Re: [v6ops] Flash renumbering

Fernando Gont <fernando@gont.com.ar> Sat, 19 September 2020 05:43 UTC

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To: otroan@employees.org, Vasilenko Eduard <vasilenko.eduard@huawei.com>
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From: Fernando Gont <fernando@gont.com.ar>
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Date: Sat, 19 Sep 2020 02:35:27 -0300
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Subject: Re: [v6ops] Flash renumbering
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Hi, Ole,

On 18/9/20 06:32, otroan@employees.org wrote:
>>> SLAAC is only one of the victims of flash renumbering. (If there was more
>>> widespread use of ULAs that might not be true.)
>> [Ed: ] But How? Subscriber needs access to Global Internet.
>> Is it possible to connect Google by ULA?
> 
> If you have ephemeral global addresses, at the two extremes on the scale you have:

At the end of the day, global addresses *are* ephemeral. And the case 
where they are not should be treated as a special case.


> 
> 1) ULA + NAT.
>     Aka the IPv4 model. Provides stable addressing on the local network.
>     Transport sessions do not survive renumbering events.
> 
> 2) Ephemeral addressing support on hosts.
>     Including support in the network layer, transport layer and application layer.
>     This is not any different than what a host supporting multi-prefix multi-homing
>     needs to do. It means transport / application layer must detect changes in
>     connectivity and change address pairs as required.

I think 2) should be split into multiple pieces.

One part is having the network layer handle multiple prefixes and 
fresh/stale information nicely. Then transport/app may need to improve 
on that -- e.g., make connections survive across address changes, make 
appropriate choices for src/dst addresses, etc.

The network part is currently very broken, due, among other things, to 
like of widespread support for RFC8028. MP-TCP, for example, has taken 
care of *part* of the transport/app layer issues.

Thanks,
-- 
Fernando Gont
e-mail: fernando@gont.com.ar || fgont@si6networks.com
PGP Fingerprint: 7809 84F5 322E 45C7 F1C9 3945 96EE A9EF D076 FFF1