Speed problems with enterprise wireless-n

Unanswered Question
May 2nd, 2012

Hi Guys, new here!

We had a wireless network installed a few years ago which the support has now lapsed on. We are having a number of issues with throughput...

Controller x1:

WLC-5508-01

AP's x63:

AIR-LAP1142N-E-K9

Managed with Cisco WCS

Our G devices report to be connecting at 54G, tests with iperf show throughput of ~16Mbps, N devices connect between 21.5Mbps and 72Mbps and also only show around 20Mbps throughput with iperf. File copying from servers gets around 2.5Mb/sec transfer rates. There are no obvious alerts/events on the kit in WCS, I have rebooted a number of AP's to no avail. inSSIDer shows the AP's and their 300Mbps capability, but my N devices don't get anywhere near that speed, even when i'm stood directly underneath it with a device. I believe it is a dual band setup, as each AP has a seperate profile in WCS for b/g devices and a/n devices. The nics's in the devices are dual-band intel 6200's.

SSID's are secured with WPA2/AES/MAC Filtered, 802.1x RADIUS auth, linked with Server 2008 R2 DC via NPS

Could anyone shed any light on a potential problem or advise on troubleshooting techniques... this isn't really my area of expertise!

Thanks!

I have this problem too.
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Stephen Rodriguez Wed, 05/02/2012 - 07:14

What are the end points for N?  you'll want to look at the specs of the WNIC to see how many spatial streams that they support.

For N to work, you need to either be Open, or WPA2/AES and have WMM enabled.  If the clients are showing a connection to the AP of 72Mbps, then that should all be ok.

To be able to get the 300M, you would need to channel bond the 5Ghz to the 40MHz wide channel.

Steve

Leo Laohoo Wed, 05/02/2012 - 16:57
inSSIDer shows the AP's and their 300Mbps capability, but my N devices don't get anywhere near that speed, even when i'm stood directly underneath it with a device.

What clients?    If you are talking about iPhones and iPads you're ain't going to go near 100 Mbps in wireless.  The highest rate the iPhones and iPads can go is MCS rate 7.

Designing 'iPad WLANs' poses new, renewed challenges

daviwatk Wed, 05/02/2012 - 18:33

Be sure to verify the items Stephen and leolaohoo are mentioning.  The Intel 6200 series contains several models.  To achieve the 300Mbs, you will need 2 spatial streams minimum, and be connected on your 5Ghz spectrum with bonded channels.  Also make applicable changes at WLC to achieve N throughput.

Troubleshoot 802.11n Speeds

http://www.cisco.com/en/US/products/ps6366/products_tech_note09186a0080a3443f.shtml

Configure 802.11n on the WLC

http://www.cisco.com/en/US/products/ps6366/products_tech_note09186a0080a3443f.shtml

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Posted May 2, 2012 at 6:41 AM
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