topic Re: ap550 high rx CRC rate (42%) on only one radio. in Aerohive Migrated Content

ap550 high rx CRC rate (42%) on only one radio.

w1f1n00b — Tue, 17 Sep 2019 02:49:04 GMT

Here are a few relevant points. I'm wondering why there is such a difference between radios. Loudest neighbor is -64.

sh int wifi0 - High Collision

Noise Floor -95

CRC error rate 0.00%

sh int wifi0 _count

42% rx CRC rate

sh int wifi1 - Good

Noise Floor -95

CRC error rate 0.00%

sh int wifi1 _count

0% rx CRC rate

Re: ap550 high rx CRC rate (42%) on only one radio.

w1f1n00b — Tue, 17 Sep 2019 02:49:41 GMT

HiveOS - 10.0r7a

Re: ap550 high rx CRC rate (42%) on only one radio.

w1f1n00b — Thu, 19 Sep 2019 22:40:10 GMT

I'm keeping an eye out for this and seeing it in several locations. As per the standard line, CRC errors are mainly environmental. Is 2.4Ghz more susceptible to this problem or is 5Ghz equally effected?

Re: ap550 high rx CRC rate (42%) on only one radio.

ashley_finch — Fri, 20 Sep 2019 15:51:24 GMT

2.4GHz is more susceptible to interference for a few reasons. Primarily there are only 3 non overlapping channels (1,6,11), so the AP doesn't have much to choose from. Certain environments are worse than others, such as multi tenanted buildings as you'll find a lot of other APs not just your own using the same channel. APs aren't the only issue, mobile hotspots will pop up on the 2.4GHz, then you also have other devices such as bluetooth and also microwaves using this. Power levels can also inadvertently cause CRC errors due to a hidden node issue along with multipath.

5GHz is still susceptible to interference but you have many more channels to choose from, hence you're more likely to be able to move away from the interference source.

Is that -64 neighbor on the same channel as the AP you were looking at?

Re: ap550 high rx CRC rate (42%) on only one radio.

w1f1n00b — Wed, 25 Sep 2019 03:00:53 GMT

It's not on the same channel. I'm fairly vigilant when it comes to co-channel interference. That's partly why I'm so stumped on this.

I took data from another site and the data below is what I'm seeing. All AP250's running 10.0r7a with dual 5Ghz radio config.

I can't seem to find any coordination between why some are so high and others so low, even on the same AP. These are all similarly designed classrooms. I'm planning to collect more data from these same devices to see if I can pin anything down.

Re: ap550 high rx CRC rate (42%) on only one radio.

w1f1n00b — Wed, 25 Sep 2019 03:10:39 GMT

Here's the same data pulled just now. The above image is from last week.

Re: ap550 high rx CRC rate (42%) on only one radio.

sderikonja1 — Tue, 01 Oct 2019 21:00:12 GMT

Do you have an AP in each classroom?

Re: ap550 high rx CRC rate (42%) on only one radio.

w1f1n00b — Tue, 01 Oct 2019 23:48:31 GMT

This particular location is about 1:3

Re: ap550 high rx CRC rate (42%) on only one radio.

sderikonja1 — Wed, 02 Oct 2019 00:46:40 GMT

Average client count per AP?

Type of clients?

Is dynamic channel switching enabled?

That is quite of bit of CRC on 5 GHz.

Re: ap550 high rx CRC rate (42%) on only one radio.

w1f1n00b — Wed, 02 Oct 2019 01:15:22 GMT

Most APs won't see more than 30 clients, with an avg around 10 (just ballpark after glancing at today's history on several). Clients are primarily Windows laptops (Lenovo Yoga, HP Probooks).

Dynamic channel switching is enabled.

Re: ap550 high rx CRC rate (42%) on only one radio.

sderikonja1 — Wed, 02 Oct 2019 01:34:21 GMT

That is a low client count for an AP250, especially with dual 5 Ghz enabled. Have you tried disabling second 5G interface to see what that does for CRC count?

I have played with dynamic channel switching for a year and did not like the unpredictable environment it created.

Re: ap550 high rx CRC rate (42%) on only one radio.

w1f1n00b — Wed, 02 Oct 2019 01:42:23 GMT

I'll make the change tonight and report back CRC #s tomorrow. I honestly hadn't thought of doing that but really want to get to the bottom of this. Thanks for the suggestion.

Re: ap550 high rx CRC rate (42%) on only one radio.

w1f1n00b — Thu, 03 Oct 2019 20:59:06 GMT

I thought I replied on Monday but apparently not. Thank you for the radio suggestion. I hadn't thought to try that. I turned off int wifi0 on all of these APs Monday night. Here are the numbers today. I'm also including a partial map so you can get an idea of the layout. Still, nothing seems to make much sense.

Re: ap550 high rx CRC rate (42%) on only one radio.

w1f1n00b — Thu, 03 Oct 2019 21:00:26 GMT

I'm also wondering if it's normal for an interface that is down to report crc #s, as that is what I'm seeing here.

Re: ap550 high rx CRC rate (42%) on only one radio.

sderikonja1 — Thu, 03 Oct 2019 23:25:25 GMT

Still high CRC numbers. Yesterday I spoke to Aerohive support and mentioned CRC errors. Supposedly 10.0r8 should address this issue as the numbers you are seeing could be false positives. Can you go onsite and do a packet capture? Have you received any complaints from end users? Slow wifi or frequent disconnects?

Disabled interface is administratively down and while not broadcasting, the radio remains active.

Re: ap550 high rx CRC rate (42%) on only one radio.

w1f1n00b — Thu, 03 Oct 2019 23:31:55 GMT

I am having reports of frequent disconnects but only in the area of AP #28. That's what got me started looking into this, but I'm also see high CRC #s at other locations as well. I'd suspected maybe false reporting, but last I heard that was resolved as of 10.0r5. If it's ongoing it would be nice to know officially.

As to the pcap, I'm a little weak in that area. I know how to do it, but wouldn't know what to look for off the top of my head.

Re: ap550 high rx CRC rate (42%) on only one radio.

sderikonja1 — Thu, 03 Oct 2019 23:47:31 GMT

Mac Book Pro is easiest to capture packets with. You can filter for retries yourself or use https://support.metageek.com/hc/en-us/articles/115013527388-Wireshark-Configuration-Profile

Linux works too but is more complex.

In Windows there is Acrylic Professional https://www.acrylicwifi.com/en/wlan-wifi-wireless-network-software-tools/wifi-analyzer-acrylic-professional/

Again you need the proper wireless adapter.

Another way is to use an Aerohive access point in remote capture mode. Search the forum for config samples.

Re: ap550 high rx CRC rate (42%) on only one radio.

tandrews — Tue, 28 Jan 2020 04:09:15 GMT

John... We have been dealing with similar issues. One particular location in our high school was giving us fits. We cranked radio power way down, shut off 2.4Ghz radios, etc. We noticed high CRC rates on wifi0 and our support rep suggested moving the APs. So we generally tried to avoid close to walls and near hanging objects (TVs, Projectors, etc.). It has been about a month with these changes and (knock on wood) we have had no complaints from users in that area.