[Kea-users] dhcp6 address assignment

[Marek Greško]

Hmm, I would expect reservations are not offered if not within the subnet.

M.





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------- Original Message -------
On Wednesday, October 19th, 2022 at 19:12, perl-list <perl-list at network1.net> wrote:


> 
> ----- Original Message -----
> 
> > From: "Marek Greško via Kea-users" kea-users at lists.isc.org
> > To: "Dan Oachs" doachs at gac.edu
> > Cc: "kea-users" kea-users at lists.isc.org
> > Sent: Wednesday, October 19, 2022 12:59:56 PM
> > Subject: Re: [Kea-users] dhcp6 address assignment
> 
> > Hello,
> 
> > I run into another problems with this. To simplify the migration I use global
> > reservations. I have two definitions for that machine. One for ethernet adapter
> > and one for wifi adapter. Unfortunately the DUID is the same with both
> > interfaces so the kea-dhcp6 cannot start with that configuration. ISC DHCPD6
> > hed no problem with that and everything was working correctly. It was because I
> > was able to define both mac address and duid. Since I defined different value
> > for mac for wifi there was no conflict.
> 
> > Probably the only one solution for this is to drop global reservations and
> > switch to per subnet reservations?
> 
> 
> It would seem it is best to not use global reservations in your scenario:
> 
> "This feature can be used to assign certain parameters, such as hostname or other dedicated, host-specific options. It can also be used to assign addresses or prefixes. However, global reservations that assign either of these bypass the whole topology determination provided by the DHCP logic implemented in Kea. It is very easy to misuse this feature and get a configuration that is inconsistent. To give a specific example, imagine a global reservation for the address 2001:db8:1111::1 and two subnets 2001:db8:1111::/48 and 2001:db8:ffff::/48. If global reservations are used in both subnets and a device matching global host reservations visits part of the network that is covered by 2001:db8:ffff::/48, it will get the IP address 2001:db8:ffff::1, which is outside of the prefix announced by its local router using router advertisements. Such a configuration is unusable or, at the very least, riddled with issues, such as downlink traffic not reaching the device."
> 
> https://kea.readthedocs.io/en/kea-2.2.0/arm/dhcp6-srv.html?highlight=global reservation#global-reservations-in-dhcpv6
> 
> > Thanks
> 
> > Marek
> 
> > ------- Original Message -------
> > On Tuesday, October 18th, 2022 at 20:48, Dan Oachs doachs at gac.edu wrote:
> 
> > > Have you looked at using multiple reservations for the same IP? Would that solve
> > > any of your issues?
> 
> > > [
> > > https://kea.readthedocs.io/en/latest/arm/dhcp6-srv.html?highlight=unique#multiple-reservations-for-the-same-ip
> > > |
> > > https://kea.readthedocs.io/en/latest/arm/dhcp6-srv.html?highlight=unique#multiple-reservations-for-the-same-ip
> > > ]
> 
> > > --Dan
> 
> > > On Tue, Oct 18, 2022 at 1:15 PM Marek Greško via Kea-users < [
> > > mailto:kea-users at lists.isc.org | kea-users at lists.isc.org ] > wrote:
> 
> > > > Hello,
> 
> > > > I am in a phase of migration ISC DHCPD into kea and I am suffering several
> > > > problems in ipv6 address assignment.
> 
> > > > 1. I used to assign same ipv6 address for the same machine which was dial boot
> > > > linux/windows. It was possible by assigning same ipv6 address to both DUIDs
> > > > before. But in kea this is not allowed. I found out there is a possibility to
> > > > assign ipv6 address by MAC address which was not possible in ISC DHCPD. I was
> > > > very happy with that finding but fallen into second problem.
> > > > 2. The windows machine got 2 interfaces ethernet and wifi. I configured kea to
> > > > assign one ipv6 address to the ethernet adapter and another one to the wifi
> > > > adapter. But after investigating logs kea was receiving dhcp6 request over wifi
> > > > using the ethernet adapter mac address. How is this possible? Is it possible
> > > > the MAC address in DHCP does not match L2 MAC address? I did not sniff the
> > > > request, yet. I decided to switch back to DUID assignment since this problem is
> > > > worse than the previous.
> > > > 3. Maybe it would be possible to overcome the above problems if kea is able to
> > > > match both DUID and MAC address, but it is not allowed in kea. I am ought to
> > > > select one option only. Why?
> 
> > > > Thanks
> 
> > > > Marek
> 
> > > > Thanks
> 
> > > > Marek
> 
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