Use wifi and ethernet simultaneously?

Question

I have an ethernet connection that is very fast but imposes severe speed restrictions after 4gb of usage in a day. There is also a wifi connection that is slightly slower, but with no limit, so its much faster than the ethernet after the limit.

By default, how does Mac OS X (Lion) choose between two available networks for sending traffic? (Windows is addressed here: https://superuser.com/a/390048/23318)

If an app is connecting through wifi, and I switch off wifi mid-download, can it automatically switch to using the ethernet connection? Is there any app that can act as a proxy for both interfaces, so that applications only deal with one connection, and then the app can choose between wifi and wired depending on which connection is available and faster.

Alternatively, how do I go about configuring multihoming given that I can't change the network settings on the router side, just on my machine. Also, how would the multihoming be extended to apply to a Windows 8 VM running on top of OS X?

Answer 1

Take a look in System Preferences → Network → Gear (next to +-) → Set service order.

Answer 2

I know this has been around a while, but you should take a look at what the team at Connectify is doing with Connectify Switchboard (http://www.connectify.me/switchboard).