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Channel bonding

Hi,

Need some advise here. My faculty of architecture decided to go all wireless this year. I've design the wireless network with a high density of 5Ghz APs. When a look at the stats, I dont have any legacy 802.11a device. Since I have a lot of user cramped in a small building and they need to send very large file, does it make more sense to use 20Mhz or 40Mhz channel. Right now, with 20 Mhz channel, I dont overlap but with 40...I've sure there will be some in the most cramped area. Advice....

Typical use a the network is sending CAD files(building plans) of 100MB to 500MB. Many one file directly from NFS servers...some could say that wireless is no good for this type of usage...but try gaining the authorisation to put wall jack in a historic building built in 1670.   

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3 REPLIES

Channel bonding

Hello Dominic,

The question to bond or not to bond, that is the real question. And my advice, BOND.

The 5 GHz side allows for many more channelsm even with hi density you can still design a network with limited over coverage. Lets look at the basic UNIIs.

UNII 1 - 4 channel

UNII 2 - 4 channel

UNII 3 - 4 channels

Just using the basic UNIIs you have a total of 6 channels to deisgn with, thats double what we have on the 2.4 GHz side. A few things you might know already, but will cover for good measure.

When you bond and take advantage of 802.11n rates you need to insure WMM is supported on the WLAN. You also need to use WPA2/AES. If you dont meet these 2 items, no 802.11n for you.

When 2 channels are bonded, 1 channel will act as your managment, meaning this is where your beacons will come out of. This allows legacy devices (802.11a) to see and use the medium if they dont support 802.11n 40 MHz.

Only problem I would be aware of, based on my expereince. Is neigboring access points that may also be bonding and causing you interference.

I hope this helps ..

__________________________________________________________________________________________ "Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin ___________________________________________________________
Hall of Fame Super Gold

Channel bonding

If I am allowed to add to George's post ...

One of my biggest gripe about wireless in a school/academy is the perception of BYOD.  In particular, it's the perception of "... manufacterer says my device(s) support 802.11n but why can't I get 802.11n speed?".

Tablets and smartphones (Androids, iPads, Blackberry, etc.) don't have enough CPU grunt and battery life to push above MCS rates 7 (35 Mbps).  Hence, according to my notes, Androids and iOS operate in the 20 Mhz channel bond.  For short, the MAXIMUM requirement for Wi-Fi they'll require is plain-ole 802.11a/b/g.

But this does not mean you shouldn't bond. On the contrary, I'd recommend bonding too because there are some laptops/netbooks that CAN push 40 Mhz.

Hall of Fame Super Silver

Re: Channel bonding

You both have great inputs all the time! I must agree with George and Leo... Bond all the time. If you have specific SSIDs for devices that you don't want them to chew up all your throughput or don't support 802.11n, disable WMM.

Sent from Cisco Technical Support iPhone App

-Scott
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