DCA not allocating 5 GHz channels properly - seems to prefer 38, 40, 44 and 48 (non-DFS channels)

[ds_warwick]

We have a large wireless network, 3000 access points (Aironet 3602 and 3702) across 8 x WiSM2 controllers running 8.0.110.0 code.

I've noticed recently that most of our 5 GHz radios are being allocated to channels 36, 40, 44 or 48 by Dynamic Channel Allocation (DCA). Even in high density areas we can see neighbouring access points using these channels with resulting co-channel interference and high airtime utilisation.

We have always used Radio Resource Management (RRM) and we opted to use all 5 GHz channels available in Europe including the extended ones up to channel 140, however 72% of access points seem to be allocated either 36, 40, 44 or 48.

I've looked at some old surveys carried out last year and I can see that the spread of channels was much broader across all the available ones instead of in this tight group.

Reluctantly, as a workaround, I've found myself manually allocating 5 GHz channels in key areas where utilisation is likely to be high.

Has anyone else seen this behaviour?

[Rasika Nayanajith]

We have a large wireless network, 3000 access points (Aironet 3602 and 3702) across 8 x WiSM2 controllers running 8.0.110.0 code.

I would minimum running 8.0.132.0 (8.0MR3) or go for 8.0.140.0 (8.0MR4) when it release.

https://supportforums.cisco.com/discussion/13014826/80mr4-beta-availability

What you see may be code defects of the version you running.

HTH

Rasika

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[ds_warwick]

Hi Rasika,

I have considered that it might be a code defect, however I am unable to find any reference to this issue in the Cisco bug search tool.

Upgrading is disruptive for the network so I'd need to know that the issue is definitely going to be fixed by an upgrade.

Darren.