Wireless Access

Reply
Occasional Contributor II
Posts: 33
Registered: ‎06-28-2015

When does an ap (can be the connected one or off channel ones) report/update a new client snr?

I tried to answer this question for a few weeks already. Unfortunately, several tests gave me results that even confuse me more.

 

For example, I put a phone connected, screen-off, and logged its wifi scan activities at the client side overnight. For each scan, it did have quite a lot (20~50) scan results. I was assuming that each result means a corresponding ap (either on the connected channel or a different channel) is active and replies (probe response).

 

However, when I checked out snr report history at Aruba side, over the period there are only 3 ap's that were continuously reporting the client's snr. What about others that can be seen in the client scan log?

 

Even confusing, they reported at a pretty high rate (roughly every 5 minutes), but actually over the period my client scans at every half-an-hour on average. 

 

Please help me out. Thanks

Guru Elite
Posts: 21,490
Registered: ‎03-29-2007

Re: When does an ap (can be the connected one or off channel ones) report/update a new client snr?

An AP only reports client SNRs for clients that are associated to them, in general.  There are other applications like RTLS where access points can report on the signal strength of unassociated clients.



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Occasional Contributor II
Posts: 33
Registered: ‎06-28-2015

Re: When does an ap (can be the connected one or off channel ones) report/update a new client snr?

[ Edited ]

Thank you, but this is apparently not the case here. Let us see a trace:

 

                                          ap1                          ap2                 ap3              ap4

2015-08-15 03:02:55                                                                                    11

2015-08-15 03:02:56         23     

2015-08-15 03:04:03                                         53

2015-08-15 03:06:27         24                     

2015-08-15 03:06:52                                         51

2015-08-15 03:07:19                                         53

2015-08-15 03:08:44         22                                                                 

2015-08-15 03:09:23                                                                 13

2015-08-15 03:11:01                                         51

..... 

 

I am assuming my client was associated with ap2, then what to do with ap1, ap3 and ap4?

Occasional Contributor II
Posts: 33
Registered: ‎06-28-2015

Re: When does an ap (can be the connected one or off channel ones) report/update a new client snr?

[ Edited ]

Thank you, but this is not the case here. Consider the following trace:

 

                                           ap1       ap2      ap3      ap4

2015-08-15 03:02:17          21

2015-08-15 03:03:07                       52

2015-08-15 03:03:41                       51

2015-08-15 03:04:55                                    12

2015-08-15 03:06:22          23

2015-08-15 03:07:10                       52

2015-08-15 03:08:35                                                8

2015-08-15 03:11:06          22

 

I am assuming my client was associated with ap2, then what to do with ap1, ap3 and ap4?

Thank you.

Guru Elite
Posts: 21,490
Registered: ‎03-29-2007

Re: When does an ap (can be the connected one or off channel ones) report/update a new client snr?

What are you using to get that information?


Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Occasional Contributor II
Posts: 33
Registered: ‎06-28-2015

Re: When does an ap (can be the connected one or off channel ones) report/update a new client snr?

Periodically poll the controller.

Occasional Contributor II
Posts: 33
Registered: ‎06-28-2015

Re: When does an ap (can be the connected one or off channel ones) report/update a new client snr?

Is there any document to talk about this? I need a clear and thorough answer to the question "when an ap would update a client (either associated ones or others) 's snr"

 

Thank you

Guru Elite
Posts: 21,490
Registered: ‎03-29-2007

Re: When does an ap (can be the connected one or off channel ones) report/update a new client snr?

[ Edited ]
There is no document about this. The only reliable way to get a client's SNR is on the access point it is connected to. What command are you using to poll the controller?


Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Moderator
Posts: 321
Registered: ‎08-28-2009

Re: When does an ap (can be the connected one or off channel ones) report/update a new client snr?

[ Edited ]

nzhang27 wrote:

Periodically poll the controller.


what exactly are you polling ? please show us the exact source of the values, then we can tell you where they come from.

 

There are at least 2 different ways that SNR is collected, one of them is from direct connection, the other is through the general air-monitor function that every AP has. If a client becomes a "monitored client" then those APs will start to track SNR and populate the wlsxMonStationInfoTable with it's view of the client SNR (termed RSSI in MIB however).

 

The update frequency depends on whether you are using CLI commands or SNMP to find these values, hence the question about where exactly you are getting the values from

 

regards

-jeff

Occasional Contributor II
Posts: 33
Registered: ‎06-28-2015

Re: When does an ap (can be the connected one or off channel ones) report/update a new client snr?

Thank you for your reply. 

 

There are at least 2 different ways that SNR is collected, one of them is from direct connection, the other is through the general air-monitor function that every AP has. If a client becomes a "monitored client" then those APs will start to track SNR and populate the wlsxMonStationInfoTable with it's view of the client SNR (termed RSSI in MIB however).

 

I really care about how/why/when NON-associated APs report a client's snr. Two derived questions: 1) when does an  ap start/resume doing "air-monitoring" job? and 2) when does a client become a "monitored client"?

what exactly are you polling ? please show us the exact source of the values, then we can tell you where they come from.

 

The update frequency depends on whether you are using CLI commands or SNMP to find these values, hence the question about where exactly you are getting the values from

 

I use perl script that has following SNMP logic every 3 seconds. 

                my @snmpW=();
 
                &SNMP::addMibDirs("/usr/share/snmp/mibs/" );
                &SNMP::loadModules('WLSX-MON-MIB');

                &SNMP::initMib();
 
                my %snmpparms;
                $snmpparms{Community} = $communityString;
                $snmpparms{DestHost} = inet_ntoa(inet_aton($controller));
                $snmpparms{Version} = $sver;
                $snmpparms{UseSprintValue} = '1';
                $sess = new SNMP::Session(%snmpparms);

                $vb = new SNMP::Varbind([$rssiMibString]); 

The table I showed in earlier replies is something after few script processing. 

 

 

 

 

 

 

 

 

 

 

 

Search Airheads
Showing results for 
Search instead for 
Did you mean: