What are "healthy" values for % utilization and errors?

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I've inherited a network in an office with lots of small conference rooms and 8-10 other Wifi networks belonging to other companies (ie. out of my control), and am trying to bring even a minimum amount of reliability to the network.

There are currently 4 x AH230s in a roughly 90' x 60' office, but think "rabbit's warren" as a description of the layout (back third is also split level, we occupy the top part). The justification I got on why so many APs was that "no one could connect." There are 2 SSIDs (corp and guest).

I've been working with Aerohive TS and I've turned off 2.4GHz on all but one of the APs (power at 15) and have reduced the 5HZ power to 1 or 2, depending on the coverage requirements (ie. how many little offices there are with walls).

The AP with the remaining 2.4GHz radio has a lot of connections, but reading through the docs, I see that's not as important as channel utilization ... this morning around 11, the 2.4GHz channel (6) was unusable.

What are the rules of thumb for channel / airtime utilization and errors so I can tell if radio / placement adjustments have had a positive impact or not?

Thanks,
Graham
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Graham Dunn

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Posted 2 years ago

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Erik Gunnarsson

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When channel utilization gets around 80%, the communications usually falls apart.
Around 10-15% errors could be quite normal in a dense environment.

Disable some of the lower data-rates (1, 2, 5.5, 11 mbps) might help you somewhat, but since you can't control surrounding ap's it might not be enough.

Seems like a lot of your clients use 2,4ghz. I don't know how your setup is or what kind of clients you have, but a lot of client choose channel based on signal strength (not only..)

If you have a high output level (15dbm) on 2,4 and 1dbm on 5ghz you may trick some clients to prefer 2,4.

Do you have a lot of other surrounding APs on 5ghz? If your APs are on different channels you don't have to lower the power that much.

Have you tried "band steering" in Aerohive to try to get clients to use 5ghz?

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Graham Dunn

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18Mbps is set as the "basic" data rate in both SSIDs and band steering is enabled.

I've increased the power output on 5GHz and it helped shift more clients off 2.4GHz. There's one other AP on the same 5GHz channel, it sees this AP (via acsp neighbor listing) at -87dbm.

Just to clarify, radio power is only a problem when you have radios on the same 2.4 or 5GHz channel? (in the absence of other interference) So if I only had 3 APs, I could put them on 36, 44 and 157 and then turn them all the way up with no interference to each other?

Thanks,
Graham
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Erik Gunnarsson

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You're correct about the channels and power.
On 2,4 if you use channel 1, 6, 11 they should not interfere with each other. On 5ghz 36 and 44 are non overlapping. But if you use 40mhz channels and the ap:s are very close, you could get some interference from adjacent channels.
Generally in my opinion, there is no reason to have higher power level on the ap than the client could talk back with. A laptop generally around 15-17dbm and handheld devices around 10-12dbm. If you lower the level on the AP, TPM (802.11h) tells the client to lower their output to match the ap.
A higher output gives you a bigger physical area covered and usually gives you more clients to share the airtime.

A values of -87dbm should be bad. Wifi backoff algoritm listen if the channel is free a -82dbm and doesn't care about 802.11 packets bellow that level. But some of you clients could be closer to that source than your ap and might have to share airtime on that channel
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Graham Dunn

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Sorry, is that "-87dbm should be bad", or "shouldn't be bad"?
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Erik Gunnarsson

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Sorry for the typo, I meant "shouldn't be bad"
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Graham Dunn

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I've moved the AP to channel 6 (there were two loud sources on Channel 1 and 11 that I can't control - NETGEAR_EXT and iHub_00603503c557)


So this is the network with user traffic and then overnight (24hour window). There's a lot of 2.4GHz interference shown (or is that typical?).

 Large-AH-8f4280#show acsp neighbor

wifi0(10) ACSP neighbor list:
Bssid Mode Ssid/Hive Chan Rssi(dBm) Aerohive AP CU CRC STA Channel-width
2ac6:8e10:afdb Access NETGEAR_EXT 1 -50 no -- -- -- 20
9c5d:128f:4ad4 Access KikGuest 1 -74 yes 32 0 14 20
9c5d:128f:4ad5 Access KikWifi 1 -74 yes 34 0 14 20
9c5d:123d:d8d4 Access KikGuest 11 -80 yes 15 0 5 20
9c5d:123d:d8d5 Access KikWifi 11 -81 yes 15 0 5 20
0023:5eaf:ebc2 Access IFS Guest 1 -79 no -- -- -- 20
0023:5eaf:ebc3 Access IFS 1 -77 no -- -- -- 20
001a:8c09:f131 Access BlueSprings-Wireless1 -85 no -- -- -- 20
0023:5eaf:ebc1 Access IFS Smart 1 -77 no -- -- -- 20
0023:5eaf:ebc0 Access 1 -77 no -
- -- -- 20
640f:2812:bd21 Access BELL842 4 -85 no -- -- -- 20
d8c7:c8e8:3880 Access Indigo_Bell_WiFi 6 -83 no -- -- -- 20
000c:41d6:1f98 Access 6 -89 no -- -- -- 20
1e0e:8e40:4dd0 Access LIR 6 -84 no -- -- -- 20
bcee:7b56:444a Access isn 8 -82 no -- -- -- 40-
78ac:c086:7de5 Access HP867DE5 10 -80 no -- -- -- 20
6c70:9fe5:b562 Access Sk's Wi-Fi Network 11 -79 no -- -- -- 20
000e:8f77:0602 Access iHub_00603503c557 11 -59 no -- -- -- 20
d8eb:97bc:8f78 Access Gehl&Gehl 11 -77 no -- -- -- 20
8a15:0473:d750 Access 6 -82 no -- -- -- 20
84a4:238d:dcee Access 11 -90 no -
- -- -- 20
8a15:0473:d754 Access 6 -73 no -- -- -- 20
0012:5f03:5d18 Access LiteShow3 10 -90 no -- -- -- 40-
d8c7:c8e8:3881 Access 6 -80 no -- -- -- 20
606d:c71c:f84f Access HP-Print-4F-LaserJet Pro MFP6 -83 no -- -- -- 20
001a:8c09:f130 Access SophosGuest 1 -87 no -- -- -- 20
wifi1(11) ACSP neighbor list:
Bssid Mode Ssid/Hive Chan Rssi(dBm) Aerohive AP CU CRC STA Channel-width
9c5d:123d:d8e4 Access KikGuest 157 -93 yes 22 0 18 80
9c5d:123d:d8e5 Access KikWifi 157 -93 yes 22 0 18 80
Large-AH-8f4280#
(Edited)
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mr bee

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How did you manage to get following widgets (channel usage, errors and airtime usage over  ? I can not selects them in HM on prem 6.8r4 :-S
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Graham Dunn

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This is HMOL, HiveManager®Enterprise   6.8r3. It's in the 
Dashboard -> Network Summary tab, then click on the Edit icon on the top right.
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mr bee

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I have checked there but no global over time reports there, only top 10 reports :-S Can these be found in HMOL under "clients", "aerohive devices" or "others" ?


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Graham Dunn

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It looks like a lot of these have been moved into Additional Reports->Wifi Devices
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mr bee

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Indeed, thanks a lot !
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mr bee

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according to Marko Tisler, lead trainer, retry rate is thé best KPI: <10%: perfect wifi; 10-20%: still ok; >20%: will encounter some problems
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Joel Brooks

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Graham, is there any reason not to utilize DFS channels in your vicinity? Close to an airport or weather station? unfortunately, it sounds like you are cornered on the 2.4 spectrum due to so many rogue APs around you.