[Kea-users] IPV6 client gets the wrong IP for sometime after a reboot

[Veronique Lefebure]

More on this:

The mac address is in the host-reservation in the configuration file.
Why is it is used by KEA at the first boot and not at the second one ?

and even more, KEA knows about the mac address since it identifies the host-reservation; it logs out the following:

2023-01-16 17:52:09.477 DEBUG [kea-dhcp6.alloc-engine/21898.139652277565632] ALLOC_ENGINE_V6_ALLOC_NO_LEASES_HR no leases found but reservations exist for client duid=[second_duid], tid=0xedb614


2023-01-16 17:52:09.478 DEBUG [kea-dhcp6.alloc-engine/21898.139652277565632] ALLOC_ENGINE_V6_ALLOC_UNRESERVED no static reservations available - trying to dynamically allocate leases for client duid=[second_duid], tid=0xedb614


The problem is just that KEA thinks that the lease is not available.
In addition I have done a traffic capture, and I confirm that the client mac address is communicated each time to KEA via option 79.

Thanks for any help you may add on this point,
Cheers,
Veronique

________________________________
From: Kea-users <kea-users-bounces at lists.isc.org> on behalf of Darren Ankney <darren.ankney at gmail.com>
Sent: Tuesday, January 17, 2023 12:32 PM
To: kea-users at lists.isc.org <kea-users at lists.isc.org>
Subject: Re: [Kea-users] IPV6 client gets the wrong IP for sometime after a reboot

The trouble is that the server has no way to know it’s the same client if the DUID is unstable.  If the mac address is available, you can assign a reservation based on that.  Then it wouldn’t matter what DUID the client provides.  This is the same behavior as in ISC DHCP concerning DHCPv6.  It is defined in RFC 8415.  Basically: The DUID must be present and the client must use the same DUID.  The server must use that as the identifier to assign leases.

On Jan 17, 2023, at 6:18 AM, Veronique Lefebure <Veronique.Lefebure at cern.ch> wrote:

Waw. The client behaviour is not under control of the DHCP server admins..
This is a behaviour different from the ISC DHCP server behaviour, right ?
________________________________
From: Kea-users <kea-users-bounces at lists.isc.org> on behalf of Kevin P. Fleming <lists.kea-users at kevin.km6g.us>
Sent: Tuesday, January 17, 2023 12:00 PM
To: kea-users at lists.isc.org <kea-users at lists.isc.org>
Subject: Re: [Kea-users] IPV6 client gets the wrong IP for sometime after a reboot

On Tue, Jan 17, 2023, at 04:54, Veronique Lefebure wrote:
Hi,

I have observed that an IPV6 client gets the wrong IP when it reboots.
See detailed logs below.
The problem seems to be due to the fact the DUID of the client changes after reboot.
Anyone else has observed the same ?
How to go around that and make sure that the client gets the correct IP straightaway after reboot ?

You'll need to find a way to configure the client to use a stable DUID if you want it to be given a lease from a host reservation.

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