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Investigating ARM History in Aruba Instant

Guest Blogger

Pasted Graphic 2.pngI really like Aruba Instant. It's a great solution for branch offices, many retail locations, and if you are a Wi-Fi guy, maybe even your home. A Virtual Controller gives you all the basics and even quite a few advanced features without having to run a traditional hardware controller. That's all fine and dandy until you decide to debug something. There's a lot of detail not obviously exposed in the GUI, but it's there and you can find a lot about what's actually happening in an Instant deployment using the support features and might even learn a bit of CLI goodness while you are at it.




The other day I really wanted to know about ARM status. I was troubleshooting a connectivity issue and wanted to see if the channels were changing. Finding what channel, you are currently on is easy enough, but if you'd like to know what's changed and why, you need to dive into the support menu.

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If you like, you can run a tech support dump, which you may well have done before. That's well over 8000 lines of data to look through. It can be hard to find what you want and it doesn't even include everything! You can be more targeted with your command selection and give yourself an easier amount of data to work with. You can even search for terms here and it'll limit the options to match your term, making it easier to find that command you actually want. Let's search for "arm":

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That's a much more reasonable list of options to work with. "AP ARM History" sounds like a useful command. Let's see what's changed recently.

 1/30/2017 19:27:09 PM    Target: 225    Command: show ap arm history 

Interface :wifi0
ARM History
Time of Change       Old Channel  New Channel  Old Power  New Power  Reason  Result
--------------       -----------  -----------  ---------  ---------  ------  ------
2017-01-30 12:01:12  116+         116+         21         24         P+      Configured
2017-01-30 11:53:35  116+         116+         18         21         P+      Configured
2017-01-30 11:47:23  116+         116+         24         18         P-      Configured
2017-01-13 20:15:28  36+          116+         24         24         N       Configured
2016-12-22 11:00:57  100E         100E         Max        24         P-      Configured

Interface :wifi1
ARM History
Time of Change       Old Channel  New Channel  Old Power  New Power  Reason  Result
--------------       -----------  -----------  ---------  ---------  ------  ------
2016-12-23 07:45:51  6            6            21         24         P+      Configured
2016-12-23 07:37:57  6            6            18         21         P+      Configured
2016-12-23 07:31:34  6            6            15         18         P+      Configured
2016-12-22 11:13:33  6            6            18         15         P-      Configured
2016-12-22 11:05:50  6            6            24         18         P-      Configured
2016-12-22 11:00:58  6            6            Max        24         P-      Configured

I: Interference, R: Radar detection, N: Noise exceeded, Q: Bad Channel Quality E: Error threshold exceeded, INV: Invalid Channel, G: Rogue AP Containment, M: Empty Channel, P+: Increase Power, P-: Decrease Power, 40INT: 40MHZ intol detected on 2.4G, NO40INT: 40MHz intol cleared on 2.4G, OFF: Turn off Radio, ON: Turn on Radio, D: Dynamic Bandwidth Switch, I*: CCA Interference

Note the top line where it says "Command". Now we know to find this data in the CLI, we can run "show ap arm history". This is a great way to learn the CLI, if that's of interest to you. As an aside, don't knock the CLI. Knowing how to use the CLI can be particularly useful when you have to troubleshoot from remote. It's a lot quicker than the GUI!


This looks like some pretty approachable data. Let's talk about the data we have here:

  • We have both radios listed.
  • We see 2.4GHz has been on channel 6 for over a month.
  • We see that the 5GHz radio has changed channels a couple times, when those changes happened, and that one of them was due to too much RF noise.
  • We see that both radios have changed power levels a few times.

Let's say you had a trouble report that complained of all the client devices losing their connections the evening of January 13th. We have a log line that could explain that:

Time of Change       Old Channel  New Channel  Old Power  New Power  Reason  Result
--------------       -----------  -----------  ---------  ---------  ------  ------
2017-01-13 20:15:28  36+          116+         24         24         N       Configured

At 8:15PM on January 13th, the AP switched from channel 36 to channel 116 because of noise. Power levels remained the same. We now have a plausible explanation for why the incident on the 13th occurred. Problem explained and probably resolved by ARM moving away from the interference. If you stick the the GUI, you won’t be finding out what happened.


There's more in that Virtual Controller than just the obvious GUI components or what you may see in Aruba Central. Get into the controller, poke around a bit. See what you can find out. Dig around that support menu. You can find and learn a lot about how your wireless system is working from those commands and might even discover problems you didn't know existed. Proactively solving problems before they impact your users is always a win!


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