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  • Let's say you have 3 Cisco maybe 3602 APs 5Ghz, TPC, UNII-1. They are all within 150' of each other viz. triangle. With no clients in the vicinity we see in the WLC two APs at near zero power levels and one at max power.

    Question is should all APs settle to maybe power level of 4 or is RRM really working with one AP at max power covering the other two AP?

    Now if a client comes in range of an AP at low power will that AP turn up its power?

  • Interestingly, today Devin Akin (ex-CTO of CWNP), presented a webinar entitled " Why RRM Will Always Be Sub-Optimal" on Brighttalk.

    At some point in time, if you search on that title you will find the recorded program .    It was excellent  !

    It should fully answer your question, and more. 

  • Devin is great, but that discussion had some questionable moments.

    There is a new version of the Cisco RRM doc in works but I would start out with this link:

    http://www.cisco.com/c/en/us/support/docs/wireless-mobility/wireless-lan-wlan/71113-rrm-new.html

    3 APs within 150' of each other is pretty close but the thing to remember is that RRM doesn't solely focus on frequency, it looks at channel as well. RRM triggers its changes based of the number of APs heard on a given channel with other items taken into consideration using the CleanAir chips. 

    Clients only impact it from a coverage hole detection if that is configured, but given 3 APs in close proximity you probably won't be seeing that.

    What version of code are you running? Are these 3602i's or e's? RRM is impacted by all of these and it won't fix a bad design, not saying you have a bad design but you need to start with a solid foundation first.

  • Thanks a lot. Watching now for second time.

  • Blake,

    Thanks for this Cisco link.   

    Other than Cisco's notes about RRM not working very well with client power-saving modes, I did not see anything that really conflicted with what Devin had to say. 

    Could you be a little more specific as to what he missed ? 

    Thanks

  • Just for reference you would actually need a minimum of 4 aps for RRM to actually work I believe,

  • Technically yes, 1 AP needs to hear 3 others, so a total of 4 need to be on the same channel.

  • Good question Pingu.

    Thanks Blake, for the answer.

  • Blake,

    The Cisco document you referenced spoke of using RSSI as an RRM tuning parameter.

    I know from extensive lab measurements, that many manufacturers (not Cisco) output power claims and RSSI numbers are sometimes very far from the truth...

    Has there been any movement towards using RCPI values instead of RSSI ?

    RCPI is still not very accurate (IMO), but it seems like it would be a step in the right direction.

    Thanks

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