Clients Connect to N AP's on 5508 and get different Transfer rates than on 4404

[Glenn Sutherland]

I have have 2x 4404's (2x) and 2x 5508's all are running 7.0.240.0. When I take an 1142 and associate it to a 4404 I can connect a test client using N at 144Mbps and I can get transfer rates averaging 70Mbps (using iperf tests). When I take the same AP and associate it to a 5508, (same SSID, etc) I connect at 144Mbps but only get average 6Mbps transfer rates. I get the same results with 1252's. I get the same results if I wipe the config on the 5508 and start from scratch. It only happens when connecting at a/n, when I use a b/g AP such as 1132 I connect at 54Mbps on either controller and get transfer rates of 24Mbps. I have enabled disabled LAG (rebooted), moved the 5508 to connect to the same swtich ports, swapped GBICs. The issue happens on both 5508s, TAC has been unable to resolve this and they are confused as well.

Some of the other things I have tried:

• •-          You are facing the issue on 5508's WLC only.
• •-          Both the WLC and the client reports high connection speed “144Mbps”
• •-          iPerf between wireless and wired showed the following:
  • on 4400: 
    • [124]  0.0-16.9 sec   154 MBytes  76.5 Mbits/sec
  • On 5500: 
    • [124]  0.0-94.3 sec  70.2 MBytes  6.25 Mbits/sec
• •-          The AP is the same AP, you just bounce it from 1 WLC to another.
• •-          The location of the AP is the same in all the tests, but it can be replicated with an 1142 anywhere on site and get the same results.
• •-          The test PC is the same in both cases
• •-          The configuration is the same on both WLC’s confirmed visaully in GUI and via CLI outputs and compaired.
• •-          The switch is the same, but have tired swapping 4404 and 5508 in data center.
• •-          Tried to swap the GBICs.
• •-          Used different ports on the 5508 (not just diff GBICs)
• •-          Disabled the LAG to rule out the load balancing algorithm.
• •-       Replaced the patch cables
• Used same ip space that the 4404 is using without sucess.
• Upgraded my second 5508 to version 7.5 and exact same resutls.

Any ideas?

[Scott Fella]

What do you see on the 2.4ghz as far as throughput on the 5508?

Sent from Cisco Technical Support iPhone App

[Glenn Sutherland]

Well, your question prompted me to test first the a/n antenna (5ghz?) disabled on the AP:

- When AP is on 4404 I get 50+Mbps, when connected to the 5508 I get 2Mbps

Then I tried enabled only the a/n antenna, and disabling b/g/n:

- I got 70+Mbps on both the 4404 and the 5508.

It would appear that when I force the clinet to use b/g/n it works fine on the 4404 but not on the 5508. When the client is forced to use a/n it works fine on both controllers.

[arybczonek]

Hi 

In my 5508 WLC i have exactly the same problem as you  gsutherland 

I tried apply this command config 802.11b 11nSupport a-mpdu tx priority all disable

and i get message 

"802.11b network not disabled"

Why i must turn off b standard ?

Thanks for respons 

[Leo Laohoo]

Stupid Question:  How did you configure your 5508?  Did you configure the 5508 by copying the config of the 4400, change the IP address, and push the config to the 4400?

[Glenn Sutherland]

I have configured the 5508 from scratch. Will a config from a 4404 load on a 5508? If so I will TFTP it over.

[Glenn Sutherland]

TAC has resolved the issue. We issued the following comand to disable MPDU:

config 802.11b 11nSupport a-mpdu tx priority all disable

For some reason that had been disabled on the 4404 long ago (possibly 9 years ago when the vendor was on site assisting install) and that is why the 4404 worked fine. Once it was disabled on teh 5508 we started getting the speeds expected.

Thanks for the input, I have been working on this for 2 weeks, the solutoin always seems to be some CLI only comamnd to change settings not visable in GUI.

Cheers.

[Yahya Jaber]

Hi Glenn,

Good it was solved for you

[arybczonek]

Hi 

In my 5508 WLC i have exactly the same problem as you  gsutherland 

I tried apply this command config 802.11b 11nSupport a-mpdu tx priority all disable

and i get message 

"802.11b network not disabled"

Why i must turn off b standard ?

Thanks for respons 

[arybczonek]

Hi 

In my 5508 WLC i have exactly the same problem as you  gsutherland 

I tried apply this command config 802.11b 11nSupport a-mpdu tx priority all disable

and i get message 

"802.11b network not disabled"

Why i must turn off b standard ?

Thanks for respons 

[Scott Fella]

You need to disable the 2.4ghz network before you can issue that command. It doesn't mean 802.11b, but the 2.4ghz in general.  So if you uncheck 802.11b network from the GUI and hit apply, that will disable the 2.4ghz radios and you can apply that command. 

-Scott