Everything blocks after a setup. FreeBSD issue.

[karlbrose]

actually, in order to multihome between two providers that operate their own networks you need to use BGP.

OSPF or RIP would only really work well for redundant connections to the same network.

No, you don't want or need to run BGP. Rubbish.
For BGP you need to establish your own AS and even then the providers of these tunnels aren't going to peer with you and accept your routes which they already aggregate.  Your network is not really multi-homed by the most common definition, in fact, you just have two leaf networks with different prefixes overlaid on (perhaps) the same Ethernet. Sending the wrong source prefix up the wrong provider channel will not be favorably viewed by the providers.
Of course nothing keeps you from running private BGP for your own pleasure, but it's not for your upstream routing.

[testmonster]

Setting up two tunnels to two different tunnel brokers isn't multihoming if you aren't running BGP.

Sending packets from one providers IPv6 address range out a different provider is generally frowned on, and likely to be filtered.

If you have your own ASN and your own IPv6 address space and you get two transit providers (even if via tunnels) you can multihome.

Admittedly, BGP is more complex than most companies or individuals can justify.

The original question at the start of this thread is from somebody trying to get redundancy via tunnels to two different providers, the answer is it aint going to happen correctly without BGP, all other methods are ugly hacks.