DHCP Drops Packets

[Randall C Grimshaw]

I think Bjarne may have just posted the solution to your problem this morning. Check the list for the subject "Performance issue ( maybe ) - followup and solution"
His solution was to tune the linux kernel.



From: dhcp-users-bounces+rgrimsha=syr.edu at lists.isc.org [mailto:dhcp-users-bounces+rgrimsha=syr.edu at lists.isc.org] On Behalf Of Nathan McDavit-Van Fleet
Sent: Thursday, November 11, 2010 4:45 PM
To: 'Users of ISC DHCP'
Subject: DHCP Drops Packets


Hello All,



For some reason it appears as if our DHCP server 4.1.2 is not responding to packets. We Wiresharked in front of the DHCP server and saw that ~10 Discover packets were going into the server. Unfortunately only one of those packets made it to the DHCP log itself. We've had similar issues with DHCPRequest packets as well. We've been seeing a big delay for clients trying to get an IP address.



Is this to do with the load of on the server itself? I haven't found a dependable recommendation for load averages, but for example our leases file is 4.1MB and our lease time is 3600 seconds with about 3000 users or so.



I also tcpdump'd the server and at least MORE of the packets made it to the interface than made it to DHCPD. I disabled iptables, added 255.255.255.255 to my hosts file and verified SELinux had the exceptions needed.



Past that I don't know where to turn.  Hopefully someone here has a suggest.



Thanks,



-Nathan

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