Wireless Access

 

I've got a user with complaints of wireless problems - standard problems ("doesn't work," "get kicked off," etc....you know, all the really helpful complaints!

 

 

Found this in the logs today, but not quite sure what to make of it.  Seems the AP is switching channels, but I'm not sure why.

 

2013-07-09	14:32:38	An AP (NAME 00:24:6c:c7:e3:04 and MAC 00:24:6c:c7:e3:04 RADIO 1) changed its channel from channel 11 (secchan offset 1) to channel 1 (secchan offset 1) due to reason 8.
2013-07-09	14:32:38	Radio 1 on AP (00:24:6c:c7:e3:04) has changed. Change type is 3
2013-07-09	14:32:38	Radio attributes of Radio 00:24:6c:c7:e3:04::0 with IP address 10.70.197.103 have changed. Channel is 1, Transmit Power is 32
2013-07-09	14:32:39	An AP (NAME 00:24:6c:c7:e3:04 and MAC 00:24:6c:c7:e3:04 RADIO 1) changed its channel from channel 1 (secchan offset 1) to channel 11 (secchan offset 1) due to reason 11.
2013-07-09	14:32:39	Radio 1 on AP (00:24:6c:c7:e3:04) has changed. Change type is 3
2013-07-09	14:32:39	Radio attributes of Radio 00:24:6c:c7:e3:04::0 with IP address 10.70.197.103 have changed. Channel is 11, Transmit Power is 32

Can you correlate those times with events showed in the show ap arm history ap-name <apname>


Maybe these are the Reasons but numbered? :
Interference (I)
Power +
Power -

Looks to be Interference and Noise exceeded:

 

ARM History
-----------
Time of Change       Old Channel  New Channel  Old Power  New Power  Reason
--------------       -----------  -----------  ---------  ---------  ------
2013-07-09 14:51:39  1            11           21         21         N
2013-07-09 14:51:38  11           1            21         21         I
2013-07-09 14:32:39  1            11           21         21         N
2013-07-09 14:32:38  11           1            21         21         I
2013-07-09 14:21:46  1            11           21         21         N
2013-07-09 14:21:45  11           1            21         21         I
2013-07-09 14:15:29  1            11           21         21         N
2013-07-09 14:15:28  11           1            21         21         I
2013-07-09 14:11:05  1            11           21         21         N
2013-07-09 14:11:04  11           1            21         21         I
2013-07-09 14:06:54  1            11           21         21         N
2013-07-09 14:06:53  11           1            21         21         I
2013-07-09 13:59:04  1            11           21         21         N
2013-07-09 13:59:03  11           1            21         21         I
2013-07-09 13:48:13  1            11           21         21         N
2013-07-09 13:48:12  11           1            21         21         I
2013-07-09 13:11:12  1            11           21         21         N
2013-07-09 13:11:11  11           1            21         21         I
2013-07-09 13:06:52  1            11           21         21         N
2013-07-09 13:06:51  11           1            21         21         I
2013-07-09 12:50:45  1            11           21         21         N
2013-07-09 12:50:44  11           1            21         21         I
2013-07-09 12:43:28  1            11           21         21         N
2013-07-09 12:43:27  11           1            21         21         I
2013-07-09 12:24:44  1            11           21         21         N
2013-07-09 12:24:43  11           1            21         21         I
2013-07-09 12:18:56  1            11           21         21         N
2013-07-09 12:18:55  11           1            21         21         I
2013-07-09 12:12:42  1            11           21         21         N
2013-07-09 12:12:41  11           1            21         21         I
2013-07-09 12:00:49  1            11           21         21         N
2013-07-09 12:00:48  11           1            21         21         I
I: Interference, R: Radar detection, N: Noise exceeded, E: Error threshold exceeded, INV: Invalid Channel, G: Rogue AP Containment, M: Empty Channel, P+: Increase Power, P-: Decrease Power, OFF: Turn off Radio, ON: Turn on Radio

 

I've got 4 access points out there (approx 15k sq ft spread over 2 levels).  According to the dashboard 2 are Ch 11 and 2 are Ch 1 - all have a Noise Floor of -92 to -94 dBm.

 

The primary complaint seems to be the random disconnects - I'm assuming the clients are getting briefly disconnected when the AP decides to change the channel.

 

They are currently using AP93, but I'm toying with the idea of replacing 2 of those with AP105 (ongoing project) to see if it will help.  I don't believe the main complainer is using a dual-band card, so I don't know if that will be helpful.

 

I didn't think that a noise floor of -92 to -94 dBm was particularly bad.

 

Are those devices connecting using 802.11g because based on the output you provided it looks like your ARM power level is set to a minimum of 21 and you have neighbor APs that ate too close and its causing RF issues : Interference and High Noise floor .

Can you check the minimum power levels under the ARM settings for the AP-Groups those APs are using?

