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Re: IPv6 Stable Private Addresses RFC 7217

On 11/06/2014 23:37, David Laight wrote:
On Thu, Jun 05, 2014 at 02:37:53PM -0400, Ted Lemon wrote:
On Jun 5, 2014, at 2:07 PM, Joerg Sonnenberger <> wrote:
> More the latter case, but the former is the root source.

So, if you want a stable address, why aren't you configuring one manually?

Because I want a central repository of the stable addresses.
My preferred way to use DHCP is for it to give out fixed addresses
to each client, and without a pool of 'spare' addresses.

Even if addresses are allocated from a pool, I want a system to (usually) have the same address after a reboot. Even when the shutdown sequence gives up
the DHCP lease.

What we are talking about here is part of the RA/RS protocol.
DHCP is separate still in IPv6.

The prefix in the RA has a flag to say "create an an automatic address for this prefix". This discussion is about changing the hardware element of the address into a stable private stateless one, generated by the host. The latest dhcpcd code also uses the same logic to generate stable private LL addresses as well, provided it beats another operation bringing the interface up at boot time (like say wpa_supplicant or ifconfig).

The same RA can also have flags to say obtain an address statefully via DHCP. I don't know of a use case where you would want both flags set but it's possible and dhcpcd allows this.

I've had to setup and run my own dhcp server at work (and I had to hack
the ISC source) because the corporate server is so broken.
It wouldn't give a machine back the same IP address after a reboot.

A broken server should not form part of this discussion.
But they are the bane of my life at times.


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