That's not a very good example.
1) I can count on one hand the number of times my Internet connection has gone down in the past 5 years.
2) I can count on zero hands the number of times I've tried to print from a phone, ever.
1) I can count on one hand the number of times my Internet connection has gone down in the past 5 years.
2) I can count on zero hands the number of times I've tried to print from a phone, ever.
But you want a more complex challenge? Here you go!
You have a small business office that has two Internet uplinks for redundancy. You want to balance the load across them and failover broken links.
This can be done with literally zero setup with IPv4.
Good times!
When v6 was “invented” I believe they thought “everyone” would have PI addresses, as was (relatively) common 30 years ago.
If everyone has their own PI space, and used BGP with their ISPs this would also be “zero setup” with v6 as that’s the entire point of BGP and PI addresses.
It was a definite failure of imagination that they did not think of how this would work if you don’t control your own IP space.
If you have ISPs you can peer with over BGP and your own PI IP space this does “just work” as you’d expect. The same way it “just works” with v4 in a NATless world.
A lot of the things that “just work” in v4 are really just NAT sweeping the rough edges under the rug. The same problems exist in v4, but don’t get seen in practice as local / global addresses are effectively always different on your network (unless you’re lucky enough to be a legacy allocation that has an /8 of v4 I suppose).
If you enforce that same “separation” in v6 (with NPT, or NAT) surprise the “problems” also go away, like they do in v4.
The needs for dual-homing and failover were completely glossed over in the IPv6 design, and the IETF has not acknowledged these needs even to this day.
It's the same with IPv4, by the way. An ISP can assign you a block from their allocation, you can still announce it with your own ASN as long as it doesn't violate the issuing provider's policy, you're still a customer, etc.
And it's more of the "it's the thought that counts" thing. Multihoming was considered to be something rather exotic and mostly a requirement for ISPs or large companies.
The real problem is BGP isn't available from most home or "small business" internet connections. You can't multihome even if you want to. You need a DIA / enterprise plan, or you need to use tunneling (which is what I do, from several BGP capable VPSes, in a configuration that is too complex for the typical SMB.)
They thought about these things and put features into the protocol to support them. This is, once again, the opposite of your belief that they didn't.