways to do load-balancing and 
failover at the router/nat level, and at L2, but have run 
into a bit of a problem figuring how to use two solaris 
boxes (firewalls) as gateways for all servers/clients 
behind them in some kind of HA/failover configuration. 

i'd like to minimize the client/server side configuration 
as much as possible (and the environment may include 
NT, Macs, or other such ilk which will not easily supporting 
a useful routing protocol), so something like installing gated 
on all of the boxes, and implementing an ospf environment
is an unsavory proposition. 

i'd like something like HSRP, but for solaris/unix, and preferably
free.

i'm aware of several vendor HA solutions, but they are mostly 
overkill for our application. i've looked into IRDP (rfc1256), 
but i cant find any information about vendor support.

any pointers to relevant info would be appreciated, including
any general resources for HA/network redundancy/failover stuff
(preferably non-commercial). 

-foo