DHCP troubles over a wireless connection - TechRepublic
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January 22, 2007 at 12:55 PM
awalworth

DHCP troubles over a wireless connection

by awalworth . Updated 19 years, 5 months ago

Greetings –
I’m seeing some pretty funny stuff going on and I’m wondering if anyone
has seen it before…

Background –
My PC is a Windows XP SP2 laptop with integrated wireless
DHCP server is a Windows 2k Server box
WAP is a Nortel BAP120
Switch is a Nortel BES

I am having this problem in my office and a client is also having this
problem. At the end of the DHCP lease, When switching SSIDs or
networks (from home to work) I have noticed that Windows will connect
to the wireless network with no problem. A quick sniff of the network
shows broadcast traffic. Included in the Broadcast traffic is my
laptop’s DHCP Discover packet requesting the last IP it had (as Windows
does). I am also seeing the DHCP Offer packet from the DHCP server
with the valid IP information. All is normal until this point. My
laptop does not send the DHCP Request packet back to the DHCP server.
Instead it waits a few seconds and sends another DHCP Discover. It is
simply ignoring the DHCP Offer.

The work-around for this is to simply to a “repair” in Windows on the
wireless adapter. Windows connects to the WLAN, sends the DHCP
Discover, gets the DHCP Offer, sends the DHCP Request, recieves the
DHCP ACK and all is well.

So here are the remainder of the details. It doesn’t just happen with
my computer. It happens with every Windows XP SP2 machine. We haven’t
yet tried a real Windows 2k machine (a VM on my laptop did not have the
problem using MS Virtual PC). Our WiFi IP Phones do not have this
problem when their DHCP leases expire.

Any thoughts? I am stumped!!!

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