DHCP and zeroconf?

[bluemoon]

Or, you can load-balance the two cards and use both for improved performance!

Not without supporting that at the other end as well; it's called bonding and requires you to set that up on both sides.

For simplest case of just "pick a interface for new connection" (with balance-rr or balance-xor), it does not require any setting on the other end, as if there were two computers.

[Candy]

For simplest case of just "pick a interface for new connection" (with balance-rr or balance-xor), it does not require any setting on the other end, as if there were two computers.

TIL. Still, it requires you to at least correctly guess that they go to the same internet. I don't think I want to guess that for a user so for now I'll postpone bonding.

[Combuster]

Well, loadbalancing or failovers on the client's end is already advantageous if you mix for instance a wifi and a wired connection. Wired is of course generally better, but if you have one of those cheap-@$$ routers your link goes down once in a while after which you want to use the packet loss as an indicator for switching networks.

Of course, if you can't detect the presence of a plugged-in cable, the situation is even easier to create,

[FallenAvatar]

...

Yeah... I'm trying to get it working well for logical setups and not fail too badly for bad setups.

This doesn't account for the gateway / dns part of it. What happens if you have two DNS servers and two gateways for "other" traffic? That pretty much implies that the "subnet" is identical; both claim to map the entire internet, so every two cards would boil down to #3.

...

Just pick a default card for "internet" access. And that in no way implies the subnets are identical, subnets are used to describe what is "intranet" vs "internet". You could have one card whose subnet is 192.168.0.0, and another that is 10.0.0.0.

Likely, only one of those cards will actually have internet access. You could pick a default randomly, try to hit something on the internet, wait, and if it fails change the default to the other card.

- Monk