R: R: R: Relay agent with dhcp server on same subnet

Autuori Gianluigi Autuori.Gianluigi.Wintime at ansaldobreda.it
Thu Nov 19 09:35:40 UTC 2009

So the only way to do it correctly is to use a switch that suppress the original broadcast DHCP packets. The one I use doesn't permit this.
Gianluigi Autuori

-----Messaggio originale-----
Da: dhcp-users-bounces at lists.isc.org [mailto:dhcp-users-bounces at lists.isc.org] Per conto di Bruce Hudson
Inviato: mercoledì 18 novembre 2009 22.45
A: dhcp-users at lists.isc.org
Oggetto: Re: R: R: Relay agent with dhcp server on same subnet

> I think server nakew client request because there isn't any 
> agent.circuit-id field in its packet.

    You are correct. Your switch is acting as a DHCP relay but it does not appear to be suppressing the original broadcast DHCP packets. This means your server is seeing every request twice: once directly from the client without relay information and one via the switch that includes the relay option. 

    The direct DISCOVER would have generated an error message in the server's log that no addresses were free and dropped. However, the direct REQUEST generates a NAK.

    This is probably a configuration error in the switch.
Bruce A. Hudson				| Bruce.Hudson at Dal.CA
ITS, Networks and Systems		|
Dalhousie University			|
Halifax, Nova Scotia, Canada		| (902) 494-3405
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