[Dibbler] Sharing a Prefix-Delegation Pool across multiple Interfaces?

Tomek Mrugalski thomson at klub.com.pl
Thu Sep 1 01:07:58 CEST 2016

On 28/08/16 12:16, dibbler at yanosz.net wrote:
> Hello folks,
> I got stuck configuring dibbler for prefix delegation:
> I have rather small pool for prefix delegation (/56 in total). I want to
> assign parts of it to different clients.
> Unfortunately, these clients are connecting through different
> VPN-interfaces and I've no control on the concrete interface being used.
> Thus, I'd like to define a pool shared among all interfaces.
Not really possible in Dibbler.

> If possible, a client (identified by its DUID) should be able to get the
> same prefix no matter what interface is being used.
> Looking at the documentation, I see examples for assigning pools and
> client configurations to specific interfaces, only.
> How can I configure dibbler to manage a pool and client definition
> outside interface definition? - Or -
You can't. That would require writing new code.

> Can I use wildcards, that a configuration applies to all
> tap-VPN-interfaces?
If you use relays, you can try (ab)using guess-mode and define a single
relayed interface without specifying its interface-id. If you're lucky,
dibbler will get confused and will try to pick the first interface. If
your configuration has only one interface, it's possible that Dibbler
could get confused always the same way and would pick the sole
interface. This is really abusing the feature, so if it works - great.
If not, you're out of luck.

> Do you have any idea on how to use dibbler in this scenario?
Not really, except trying guess-mode. The best way to solve this
scenario would be to use Kea and write a simple hook, installed on
subnet6_select that enforces always picking specific subnet.
See http://kea.isc.org and
http://git.kea.isc.org/~tester/kea/doxygen/d1/d02/dhcpv6Hooks.html for

Hope that helps,

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