[TriLUG] linux routing example

[Mike Mueller]

On Wednesday 29 October 2003 12:48, Jason Tower wrote:
> On Wednesday 29 October 2003 12:26, Mike Mueller wrote:
> > On Wednesday 29 October 2003 12:05, Jason Tower wrote:
> > > the catch was,
> > > they wanted to have zero downtime when they made the DNS changes so
> > > the web server had to function properly on both T1s simultaneously
> > > (the two T1s were from different ISPs and had totally different
> > > subnets).  this is harder than it seems at first glance; in order
> > > for this to function you have to make sure that traffic "leaves" on
> > > the same interface it arrived on, regardless of which route is
> > > preferred.
> >
> > I stumbled on the zero downtime and iso-interface enter/exit
> > requirements; if one of the T1 interfaces goes down, what happens to
> > responses to queries that entered on the downed interface?  are they
> > abandoned or rerouted to the other interface?
>
> even if they were re-routed thru the still active interface, it would
> probably break the tcp connection since the host at the other end would
> see a different source IP.  however, this is only conjecture since i
> have not tried it.

Tartar Sauce!  This setup is for ISP transition and not high-availability.  
This setup makes perfect sense for ISP transition.  I was going in the HA 
direction with my questions. (just found this: http://linux-ha.org/failover/) 
-- 
Mike Mueller
324881 (08/20/2003)
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