Radio Health Indicator

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  • Updated 5 years ago
Would it be possible to get radio health indicators in the the Monitor -> Access Points screen? The indicators could be an icon for for each radio (2.4 and 5 GHz) that is green (low collisions/errors), orange (fair collisions/errors) or red (high collisions/errors).

I know that this information is available in the Dashboard screen but the table format of the Monitor -> Access Points screen may be more suitable for reports.
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Crowdie, Champ

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Posted 5 years ago

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Bradley Chambers, Champ

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Good idea!
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Andrew MacTaggart, Champ

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It's a good Idea

I don't think collisions can be counted, just assumed based on lack of ack, retries and corrupted frames.

from CWAP Official Study Guide
"Any entity operating in a half-duplex, wireless medium is going to be unable to detect collisions."
Credit to be given to the authors
David A. Westcott,David D. Coleman, Peter Mackenzie, and Ben Miller

Cheers
A
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Crowdie, Champ

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Monitor -> Aerohive APs -> [AP Name] -> Utilities... -> Status -> WiFi Status Summary



We don't need an exact collision count just a status indicator.
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Andrew MacTaggart, Champ

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Thanks Crowdie

New tool for me, Thanks for that.

but how is the High Collision status determined, and is it real time or based on a specific time period

It must be determined by the amount of retries or corupted frames, TX errors or RX errors. because collisions must be assumed

Looking at a few of my APs they all indicate High Collision
but when I use my airpcap device and eyepa, I get a clean bill of health for random samplings.

I just pushed configs to the APs and the interface changed from High collision to Good. So it must be a collective indicator over time.

According to the Help file

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

This must be frame corruption of received frames, where the CRC has failed, assuming a collision has occured.

Interface

View details about all the interfaces on the selected device. There are four types of interfaces: a logical Layer 3 interface (mgt0), a physical Ethernet interface (eth0), two logical wireless interfaces (wifi0 and wifi1), and multiple subinterfaces (wifi0.1 - wifi0.4 and wifi1.1 - wifi1.4). For each type of interface, you can view its MAC address and state (up or down), and—where applicable—its mode (access or backhaul), VLAN ID number, radio mode, hive membership, and SSID.

WiFi Status Summary

(This option is unavailable on Aerohive switches and VPN gateways.) HiveManager 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%.
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Crowdie, Champ

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Did you do packet captures at the access point as well as at the wireless client?

Just taking a packet capture at the affected wireless client may not capture issues closer to the access point - think hidden node, for example.
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Andrew MacTaggart, Champ

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The Airpcap device just catches all packets in the air on a selected channel, including AP as a client, it is independant hardware.

Cheers
A
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Crowdie, Champ

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Your Airpcap device will capture the frames that it can hear. If your position is a fair distance from the access point you may not capture all the traffic by the access point including CRC errors. For this reason it is considered best practice to take captures at the source and the destination.

When I am teaching this I use the classic hidden node example. The two wireless clients are separated by a wall and cannot detect each other but both can see the access point. Both wireless clients transmit to the same access point and the collision occurs by the access point. If you only packet capture at one of the wireless client's locations you will, most likely, not detect the CRC error caused by the collision. A packet capture at the access point will, most likely, detect the CRC error caused by the collision.

Yes, the example is a generalisation but it, for the most part, gets the point across.
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Andrew MacTaggart, Champ

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@Crowdie

First thanks for pointing out this feature. That's 2 things learned in 1 day.

http://blogs.aerohive.com/blog/wi-fi-...

Do you have this working? If so what version of wireshark are you using
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Crowdie, Champ

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I have used remote sniffing a number of times. The Linux version has traditionally been more feature rich than the Windows version but the Windows v1.1 is catching up.