strange problem trying to migrate to a new DHCP server

Bracey, John JBracey at
Tue May 13 16:01:01 UTC 2008

Hello All:


We're trying to migrate from our old DHCP server (running version
3.0.1-10 EL3) to our new DHCP server (running version 3.0.1-59 EL4).
Both servers are running IPTables as the host firewall with the
following rules in place:


-A RH-Firewall-1-INPUT -p tcp -m tcp --dport 67 -m state --state NEW -j

-A RH-Firewall-1-INPUT -p udp -m udp --dport 67 -m state --state NEW -j

-A RH-Firewall-1-INPUT -p tcp -m tcp --dport 68 -m state --state NEW -j

-A RH-Firewall-1-INPUT -p udp -m udp --dport 68 -m state --state NEW -j


We copied the dhcpd.conf, dhcpd.master file (the file gets included by
dhcpd.conf, it has all our statics defined), and the dhcpd.leases files
over to the new server, shut down the old server and start up the new
one (we already have the new one set up on our router interfaces for
dhcp relay (ip helper address)).


Tailing the logs after the switch and testing a couple of our vlans,
everything looked successful.  This was last Friday.


Come Monday morning we had a handful of reports of folks on certain
vlans weren't able to get leases.  I was able to replicate this on my
second desktop in my office; it would make the DHCP request and get no
reply from the server.  On the server I would see the request come in
from my second desktop, an IP would be offered.  Somewhere the offer is
getting munched.


This may not even be a server problem (as I do see the offer in the
server logs).  From what I can tell so far there is no difference
between a vlan that is working and one that is not looking at the cisco
router and switch configs (6500 cores, HSRP on the vlans, same core
switch is the active router on all the vlans).


So, have any of you run into similar issues?



John K. Bracey, Sr. Network Analyst 

NTA Change Management Group Chair

Communications Services / Network Operations

California State University, Chico




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