Smart Steering

With the rapid explosion of BYOD and guest WiFi, a wide variety of devices from different manufacturers and operating systems are seen connecting to the wireless network. When it comes to roaming or switching networks, the client always decides when to roam and which access point to roam to. This roaming behavior is unique to each client device. Each device also has different transmit powers, antenna orientation, and power-save mode decision, making the whole roaming process more unpredictable.

The wireless world talks about the problem of Sticky Clients. In the wireless world, a client usually connects to the access point that offers the best signal strength in its first attempt. A Sticky Client is a device that tends to stay associated with an access point, even when the signal strength is poor, rather than roaming to another Access point in the vicinity that might offer better signal strength. This happens in a large network set-up that uses multiple Access points to provide WiFi coverage to the clients.

For example, in an office setup, there could be more than one laptop or tablet connected to an access point at a particular time. If one of the laptops moves away from the access point as shown in the figure below, it is expected to detect the access points that fall in its range and connect to one of those that provide better signal strength. In the case of a "sticky client", the client does not roam or switch to another access point. Instead, it continues to stay connected to the distant access point. The figure illustrates that a laptop continues its association with the distant access point even after moving to different locations and having poor signal strength; when it would receive a better signal strength if connected to the nearest access point.

This causes degradation in network speed not only for the sticky client, but also for other clients that may be connected to the same access point. Most clients continue to be associated with the current access point even though there might be neighboring access points providing better connectivity that they can connect to.

Figure 1. Sticky client with poor signal strength