Dear Francis, thanks for confirming. Indeed, https://kea.readthedocs.io/en/latest/arm/dhcp4-srv.html?highlight=8.3#global-reservations-in-dhcpv4 clearly says:
"global reservations that assign addresses 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" . So, in order to get the same behaviour with KEA than the one we had with ISC DHCP, we now need 2 host-reservations for one mac address: - #1 : one host-reservation in the subnet, where we reserve an IP that matches the subnet - #2 : one additional host-reservation, at the global level, with no reserved IP, for the client to get a dynamic IP in case it is not connected to the expected subnet. In ISC DHCP, host-reservation #1 was enough to get both. Am I correct ? Thanks again, Veronique > On 30/08/2022 17:41 Francis Dupont <[email protected]> wrote: > > > Veronique Lefebure writes: > > I would like to understand why KEA allocates an IP which should not be > > alloc > > ated. > > > > > > I have, on purpose (for testing KEA behaviour), declared the following > > globa > > l host reservation: > > => the answer is here: you use a global host reservation with a reserved > address so as it is documented this breaks localization aka subnet selection > so you can get exactly the kind of results you got... > > > My question is: > > ISC DHCP would not do that. > > in ISC DHCP there is no global reservations for an address even it is not > obvious from the syntax: the reservation is attached to the subnet the > address belongs to. > > > Is it expected that KEA does not behave the same way ? > > => yes, host reservation model is very different in KEA. > > > Is there any tuning that can be used so that KEA behaves the same way as > > ISC > > DHCP used to behave ? > > => put reservations with an address in a subnet the address belongs to. > Note you can still use global reservations for other things as KNOWN / > UNKNOWN classification, option setting, etc. With last versions of KEA > you have also optional early global reservation lookup too. > > Regards > > Francis Dupont <[email protected]> -- ISC funds the development of this software with paid support subscriptions. Contact us at https://www.isc.org/contact/ for more information. To unsubscribe visit https://lists.isc.org/mailman/listinfo/kea-users. Kea-users mailing list [email protected] https://lists.isc.org/mailman/listinfo/kea-users
