Wireless Issue high ping

[Makrem YAHYAOUI]

Hello all!

I have a problem with users which are connected to our customer Wi-Fi network. When I do ping to IP address of WLC, wirless gateway or LAN DATACENETR or Google DNS I see that 15% of packets are dropped and sometimes ping is around 1-2289ms ( on wired network everything is working fine).  I'm using Cisco WLC 2504 and 16 AP (AIR-LAP1041N-E-K9). I have this issue even when I'm sitting almost next to AP. Software Version on WLC:  8.2.166.0

From Best Practices this is marked as done:

Infrastructure: Application Visibillity, Disable Aironet IE, NTP, Multicast Forwarding,Virtual Gateway IP, WLAN not on Management Interface

Security: Client Exclusion, Legacy IDS, Min Rogue RSSI Threshold, WLAN with 802.1X

RF Management: Auto Coverage Hole Detection, Auto Dynamic Channel Assignment, Auto Transmit Power Control, CleanAir Detection, DCA Cisco AP Load, Event Driven RRM, High SSID Counts, Wifi Interference 

If you need tech-support, i'll post it later

Need help please,

[Sandeep Choudhary]

Hi,

1. The first thing to do is to isolate the issue. Let's make sure that the problem is definitely related to the wireless network. Take a Laptop and connect to the same switch that the WLC is connected to. Run the same SSH, ping tests... If that is working fine, then lets proceed.

2. Another test .... create a open SSID and test from that and see if you still are having issues. That can eliminate an issue in the controller, and network side.

3. Have you tried your SSID on 2.4 GHz and 5 GHz only . Not mix, but one or the other and compared results?

4. If only one clinet has issue then Check NIC driver !!!

Regards

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[Makrem YAHYAOUI]

Hi Sandeep, 

Thank you for your reply,

To answer your question:

1. 

-> we have isolated the issue, we have already connect to the same switch that the WLC is connected to. and run the same ping test without drop and without high ping since it's 1ms

2. Another test .... create a open SSID and test from that and see if you still are having issues. That can eliminate an issue in the controller, and network side.

We have created an open SSID and test with WLC but getting the same issues. we don't have this issue when we configure and Autonomous AP.

3. Only with 2.4 GHz.

4. The issue occur with the most wirelles client!!!

[patoberli]

You could have a very overloaded 2.4 GHz.

On your WLC web GUI, click on the Home link on the top right (if you are in the Advanced settings GUI), now select AP Performance.

How is the Channel Utilization and Interference of your 2.4 GHz radios?

If it's > 60% for most APs you have a problem. Could you maybe post a screenshot of that screen?

[Makrem YAHYAOUI]

Hi Patoberli,

Here bellow the screenshot of the Channel Utilization and Interference of your 2.4 GHz radios as your request 

 it's < 60% for most APs

[patoberli]

Ok, this looks mostly fine, besides the one AP with all the Coverage Hole events. But this could also be normal, depending on your AP setup.
Do you have CleanAir enabled on the APs?

[Makrem YAHYAOUI]

Yes Patoberli,

We have the Cleanair enabled on the AP, it is globaly enabled with the best practice section.

[Sandeep Choudhary · Accepted solution]

also..

1. check the swicthport config where WLC is connected.

2. find any RF interference nearby APs...

[Makrem YAHYAOUI]

Hi Sandeep,

Hereby attached, you can find performance summary for all AP, I can see some AP with up to 50% of interference.

[patoberli]

What I can see with those two APs, they are running with a very strong signal, maybe to strong.
Do you DCA and TPC enabled and with which settings? You find this under Advanced -
Wireless - 802.11b > RRM.

[Makrem YAHYAOUI]

here the config of TPC and DCA under Wireless - 802.11b > RRM

[patoberli · Accepted solution]

Ok, try the following under DCA:
Avoid Cisco AP load - enable
Avoiced Persistent ... - enable

TPC looks fine, leave it as it is for the moment.
Oh, under Network, make sure you disable all 802.11b rates plus change the slowest 802.11g ones to supported (disable 1, 2, 5.5, 11 / set to supported 6, 9, 12, 48, 54) and the rest to mandatory. You need to disable the "802.11b/g Network Status" to change this (which will disable your 2.4 ghz wireless), don't forget to re-enable it.
This will disable support for 802.11b clients and will increase the throughput for all others. Please note, clients with a very low reception of the signal might not anymore connect. If this happens, change 12 to Mandatory.

[Scott Fella]

Is this a new install?  Curious if this was an upgrade and then you had reported issues or not?  You have any other sites running that code or a different code with different experience? 

Our sites in downtown buildings are also high CU on 2.4ghz and lowering the tx power to almost the minimum and disabling others have helped. I don’t know how dense or sparse your deployment is, but if RRM is setting the tx power high, I’m going to assume that it’s not a very dense environment. I have tested with users on AP’s (2.4GHz) with CU around 70% with no user experience issue. Not saying that high CU is bad, because it really is, but you should look at other things also. Seems like you probably are seeing high retries and that’s causing the slowness and poor experience. For DCA, maybe set your max tx to 11 and see if that lowered the CU. Make sure that you have adequate coverage and signal strength in the areas between AP’s just in case. 

Adjusting your data rates should help also like patoberli mentioned. However, you need to make sure you have coverage.