>> What I would like to do, is to take the subnet
>> 2001:470:1f01:409:0:f00d:3:0/112 and route it [...]

I can't help with that; I've never used gif as far as I can recall.

But itojun writes that

> with IPv6 subnet mask is ALWAYS /64.

This..."turns out not to be the case".  I'm using a /96 on my house LAN
right now, and a /127 on my link to my provider, and both work fine.
(gif may or may not assume (or require) a /64 netmask; I don't know -
though I would certainly treat it as a bug if it does.  But itojun's
blanket statement that IPv6 subnet masks are "ALWAYS /64" is simply
false.)

> please avoid using something like /112 (if you have multiple subnet
> in your home, you should ask hurricane /48 block).

Must be nice to live in an ideal world, where you can decree that
everyone does things the way you think they ought to be done.

Some of us don't have that luxury.

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