I found some info on channel quality here (external source).
These metrics change all the time, and ARM will not immediately move to another channel if that seems only 'just better', there needs to be a significant improvement to avoid constant channel changing. Also the algorithms have changed over time, and may be slightly different for Instant, Controllers, Mobility Conductor and Aruba Central managed APs (in simple to most advanced order).
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Herman Robers
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Original Message:
Sent: Jun 14, 2023 04:08 AM
From: knizmi1
Subject: channel quality vs. interference index
Does anybody know how channel quality is calculated in regard to interfence index? I do not understand this when running show ap arm rf-summary.
I have the following rf-summary table:
Channel Summary
---------------
phy-type channel retry phy-err mac-err noise util(Qual) cov-idx(Total) intf_idx(Total)
-------- ------- ----- ------- ------- ----- ---------- -------------- ---------------
5GHz 36 0 0 0 92 4/4/0/0/100 5/0(5) 39/0//0/0(39)
5GHz 40 0 0 0 92 0/0/0/0/100 0/0(0) 19/29//0/0(48)
5GHz 44 7 0 0 94 7/5/1/0/99 14/0(14) 49/0//0/0(49)
5GHz 48 0 0 0 92 0/0/0/0/100 0/0(0) 24/19//0/0(43)
5GHz 52 0 0 0 92 0/0/0/0/100 0/0(0) 8/0//0/0(8)
5GHz 56 0 0 0 92 0/0/0/0/100 0/0(0) 4/23//0/0(27)
5GHz 60 0 0 0 92 4/4/0/0/100 12/0(12) 61/0//0/0(61)
5GHz 64 0 0 0 92 1/1/0/0/100 0/0(0) 12/20//0/0(32)
5GHz 100 0 0 0 92 0/0/0/0/100 0/0(0) 0/0//0/0(0)
5GHz 104 0 0 0 92 0/0/0/0/100 0/0(0) 0/2//0/0(2)
5GHz 108 0 0 0 92 0/0/0/0/100 0/0(0) 7/0//0/0(7)
5GHz 112 0 0 0 92 0/0/0/0/100 0/0(0) 4/2//0/0(6)
5GHz 116 0 0 0 92 7/7/0/0/100 0/0(0) 2/0//0/0(2)
5GHz 120 0 0 0 92 0/0/0/0/100 0/0(0) 0/0//0/0(0)
5GHz 124 0 0 0 92 0/0/0/0/100 0/0(0) 0/0//0/0(0)
5GHz 128 0 0 0 92 0/0/0/0/100 0/0(0) 0/8//0/0(8)
5GHz 132 0 0 0 92 0/0/0/0/100 4/0(4) 24/0//0/0(24)
5GHz 136 0 0 0 92 0/0/0/0/100 0/0(0) 12/8//0/0(20)
5GHz 140 0 0 0 92 0/0/0/0/100 0/0(0) 0/0//0/0(0)
I can see that the channel pair 44-48 is OK according to util(Qual), but at the same time it has the highest intf_idx(Total). The AP always chooses 44+ as its 5GHz channel, likely because of the relatively low noise level on ch. 44.
So what exactly does Interference index mean? Is 49/0//0/0(49) a lot or is this something I need not worry about? And how does this correspond to channel quality?
I have read the description at https://www.arubanetworks.com/techdocs/CLI-Bank/Content/instant/sh-ap-arm.htm, but it does not make things clear at all.