Wireless Access

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Frequent Contributor I
Posts: 83
Registered: ‎10-27-2013

Low Client Health reported

Hi

 

I have been playing around a bit with my 5Ghz setup and came across a bit of a funny result regarding client health. I am not sure what the reasoning is for the low health.

 

I am using a Linux client (Ubuntu 14.04 LTS) with a Proxim 802.11a/b/g/n USB dongle. The AP I am connecting to is a Aruba 104 with external antennas - I am aproximately 3 to 4 meters away from the AP. I am connecting on 5Ghz with HT enabled (40Mhz).

 

From the client I am experiencing no issues what so ever - I am using a tool called "wavemon" to monitor my connection from the client. It is reporting a Good signal level of -40to-43dBm with link quality between 97% and 100% - my bitrate does fluctuate between 120Mbits to 300Mbits. So from the client ALL looks good :)

 

However when I look at the client from the controller it is reporting client health between 40% and 60% which as far as I understand would indicate connectivity problems for the client. SNR appears reasonable between 30 and 45. Dropped frames to client is very low at 0-2% however retried frames is sitting at arround 22% to 41%. I am running Aruba OS 6.4.2.3 on my controller.


So the Questions

Q1.) What factors determine Client Health from the controller perspective?
Q2.) How can I get more information regarding the retried frames as seen from the controller?
Q3.) JHow can I adress and correct the retried frame rate?

 

Attached is a screenshot showing the client health aswell as the wavemon output running on the client.

gem
Contributor I
Posts: 29
Registered: ‎09-27-2013

Re: Low Client Health reported

Have you tried running a spectrum analyzer? Maybe you have co-channel interference there if for example you have a very dense deployment or to nearby APs on the same channel.
Frequent Contributor I
Posts: 83
Registered: ‎10-27-2013

Re: Low Client Health reported

Hi

 

Unfortunately I haven't got a Spectrum analyzer so can't check that info. Also I am not familiar with the aruba Beacon setup on the APs to check the air in that perspective (if it is simple enough I can maybe look at trying that, but don't know if it will supply the information needed).

 

I checked the channel assignments of all the APs in the vacinity and they all are spread out quite nicely, there doesn't appear to be any overlapping channels on 2.4 or the 5Ghz.

 

Below is the output from ARM for the specific AP I am connecting to - I am not sure what Pairwise_intf_index stands for or what it means... :/

 

(TCM-MID-Aruba-WLC-01) #show ap arm rf-summary ap-name B-Block_GndFlr_Networks

Channel Summary
---------------
channel  retry  phy-err  mac-err  noise  util(Qual)     cov-idx(Total)  intf_idx(Total)
-------  -----  -------  -------  -----  ----------     --------------  ---------------
36       0      0        0        93     0/0/0/0/89     0/0(0)          0/0//0/0(0)
40       0      0        0        91     13/0/2/0/89    0/0(0)          0/0//0/0(0)
44       0      0        0        91     13/0/2/0/89    0/0(0)          0/0//0/0(0)
48       0      0        0        91     12/0/2/0/89    0/0(0)          0/6//0/0(6)
52       0      0        0        91     12/2/0/0/90    0/0(0)          11/0//0/0(11)
56       0      0        0        89     10/0/0/0/90    0/0(0)          0/4//0/0(4)
60       0      0        0        90     10/0/0/0/90    0/0(0)          0/0//0/0(0)
64       0      0        0        91     10/0/0/0/90    0/0(0)          0/0//0/0(0)
100      0      0        0        90     0/0/0/0/89     0/0(0)          14/0//0/0(14)
104      0      0        0        92     10/0/0/0/90    0/0(0)          0/5//0/0(5)
108      0      0        0        91     10/0/0/0/90    0/0(0)          0/0//0/0(0)
112      0      0        0        91     10/0/0/0/90    0/0(0)          0/2//0/0(2)
116      9      0        1        90     1/0/1/0/91     8/0(8)          5/0//0/0(5)
120      0      0        0        92     10/0/0/0/90    0/0(0)          0/2//0/0(2)
124      0      0        0        91     10/0/0/0/90    0/0(0)          0/0//0/0(0)
128      0      0        0        90     10/0/0/0/90    0/0(0)          0/15//0/0(15)
132      0      0        0        90     12/1/0/0/89    0/0(0)          44/0//0/0(44)
136      0      0        0        91     10/0/0/1/90    0/0(0)          0/15//0/0(15)
140      0      0        0        91     10/0/0/0/90    0/0(0)          0/0//0/0(0)
1        0      0        0        90     14/9/3/0/84    7/0(7)          93/1//206/13(313)
6        3      0        0        96     12/1/9/0/88    7/0(7)          0/22//3/28(53)
11       0      0        0        92     42/16/16/0/40  4/3(7)          36/0//30/3(69)

Columns:util(Qual): ch-util/rx/tx/ext-ch-util/quality

HT Channel Summary
------------------
channel_pair  Pairwise_intf_index
------------  -------------------
116-120       7
52-56         15
100-104       19
124-128       15
36-40         0
60-64         0
108-112       2
132-136       59
44-48         6

Interface Name           :wifi0
Current ARM Assignment   :116+/24
Covered channels a/g     :1/0                     
Free channels a/g        :17/0
ARM Edge State           :enable
Last check channel/pwr   :4m:50s/2m:44s
Last change channel/pwr  :20h:8m:1s/20h:8m:1s
Next Check channel/pwr   :1m:38s/1m:33s
Assignment Mode          :Single Band

Interface Name           :wifi1
Current ARM Assignment   :6/21
Covered channels a/g     :0/3
Free channels a/g        :0/0
ARM Edge State           :enable
Last check channel/pwr   :32s/1m:25s
Last change channel/pwr  :10h:38m:38s/10h:38m:38s
Next Check channel/pwr   :5m:54s/3m:16s
Assignment Mode          :Single Band

 

Frequent Contributor I
Posts: 91
Registered: ‎08-10-2015

Re: Low Client Health reported

[ Edited ]

I know this thread is a few months old, but I found it while trying to figure out how client health is measured, then I found the answer in another place.  I know that was #1 on your list of questions, so I'll put the answer here for good measure in case someone happens upon this thread later:

 

http://www.arubanetworks.com/techdocs/ArubaOS_64_Web_Help/Content/ArubaFrameStyles/Dashboard_Monitoring/Performance.htm#dashboard_monitoring_3635553299_1098760

 

An AP’s client health is the efficiency at which that AP transmits downstream traffic to a particular client. This value is determined by comparing the amount of time the AP spends transmitting data to a client to the amount of time that would be required under ideal conditions, that is, at the maximum Rx rate supported by client, with no data retries.

A client health metric of 100% means the actual airtime the AP spends transmitting data is equal to the ideal amount of time required to send data to the client. A client health metric of 50% means the AP is taking twice as long as is ideal, or is sending one extra transmission to that client for every packet. A metric of 25% means the AP is taking four times longer than the ideal transmission time, or sending 3 extra transmissions to that client for every packet.

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