What happens under Windows (XP Pro SP3, specifically) when you have multiple network interfaces configured on the same subnet, like when your ethernet is plugged in and your WiFi is active at the same time?

My company is refreshing everyone's laptop and once I got to the last few, I started to get complaints about Dell's network profile switcher utility. Turns out that while it works fine in the office, as soon as you actually try to switch to a different profile it completely wigs out. Long story short: Dell support's only (and first, honestly) solution was to disable the switcher.

But now that it's gone, I'm worried that people are going to be working at their desks and unintentionally using their WiFi connection. It's connected to the same network, and there's WPA2-Enterprise involved, so I'm not too worried about security, just performance.

Will Windows prefer the faster connection? I don't think it does. Is there some way to get it to prefer one? Is there a generic utility that will do this? (That's gratis. I have zero budget for this.)

In general, how does everyone else handle this situation?


Connections have metrics that influence their preference, the lower -- the better. Windows will probably assign correct metrics automatically. See KB299540. When both connections are active verify the assignment with

    route print

You can assign metrics manually if needed. See also KB894564.

  • Well that makes sense. I guess I could manually tweak the metrics if needed, not that that's exactly a tidy solution. (I always assume that Windows does things wrong to the point that I never look in obvious places. I really need to cut that out.) – wfaulk Sep 23 '09 at 22:46
  • This is exactly what XP does on my laptop. I have a 10/100 onboard NIC, and an 802.11b/g wireless card. The 10/100 gets a default metric of 20, and the WiFi gets 25, so if both are connected, the 10/100 interface is preferred. – James Sneeringer Sep 24 '09 at 1:25

If connected to a replicator, the wireless network adapter could be disabled for the docked profile, using the system control panel > device manager.

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