exceedingly long time in assigning ip addresses

Chris Buxton chris.p.buxton at gmail.com
Mon Dec 13 17:36:24 UTC 2010

Since both DHCP servers are on the same LAN, could it be that the other server has "authoritative" set? If so, is it possible to set that server as "not authoritative"?

The difference is whether the other server sends NAK responses to requests. It could be that for the clients in question, the other server's NAK is beating your server's ACK.

Chris Buxton
BlueCat Networks

On Dec 13, 2010, at 7:41 AM, Massimo Manghi wrote:

> Hi
> I've been lurking on the list for a while now hoping to see someone to bring up this or a similar problem.
> I'm managing a medium size network (a zone of a larger campus size network) and I've used dhcp for assigning ip addresses for quite a long time now. During the last year an increasing number of windows clients are having problems when they are started up. IP address negotiation can take as long as 30 mins while the dhcp log shows a series of the usual messages, apparently displaying a flawless exchange
> Dec 13 15:15:03 yyyyyy dhcpd: DHCPDISCOVER from 00:26:18:bc:fc:39 via eth0
> Dec 13 15:15:03 yyyyyy dhcpd: DHCPOFFER on xxx.xxx.xxx.54 to 00:26:18:bc:fc:39 via eth0
> Dec 13 15:15:03 yyyyyy dhcpd: DHCPREQUEST for xxx.xxx.xxx.54 (xxx.xxx.xxx.1) from 00:26:18:bc:fc:39 via eth0
> Dec 13 15:15:03 yyyyyy dhcpd: DHCPACK on xxx.xxx.xxx.54 to 00:26:18:bc:fc:39 via eth0
> these 4 messages are repeated every second for as long as necessary for some magic event to eventually overcome the problem.
> Since my organization prescribes that every ip must have a physical person associated to it (to allow fast intervention in case the pc is taken over by some trojan or virus or p2p software) my server has no free leases, therefore every ip is statically linked to a mac address.
> on this network another dhcp server exists, they manage a very small group of clients belonging to a different ip zone (though they share the same lan with my zone) and they too don't serve free leases.
> not every client has this problem, this seem restricted to windows clients located in a specific section of the building. This suggests an interference between the 2 dhcp servers exists and the problem to be matter of timing (being a server faster to respond than the other on that section of the lan). Are there time parameters to be set that can be adjusted to make the negotiation tolerant of these interferences?
> thanks for any suggestion
> -- Massimo
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