Odd DHCP behavior (Vista losing IP?)

Jason Frisvold frisvolj at lafayette.edu
Wed Apr 14 18:40:27 UTC 2010


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On 04/14/2010 10:06 AM, Denis Laventure wrote:
> Hi Jason,
> 
> I have the exact same problem here, but I don't have Vista PCs on the campus. The same problem appends with a lot of XP machines and I can't reproduce it in lab... 
> 
> Are you sure the problem is your DHCP server? After several tests and captures I'm starting to think it's related to our cisco routers (4506) security configuration, but I'm not sure yet... We use DHCP_SNOOPING and IP_SOURCE_GUARD on every network port that have this behavior. When a PC loses his IP and get a 169.254.x.x IP, if I remove the security on the port, everything return to normal... 

Nope, I don't know that it's a dhcp server problem, but since it's dhcp
related, I thought this was a good place to start.  I do not believe we
are using dhcp_snooping or ip_source_guard, though we do have port
security enabled.  Regardless, I would expect it to be more widespread
if it were a switch issue as we have a uniform config across the
campus..  This is good info, though, and I can try some alternate
settings on that particular switch to see if it makes a difference.

> I hope this can help,
> 
> Denis

- -- 
- ---------------------------
Jason Frisvold
Network Engineer
frisvolj at lafayette.edu
- ---------------------------
"What I cannot create, I do not understand"
   - Richard Feynman
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