[This blog post was resurrected from cache from my original T2R2 blog (cameronfuller.spaces.live.com) as it still has value but is no longer available on the Internet outside of searching through older cache sites]
A while back I needed to do some testing with two domain controllers which were connected via a router (testing multiple Active Directory sites and replication). I was trying to come up with a way that I could effectively test this in my VirtualPC environment and was kinda stumped due to the amount of memory on my Host system. As I was running multiple Virtuals (generally 3-4 at a time on a system with two gigs of memory), I didn’t have much memory left to run a full Windows XP system to emulate a router. I decided to do a test if I could create a low-memory-cost Virtual Router in Windows 98. With thanks to google and some luck I ran across the following article which discusses how to route in Windows 98:
I configured my “router” with two network adapters (both set to “local only” within Virtual PC) and hard-coded both networks (10.0.10.x and 10.0.11.x) as the .1 address. So my “router” has IP addresses 10.0.10.1 and 10.0.11.1. I made the required alteration to the EnableRouting string and set it to “1” within HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\MSTCP using regedit. Finally, after verifying that I could ping systems on both networks (10.0.10.x and 10.0.11.x) from the router I set the default gateway on both networks to their corresponding router address (for the 10.0.10.x network their gateway is 10.0.10.1 and for the 10.0.11.x network their gateway is 10.0.11.1). I was able to install a domain controller in the “remote” network and could simulate the failure of the loss of the router by just pausing the router virtual.
My current “router” is running on 12 mb of memory (with video and code cache it is using a total of 25 mb). Don’t try to run it with less than 11 mb of memory / for some reason (probably unsupported levels of memory) it won’t boot into Windows 98. Not a bad memory footprint to provide a router in your virtuals, and it boots and shuts down in Virtual PC like lightening. Also, the VPC itself is less than a full cd-rom in size so it’s easy to transfer around.
Quick production reminder here. This is an isolated environment without Internet connectivity. Windows 98 isn’t a supported environment any longer and can easily be compromised, so this is NOT recommended for any environment where it isn’t completely isolated from the Internet/other production systems.