exceedingly long time in assigning ip addresses

Massimo Manghi massimo.manghi at unipr.it
Mon Dec 13 15:41:09 UTC 2010


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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