Serious package loss when TE Terminal and Telepresence system in conference holding by SMC2.0 with standalone SC

Publication Date:  2015-06-09 Views:  158 Downloads:  0
Issue Description
The customer found a serious package loss phenomenon when calling in a conference and bad image effect displayed but all went well when using point-to-point way in ip address.
Alarm Information

no alarm, but nearly 10% pacakge loss displayed in Nlog statistic.

Handling Process

1. We first tried to change the bandwidth of conference and image resolution ratio but it didn't work.

2. We doubt a bad network may be involved. It works a bit after network optimization operating by the customer, but package loss problem still exist.

3. Capture media stream package on MCU, SC, TP and analyze it.

MCU ip address: 192.168.211.112

TP3106-70 ip address: 192.168.211.115

Standalone SC ip address: 192.168.211.111

MCU package capture: 

TP package capture:

4. We found out that TP system and MCU both send theirmedia stream to SC when in a conference and all packages are transmitting by SC.  According to the customer's current networking mode, media stream should not be transmitted by SC and the configuration of SC may have a problem.

Root Cause

Because of the configuration policy that there's no need to open media route function which is open in default, all media stream was handled by SC where media stream was processed repeatedly and thus caused package loss.

Solution

Modify the configuration by closing media route function and capture the package.

It turned out except for few registration signaling packages, no more pacakge sent to SC and no package loss occured when holding a conference by SMC2.0.

Suggestions
It is common to check network condition when confronting a calling problem or package loss problem. What if problem still exist when a network optimization has been done? Thus we need to check our own device and find the reason. Independent SC is a newly released product and we should analyze the media stream trend and make it clear. Mastering basic media stream analyzing method and H323 protocol knowledge can greatly improve our troubleshooting ability when it comes to a calling issue.

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