I believe it is at 9 - I haven't played with any of these settings since we first deployed the stuff 3 years ago, so all the settings are from our SE, which I believe are pretty much default:

 

There's something in your environment that its causing interference (unhealthy RF environment )

Run this command :
show ap monitor ap-list ap-name <apname>

Looks like we have a bunch of interfering networks:

 

 Monitored AP Table
------------------
bssid              essid          chan  ap-type               phy-type        dos      dt/mt          ut/it    encr            nstas  avg-rssi  curr-rssi  wmacs  ibss
-----              -----          ----  -------               --------        ---      -----          -----    ----            -----  --------  ---------  -----  ----
00:24:6c:fe:30:40  LnF-PEAP       11    valid                 80211b/g        disable  411721/411701  1/0      wpa-8021x-tkip  0      35        35         0      no
00:24:6c:fe:30:41  OPEN_Link      11    valid                 80211b/g-HT-20  disable  411721/411715  0/0      open            0      35        35         3      no
00:26:b8:ad:ba:58  YYT4L          11    interfering           80211b/g-HT-20  disable  411719/411476  0/0      wep             0      7         8          4      no
00:7f:28:94:95:97  4N9SH          6     suspected-rogue(20%)  80211b/g-HT-20  disable  87777/3045     17/1     wpa2-psk-tkip   0      26        26         0      no
08:17:35:d0:2b:f6  CBCONSTRUCT    11    interfering           80211b/g-HT-20  disable  44664/44664    3/2      wpa2-psk-aes    0      4         5          0      no
00:18:39:0a:0f:8b  Keystone Blue  11    interfering           80211b/g        disable  19105/19105    63/62    wpa-psk-tkip    0      0         5          0      no
d8:c7:c8:76:34:90  TITLE_Link     11    valid                 80211b/g-HT-20  disable  14643/14643    0/0      open            0      5         6          0      no
d8:c7:c8:76:34:91  Title-PEAP     11    valid                 80211b/g-HT-20  disable  12717/12717    0/0      wpa2-8021x-aes  0      7         6          0      no
00:26:f3:d2:80:68  ALtecA         6     interfering           80211b/g-HT-40  disable  10622/210      17/1     wpa-psk-tkip    0      19        19         0      no
00:13:10:44:0f:58  KGZ1           6     interfering           80211b/g        disable  6230/136       93/3     wep             0      0         17         0      no
68:7f:74:d3:c1:8e  Charlie        11    interfering           80211b/g-HT-20  disable  4994/2644      55/54    wpa-psk-tkip    0      0         3          1      no
68:7f:74:d3:c1:8f  Charlie-guest  11    interfering           80211b/g-HT-20  disable  4689/2610      47/46    open            0      0         7          0      no
00:19:70:13:26:d4                 11    interfering           80211b          disable  562/562        504/247  wep             0      0         9          0      no
00:26:f3:d2:80:6a                 6     interfering           80211b/g-HT-40  disable  442/14         174/5    wpa-psk-tkip    0      0         18         0      no
00:26:f3:d2:80:69                 6     interfering           80211b/g-HT-40  disable  17/2           17/2     wpa2-psk-aes    0      18        18         0      no
Start:0
Length:15
Total:15

 

 

 

That's whats causing your problem , a lot of devices on ch 11 interference .
You need to identify those devices if you don't know what those are.

If you don't any controller over those devices you should consider lowering the power levels under ARM . Is there a particular you client aware disabled ?

unfortunately I don't have any control over any of those networks other my 4 networks (the PEAP and Link are mine....I wasn't aware our associated business was in the same building, but it is a separate network.

 

I'm not sure why we are not using client aware.  Like I said, our SE came in, did a proof of concept, got us up and running and basically gave me cookie cutter instructions on how to deploy to the rest of my sites.

 

It's been a few years, but I think that was one of those settings that he said not to change because it can cause more problems than it can fix????

 

I don't have any problem changing it if it will fix the issue.....I can always change it back.

I don't think client aware is your issue necessarily i think it is those neighbor APs in your building .

Client aware is a good thing to have enabled but if I got disabled because it was causing issues it may have been a bug or known issue with the AOS code it was installed or currently installed.

I've gone into the profile and changed it back to default (with client aware) to see if it helps.

 

I went back and looked at the interference again and many of the networks are now using CH 6.  I wonder if the levels get so bad that all of the networks start changing at the same time.  Maybe by making my AP "stubborn" the problem won't be so evident.
  I have a feeling my users are less likely to notice the interference than they are the random drops do to channel changing.

 

 

Thank you for your help....you've given me a few more helpful commands to stash away for future troubleshooting.

 

 

If the Client Aware option is enabled, the AP does not change channels if there is active client traffic on that AP. If Client Aware is disabled, the AP may change to a more optimal channel, but this change may also disrupt current client traffic.
Default: enabled

Read this :
http://www.arubanetworks.com/wp-content/uploads/arubaarm1.pdf

Usually is that your signal is very good (but of course not quality signal) but you have a lot of drops (packet loss) which make things very slow or you can't barely reach anything depending on how serious is the interference event and from the user perspective it feels like they have been kicked off the wireless network.

I honestly never seen the channel/power change because of noise but for interference , min/max power , Empty channel or Error threshold so its possible that you have a serious interference issue.

If you have the RFProtect module (license) and AOS 6.x.x you could turn on one of your not use APs into a spectrum monitor 802.11g spectrum in that area and do some spectrum analysis ( the duty cycle info ) on those channels

http://www.arubanetworks.com/pdf/technology/TB_Spectrum-Analyzer.pdf