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Dominic Stalder

Inter-Controller mobility between Cisco WLC 8.8 and 8.3

Hey guys


our Cisco WLAN IP Phones 7925 and 8821 have a strange behaviour: they roam very frequently (about every 4-5 seconds) between access points on different floors - even if I am standing right beside the access point on the same floor. The main problem is, one floor has a newer WLC with newer access points, while the other floor is covered by an older WLC with older access points:


Floor A: Cisco WLC 3504, Version, Cisco Aironet 4800I Access Points

Floor B: Cisco WLC 2504, Version, Cisco Aironet 1040 and 1140 Access Points


As you can see, the WLC on floor B can not be upgraded higher than 8.3 because of the very old Cisco Aironet 1040 access points.


First of all, does someone know if there are limitations or any compatibility guides, where I can see, wich AireOS version can communicate with any other version (mobility groups)?


And secondly, did anybody else have this strange behaviour of roaming / hopping that fast between access point, when stationary?


Thanks in advance and best regards


Dominic Stalder

Please forget about the question of Inter-Release Controller Mobility (IRCM), just found it in the general CUWN compatibility matrix:

This should seem to work, see attachment.

Haydn Andrews
Rising star

The roaming behavior and which AP to connect to is ultimately the devices. The reason it might be connecting to the other levels is the SNR and RSSI are better from those APs, data rates, PHY type (N/ ac etc) or any combination of reasons why it prefers one over the other.

I have seen devices bounce between APs if its right between what its metrics to roam are. There might be a setting on the phone to make it roam less frequent.


The wireless compatibility matrix will show what APs will support what codes:


those 1040 and 1140 APs are EOL so you should consider upgrading them.


Solutions to your issue i can see:

  • If roaming between the floors with the handsets are not required, then a different SSID on each different WLC.
  • Upgrade the EOL APs
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Leo Laohoo
VIP Community Legend

Just want to say that the 8821, even running the latest firmware, does not roam as smooth as a 7925G.  

Hi Leo


thanks for the information; I know that the Cisco IP Phone 8821 are not (let's say :-)) the best devices concerning roaming, but we tried an older Cisco IP Phone 7925G at the same spot and this device is hopping exactly as often as the 8821 in this case right here.


Best regards


@Dominic Stalder wrote:

Floor A: Cisco WLC 3504, Version, Cisco Aironet 4800I Access Points

Wait a second.  I know exactly what is wrong ... CSCvn05881.

Upgrade to and see if it makes any difference.  

Release Notes for Cisco Wireless Controllers and Lightweight Access Points

Hi Leo

Thanks for the hint; I checked the bug search last week and saw this bug too, but checked also the debugs on our and did not see the output they provide in the bug report. But I already upgraded the Cisco WLC to yesterday and will check if it did help, when I am back in the office.

Best regards and thanks for your kind help so far
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