Does it make sense to keep different SSIDs for 2.4GHz and 5GHz wireless networks?

Question

My router can have different SSIDs for 2.4 and 5 GHz and I'm not sure if it's better to have the same SSID or not.

Initially I put the same network but I got confused when the MacBook Pro displayed me two networks with the same name, an I was not able to distinguish between then.

So the next step was to configure two networks, "home" and "home-slow".

I would like to know what are the pros/cons for these configs.

Note, I do have a Cisco E4200 router, configured:

• 5GHz - SSID "home" - Mixed - Auto 20 MHz/40MHz - Auto-DFS
• 2.4GHz - SSID "home-slow" - Mixed - Auto 20 MHz/40MHz - Auto

Note, iPhone4 and HTC Desire HD do not see the 5GHz network, only the 2.4 one, not sure why. MacBook Pro seems to detect both of them.

Answer 1

Most wireless stacks do not consider these networks to be different to each other, so 2.4GHz has the same weighting as 5GHz.

If this isn't important to you, then keeping the SSIDs the same will mean it will pick whichever it sees first.

If you keep the SSIDs different, it means that you can prioritise 5GHz over 2.4GHz by adding both to your Wi-Fi connections, and saying that one is better than the other.

Note that 5GHz is not inherently faster than 2.4GHz. They both have the same theoretical maximums, 150 megabits per second (single radio chain), 300 megabits per second (two radio chains and two spacial streams), or 450 megabits per second (three radio chains and three spacial streams). However because the 5GHz frequency band is less crowded, there is more chance that the AP can get a full 40MHz band of radio to carry data.

Answer 2

If you have high quality Wi-Fi client devices, it's best to use the same SSID for both bands so your clients will automatically roam to the band that suits their needs best.

If you have low-quality Wi-Fi client devices, you might need to second-guess their band-choice decisions, so you might want to have separate SSIDs.

Your MacBook Pro should not have shown you two networks with the exact same name, unless you had accidentally configured two different security types for the two networks. Or maybe you thought you had configured the exact same name for both bands, but you'd accidentally put a space at the end of one of the names and didn't notice.

Your iPhone 4 doesn't have a 5GHz radio, which is why it can't see your 5GHz network. I suspect the same is true of your HTC Desire HD.

I recommend that you leave your 2.4GHz network set to 20MHz-only. Using 40MHz in 2.4GHz doesn't leave enough room for other uses of the band, such as Bluetooth. All of Apple's N-capable gear limits itself to 20MHz operation in 2.4GHz (even if the third-party Wi-Fi AP is configured to allow 40MHz operation in 2.4GHz), in order to leave room for Bluetooth. So your MacBook Pro is only going to use 40MHz-wide channels in 5GHz.

Answer 3

It is best to keep different SSID's for each network. It is most likely that your router separates the two bands just as it separates Wifi from ethernet. Another reason that this is important is that you don't want to have two devices with the same hostname on the same network; Some routers use their SSID as their hostname.

So, I suggest you name one Foo and the other Foo5. If you later add a repeater, give it the same SSID of whichever signal it's repeating.

As for which devices you connect to which frequency, it is completely up to you. 5ghz offers much faster speeds and a wider range. That means that with crowded networks, 5ghz has a more dramatic performance increase. Devices that don't require much bandwidth, or those which are farther away should remain on the slower 2.4ghz. Think of the 2.4ghz band as a 'legacy' band, simply there to help ease transition into 5ghz.