Simon Bullen's Weblog

Can an Apple iphone kill a Cisco network ?

Well the short answer is yes it can !

The problem started a week ago (Friday 13th believe it or not)at Duke university when IT staff found out that they were getting up to 30,000 ARP requests per second knocking out up to 30 wireless access points for between 10 and 15 minutes. 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.The problem is when the iphone does not get an answer it just keeps asking.

The "misbehaving" iPhones flood the access points with up to 18,000 address requests per second, nearly 10Mbps of bandwidth, which monopolises the AP’s airtime.

Kevin Miller, assistant director, communications infrastructure, with Duke’s Office of Information Technology stated “I don’t believe it’s a Cisco problem in any way, shape, or form,”

Whoops ! Bad call Kevin.

A week later and Duke’s chief information officer is saying:-

“Cisco has provided a fix that has been applied to Duke’s network and there have been no recurrences of the problem since, We are working to fully characterize the issue and will have additional information as soon as possible.”

“Earlier reports that this was a problem with the iPhone in particular have proved to be inaccurate,”

Earlier on Friday, July 20, a Cisco PR spokeswoman via a two-sentence e-mail message said that the networking problem experienced at Duke was “caused by a Cisco-based network issue.” When more details were requested, the spokeswoman replied in e-mail, “this is all we are disclosing at this time.”

Posted at 08:29AM Jul 23, 2007 by Simon Bullen in Networking  |  Comments[0]