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SIG add scrambling to h.323 cause the terminal audio pass in one-way

Publication Date:  2012-09-27 Views:  194 Downloads:  0

Issue Description

The terminal image is normal point to point; in multi-point case, the image is normal audio pass by one way with noise, sometime the branch sits can hear main site but the main site can not hear the branch sites.

Alarm Information


Handling Process

1,Check the each boards in MCU, state indicator lights are normal, local operation bench has no alarm.
2,Hold multi-point meeting, do the FAPU audio outloop for one of the fault terminals, and the audio is normal; do the FAPU audio outloop for another  fault terminals, and the audio is not normal, replace the FAPU board, the fault still alive.
3,Hold a 4 terminals conference, test each FAPU board and the fault still alive, replace the ME16 board and MIPU board and the terminals, the audio is still pass by one-way.
4,Check the network and the point to point is normal so the network under the terminal and RT4 is OK. The CISCO6509 switch may has problem, but it is OK after examined.
5,Add a HUB between the RT12 and the terminal to capture message packet, and find the sequence number of RTP message is abnormal, capture and analyze level by level, and find the RTP message is modified when it pass CISCO6509. We communicate with carrier and learn that a few days before, the carrier add scrambling to the audio that pass the H.323 protocol in CISCO6509, video conference terminal IP address did not add the whitelist, after add scrambling, it can only pass in one-way. We add the terminal IP address to the whitelist in SIG, and it become OK.

Root Cause

1,MCU hardware or network problem
2,Date configuration problem