issue with inter WLAN roaming feature

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  • Updated 10 months ago
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Hi,

I'm just back from the customer site troubleshooting a VoWLAN issue - a lot of calls with bad voice quality, packet loss on the SIP call.

Setup: 2x C25, v.9.21.17, APs on both controller, availability and mobility enabled, sync config.

I've solved the issue by enabling "inter WLAN roaming" but I don't unterstand how that is the root cause of the issue.

During the troubleshooting session I've found in the station events of the client home controller messages like this....

08/30/17 12:08:30 EventType[De-registration] MAC[00:1A:E8:60:EE:8C] BSSID[20:B3:99:1C:06:38] Details: VNS[WL3] Cause[Roaming to another WLAN service and permit inter WLAN roaming disabled]

And on the 2nd controller..

08/30/17 12:08:30 EventType[De-registration] MAC[00:1A:E8:60:EE:8C] BSSID[20:B3:99:1B:BE:38] Details: VNS[WL3] Cause[Request from Other Controller]

08/30/17 12:08:30 EventType[Registration] MAC[00:1A:E8:60:EE:8C] AP[11502458235K0000] SSID[WL3] BSSID[20:B3:99:1B:BE:38] Details: Radio[2]

I don't unterstand it... as per the information from the 7.41 KT....

Inter-WLAN roaming means roaming between 2 different WLAN Services having
-same SSID
-same privacy settings

That is the same WLAN service so I don't get.

Or was the behavior changed in the newer software version.

Thanks,
Ron
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Posted 10 months ago

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Ostrovsky, Yury, Employee

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Ron , are the VoIP phones are dual-radio (2.4 and 5G) ? 
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Ronald Dvorak, Embassador

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WL3 (=OAM of the Ascom i62) - yes, they are dual but set to 2.4 only.
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Ostrovsky, Yury, Employee

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Ok , yes as per your logs , seen that De-reg was requested by the controller in pair. Can I understand a bit better the deployment . They have two controllers , and APs cover the same area and client do inter-controller roam, is that right?  
First of all - what type of security they are using (open/PSK/dot1X) . Then , when they do roam they are in the same VLAN/subnet , correct ? Tunneled or locally bridged? 
 I believe long time ago (v9) I have seen some issues caused by enabled mobility . In some cases , mobility is an additional layer of complexity which can be avoided by the design. I am not saying its a bad or poorly made feature , but just can be avoided to remove complexity in session management. This feature required for the L3 roaming for sure and works great. Also if you have more then two controllers in deployment which covers the same geographical area they you would need to enable Mobility. Otherwise , with no L3 roaming , the pair of controller (in HA/Fast Failover mode) will cover the session management , and the client moving from one controller to another will be holding the same session thanks for HA/FF feature.
  
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OK here more details...

2x C25, the APs are split on both controllers because there are too many to just have them on one.

It's only 1 building, to make it easy let's say APs of controller#1 are on the first floor and APs of controller#2 on the 2nd. floor.

topology is bridge@AP (same VLAN), WLAN service is PSK AES, mobility and availability is enabled
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Ostrovsky, Yury, Employee

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Ok , in this case please disable Mobility , you don't need it. Make sure the FF feature on HA page is enabled. 
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Bin, Employee

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Hi,  If you do not select Inter-WLAN roaming, when the client roams among VNSs, the existing session terminates and a new session starts with the client having to associated and authenticate again.