Troubleshooting Voice-over-WLAN

Userlevel 6
For troubleshooting of voice quality problems and session interupts of a ascom wlan phone i am looking for some troubleshooting tools / reports / debug onboard with recent EWC. We use V9.15.08.

What i am looking for as combination of station events logs (for roaming information) and client reports (for WiFi Signal strenght of that station). Additionally it should be filtered to that special wlan client which i want to analyse. And this combined data should be saved in a log or report maybe every 10 seconds.

Does anybody knew a way to analyse this issue with the onboard tools of EWC ? I want to avoid to sit in front of the ewc dashboard and have to control and following both reports / logs during all the time i want to analyse.


5 replies

Userlevel 7
Could you provide some more details...
- is it a Acscom i62?
- do you get the voice quality problems and session interupts during roaming or only at the begin of the call?
- what topology is used for the VoWLAN phones.

Userlevel 6
my first guess is that wireless coverage is not enough in this area. So my task is to determine that the signal strenght is to bad.

Because of this i ask for such a report to see which AP is used and with which signal strenght. Because i am not on (customer) site i need this as a kind of log file or report which i can start one time and can be review some days later.
Userlevel 7
Only Netsight OneView is able to collect history client data and even then I don't use that to troubleshoot voice client issues.
If you check the report > clients by AP you'd see the RSSI from the AP point of view.
Most of the time the voice client point of view is more important.

In case we are talking about a Ascom i62 just connect via https to the phone IP and go to > troubleshoot > log > syslog.
Here you'd see whether roaming is working and if you've enough coverage.
i.e. here a roaming event of the phone from AP X with signal -74 to AP Y with signal -56, the APs in the {...} show other APs that the client could "see" but have a lower signal = lower priority and are not used to roam to....
2015-08-25 13:47:18.076,750 - From AP: d8:84:66:0e:3f:10 - RSSI: -74 - Ch: 56 - To AP: d8:84:66:0e:37:c0 - RSSI: -54 - Ch: 44 {AP: d8:84:66:0e:2c:d0 - RSSI: 72 - Ch: 60} {AP: d8:84:66:0e:3e:90 - RSSI: 62 - Ch: 36} {AP: d8:84:66:36:f4:50 - RSSI: 64 - Ch: 36} {AP: d8:84:66:02:dd:90 - RSSI: 72 - Ch: 48} {AP: d8:84:66:0e:39:40 - RSSI: 74 - Ch: 108}

You'd recognize bad coverage if the "from AP" signal is very high as normaly the phone should roam at 70dBm, so if you'd see 75+ you know that the phone hasn't found a better AP/signal before the new AP was in reach.

If you setup a call it looks like this on the phone....

2015-08-25 14:04:22.126,625 - Incoming call
2015-08-25 14:04:22.212,500 - Setting WLAN power mode: active
2015-08-25 14:04:23.546,375 - Voice Tx IP DSCP: 0x2e UP: 6
2015-08-25 14:04:23.557,625 - Voice Rx IP DSCP: 0x0c UP: 0
2015-08-25 14:04:24.009,375 - Call start - AP: d8:84:66:0e:3e:90 - RSSI: -40 - Codec: G711A
2015-08-25 14:04:25.686,250 - From AP: d8:84:66:0e:3e:90 - RSSI: -44 - Ch: 36 - To AP: d8:84:66:36:f4:50 - RSSI: -35 - Ch: 36 {AP: d8:84:66:02:dd:90 - RSSI: 48 - Ch: 48} {AP: d8:84:66:0e:39:40 - RSSI: 64 - Ch: 108} {AP: d8:84:66:0e:37:c0 - RSSI: 70 - Ch: 44}
2015-08-25 14:04:38.926,000 - Call disconnected by user
2015-08-25 14:04:38.004,500 - Setting WLAN power mode: long doze
2015-08-25 14:04:39.014,250 - AP: d8:84:66:36:f4:50 - RSSI: -48 - Rx packet loss: 0% - Rx packet: 745 - Tx packet: 751 - Rx min pkt interval: 0 ms - Rx max pkt interval: 170 ms - Rx average jitter: 7 samples - Call ended

Here the last message is the interesting one, if you see a big difference in rx and tx packets you've one way audio, a lot of discarded packets in one direction.

You'd also do a remote AP wireshark trace...

Another thing is to forward the station events to a syslog server so you'd keep older roaming events, controller GUI > controller > logs > Forward station session events as traps

Userlevel 6
Hi Ron,
thanks for your practical advices. Now i am having a approach to start analysing this issue.

Indeed we are using a alcatel branded i62 phone.

Userlevel 7
I use this guide all the time, attached for reference....