AP230 2.4G Channel RF overcrowded, clients can't see SSID

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Clients can't see SSID any more, no client connected but Rx utilization still 100%

Summary state=Channel RF overcrowded

Rx airtime=0.00 ms; Tx airtime=0.00 ms; CRC error airtime=2976.42 s;Rx airtime percent=0.00%; Tx airtime percent=0.00%; CRC error airtime percent=0.00%;
Tx utilization=1%; Rx utilization=21%; Interference utilization=78%; Total utilization=100%;

Not sure why my last post was deleted. Aerohive is the first vendor that took my money and censors my posts. Good way to never get a customer back.
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asdfdfsadfs

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Posted 1 year ago

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Rob Pritchard

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So it's just the 2.4Ghz clients that can't see the SSID?  The 5Ghz clients are fine?
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asdfdfsadfs

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5G clients are fine, no noticeable issues

state is High collision, Tx utilization=2%; Rx utilization=3%; Interference utilization=1%; Total utilization=6%
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Rob Pritchard

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Are you able to determine what's causing the high interference utilization on 2.4Ghz?
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asdfdfsadfs

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every channel (1,6,11) has 3 or 4 APs that I don't have control over. Capture shows most of them are sending beacon at 10pps while AP230 sends nothing....
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Sam Lynn, Moderator

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Hello asdfdfsadfs,

I am the Moderator for the Aerohive Community and I just wanted to let you know that your last post was not deleted. It was flagged as possible spam (likely due to the length but I am still checking in to this), but that should be corrected now. I'm very sorry for the confusion.

As for your question, your 2.4GHz radio seems to be experiencing severe Radio Frequency Interference based on the data you are showing (in this post and the previous one that I reviewed as well). To make sure the APs still know about the SSID we'll want to run the command "show ssid", and you'll want to check your device specific settings to make sure the SSID was not disabled.

It should be noted that it is very unlikely for RF interference to cause an SSID to stop broadcasting. The typical symptoms that come with RF interference are slow wifi and frequent disconnections. For the interference, there are several configuration changes we can make to help with that. Please note that the paths outlined below are for Hive Manager Classic; if you are using Hive Manager NG please let us know and I'll correct those paths for you.

To help with the high collisionstate and high retry rates we want to enable unicast data. The differencebetween multicast and unicast data is that multicast data is akin to shoutingin a crowded room to get a message to one person. The intended target gets themessage, but everyone else has to ignore it. Unicast data is akin to speakingdirectly to one person. This helps take some of the unnecessary traffic off ofyour network, which will help to lower the total utilization on your network.To do this we would go to Configuration> Select the network policy> Openthe SSID> Expand Advanced> Under IP Multicast select always or auto. Thedifference is the always setting will enable only unicast data (which is notwhat we want, as some background and management functions can only usemulticast data, so turning multicast off complete is not ideal), the autosetting will only switch to unicast data once it reaches a specific threshold,which you can set here as well once you select the auto option.  We strongly recommend you select the autooption here.

Also, if you could lower the datarates on your SSIDs, this will require a stronger connection between the APand the client device. This will mean that the client device needs to be closerto the AP before connecting. Not only will this reduce the chances ofunintentional roaming, but it will also reduce the distance the packets need totravel, which will also reduce collision and interference on your network. Tolower the data rates we need to go to Configuration> Open the NetworkPolicy> Open the SSID> Expand radio and rates> In the 2.4 GHz 11/bgRate Setting box, we want to turn 1Mbps-9Mbps to N/A. In the 5.0 GHz 11a RateSetting box we want to turn 6Mbps and 9 Mbps to N/A. Finally, in the 2.4 GHzand 5.0 Ghz 11n MCS Rate Settings, we want to turn MCS 0, MCS 8, and MCS 16 toN/A. 

Hope this helps!
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asdfdfsadfs

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Thanks for clarifying. I lowered datarate, still 2.4G SSID is not seen.


SSID is active

3 is 2.4G only, 2 is 5G only, 1 and 4 are 2.4G/5G. 2.4GHz clients are unable to see any of them. 5GHz clients can connects to all 3 5G enabled SSID.

