Band Steering

In a typical wifi access point (AP) that can do both the 2.4GHz and 5GHz at the same time, your wireless client such as a laptop or smart phone can either connect to one band or the other, but not to both at the same time. In other words, as a start, you can associate the client to the 2.4GHz band with its corresponding WPA password. The client will remember this association so that the next time this 2.4 GHz SSID is in range, the association will automatically re-establish. You do not need to put in the password again. Then you will tell the client to associate to the 5GHz band and go through the same routine. Now, your client remembers and caches the log in credentials for both SSIDs for future encounters.

Your client device will see both SSIDs. If you name the two signals with the same SSID, this SSID will appear twice on the detected list. This "duplication" only serves to confuse you. Therefore for dual band APs, you should give each band a unique name that will tell you that one is 2.4GHz and the other is 5GHz. Examples being MyNetwork24 and MyNetwork5.

If you want to switch over from one band to the other, you have to do this manually. Certain high end APs have a feature called band steering. Basically, the AP will associate with the client at 2.4GHz first but when it detects too much congestion at this band, the AP will automatically tell the client to switch over to that of 5GHz. As you recall, the client already has the passwords cached for both bands. You do not need to do the switch manually and certainly not having to enter the password every time. Therefore band steering is a convenient way to get the best of both worlds.

The least expensive AP that I can find so far that has this feature is Engenius EAP600. At about $150, it's more expensive than the other dual band APs that can be found at half the cost, but with band steering, it's worth the extra cost in my opinion. Another access point that does band steering that also can participate in mesh networking is one made by Open-Mesh. The cheapest model is the MR600 that goes for $175.

Imagine you are in the same room as this EAP600 enjoying the faster speed of the 5GHz signal, but as you walk away, this 5GHz signal gets weaker because of its shorter wavelength nature. Eventually, the association to the 5GHz is terminated. However because of band steering, the client device will automatically jump to the 2.4GHz band and maintain the network connection. The 2.4GHz signal has longer range and less susceptible to blockage, but it is prone to interference from co-existing 2.4GHz signals. The 2.4GHz signal also has longer wavelength so less data can piggyback on its waves. Therefore, the data transmission speed of the 2.4GHz is perceived to be slower (and it is). Conversely, when you walk back into the room, the reverse will happen. The client device will re-associate with the 5GHz band to give the data speed a boost.

Below is m info on how to set band steering with a cluster of APs that support it. The video does not use EAP600 as example so I am not sure if EAP600 can be used in these clustering. EAP600 is categorized as an enterprise AP so it should be able to be managed as such.
https://www.youtube.com/watch?v=sbiYJYFSAb0

General info on band steering itself
https://www.youtube.com/watch?v=uGmfPwbs2Jg

Introduction to Open-Mesh Access Points
http://youtu.be/1YOoT3NxgYg