One thing that has annoyed me for a while is that when I dock my laptop I lose all the current connections - so I have to close down Gnus and start it again, the same goes for jabber.el.
So this evening I looked for a solution, and found all kinds of suggestions about bonding, bridging, NAT, ebtables, arp routing and things.
It all looked... complicated. The recipe I tried... did not work.
Then I saw someone who wrote "Just assign both interfaces the same static IP address."
So I did. And it works.
If I am on wifi and plug in the cable, 5-10s later, the cabled network kicks in, and because I've set up metric on the interfaces for priority [I guess], the cable takes over. When I unplug the cable, it takes around 25-30s before the wifi takes over, but connections in Gnus and jabber.el "survive" unscathed.
This is great - \o/