Off Topic: Apple iPhone Kills Cisco WLAN

***Update: It WAS a Cisco issue – not an Apple iPhone issue*** 

Here’s a disturbing article from Network World describing how the new iPhones are killing Duke’s Cisco WLAN.  It appears that the new iPhones are sending tons of ARP requests and eating up bandwidth and CPU cycles on the WLAN APs and controllers.

…the misbehaving iPhones flood the access points with up to 18,000 address requests per second, nearly 10Mbps of bandwidth, and monopolizing the AP’s airtime.

The requests are for what is, at least for Duke’s network, an invalid router address. Devices use the Address Resolution Protocol (ARP) to request the MAC address of the destination node, for which it already has the IP address. When it doesn’t get an answer, the iPhone just keeps asking.

“I’m not exactly sure where the ‘bad’ router address is coming from,” Miller says. One possibility: each offending iPhone may have been first connected to a home wireless router or gateway, and it may automatically and repeatedly be trying to reconnect to it again when something happens to the iPhone’s initial connection on the Duke WLAN.

Most of the WLAN is comprised of Cisco thin access points and controllers. Some older autonomous Cisco Aironet access points tend to uncover the flooding first, since they try to resolve the ARP request themselves. But Miller’s team has seen the CPU utilization on the WLAN controllers spiking as they try to process the request flood passed on to them in control traffic from the thin access points.

“I don’t believe it’s a Cisco problem in any way, shape, or form,” he says firmly.

So far, the communication with Apple has been “one-way,” Miller says, with the Duke team filing the problem ticket. He says Apple has told him the problem is being “escalated” but as of midafternoon Monday, nothing substantive had been heard from Apple.

It will be interesting to see what the problem turns out to be.  The article mentions that Duke is using both automonous APs as well as the newer lightweight APs with wireless controllers.  What is NOT mentioned is what type of authentication they are using.  It would be interesting to get more information about their WLAN as I would like to know if we can start expecting some fuckwit with their shiny new iPhone to take down our corporate WLAN.

Sorry for highlighting the anti-Apple comments in the last paragraph.  I have a lot of friends who are members of the Apple cult, so it’s fun to hate on Apple every now and then.