Windows 2000 AS routing question

[Mucman]

We got a new ethernet access client yesterday and he could not get past his gateway... I double checked the router config and it was all good and so was
the VLAN info... I setup my machine on their switchport and confirmed that the connection works! He on the other hand could not ping anything outside the gateway we assigned to them... After going over his settings over the phone I could not figure it out so I payed them a visit to see what was going on... Here is what it was :

They had 2 NICs in the machine. The public nic was configured fine. The other nic was configured with a private IP and also had a default gateway setup (a private IP). I did a ROUTE PRINT and I see two routes for 0.0.0.0, one going to the public gateway and the other going to the private. When I would try to ping an outside IP it would always route it to the private gateway (which did not exist , btw)... how come Windows never tried to send it to the public gateway? It worked once I removed the gateway settings on the private interface.

 

[Mucman]

hmm bump?

 

[mobly99]

Win2K/NT does not deal too well with multihomed computers with multiple default routes of the same cost. What you will usually find is that the NIC that initializes first will be the one who's default route is used. Win2K does support dead gateway detection for TCP - which can lead to wacky things happening like a telnet session using the live gateway, yet a ping attempting to go through the dead gateway.
I beleive there have been some fixes with XP that improve this.

Long story short, life is best on a multihomed 2K computer with just one default route via one of the NICS. If you absolutely needed to support some kind of a more dynamic routing scenario 2K server will talk RIP 1 or 2 and even OSPF (again I say if you absolutely HAD TO).

In your case, this seems like just a user misconfiguration and the best thing to do to prevent it from happening again would be to go into the advanged TCP/IP settings on the second NIC that shouldn't have the default gateway and set its interface metric to 2 or higher, so that if they put in a default gateway again, it will always use the intended default gateway which has an interface metric of 1.

-Dave

 

[Mucman]

mobly99 - thanks for the info! This brings a question though... if we was to reverse the nics he had these settings on, it would have worked then? The settings would be exactly how they were before but because they would be on the opposite NICs the default gateway would have become the proper one?

Anyways, it was a good learning experience for me