From: Michael Snyder (msnyder@revolutioncomputer.com)
Date: Thu Sep 23 2004 - 22:54:59 GMT-3
I got a production network and I was troubleshooting and problem with
some win98 pc's. It's got about 110 win2000/xp machines on it that
don't have a problem with dhcp, but about 12 out of 30 win98 machines
can't get a unicast dhcp renewal but can get new broadcast lease.
Our thinking now is that it's just a patch problem.
------------------------------------------------------------------------
---But some sniffer captures brought up another question.
(dhcp server x.x.10.2)-(x.x.10.1 router/ip helper)-(client pc's x.x.100.x) Server subnet .10/24 and client subnet of .100/24
In the captures I saw the clients 0.0.0.0 request broadcast to 255.255.255.255 get answered by an x.x.10.1 direct unicast to the clients new ip on the x.x.100.x side.
Now also the unicast renewals went to the x.x.10.2 and was answered by x.x.10.2
I always assumed that all dhcp traffic would go to the address of the ip helper router, but it seems only the incoming client broadcasts are relayed by it, and everything else is direct unicast to/from the far subnet dhcp server.
Does this sound right? I've read the rfc's but they aren't clear about what IP source addresses I should see using ip helper from the clients viewpoint.
If anyone can share some expertise on what I should be seeing, it would be very helpful.
Thanks in Advance,
Michael Snyder Lead Network Engineer CCSP/DP, MCSE NT/2000 Revolution Computer Systems
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