[Kea-users] [EXTERNAL] Re: Dhcp6 Prefix Exclude use case question

[Darren Ankney]

Hi Dan,

I've never tested the configuration, but it seems to be the case based
on the documentation.

Thank you,

Darren Ankney

On Fri, Jun 23, 2023 at 8:38 AM Geist, Dan (CCI-Atlanta)
<Dan.Geist at cox.com> wrote:
>
> Thanks, Darren. This mostly has to do with how the clients in the space USE the v6 PDs. It’s a MAP-T environment where use of that block correlates to that client devices sending all traffic using source-ports of 1-1023 (which is obviously problematic). Unlikely corner case, just trying to ensure this will work the way we are hoping IF it’s used.
>
>
>
> Thanks.
> Dan
>
>
>
> From: Kea-users <kea-users-bounces at lists.isc.org> on behalf of Darren Ankney <darren.ankney at gmail.com>
> Date: Friday, June 23, 2023 at 6:31 AM
> To: kea-users at lists.isc.org <kea-users at lists.isc.org>
> Subject: [EXTERNAL] Re: [Kea-users] Dhcp6 Prefix Exclude use case question
>
> Hi Dan,
>
> I don't think that is the purpose of the option, but I suppose if no
> device asks for an excluded prefix then the prefix will not be
> allocated to any device.  How would you be able to guarantee this?  I
> would think a better solution would be to engineer your network
> differently such that you don't need to leave off part of the prefix
> delegation.  Surely there are plenty of IPv6 subnets to go around to
> accomplish this?
>
> Thank you,
>
> Darren Ankney
>
> On Wed, Jun 21, 2023 at 5:09 PM Dan Geist <dan at polter.net> wrote:
> >
> > Greetings, all. I'm exploring using the "prefix exclude" feature to do something a little different than what it's RFC describes and would like to know if my scenario would work. In the kea ARM, the example config is as follows:
> >
> > "Dhcp6": {
> >     "subnet6": [
> >         {
> >             "subnet": "2001:db8:1::/48",
> >             "pd-pools": [
> >                 {
> >                     "prefix": "2001:db8:1:8000::",
> >                     "prefix-len": 56,
> >                     "delegated-len": 64,
> >                     "excluded-prefix": "2001:db8:1:8000:cafe:80::",
> >                     "excluded-prefix-len": 72
> >                 }
> >             ]
> >         }
> >     ]
> > }
> >
> > This allows a device that sends a Prefix Exclude option to be allocated the indicated /72.
> >
> > In my environment, we'd like to be able to allocate PDs from a block that is discrete from the subnet and in which the very first PD is NEVER assigned, ala:
> >
> > "Dhcp6": {
> >     "subnet6": [
> >         {
> >             "subnet": "2001:db8:1::/48",
> >             "pd-pools": [
> >                 {
> >                     "prefix": "2001:db8:2::",
> >                     "prefix-len": 48,
> >                     "delegated-len": 60,
> >                     "excluded-prefix": "2001:db8:2::",
> >                     "excluded-prefix-len": 60
> >                 }
> >             ]
> >         }
> >     ]
> > }
> >
> > Assuming I don't have any dhcpv6 endpoint devices sending the excluded prefix option, does this accomplish what I'm attempting, which is: never use the first /60 from the PD /48 prefix?
> >
> > Thanks
> > Dan
> >
> > --
> > Dan Geist dan(@)polter.net
> >
> > --
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