Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Wireless performance question.

Trying to understand any performance issues on our wireless network.

I went to NCS and ran a report  for busiest APs (did all of them since we have 40 of the).

80% of the APs have Channel Utilization over 50% .. about 10 of them are between 70 and 80 %

Most APs have about 5 clients attached. These are usually Iphones etc.

I am trying to understand why the chanel usage would be so high and what I can do about it.

the controller is a 5500 and the AP's are aircap 3602s.

Any suggestions would be great!!

Thanks

  • Security and Network Management
10 REPLIES
New Member

Wireless performance question.

Do you have the lower B data rates enabled? 1-9? If so, disabling everything lower than 11 will probably help.

Another step you can take in troubleshooting is changing one of the APs to SE-Connect mode, and connect to it with Cisco Spectrum Analyzer. You will be able to check the RF space and see if you can tell when is driving up the utilization in the air.   

Re:Wireless performance question.

To add to what michael said, how many SSIDs do you have enabled. Each one beacons at the lowest mandatory rate. Low mandatory rate and 4+ SSIDs can spell high utilization. Also could mean high co-channel interference.


Sent from Cisco Technical Support Android App

New Member

Re:Wireless performance question.

Thanks  for the suggestions.

i took a look this morning at 8am .. there were 60 clients connected and utilisation for most of the APs was still between 50 and 70%.

We have 3 SSIDs associated to these APs.

Michael, I will have to google most of your reply to undestand it.. I will get back to you on that

Thanks

Drew

New Member

Re:Wireless performance question.

So I went on the 5500.. wireless... 802.11b/g/n .. Network and disabled data rates up to and including 9mbps.

Didnt notice a difference.

I have a backup AP here.. I will take a crack at the spectrum analyzer and get back to you.

Hall of Fame Super Silver

Re: Re:Wireless performance question.

If your in a downtown area with a lot of neighboring RF, you can see high utilization. If your playing with data rates, try to disable all data rates below 11mbps. If you don't need to support 802.11b clients, then also disable 11mbps. Try setting 24mbps and 54mbps as mandatory and the rest supported which are not disabled.

Sent from Cisco Technical Support iPad App

Thanks, Scott *****Help out other by using the rating system and marking answered questions as "Answered"*****
New Member

Re: Re:Wireless performance question.

Thanks Scott. I just tried it. Will see how it goes.

Michael: I looked and only found Cisco Spectrum Expert... but I dont think it is free. Is that what you were refering to ?

Hall of Fame Super Silver

Re: Re:Wireless performance question.

Just wanted to add. In very high density environments like stadiums, you can hit 100% channel utilization. You can also see from the client end when the time slot for the client opens up as you can see a burst in throughout. In downtown area here in Chicago, channel utilization can be very high. I once did three installs for various companies all in the same building and they were adjacent to each other. It's just how things are at times. Having CleanAir can help you see interfering devices but a spectrum analyzer can also help you understand the RF around you.

Sent from Cisco Technical Support iPhone App

Thanks, Scott *****Help out other by using the rating system and marking answered questions as "Answered"*****
New Member

Re: Re:Wireless performance question.

Thanks.. just found this on youtube... using NCS and CleanAir to troubleshoot Interferance.

https://www.youtube.com/watch?v=fIpLoomYhBM

Will take a crack and let you know how it goes.

Thanks again.

Hall of Fame Super Silver

Re: Re:Wireless performance question.

The WLC config Analyzer can also help you look at the CleanAir detected devices

https://supportforums.cisco.com/docs/DOC-1373

Sent from Cisco Technical Support iPhone App

Thanks, Scott *****Help out other by using the rating system and marking answered questions as "Answered"*****
277
Views
14
Helpful
10
Replies
This widget could not be displayed.