Multihoming Windows XP Pro (XP Pro, SP1)

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We are trying to set up a videoconferencing solution for few of our workers but the videoconferencing is being blocked by our firewall (Even though it has dynamic NAT, it still doesn’t work and Watchguard company has claimed that it is a “bug” and a workaround would arrive sometime later). Since we can’t videoconference through our firewall, we have set up a hub to connect to “Optional” port which will allow computers to videoconference through. However, this solution requires that the computer that is to be used as a videoconferencing station to have a static “public IP” address which does not allow the station to access Email and other resources on the LAN because the computer is now considered “outside” of our LAN and gets blocked by our firewall. We managed to create routing information so that those computers could access LAN resources based on the IP addy but this solution isn’t working too well (Exchange, Network Places and intranet either is very slow or doesn’t run at all).

I had an idea of using multihoming (Setting up one NIC to connect to internal LAN resources and one connected to Optional port on our firewall, setting up a static IP addy) and in perfect world, Windows XP would automatically use internal NIC to access internal LAN resources and whenever we needed to use videoconferencing or use Web, XP would automatically switch to NIC that is connected to Optional port.

Unfortunately, XP seems to prefer to use the NIC that is hooked up to our Optional Port for everything and completely ignoring the NIC that accesses internal LAN. I am pretty new to multihoming, is there something I missed? Some kind of setting that I can change so that XP would know that everything must go through the NIC that is hooked up to our LAN and switch to external NIC ONLY for Web and videoconferencing?

Thanks in advance.

Brent

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Check configuration of the NIC connected to “optional port” – remove all unnecessary items (clients, file sharing, unused protocols), make sure that TCP/IP protocol settings have all IP addresses right.

If it not the case and you use videoconferencing not too often, consider to create two different hardware profiles with different NICs enabled – in that case you will need to reboot the computer to change Videoconference configuration to regular Workstation configuration and vice versa.

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Doing what you suggested didn’t work…but I figured out another way that seems to work. I’m posting for future reference, so others might be able to use the solution as well.

I added persistent routes in the routing table for the workstation, I specifically told the route table to use internal NIC whenever it needs to access specific servers (We have only 8 servers) which forced XP to use the internal NIC whenever it accesses those list of IP addresses.

The only drawback is that it wouldn’t work with servers with dynamic IP (I don’t think this is a common practice) or a company that has server farm because of the sheer amount of IP addresses to list in the route table.

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