Analyzing Channel Utilization Mesh Networks

TH09 · ‎02-13-2021

Hi Wireless Experts!

We are running an outdoor wireless mesh around 300-400 Mesh APs and see high channel utilization on some channels.

My ask:

1. How can I determine what factors are causing high channel utilization?

2. How can I leverage Prime to find out the above? What Prime reports can come in handy here to help me determine the factors?

3. Once those factors are determined, what can be done to those factors to bring that channel utilization number down.

Cheers!

Grendizer · ‎02-17-2021

You can use dedicated Spectrum Analyzer programs or simply from the WLC MONITOR > Access Points > Radios > pick a radio > details

From PI, you can use Reports > Report Launch Pad > Performance > AP RF Quality > AP RF Quality or AP RF Quality History (this per WLC, floor area, outdoor area)

There are many factors and devices that cause high channel utilization, if you’re using Spectrum Analyzer, you should be able to generate a report for all that.

What you really need to watch is your mesh link

So you can use the below command to see the SNR uplink “snrUp” and SNR downlink “snrDown”

(Cisco Controller) >show mesh path MAPNAME

Or from the AP:

MAP#show mesh status

And for the RAP:

(Cisco Controller) >show mesh neigh detail RAPNAME

And overall:

(Cisco Controller) >show mesh ap tree

snrUp is the SNR of another AP we can hear.

snrDown is the SNR of how another AP hears us. It is sent to us by the other AP.

linkSnr is the smoothed SNR of the bi-directional link.

(we don't want to see SNR uplink and downlink are off by 10 dB or more) if so, there is RF problem, RF has interference, LOS is obstructed, or hardware is bad.

You can see the same thing from PI:

Monitor > Wireless Technologies > Access Point Radios > APNAME > Mesh > Mesh Links

or from:

Inventory > Device Management > Network Devices > Device Groups > Device Type > Unified AP > Cisco XXXXX Series Unified Access Points > APNAME > Mesh > Mesh Links

From both above, you can see Mesh Link Alarms and you can setup Alarm Notification Policies for what you need to be notified by email for example or send those alarms to a Northbound trap receiver, all that can be done from:

Administration > Settings > System Settings > Alarms and Events > Alarm Notification Policies > + > select the Virtual Domain > uncheck all except Mesh Links "or add more if you like" > choose Email or Northbound trap receiver and complete it.

TH09 · ‎02-22-2021

Hi Grendizer,

When I do a show mesh neigh details on one of the RAPs, I see the followings, when you say we dont want to see sU and sD off by 10, do you mean, the difference needs to be less that 10?

So for the first one for example, 23-18 = 5 (So this is good as it is less than 10)

And we see Ch 165 has the highest CH util, could it be due to one or more poor SNRs in the ch?

