WLC-4402 : Users complaint slow down load

Unanswered Question


My users complaint the down load speed is slow when using wireless.  I checked and indeed is slow.

Before this happen, my WLC is running 802.11b/g.  So my thought maybe the 802.11b can slow down

on the users so I changed WLAN to run on 802.11g only.  Well, it is still slow.  If anyone has any idea

on this is appreciated.

The WLC-4402 is running on version 4.1.185 and all 19 LAPs is 1242AG with IOS version 12.4(3g)JA2

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Leo Laohoo Wed, 04/14/2010 - 15:38

I'd be looking at possible channel conflict with other wireless APs nearby.

Hi  leolaohoo,

Thank you for your input.  I checked and I am not certain to define if there is any channel conflict of the nearby AP but I do see from

time to time the Interference Profile Failed and then Passed.  I checked the MAC address and pin down to certain WAP but not able

to isolate what device causing interference.  It is a good advice to look for.

George Stefanick Thu, 04/15/2010 - 07:55


Can you elaborate on what you mean by slow ?

How big of a pipe do you have to the Internet?

Have you compared wired and wireless downloading?

What is your channel utilization?

Hello George,

Thank you for your reply.  Here are the answers for you questions:

When users download a 4G file, it took about near 1 hour a Gig.

The Internet pipe is a Gig

Comparision between wire and wireless was significant different.  For wire was over 1M/Bps while wireless around 170KBps.

Channel Utilization is depending on what channel and is changing from time to time.

     Channel 1 is between 17 and 62, Channel 6 is between 9 and 33, and Channel 11 is between 28 and 45.

Hope this help.

George Stefanick Fri, 04/16/2010 - 10:16


"Channel Utilization is depending on what channel and is changing from time to time.

     Channel 1 is between 17 and 62, Channel 6 is between 9 and 33, and Channel 11 is between 28 and 45"

Do your APs have 802.11a radios? If so, move your asscoation to the 802.11a side and run your test... Your channel utlization is high, very high. I assume you have 1 PHY rate set to mandatory and lower data rates are enabled 1,2,5.5 ?

Lets clean up the utilization first and see the results before you go further...

Test the 802.11a side ...

Hi George,

The APs has 802.11a and it was disable about a year ago.  The data rate is disable on 1 and 2.

5.5 and 11 are mandatory and the rest are supported.  Since 802.11b was disable a couple day

ago, some users said some what better.  Now all APs are running on 802.11g.

Please let me know if there is another way to clean up the utilization.

George Stefanick Fri, 04/16/2010 - 12:28

After you made the move to 'g' and 1 and 2 are off ~~ you still are seeing utlization above 30+ percent? Something isnt right ...

Are your channels close together?

How many SSIDs do you have currently active ?

The channels are not close together.  There are only 2 SSID.

Anyway I have been testing after open a case with TAC and this wireless TAC is good.

He suggested disable few functions and the speed increasing about 5 to 6 times.  Althought I am still see hight utilization over 30+.

Still interest in find out why.

Here is how to make the wireless running better (this is also for you Leolaohoo)

From WLAN under Advance uncheck Aironet IE, Client Exclusion, and Infrastructure MFP Protection.

George and Leolaohoo,

Thank you for your input.  I am still interesting to find out what cause high channel utilization.

Leo Laohoo Fri, 04/16/2010 - 17:23

1Gb to the internet?  Wow!  That's hefty.  What is the make and model of your router?

Have you tried 4gb file from your server?  I want to know if the bottleneck is your link to the internet or the wireless.

Actually is a Cisco switch with enable L3 and the model is 3560G.  Yep, it is a gig.  The traffic is constantly around 350M and sometimes

it spiked up to 650M.  I was not able to down load the same file since I do not have the login ID.  I tested the down load from Microsoft

service pack between wire and wireless and wire is somewhere 900K while wireless is around 170K if I remember correctly.


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