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Wi-Fi Roaming 101

Wi-Fi roaming is often a tumultuous subject.  The crux of the issue is, with Wi-Fi the roaming decision is left to the client.

In the recent years, there have been great strides in improving Wi-Fi roaming with the creation of standards-based roaming technologies.  Cisco first pioneered fast roaming many years ago with CCKM (Cisco Centralized Key Management), which was the foundation for 802.11r.  11r which was ratified by the IEEE in 2008, allows for fast roaming, even on a secure 802.1X SSID.  With 802.11r it is possible to roam without disruption during a voice or video call.

While client support of 802.11r is largely lacking in the laptop space,  there is large support in the smartphone realm.  Apple iOS devices have supported 11r since iOS 6 (http://support.apple.com/kb/HT5535).  The recent Samsung smartphones, such as the Galaxy S4, S5, and Note 3, also support 11r.

Note: Some non-802.11r clients can react adversely when connected to an 11r WLAN.  The current recommendation from Cisco is to have a separate WLAN for 802.11r clients.

802.11k is another amendment from the IEEE that helps to improve roaming.  802.11k provides a whole slew of information to the client, which allows the client to understand the RF environment and make an informed roaming decision.  This information can include channel load and AP neighbor lists.

11r and 11k help, however, that does not mean the infrastructure is irrelevant in the roaming picture.  With the help of a model train, we did some testing to figure out just how much impact the infrastructure could have.  We compared Cisco to one of our competitors, whom we will call Vendor A.

This video summarizes the results and shows the train in action, or continue reading for more details:
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