Cisco 9800 Flex Wireless Tuning

[sejamc71]

I just worked with a Cisco Consultant and installed a Cisco 9800 WLC. I've migrated all of my sites from Local AP mode to Flex mode. After about 2 months, users started reporting dropping, bad wireless connections, I had a company come out and do an Ekahau scan. Found a bunch of interferers which I am addressing. I called Cisco TAC and they had me turn off a couple of channels. DCA is enabled, but I'm still seeing co-channel interference and issues. I can't seem to find any resources online with regard to doing some fine tuning to improve wireless coverage. Is anyone aware of a resource for tweaking wireless settings on the 9800-L with APs in a Flex mode configuration?

[Flavio Miranda]

Hi

  I will try to add something based on what you described:

"I just worked with a Cisco Consultant and installed a Cisco 9800 WLC. I've migrated all of my sites from Local AP mode to Flex mode."

  Not relevant but I would ask why? For any other reason besides leaving the traffic locally?

"After about 2 months, users started reporting dropping, bad wireless connections,"

   This is important if this time is accurate. You can look for events happened around this time like design changes inside the builds

"I had a company come out and do an Ekahau scan. Found a bunch of interferers which I am addressing."

Very important although depending on the interference is unlikely you can remove completelly

"I called Cisco TAC and they had me turn off a couple of channels"

  This is weird.

" DCA is enabled, but I'm still seeing co-channel interference and issues."

  If you disabled a couple of channels, the chance you have co-channel interference increase. Co-channel interference happen due the APs using the same channel on the area.

"I can't seem to find any resources online with regard to doing some fine tuning to improve wireless coverage."

 Because there will be a limited action you can take. Coverage is a result of good AP placement and good site survery while deploying the APs. If this step was not done well, you can not fix it on the configuration. 

"Is anyone aware of a resource for tweaking wireless settings on the 9800-L with APs in a Flex mode configuration?"

  Flexconnect ot Local mode is not relevant for wireless part. The wireless as the physical layer on this case will have the same problems either in local mode or flexconnect mode.

[sejamc71]

I stated some of that incorrectly. TAC had me disable some lower speeds on the 5ghz. AP placement was done way before I got here so I'm working from a repair aspect, but may need to do a full replacement of the APs to get the correct coverage

[Flavio Miranda]

Then make all sense. It is indeed a good practice disable lower data rates.

 And that´s right. It is complicate to repair a faulty installation. The AP cell overlaping must be calculated from day zero. But, AP placement is the right path to have a good coverage which result is good roaming and stable connection.

[JPavonM]

It is extremely important that you can find and disable or mitigate those interferers.

I faced a similar issue a few months back, and the main problem was that DCA was not avoiding the impacted channel due to the narrowness band of interferer, but all users in that channel were disassociating or dropping. Finally I managed to find a faulty power source on a Crestron device that I replaced and voila, everything solved (by the way, the interference was created on channel 136).

As @Flavio Miranda mentioned before, the only best practice is to create a proper design, and that not only includes placing APs to address the capacity and coverage ranges, but also to look for any source of interference to create a deployment that can cohexist, and if not, mitigate that by disconnecting the interferer or dealing with it.