How do programs "decide" which network adapter to use?

3

In Windows, how do programs "decide" which network adapter/connection to use?

I have dual ethernet ports on my motherboard. I usually only have one enabled, but recently, I've wanted to enable the second adapter and dedicate its use entirely to a local VMware virtual machine. I'm able to set VMware Workstation to bridge solely to the second ethernet adapter. However, now that I've enabled the second adapter, the rest of my computer is now defaulting all network traffic through it, instead of the other adapter.

I'm guessing this is Windows' "choice", as multiple browsers now have their traffic channeling through this newly enabled adapter.

How is it decided what network adapter for programs to use? And how can I force the channeling of programs' network data through one adapter over the other?

Coldblackice

Posted 2013-06-03T21:00:03.450

Reputation: 4 774

Answers

3

It might have to do with your Network Adapter order, this is a list that windows uses to determine what network card to use if more then one is available. once you get to the list it's easy to change the order of the items. and windows will always use the closest to the top of the list that is able to respond to the requests, it only moves down from the first one if it's not able to get the information requested.
to Get to this list you do: Control Panel > Network and Internet > Network and Sharing Center > Change Adapter Settings then once your in there, you hit "Alt+N" and select "Advanced Settings" in the first table you'll see a "connections" and a "bindings" the first one is the list your looking for, all you gotta do is figure out what card in the list is the one you want windows to use and move it to the top of the list, and hit okay. sometimes you will also have to reset your network connection on both that card and the one it's currently using, (or reboot the computer,) to get it to flip over; but once it it will now use the correct network card as long as it remains useable.

Kit Ramos

Posted 2013-06-03T21:00:03.450

Reputation: 246

Thanks. I've tried using this before, but it still seems like it doesn't "hold". I saw someone suggest somewhere that there's actually a "deeper", more intricate system of "metrics" involved, and that to really be sure of using a specific adapter, one must manually spread the metrics out between the two. Is this so? – Coldblackice – 2013-10-22T20:34:30.693

well I know on the server version of windows there is a network card metrics option, so it's possible they still could have it as a group policy option on the desktop version. – Kit Ramos – 2013-10-28T15:51:39.730