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Questions about Dual-Band routers and using g/b/n/ac together

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#1 Cyber Akuma

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Posted 23 August 2013 - 21:09

I would like to mention that I am not too good with networking hardware.

I recently got a dual-band AC router (Asus RT-AC66U) and have been hearing some conflicting advice on how the dual-band works.

First of all, if I take for example a Dual-Band N router with two 300Mbps bands. That means that you have two lanes that go up to 300Mbps, and they don't add up to 600Mbps right? I have heard it mentioned both ways, and I always assumed they don't add up the same way having two 1GHhz cpus would not add up to having a single 2Ghz CPU.

Also, I was told that each band would have it's own SSID, but when I set up my router I only saw one SSID. I assumed it was automatic and the router manages which device goes on which band until I was told that I should be seeing two SSIDs instead of one (other than setting up WiFi security and assigning specific IPs to specific devices by network name I left it more or less on default settings, I am certain that the dual band option was enabled though).

And finally, I was told that this is important because having a b or g device on a n band would slow the band down to b/g speeds. Is this true? Does that mean that when AC devices are common, and I connect an old b or g device to it, that it will slow the entire band down to below even n speeds? Or that all the n devices I have now will mean there was no point in getting an AC router unless I get rid of them all? (or stick them on their own band?).

#2 Roger H.

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Posted 23 August 2013 - 21:51

To your first question the answer is yes - 2 x 300Mbps connections - 2 separate 300Mbps lanes.


You can have 2 separate SSIDs per band or make them the same. To "see" the other SSID your device (phone, laptop, etc) need to have 5Ghz support (and the router be in a channel that the device can utilize. ie - some phones don't do the upper 5Ghz band, say channels higher than 50. Some will see 36-48 and 149-160 but don't see those middle channels).


Connecting a B or G device on 2.4Ghz radios wont slow down the whole network, it might slow the 2.4Ghz N devices but not all the way down, also only when they are active as well.


AC devices use 5Ghz so they wont be bothered by 2.4Ghz devices (B & G) which is one of the perks of simultaneous dual-band routers. It's technically 2 different networks even though they are connected.




Your B & G devices can hang out on 2.4Ghz all day, I doubt you even have B devices anymore. So if it's just G devices you'll be just fine when it comes to 2.4Gghz N devices. Keep your N devices that are capable of 5Ghz on those channels and you wont experience slow downs there.

#3 +BudMan


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Posted 24 August 2013 - 12:26

I would prob pull the B out of your statement about slowing down the network -- I am fairly sure that when a B is associated, not even active that there is quite a bit of overhead with making sure the B client doesn't transmit when the other G and N clients are talking and beacons and such. Because of this added overhead you have lower performance.

Simple enough to test.. Even on a G router, test your throughput - then turn on B compatibility mode and just connect a client in B mode. Most any wireless card should be able be hard coded to only use B mode.


A good test of this would be to set G/N only on your AP.. Run a iperf test, file copy timed, etc. Then change over AP to allow B to connect.. Run the tests again.

Then actually associate a B client and run your tests again on your G or N client. Might have to do that this afternoon ;)