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Delayed roaming

Pako1
Level 1
Level 1

I have inherited a 5 year old WLAN deployment where clients have never successfully roamed. There is a 10 - 20 second delay when moving between AP. During this break the wifi icon disappears from devices and connectivity is lost. We have a mix of iOS, Android, SurfacePro and the odd laptop on the network and all encounter the same issue. I do not see any disassociation events in the debug when this happens.

 

Where do I troubleshoot from here to track down the root cause? have attached a debug log

 

5508 (8.2.151.0) controller and mix of 3502 & 3602 AP. Dual 2.4/5Ghz

 

 

33 Replies 33

Same for me, since like always with Cisco APs. Not sure why though, but the 802.11n models showed it really strong. Now the newer 2802 which are 802.11ac based, less so.

There were models in the past, which had one more simultaneous stream in the upload direction (or was it antenna?), for those it was normal.


Thanks. Seems to be kind of normal then I guess as there a multiple threads out there discussing this. Its not an issue that causes problems in real life however since data rates are high enough for most workloads in our environment these days.

btw - just updated the driver of a Intel wireless NIC from mid 2017 to mid 2018 and data rates nearly doubled on that client. It is unbelivable that the driver on the client device always have that much impact.

The client device is the main factor and Intel has a history of really bad drivers. So I'm not surprised at all actually ;)

Btw. If you update the Wi-Fi driver for Intel Wi-Fi devices, don't forget to also upgrade the Bluetooth driver (separate download).


Pako1
Level 1
Level 1

The Corp SSID is 5Ghz only. Guest was previously 2.4 only. The drop happened roaming on both these as well as the dual. Happens to all devices on all sites which led me to think it maybe a config problem

It could also be a Radius or SSID security settings issue. But now it sounds like it's working okey'isch?


So what should I be looking at in Radius/SSID settings? Any improvement would be better than what we have now now

Pako1
Level 1
Level 1

No, still no change for our problem. We have mixed device network not just laptops like the other person asking questions in this thread

Pako1
Level 1
Level 1

Upgraded to 8.2.170.0.

Still seeing the 30-60 second connection loss when roaming

Just to confirm, you have roaming issues in building A, floor A (this is an example)?
The client has just 1 company SSID configured?
Everywhere where the client walks (and has the roaming issue) he never drops below -75 dbi signal strength?
How is the SSID configured in regards to security, what is enabled on Layer 2?
All the APs in building A floor A are on the same WLC?

3 SSID. Corp/Employee BYOD both WPA2 Enterprise and a guest with portal.

 

These are across multiple sites, most with multiple floors. Single WLC. Issue is constant across all out sites with all devices. . 

 

5Ghz seems is good signal, noise and coverage wise, 2.4 has lots of snr/channel overlap due to density used for 5ghz, Going to disable a few of the 2.4 radios to try and help that. Mixed devices seem to steer to 5ghz without problem so 2.4 isnt highly utilized but it usable. Everything works fine unless they roam (on either 2.4 or 5).

 

Another thing I have noticed is EDRRM seems to change up channels on 2.4 often and power on 2.4/5 more often. Power ranges go from 1 to 7 and I have seen it put Channel 1 on 3 adjacent AP's before which doesn't help things.

 

When roaming the client device stops, signal icon disappears like signal has gone. WLCdoesnt  log anything then 30+ sec then burst in to life and reassociates client on the new AP. Not seeing any authentication errors in WLC or RADIUS server. 

 

On an Intel test device, configure in the advanced driver settings of the Wi-Fi adapter, to prioritize the 5 GHz. I wonder if it also happens if you use "only" 5 GHz.

Regarding the channel changes, check Wireless -> 802.11b/g -> RRM -> DCA
Can you upload a screenshot of this site? Depending on the selected "Avoid" settings and your environment it's more or less changing channels.
If EDRRM is enabled, make sure it's on Low if you have a lot of foreign wireless signals. I keep it on medium on 5 GHz.

If the clients have, for whatever reason, more than 1 SSID configured, make sure Fast SSID Change is enabled under Controller -> General.

you have roaming issues in building A, floor A (this is an example)? Yes (happens on any floor, any building, any site)
The client has just 1 company SSID configured? Yes. Multiple SSID available but testing device has only 1 configured
Everywhere where the client walks (and has the roaming issue) he never drops below -75 dbi signal strength? Unknown. On the device signal appears to dissapear (iphone and android signal icon disappear). Reconnects 30+ sec later. - couldnt see a way to see signalstrength on either device
How is the SSID configured in regards to security, what is enabled on Layer 2? WPA2 enterprise. AD (RADIUS) & Cert
All the APs in building A floor A are on the same WLC? Yes

You can use a mobile phone to check the RSSI (signal), for example WifiAnalyzer on Android (it's a green symbol).
For the encryption, you have enabled "WPA2 Policy" and only AES and as Key Management 802.1x, or do you have more enabled?

Corp SSID is only 5GHz and has same problem. Roams a little quicker but not by much. Attached some SS

This looks all quite well. I would enable some features of DCA though, but it really depends on the environment.
On 2.4 GHz I've enabled:
Avoid Cisco AP load
Enabled
Avoid non-802.11b noise
Enabled
Avoid Persistent Non-WiFi Interference
Enabled

And on 5 GHz:
Avoid Foreign AP interference
Enabled
Avoid Cisco AP load
Enabled
Avoid non-802.11a noise
Enabled
Avoid Persistent Non-WiFi Interference
Enabled
-----
I've checked again your debug from the client, but I don't really see an issue. One more thing to check, on the Advanced tab of the SSID, is 802.11k enabled? If so, please test with it disabled. In my case I've also disabled Aironet IE.
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