Best practices for slowness issue of users while using WIfi

[subodh goyal]

Best practices for troubleshooting slowness issue of users while using WiFi

I have a site where multiple users are facing slowness in  all SSIDs.

What steps need to follow for troubleshooting in WLC and APs.

[Flavio Miranda]

Hi

 First do tests in a machine connected to the cable network.  If you have any link problem or any device related problem, cabling network will also face the same problem.

 If cabling network is fine, then you can be confident that is something related to wifi. 

Troubleshooting wifi is way more complex. As you should always start a troubleshooting by the lower layer of  OSI model, which means the physical layer, in Wifi it means performing a site survey to make sure that from the clients perspective you have enough signal.  This is a very important step and most companies and engineers skip this and start looking upper layers. 

[subodh goyal]

there is no issue with wired network, we have checked by connecting laptop to switch port, services are working fine while using wired network.

[marce1000]

             - Include WLC and APs model(s) too + software version(s) , 

 M.

[subodh goyal]

WLC Model- AIR-CT2504-K9
WLC version- 8.5.140.0

AP model- AIR-CAP2602E-A-K9
AP Version- 15.3(3)JF9

[marce1000]

 - As stated by other reply , basic wireless health depends on good coverage , lack of interference  , number of clients, ... ; besides that today 2504 and aireos is getting old  use latest software version  advised https://software.cisco.com/download/specialrelease/8f166c6d88b9f77aabb63f78affa9749 , as mentioned in https://www.cisco.com/c/en/us/support/docs/wireless/wireless-lan-controller-software/200046-tac-recommended-aireos.html , also have a checkup of the WLC configuration :   
                             1. Type "config paging disable" in privileged mode to set your terminal to display without any breaks.
                             2. Type "show run-config" to display the config.

                         Have the output analyzed by : https://cway.cisco.com/wireless-config-analyzer

  M.

[subodh goyal]

Level Message
30001
Version: Controller with not recommended code version:8.5.140.0
Action: Controller is running deferred or not recommended code and should be upgraded. Refer http://www.cisco.com/c/en/us/support/docs/wireless/wireless-lan-controller-software/200046-TAC-Recommended-AireOS.html
30128
CleanAir: CleanAir BLE Beacon detection signature has significant performance impact, it is recommended to run CleanAir enabled, with this specific device type disabled, unless required by deployment
Action: Ensure BLE beacon detection is disabled for best 2.4 GHz performance, unless required by deployment. Command: config 802.11b cleanair device disable ble-beacon
120003
Security: It is recommended to monitor all channels for rogue detection. Band(s): 2.4GHz,5GHz
Action: This is best practices recommendation, to improve rogue detection. This is under 802.11a/b, General tab, Monitoring Channel setting.
30006
Backup Port: AP manager interface with backup port, incorrect configuration: management
Action: Never configure a backup port for an AP-manager interface, even if it is allowed in older software versions. The redundancy is provided by the multiple AP-manager interfaces
30007
Interface: Interface does not have port assigned, incomplete CLI configuration: null
Action: Interface created without any port assignment, incomplete config. Use config interface port command to correct this problem
50003
Mobility: Peer down. This may have impact on CPU usage, and roaming. Peer(s): 10.5.13.157,10.4.13.160,10.5.13.156
Action: On some scenarios, a mobility peer down can drive CPU usage up. Please check configuration, remove any unused peer entries, and/or check controller reachability

[marce1000]

                 >...Level Message
                   30001
                  Version: Controller with not recommended code version:8.5.140.0
                  >...

                - Correct and or implement as much as possible  ofthe given  advisories  
                                   especially the ones with a red alert

 M.

[patoberli]

One more thing to check, what connection speed is reported by the client and the WLC?

And how do you define slow When browsing, when sharing files internally, ...

How is the AP radio load on an affected AP at a time where it's slow?

[Scott Fella]

First thing first.  Have you been able to replicate the issue yourself with multiple different devices?  What you are asking is very hard to provide an answer to without really knowing the environment.  As you can see from the replies, there are things that folks look at first, but they also know their environment and can eliminate major variables like density, client issues, ap's bouncing, etc.

[Leo Laohoo]

First step:  Go to the site and VERIFY.  Determine if the issue is happening to one person, some people or everyone.  

Step 2:  Verify and REPLICATE the issue.  Take a laptop, tablet and a smartphone and make attempts to replicate the issue.  It is of utmost important the tablet and smartphone are different OS, i.  e.  One is Apple OS and another is Android OS.  All three must running the latest supported firmware, particularly the Windows-based laptop. 

Let us know what the results are.

[JPavonM]

All replies here are correct, and the most important thing is been able to reproduce the issue and not rely on end-user experience as they could be making something wrong.

Check AP locations and orientations (I have seen outrageous installations), check if any non WiFi interference could be impacting (AC machines, motors, luminaries, bad power sources, ...), perform tests with no users at the office and with different devices (Apple, Android, Windows with different wireless NIC, all of them that are been used at the office), and then during business hours, check what users do when they complain (things like sharing files, remote loading resources, downloading/uploading files, and streaming audio/video, increase the utilization of the client station buffers, the AP buffers and the medium), check for congestion (not only user account by AP/radio but also for neighbour APs using same channels), and then check how is it like with updated code in the APs nad updated drivers and OS patches.

It would be great to perform a professional WLAN survey with tools that could give you not only the signal coverage, but also real SNR values, real data rates, perform active survey, see channel utilizations and look for interferences.