How to set up dual wired and wireless connections?

Solution 1:

If you're using NetworkManager, it should just work. That said, you will need to set specific settings for your wired connection.

Select your wired connection in the Connection Editor window for NetworkManager (right click on the applet icon, then select Edit Connections). Click Edit, then switch to the IPv4 Settings tab and click the Routes button at the bottom.

You can then force the wired connection to not claim the default gateway (since NM would usually prefer wired over wireless), by checking the "Use this connection only for the resources on its network" checkbox.

Solution 2:

The issue here is more of the load-balancing between the wired and wireless connection. Usually, there is only one default route (0.0.0.0, netmask 0.0.0.0), in the routing table. If there is more than one, the first one will always be used, and so the second one will not be. On the router side, if the request comes from one IP address, it will be responded on the same IP address.

What you need is known as load-balancing. I do not know whether there is a package under Ubuntu for this. But such load-balancing and fault-tolerance setup is not meant for desktop. You may want to search for such packages, for Ubuntu/Debian, but it will more likely be for servers. This article:

http://www.informit.com/articles/article.aspx?p=1381888&seqNum=3

may put you on the right track.