Too many AP's in an area?

Unanswered Question
Aug 28th, 2009

Hi,

I surveyed a hospital for VoWLAN using Ekahau survey tool and he customer is reporting cross channel interference on about 300 of the 450 AP.

They are saying the AP's are too close to each other and each AP can see about 7 others.

All the AP's are running at full TX power and nothing seems to be dynamically adjusting have I dropped a major clanger or could it be a network management, RRM type of problem.

Isnt there a dense building mode sort of setting in WCS WLC as well?

Any input would be welcomed even if its confirming I am an idiot

I have this problem too.
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terminalvelocity777 Fri, 08/28/2009 - 02:02

They have that as an option but want to try and get it working dynamically as they have to hand it over.

I am more worried its my fault on the placing the ap's

terminalvelocity777 Fri, 08/28/2009 - 07:23

Hi Rob,

Many thanks, I see what you mean I have trawled many threads today that seem to involve Hospitals and AP's.

Thanks for your threads very interesting, have you read the web page about the ripple effect on controllers?

http://www.hubbert.org/2007/02/ripple-effect-problems-with-ciscos.html

Im hoping its more of a radio management problem but if it isnt will learn from it anyway?

Thanks

Mick

ericgarnel Fri, 08/28/2009 - 07:34

that article is a bit dated and there have been a few levels of code released since then...

Also, I wonder if the author had "Avoid foreign AP interference" enabled as well as "avoid Cisco AP load" and "Avoid non-802.11b/g noise" and/or tried the measurement with the settings enabled/disabled?

ericgarnel Fri, 08/28/2009 - 05:54

You could always place some of the APs in monitor mode as well as offload rogue detection to those APs in monitor mode.

or sniffer mode...

terminalvelocity777 Fri, 08/28/2009 - 07:42

Thanks Eric will try that and hopefully we will get the RRM up and working fully too.

Im hoping fingers crossed that if they can turn the power down some of them wont have an issue.

Mick

terminalvelocity777 Fri, 08/28/2009 - 11:02

Rob,

The second thread you gave me is almost exactly the scenario of our facility, dense AP deployment and trying to run Vocera on auto power everything is up at full power.

Many thanks

Mick

George Stefanick Sun, 08/30/2009 - 03:12

I have found with high density, it is best to disable the lower data rates. Axe 1,2 data rates... This will lessen the managmnet frames going out slow and over extending the cell...

scottmac Sun, 08/30/2009 - 09:49

Are all the APs using omni antennas? If so, have you considered using controlled area / sector-style antennas? (coupled with power adjustments, either dynamic or manual).

IMHO, the initial power settings should be done manually, then allow the "automatic" features tweak and compensate from there.

If you have a large number of individual field conflicts, the number of iterations necessary to adjust the various power levels to a unified coverage area can be staggering ... you are leaving the choices up to some programmer(s) and their idea of how it ought to be (and you know how THEY are ....).

terminalvelocity777 Mon, 08/31/2009 - 03:04

Hi,

Thanks for the input,I will certainly take on board all of the suggestions so far and try to get them implemented.

I undertook the survey but dont really have any input into the management, aprt from now when they are saying 'too many AP's'.

I guess I was trying to find out of this was a common problem from the density of AP's perspective and to be honest if I had made a big mistake.

From what i can see Hospitals seem to be up there with the building most casing problems on congested installations.

I will try to get all the advice put to good use, guess I was a just worried someone might copme along and say it was just too many AP's

Mick

terminalvelocity777 Mon, 08/31/2009 - 03:05

Hi,

Thanks for the input,I will certainly take on board all of the suggestions so far and try to get them implemented.

I undertook the survey but dont really have any input into the management, aprt from now when they are saying 'too many AP's'.

I guess I was trying to find out of this was a common problem from the density of AP's perspective and to be honest if I had made a big mistake.

From what i can see Hospitals seem to be up there with the building most casing problems on congested installations.

I will try to get all the advice put to good use, guess I was a just worried someone might copme along and say it was just too many AP's

Mick

terminalvelocity777 Mon, 08/31/2009 - 03:05

Hi,

Thanks for the input,I will certainly take on board all of the suggestions so far and try to get them implemented.

I undertook the survey but dont really have any input into the management, apart from now when they are saying 'too many AP's'.

I guess I was trying to find out of this was a common problem from the density of AP's perspective and to be honest if I had made a big mistake.

From what i can see Hospitals seem to be up there with the building most causing problems on congested installations.

I will try to get all the advice put to good use, guess I was a just worried someone might copme along and say it was just too many AP's.

Am I right in thinking (or not) that the threads so far are saying that RRM doesnt work too good on auto, is there a way it can turn the power down from full power where it is at the moment?

Mick

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