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Network ist not working after a few minutes with OS X devices and 802.11ac antennas

FTBZ
Level 1
Level 1

We installed new antennas in the past weeks, model AP2802. Our network has only OS X workstations that will mainly join using 802.11ac. The WLC is a brand new 5520 running 8.2.166.

 

We noticed that many OS X devices that have joined with 802.11ac (and only with 802.11ac), have a network issue after a few minutes (but this is not the case of all devices and seems not linked to OS X version). The connection to the antenna seems working, but the L3 (L2?) seems dropped. You can't ping or connect to anything.

 

During the problem, the WLC is always showing the workstation as connected but the Link Test will give a failed result.

 

Someone has experienced similar issues?

5 Replies 5

Hi,

 Link test is not a good parameter. It relies on the CCX and ping and depending on the client and the topology both will fail and not necessarily client have problem.

 Try to run a debug for one client and share the result, this may help us to help you. Better yet if you have a sniffer.

 

 -If I helped you somehow, please, rate it as useful.-

d.friday
Level 4
Level 4

I've noticed issue with macs and 80 MHz channels,  have you tried going into the WLC and change the DCA Channel Width to  BEST, or do you have it hard set?

 


@d.friday wrote:

I've noticed issue with macs and 80 MHz channels, 

Thanks, this is a good tip. Every time that the problem occurred, I captured the data and the workstation was always in 80 MHz. The Cisco/Apple documentation is recommending using 40 MHz. Our configuration is set to "Best" at this time.

I will change our RF profiles to force 40 MHz and check if the problem disappear.


@d.friday wrote:

I've noticed issue with macs and 80 MHz channels


I confirmed that the issue is only when using the "Best" setting. Forcing workstations to 40 MHz has probably solved the issue. Thanks for the help.

FTBZ
Level 1
Level 1

After a few days, the problem is partially solved. We've no more complaints about this issue, but during a meeting I noticed the problem again on my laptop.

 

Reading again the document "Enterprise Best Practices for iOS devices and Mac computers on Cisco Wireless LAN", we decided to change to 20 MHz bandwidth. We're in a  high AP and client density and the documentation says :

 

[...] and 20 MHz for high AP/Client density deployment environments

 

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