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What would cause this event in a client monitor? Suppress stopped by high density, reason: safety-net timeout

What would cause this event in a client monitor? Suppress stopped by high density, reason: safety-net timeout

jone
New Contributor
What would cause this event in a client monitor? Suppress stopped by high density, reason: safety-net timeout
4 REPLIES 4

jone
New Contributor

Thank you, I have made the suggested changes. We are in a warehouse environment with lots of metal and people, so we do expect to have some of those issues. Hopefully these changes will help some more.

samantha_lynn
Esteemed Contributor III

Thanks for that tech data. I am seeing some interference here.

 

The first output I checked was “show acsp neighbor”. In this output we want to look at the RSSI column. These values depict how loud the neighboring APs are, or in other words how much air space they are taking up. For these values we want to see -75 or lower. The closer to 0 this value is, the louder that AP is, and the more interference you will be experiencing. In your case you have several 5GHz neighbors that are Aerohive APs are are much too loud (in the -50's).

 

46b8a37cbf72489a98ce5b19b8f78a61_0690c000006HjIMAA0.png

RSSI2

The next outputs I checked were “show int wifi0 _count” and “show int wifi1 _count”. These commands check the health of your 2.4GHz and 5GHz radios respectively. Here I am seeing that you have a 78% CRC failure rate on the 2.4GHz radio, and an 18% CRC failure rate on the 5GHz radio.

 

CRC errors are usually related to environmental interference factors. These factors include mainly metal, glass, water, or large amounts of people. All of these factors tend to reflect, refract, or generally damage your signal, leading to more retries, which leads to slower WiFi speeds. 

wifi0CRC

CRCwifi1

Some things we can do to help with interference:

 

If you could lower the data rates on your SSIDs, these will require a stronger connection between the AP and the client device. This will mean that the client device needs to be closer to the AP before connecting. Not only will this reduce the chances of unintentional roaming, but it will also reduce the distance the packets need to travel, which will also reduce collision and interference on your network. To disable the lower data rates we need to go to Configure> Select the network policy> Open the SSID> Expand Additional Settings> Customize Optional Settings (at the end of the page)>In the 2.4 GHz 11/bg Rate Setting section, we want to turn 1Mbps-9Mbps to N/A. In the 5.0 GHz 11a Rate Setting section we want to turn 6 Mbps and 9 Mbps to N/A. 

 

We want to check the Radio Profile. You can find out what Radio Profile your AP is using, and change the profile if you would like to, by going to Monitor> Click on the host name of the AP> Interface Settings (left hand side menu)> Choose either the Wifi0 or Wifi1 tab> Radio Profile drop down (if you don’t see this, make sure the Radio Status is set to “ON”). To edit this Radio Profile, make a note of the name of the object and then go to Configure> Common Objects> Radio Profiles> Select the one that you are using.

 

The first thing we want to check is your Channel Width, which you can see by scrolling down to Channel Selection section and looking at the Channel Width drop down menu. We want to see this at less than 80MHz channel width. This is because the larger the channel width, the more overlap we have between channels, and if there is a problem on one channel (RF Interference for instance) it is now shared with all of the channels we are combining.

 

The second thing we want to check is that we have Short Guard Interval disabled, which we can see by scrolling down to the Optimizing Radio Usage section> Looking at the Radio Settings at the end of this section> Making sure the box next to “Enable short guard interval” is unchecked. This setting is designed to shorten the time we have to wait between when we send one packet and when we can send the next one. The problem with this is, if we have an environment with interference, we would just be sending more packets in to a crowded environment faster, increasing the damage we are causing. If this is enabled, please disable it.

 

Finally, we want to enable band steering (on the 2.4GHz radio profile only) by looking in the Optimizing Radio Usage section again and toggeling the Band Steering to “ON”. Then we want to choose the “Encourage 5.0 GHz band usage” from the drop down menu. This will encourage (but not force) clients to connect to your 5GHz radio, which is experiencing less interference than the 2.4GHz radio. 

 

You would want to push out a delta configuration with these changes, let the APs run for at least an hour, then pull new tech data so we can check for improvements.

 

jone
New Contributor

Thanks here is one of the APs tech data.

samantha_lynn
Esteemed Contributor III

Saftey net is a period of time after which a device, when it is in an overloaded state or a client's SNR is weak, can respond to association requests. A longer period can result in longer delays during the initial WLAN connection but give a greater chance of associating with an AP that can provide superior data rates. A shorter period can accelerate the initial connection, but might result in a less optimal data rate. The default is 15 seconds. Range is 5-300 seconds (5 minutes).

 

That message is telling you the association request was outside of the safety-net time window. If you can send me tech data from the AP you are trying to connect to, I can take a look a couple things to see if we can find a cause for that. My direct email is communityhelp@aerohive.com.

 

You can also disable safety-net settings in your Radio Profile.

GTM-P2G8KFN