Slowness with 3802 connected to 9800

[pabloayalas]

Hello,

I'm checking if anyone had this experience with the new controllers connected to the 3800 access points. We have multiple 9800 WLCs that we migrated from the old AireOS 5520's. All new WLCs 9800 are running version 17.12.2. We have sites:

• 9800 with 9130AXI only
• 9800 with 3800AXI only
• 9800 with a combination between 9130AXI and 3802

Out of the blue, clients connected to the 3800 are getting download speeds of 1-2 Mbps, while clients connected to 9130AXI have full 200-300 Mbps. When asked users to move from one 3800 AP to another 9130AXI, we see an increase in download speeds. We have multiple TAC cases, but we are still waiting. What is weird is that on one of our sites, we have only 3800's; we are not seeing this behavior now. We tried rebooting the access point and switchover between HA pairs, and nothing; the only solution is to reboot the entire WLCs. Does anyone have had this experience? 

Thanks

[Leo Laohoo]

Reboot the APs. 

What the channels when they return.  See if DCA/RRM will kick in. 

[pabloayalas]

We have tried everything, but nothing seems to work. We've rebooted the access points and switchover the WLCs and still nothing. The only thing that has worked so far is rebooting both WLCs. Should we consider turning on debugging? I hate to say it, but the TAC hasn't been helpful with this issue.

[Leo Laohoo]

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@pabloayalas wrote:
switchover the WLCs

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Is this an HA SSO scenario?

[pabloayalas]

Yes, it is. We have two 9800-40 units running version 17.12.2. All configurations and management are handled through DNA-C. We attempted to switch between the WLCs to resolve the issue, but it did not have any effect. However, when we rebooted the WLCs simultaneously, the problem was resolved. Immediately after the WLCs were restarted, all clients experiencing slow internet speeds returned to normal.

[Leo Laohoo]

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@pabloayalas wrote:
However, when we rebooted the WLCs simultaneously, the problem was resolved. Immediately after the WLCs were restarted, all clients experiencing slow internet speeds returned to normal.

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What was the uptime of "system" before the reboot. 

NOTE:  When performing a double-failover, the uptime is based on uptime of the physical unit.  But the "system" uptime is based on the VSS and this will continue to tick until both units are rebooted at the same time.

[pabloayalas]

It's been less than a month. We are currently installing these new WLCs. Just for awareness, this is a BUG issue. The TAC has identified the ID (CSCwj76892) - 2802 Low downlink speed noticed due to WLC not configuring aggregation schedule parameter correctly. We are migrating from the old AireOS to the Catalyst 9800 family (IOS-XE). 

[marce1000]

   - Have a checkup of the WLCs 9800 configuration(s) with the CLI command show tech wireless and 
     feed the output from that into Wireless Config Analyzer  (do not use simple show tech as input for this procedure)
     + Consider moving on to 17.12.3 which has become an advisory release
     + Checkout : https://www.cisco.com/c/en/us/support/docs/wireless/wireless-lan-controller-software/220877-troubleshoot-wireless-speed-issues.html
      + (Added) : make sure that the wifi drivers of the clients are up to date.

 M

[pabloayalas]

@marce1000, thanks for your recommendation. This has been identified as a BUG CSCwj76892 (2802 Low downlink speed noticed due to WLC not configuring aggregation schedule parameter correctly.). This impacts when you are migrating from AireOS to IOS-XE. We are going to upgrade to the latest version, 17.12.4, which is supposed to have the BUG fix.