#show ssid
Frag=fragment threshold; RTS=request to send;
DTIM=delivery traffic indication map;

No. Name  Frag    RTS     DTIM period Max client  Mac filter     
--- ----  ----    ---     ----------- ---------- ----------
1   ntwgg 2346    2346    1           100         ntwgg          
2   ntwg5 2346    2346    1           100         ntwg5          
3   ntwg  2346    2346    1           100         ntwg           
4   ntwgl 2346    2346    1           100         ntwgl   


Multicast is already disabled. There is barely any traffic (5pps on Eth0).

I haven't been able to find out where to change interface allowed VLAN in HiveManager. If I do a config replace the APs lose connectivity because allowed VLAN is missing. IMO there should be a check to prevent management vlan not allowed on eth0/eth1. Consoling into tens/hundreds of AP is very labor intensive......
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Gary Smith, Official Rep

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In your other post you gave an output of "show interface wifi0". This output contained the line;
Tx utilization=1%; Rx utilization=13%; Interference utilization=86%; Total utilization=100%;

It seems to me that the 2.4GHz spectrum is saturated.

Can you run a couple of commands and add the ouptuts please?

"Show acsp channel-info detail | inc channel"
-  i would look at the utilisation percentages. 
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asdfdfsadfs

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CU was 100%. There is quite some interference at this location (unavoidable). But still I need to provide best-effort 2.4G support for devices without 5G. For whatever reason AP230 did not send any beacon over 2.4G. I replaced AP230 to a non-aerohive AP and clients are happy.
(Edited)
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Eastman Rivai, Official Rep

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Interference utilisation is high, this indicates high interference from non-802.11devices and/or devices on adjacent channels. In addition to Gary's advise, I  would also run spectrum analyser and check the RF environment. In the situation like this is impossible for a client to connect to this radio.
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asdfdfsadfs

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The reason clients can't connect is that ap230 does not send ANY beacon when CU is high. Several other APs I tested worked as expected (not fast, but stable connection with enough throughput for light usage). 
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Gary Smith, Official Rep

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Hi,

Please email me a techdata file from an AP230 taken at a time when there is an issue with 2.4GHz connectivity. gsmith@aerohive.com

Kind Regards,
Gary Smith
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Luke Harris

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I definitely recommend carrying out some spectrum analysis either using the in-built tester within HiveManager or using a third party product (MetaGeek) if it is available. It would also be useful to know whether this problem exists throughout your organisation or only in certain areas. 
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Gary Smith, Official Rep

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For reference, here are the explanations for the status summaries;

WiFi Status Summary (This option is unavailable on Aerohive switches and VPN gateways.) HiveManager Classic can generate a report that summarizes the status of the wireless interfaces for a selected device or devices. You can use this report to identify and correct issues such as overcrowded channels, high collision rates, and SNR (signal to noise ratio) problems.

To generate a WiFi Status Summary, from either the monitor or config view, first select the check box next to a device or devices for which you want a summary, then click Utilities > Status > WiFi Status Summary. For the selected device or devices, you will see information about the WiFi interfaces specifically, and about the device (referred to as station in the summary) in general.

There are five possible states for the WiFI interfaces:

Good: The CRC and Tx error rates are less than 5%, and channel utilization is less than 50%.

Fair: The CRC and Tx error rates are less than 10%, and channel utilization is less than 65%.

Channel RF Overcrowded: The channel utilization rate is 65% or greater.

High Collision: The CRC error rate is 10% or greater.

High Tx Error: The transmit error ration is more than 10%, which can occur when the RF environment is overcrowded and the collision rate is high.

  • In some cases, the interface will meet the requirements for both Channel RF Overcrowded and High Collision. In these cases, both states are listed in the report.
There are four states for the station. The station must meet all required conditions to be identified as being in one of these four states:

Good: SNR must be greater than 20 dB. The Tx retry ratio is less than 5%.

Fair: SNR is less than 20 dB, but greater than 15 dB. The Tx retry ratio is less than 10%.

Poor: The SNR is less than 15 dB.

High Retries: The Tx ratio is greater than 10%.