Wireless Access

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Occasional Contributor II

Unacceptable system-wide performance

A year ago at our school, we installed a new controller and installed AP 105s where all of our AP 61s had been throughout the campus. Our campus has several buildings connected to our main data center through fiber links.


On any of our wired links, we can expect read/write data transfer back to our main file server at 85 MBps or better using this software: http://download.cnet.com/LAN-Speed-Test/3000-2085_4-10908738.html If a particular building is on a gigabit switch or better it can be much higher.


In the same building where our data center is located and just a few feet away from an access point, I get about 25 MBps using a laptop with b/g/n wireless. In other buildings on campus, we have our AP 105s getting power and data from gigabit POE switches that have dedicated fiber links directly back to the data center (i.e. they are not chained to any other switches).


During the summer with no one else on campus, I get about 4-5 MBps on a wireless link. During the busiest parts of the school day, connections are often under 1 MBps.


With no known building interference and physical line of sight to an access point, the laptop is slow at 5 MBps but 1 or less is unusable. Considering the financial investment we made of switches, a new controller, and many access points, I would expect much higher data rate.


We let ARM handle management of the APs and we get a very high signal in almost all of our classrooms and dorms. There is nothing that we have changed in the AP profiles that would affect their power levels, data rates, channel distribution, or anything else that I can think of.


So, I have a few questions:


-Is there any function in the web interface or CLI to measure the percentage of bandwidth that an access point and/or a controller is currently handling? Is there any visibility on the % of total bandwidth that is being used by these devices?

 

-If I plug in my laptop to a network cable and get bandwidth in the hundreds of megabytes and then plug an access point in the same cable with my laptop right next to it, why am I suddenly getting 1-5% of the bandwidth I had before? Is there any way to check logs or any kind of values to see some sort of failures occurring within the access point? We have Airwave installed but all it tells me is that people have crummy bandwidth.

 

-Have I simply failed to uncheck a box somwhere that says "Throttle all tunneled connections" or something similar?  Nothing else about our network underperforms or operates in such a manner.

 

I have left out information I thought was irrelevant or unnecessary but I’d be happy to fill in specifics if necessary. Thanks!

 

 

Aruba Employee

Re: Unacceptable system-wide performance

One of the things I would check is the busy times on the access point you are connecting to. Here is the command on how to do that:

 

(assuming you are running 5.x code or newer)

 

show ap debug radio-stats ap-name someAP radio 0 advanced | include Busy

 

(on a dual-band AP, radio 0 is 5Ghz and radio 1 is 2.4, anything above 20 on this output probably means that there is interference, either by non-802.11 or by other APs)

 

Let us know what the readings are. Be sure to run the command about 20 times consectively, and make sure you are looking at the correct radio, in your case if you are using 2.4Ghz on an AP-105, it should be "radio 1".

Thanks,

Zach Jennings

Re: Unacceptable system-wide performance

Have you tried to benchmark it with an iperf test, with the server plugged directly into the controller, or at least on the same subnet?

 

I tested a fairly basic wireless nic that only supports up to MCS 7 and with 40 MHz channel width on a-band I would consistently get ~50 Mbps from the AP105 and ~30 Mbps on 20 MHz width.  This figure went to about ~60 Mbps at 40 MHz width when I used the AP125.

 

I don't know about the g-band though, although it shouldn't be as bad as you say.  I'd definately look at testing with different adapters to see if you get the same results.

 

:-)


If my post is helpful please give kudos, or mark as solved if it answers your post.

ACCP, ACCX #817, ACMP, ACMX #294
Guru Elite

Re: Unacceptable system-wide performance

Please check out the troubleshooting thread here:  http://community.arubanetworks.com/t5/802-11n-Basics-RF-Design-and/RF-Troubleshooting-Best-Practices/m-p/21914/highlight/true#M92

 

 



Colin Joseph
Aruba Customer Engineering

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Contributor II

Re: Unacceptable system-wide performance

+1 to using iperf connected directly to a controller port. Maybe aruba will hook us up with an iperf util on the controller one of these days :)

Re: Unacceptable system-wide performance


keith_kent wrote:

 Maybe aruba will hook us up with an iperf util on the controller one of these days :)


What a great idea.  :smileyhappy:


If my post is helpful please give kudos, or mark as solved if it answers your post.

ACCP, ACCX #817, ACMP, ACMX #294
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