Re: [v6ops] SLAAC renum: Problem Statement & Operational workarounds

Ole Troan <> Sun, 27 October 2019 22:52 UTC

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From: Ole Troan <>
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Date: Sun, 27 Oct 2019 23:52:15 +0100
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Subject: Re: [v6ops] SLAAC renum: Problem Statement & Operational workarounds
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>>> Note that we could change SLAAC to allow the lifetime of a prefix to be
>>> set to zero, instead of having to wait for 2 hours. That might be an
>>> improvement but requires careful analsysis.
>> Can you explain how operating a public service should work on this
>> type of network?
> Could you be more specific what you consider a 'public service' and what
> you expect to break?

The (only) value (sic) of IPv6 to end-users is retoration of end to end connectivity at the network layer.

I challenge you to find in the "real world" of end-users many with much trust in the ad-based "you are the product" centralised services in the current Internet.
IPv6 was meant to allow end-users to run decentralized services.

- hidden primary DNS
- mail
- web
- home-automation
- video conferencing
- jabber

All of those have great open source software.
To use Owen's paragraph:
"I don’t know of a single server which operates that way currently. Can you point to a working example?"

Assuming all the moving parts required were updated to support flash renumbering (I have little proof they even support graceful renumbering), 
if the end-user cannot trust the lifetimes in the delegated prefix, DNS with TTL=1s is presumably the only choice?

> What I described is basically what happens on IPv4 when a CPE uses NAT 
> and gets a new IPv4 address from the ISP.

If making IPv6 no better than IPv4 + NAT, then stick with IPv4 + NAT.
IPv4 NAT scales very well as it turns out.

> Flash renumbering is far from ideal, but a reality on the current internet.
> Any application that is suitable for home use is expected to deal with that
> scenario.

We don't need IPv6 to maintain the status quo.

> Note that with automatic DNS updates, you can probably run a mail server (or
> your personal 'cloud') on such a link. But that is not a common use case
> at the moment.

And don't get me wrong, I'm all for making IPv6 addressing / onlink behaviour more robust.
But not justified in this way that can be seen to allow for practices that removes any benefit of IPv6 over IPv4/NAT.