Numroutes 1, snr 0, snrUp 23, snrDown 18, linkSnr 18

Numroutes 1, snr 0, snrUp 25, snrDown 18, linkSnr 18

Numroutes 0, snr 0, snrUp 30, snrDown 30, linkSnr 30

Numroutes 0, snr 0, snrUp 41, snrDown 41, linkSnr 41

Numroutes 1, snr 0, snrUp 24, snrDown 18, linkSnr 18

Numroutes 0, snr 0, snrUp 32, snrDown 32, linkSnr 32

Numroutes 0, snr 0, snrUp 38, snrDown 38, linkSnr 38

Numroutes 0, snr 0, snrUp 32, snrDown 32, linkSnr 32

Numroutes 1, snr 0, snrUp 24, snrDown 19, linkSnr 19

Numroutes 0, snr 0, snrUp 4, snrDown 4, linkSnr 4

Numroutes 0, snr 0, snrUp 5, snrDown 5, linkSnr 5

Numroutes 0, snr 0, snrUp 4, snrDown 4, linkSnr 4

Numroutes 0, snr 0, snrUp 31, snrDown 31, linkSnr 31

Numroutes 1, snr 0, snrUp 17, snrDown 9, linkSnr 9

Numroutes 0, snr 0, snrUp 42, snrDown 42, linkSnr 42

Numroutes 1, snr 0, snrUp 17, snrDown 7, linkSnr 7

Numroutes 0, snr 0, snrUp 6, snrDown 6, linkSnr 6

Numroutes 0, snr 0, snrUp 27, snrDown 27, linkSnr 27

Numroutes 0, snr 0, snrUp 4, snrDown 4, linkSnr 4

Numroutes 0, snr 0, snrUp 33, snrDown 33, linkSnr 33

Numroutes 0, snr 0, snrUp 24, snrDown 24, linkSnr 24

Numroutes 0, snr 0, snrUp 3, snrDown 3, linkSnr 3

Numroutes 1, snr 0, snrUp 8, snrDown 7, linkSnr 6

Numroutes 1, snr 0, snrUp 13, snrDown 4, linkSnr 4

Numroutes 0, snr 0, snrUp 5, snrDown 5, linkSnr 5

Numroutes 0, snr 0, snrUp 31, snrDown 26, linkSnr 26

Numroutes 0, snr 0, snrUp 5, snrDown 5, linkSnr 5

Numroutes 1, snr 0, snrUp 24, snrDown 18, linkSnr 18

Numroutes 0, snr 0, snrUp 4, snrDown 4, linkSnr 4

Numroutes 0, snr 0, snrUp 3, snrDown 3, linkSnr 3

Numroutes 0, snr 0, snrUp 23, snrDown 23, linkSnr 23

Numroutes 0, snr 0, snrUp 32, snrDown 32, linkSnr 32

Numroutes 0, snr 0, snrUp 2, snrDown 2, linkSnr 2

Numroutes 1, snr 0, snrUp 26, snrDown 15, linkSnr 15

Numroutes 1, snr 0, snrUp 34, snrDown 28, linkSnr 27

Numroutes 0, snr 0, snrUp 5, snrDown 5, linkSnr 5

Numroutes 0, snr 0, snrUp 7, snrDown 7, linkSnr 7

Numroutes 1, snr 0, snrUp 33, snrDown 30, linkSnr 29

Numroutes 0, snr 0, snrUp 32, snrDown 32, linkSnr 32

Numroutes 1, snr 0, snrUp 32, snrDown 21, linkSnr 20

Numroutes 0, snr 0, snrUp 32, snrDown 32, linkSnr 32

Numroutes 0, snr 0, snrUp 12, snrDown 12, linkSnr 12

Numroutes 0, snr 0, snrUp 6, snrDown 6, linkSnr 6

Numroutes 0, snr 0, snrUp 9, snrDown 9, linkSnr 9

Numroutes 0, snr 0, snrUp 30, snrDown 30, linkSnr 30

Numroutes 0, snr 0, snrUp 33, snrDown 33, linkSnr 33

Numroutes 1, snr 0, snrUp 26, snrDown 18, linkSnr 18

Numroutes 0, snr 0, snrUp 28, snrDown 28, linkSnr 28

Numroutes 0, snr 0, snrUp 3, snrDown 3, linkSnr 3

Numroutes 0, snr 0, snrUp 30, snrDown 30, linkSnr 30

Numroutes 1, snr 0, snrUp 18, snrDown 15, linkSnr 15

Numroutes 1, snr 0, snrUp 25, snrDown 17, linkSnr 17

Numroutes 0, snr 0, snrUp 28, snrDown 28, linkSnr 28

Numroutes 0, snr 0, snrUp 30, snrDown 30, linkSnr 30

Numroutes 1, snr 0, snrUp 19, snrDown 8, linkSnr 8

Numroutes 0, snr 0, snrUp 6, snrDown 6, linkSnr 6

Numroutes 0, snr 0, snrUp 32, snrDown 32, linkSnr 32

Numroutes 0, snr 0, snrUp 31, snrDown 31, linkSnr 31

Numroutes 1, snr 0, snrUp 30, snrDown 25, linkSnr 24

Numroutes 0, snr 0, snrUp 27, snrDown 27, linkSnr 27

Numroutes 0, snr 0, snrUp 6, snrDown 6, linkSnr 6

Grendizer · ‎02-23-2021

the difference needs to be less than 10? Yes
And we see Ch 165 has the highest CH util, could it be due to one or more poor SNRs in the ch? It's the other way around, if you have high ch util then you will have bad snr, not sure why you're using ch 165? You should change that.

TH09 · ‎02-23-2021

I do see out of 63 APs on CH 165, 23 have less than 15 SNR. Could that be one of the reason causing High Channel Utilization?

Why not use CH 165? Is there something bad about that channel?