Redundant network router setup?

[Chuck Swiger]

On Aug 13, 2007, at 4:59 PM, Modulok wrote:
> QUESTION: Is there a way to setup a redundant router, such that I can
> offload traffic from the primary router to another machine, without
> breaking TCP sessions?

There are several ways of setting up such redundancy; the common case  
which Cisco calls VRRP, you can use under FreeBSD as CARP.  However,  
this approach is limited to pure routing; it does not handle  
replicating the NAT state tables:

> BACKGROUND: I have a FreeBSD machine acting as a gateway, running
> natd(8) through ipfw(8).

...which you mention you are using.  I don't know of any way to  
provide redundancy for existing connections going via natd.

-- 
-Chuck