On Tue, 24 Jun 2008 12:18:01 -0700, Anthony
<Anthony@discussions.microsoft.com> wrote:

>route -p add 192.168.1.0 mask 255.255.255.0 192.168.1.253 metric 1
>route -p add 192.168.1.0 mask 255.255.0.0 192.168.1.254 metric 10

I tested something similar myself recently except my test involved two
default gateways out to the Intenet. The primary with a manual metric
of 1 and the secondary with a manual metric of 20.

Although I left the primary router powered up, I zapped the dsl
synchronisation effectively killing the gateway.

>
>The data is very time-sensitive, so I cannot have much failover latency. If
>my primary route (through .253) goes down,
>
>A) How long will it take to fail over to the backup?

Only a few seconds.

>
>B) Will XP then ignore the primary route and consider the backup as the
>primary, or will XP keep checking to see if the primary is up every so often
>(how often)?

I can't say exactly how often but in my test the default gateway
automatically switched back to using the one with the lower metric
every few minutes even though it was still dead and swapped again back
to the secondary gateway on detecting it was still dead.

So it appears that it follows the same procedure each time and polls
the primary gateway for a response every few minutes.

>
>C) If my primary goes back up again, will traffic then shift back to it?

My suspicion is that it will happen after the next poll whenever it is
due. I don't know if this polling period is settable in the registry
somewhere.

Overall I would say that it was an annoyance for me getting the
occasional waits for switching between gateways. It certainly wasn't
transparent. I could tell something wasn't quite right but it could be
a lot more serious for you and you may have to look for a better
solution.


Jim.