VQM bad fo some calls

[karim_chriqi]

Hi all,

My NetVanta 3448 display some VQM indicator, and I can see loss=58 pkts. So, I suppose that for this specific call, we had 58 packets loosed. But, my costumers did not feel any problem with the quality of service. The only issue he has is the fax (it seems he is not able to receive fax). Seeing that, I decided to check at the IP level. In both interfaces toward the PBX and the backbone, I did not see any frame loosed.

Is there somebody who did experience a similar issue and is there a way to fix it?

Also, just to inform you that there are many others calls where we have 0 packets lost and 0 jitter.

1. 2014.09.26 09:03:11 VQM.EVENTS Monitoring session ended for Phone_number1 to Phone_number2, RTP=A1.B1.C1.39:41096 (SBC)->A2.B2.C2.17:10552 (ESBC), MOS (LQ/PQ)=4.14/4.08, loss=58 pkts, out-of-order=0 pkts, jitter=0 ms.

I have many Netvanta 3448 on the network; the issue is only with this costumer.

Regards.

Karim

[Anonymous]

Hi Karim:

58 packets may not be a big deal for a long call, unless they all dropped in one clump.  Was it a one-time occurrence?  If it's a pattern or can be reproduced, then I would consider monitoring the link segments between the endpoints to see if there is an issue, or maybe check QoS statistics or other relevant parameters.  What can you tell us about the topology, types of physical connections, call scenarios, etc.?

Best,

Chris

[Anonymous]

Karim:

Thank you for asking this question in the support community forum.  To add to the thoughts of Chris Jones, VQM is designed to be used as a trending tool to see the bigger picture of how the voice quality is flowing through the unit.  Once more calls than you are comfortable with are starting to show poor quality, more involved troubleshooting will need to be done such as reviewing the interfaces, gathering packet captures over time, and cross-referencing the packet captures with the VQM stats, examining the upstream QoS, etc.

Please, let me know if you have additional questions.  I will be happy to help in any way I can.

Levi

[Anonymous]

karim.chriqi:

I went ahead and flagged "Assumed Answered" on this post to make it more visible and help other members of the community find solutions more easily. If you feel like there is a better answer, feel free to come back to this post and select it with the applicable buttons.  If you have any additional information on this that others may benefit from, please come back to this post to provide an update.  If you still need assistance, we would be more than happy to continue working with you on this - just let us know in a reply.

Thanks,

Levi