[Kea-users] Kea not sending NAK

Thomas Andersen than at itu.dk
Tue Mar 1 10:02:14 UTC 2016


On a side note, it works with OFFER. Even though the client is also sending DISCOVER as bc, the relay is replying with unicast.
But i suspekt this has something to do with KEA, because with the ‘old’ dhcp (isc), our OFFER packet are sent as bc to the same clients.

Br,
Thomas



On 01/03/16 10:55, "kea-users-bounces at lists.isc.org on behalf of Thomas Andersen" <kea-users-bounces at lists.isc.org on behalf of than at itu.dk> wrote:

>Hi Ola,
>
>You are correct that the broadcast flag is set in the REQUEST message from the client side.
>However, I believe that the RFC still states that the relay should respond with unicast.
>If there is a way to configure HP to do this, I’d love to do it. But I have not been able to find such configuration parameters. :(
>
>Br,
>Thomas
>
>
>
>
>On 01/03/16 10:50, "kea-users-bounces at lists.isc.org on behalf of Ola Thoresen" <kea-users-bounces at lists.isc.org on behalf of ola at nytt.no> wrote:
>
>>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
>>
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