[Kea-users] Impact of UDP mode on HA Hot-Standby configuration

[Waldek Maleska]

Hello,

This is my first message to this mailing list so first let me thank you for
making Kea available to everyone and for all the excellent features.

I'm in the process of preparing migration from ISC-DHCP to Kea and trying
to improve our situation by deploying it in HA mode (hot standby) so I'm
testing the behaviour of Kea (and its HA) in our environment. So far all
the testing was done using a raw socket where HA worked great - standby
node listened to the DHCP to/from the active node and upon losing
connectivity of the control link and noticing unacked client requests -
standby node got promoted to active and took over.

Now I'm trying to repeat the same in UDP mode and I'm not sure if there is
an impact here on HA parameters or not. My switchover test wasn't
successful, the standby node never switched to the active role.
Documentation doesn't mention any dependency between max-unacked-clients (I
currently have it at 2) and dhcp-socket-type but I wonder: if Kea isn't
listening to the broadcast traffic, is it still able to count the unacked
requests? and if it is, how does it do that? Should max-unacked-clients be
always 0 in UDP socket mode or is that somehow not a problem?

If someone could shed some life on this, I'd appreciate it a lot.

Thank you,
Waldek Maleska
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