[Kea-users] Kea not sending NAK

[Ola Thoresen]

Just to confuse you even more, we have seen the same behaviour on 
another relay-platform.
(Unfortunately, I don't have any links to publicly available information 
about the issue).

Anyway, after debugging we discovered that the packets were sent FROM 
the client with the "broadcast" flag set.
The relay did not clear this flag, so when the reply was received by the 
relay, it was sent (correctly) as a broadcast back to the client.
The behaviour of DHCP-clients varies a lot when it comes to how it sets 
the broadcast flag:
https://blogs.technet.microsoft.com/teamdhcp/2009/02/12/dhcp-broadcast-flag-handling-in-windows-7/

So the solution for us was to force the relay to clear the broadcast 
flag on dhcp messages (I do not know if this is possible on your HP switch).
That way, the replies were unicast back to the client, and everything 
started working.


Rgds.

Ola Thoresen