Unwanted Link Layer Traffic in Large IEEE 802.11 Wireless Networks

Wireless networks have evolved into an important technology for connecting users to the Internet. As the utility of wireless technology grows, wireless networks are being deployed in more widely varying conditions. The monitoring of wireless networks continues to reveal key implementation deficiencies that need to be corrected in order to improve protocol operation and end-to-end network performance. In wireless networks, where the medium is shared, unwanted traffic can pose significant overhead and lead to suboptimal network performance. Much of the previous analyses of unwanted traffic in wireless networks focus on malicious traffic. However, another major contributor of unwanted traffic is incorrect link layer behavior. Using data we collected from the 67th Internet Engineering Task Force (IETF) meeting held in November 2006, we show that a significant portion of link layer traffic stems from mechanisms that initiate, maintain, and change client-AP associations. We further show that under conditions of high medium utilization and packet loss rate, handoffs are initiated incorrectly. We analyze the traffic to understand when handoffs occur and whether the handoffs were beneficial or should have been avoided.