[Kea-users] shared-network "interface" and "relay" parameters

[Francis Dupont]

Veronique Lefebure writes:
> I have read 
> * https://kea.readthedocs.io/en/latest/arm/dhcp4-srv.html?highlight=subnet4#l
> ocal-and-relayed-traffic-in-shared-networks
> * and https://kea.readthedocs.io/en/latest/arm/dhcp4-srv.html?highlight=subne
> t4#using-a-specific-relay-agent-for-a-subnet
> But the following is not clear to me. Can someone help clarifying ?
>
> - In ISC DHCP there is no subnet selectors (interface or relay address) , i.e
>  no  "interface" nor "relay" parameter in Shared-Network. Why is it needed in
>  KEA and not in DHCPD ? What is DHCPD using in order to select the subnet, si
> nce there is no "interface" nor "relay" parameter in the configuration file ?
>  Why does KEA not use the same mechanism ?

=> these parameters when they are set at the shared network level are
inherited by subnet members. It is just for user convenience as usually
all subnets of the same shared network share the interface the shared
network is attached to and/or relays connected to the shared network.

> - are "interface" and  "relay" exclusive or can we have both ?

=> they are not exclusive but topologies with both are uncommon.

Please note the localization process is the same for ISC DHCP and Kea:
it follows the standard so selectors are used in the same order,
and in both when shared networks are used the "selected subnet" is
in fact the selected shared network: next steps will iterate through
members, in Kea starting by the selected subnet.

Regards

Francis Dupont <fdupont at isc.org>