All wi-fi access points lose connection at once?!

[obijon]

I'm stumped, and must not be seeing something obvious.

 

Yesterday everybody who connects wirelessly lost their connection to the Internet. Once or twice they regained the connection for a very short period. They stay connected to the AP but with "limited or no connectivity" (auto-IP is assigned). I can remotely manage the APs so I know they are not down. DHCP is provided by a single domain controller, and it is working fine for wired computers. Windows Firewall is disabled domain-wide via group policy.

 

I have about 700 wired and 70 wireless computers at my school. Laptops are serviced by several APs of various brands (some DD-WRT but not all). The APs are scattered across the school, and are not centrally managed (most are of the Linksys WRT54G variety but there are a couple Cisco WAP4410s as well).

 

On one of the laptops I set a static IP in my subnet and was still unable to ping through the AP to anything on the other side. This rules out DHCP as a factor.

 

Several laptops became the Master Browser for the domain and when I disabled the Computer Browser service for the most recently elected laptop the DC immediately generated an event that the DC had been elected the master browser. This seems to indicate that some traffic is getting through the AP - how else could the DC have known that the laptop was no longer the master browser? I confirmed that Windows Firewall is disabled. I think the browser elections are a symptom, not the cause.

 

My gut feeling is that there is elevated broadcast traffic on the network and the wireless clients are effectively experiencing Denial of Service.

 

What am I missing?

Edited January 19, 2011 by obijon

[obijon]

I found the problem, it was a desktop broadcasting DHCP requests but never getting an IP for some reason. This was flooding the network with 3.7Mbps of broadcast traffic, apparently enough to overwhelm the APs. Not sure yet if the nic is bad.