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jarrod sousa

Lync video freezes using OCS Relay

Hello, i have a customer who has integrated Lync 2010 with thier VCSC running X7.2.  the original integration was setup using OCS relay method.  i know that B2BUA is the "correct" way to set this up, but i wasn't ther person who set it up.  my question is simply this:

when a VCS<>Lync call is made, video and audio gets negotiated correctly (h.263 video as there is no AMG) at 1st.  after a random period of time, the video from the VCSC to the lync client will freeze.  i have run packet captures during the call and failure and i see no change in media traffic (video or audio ports).  i have eliminated every vairable i can think of.  i made sure all the clients were on the same Lync cluster, which had a SIP trunk to the VCSC.  no traffic is going accross an edge server or the WAN.  it never fails to happen, but the timing is not consistent.

i have read in other support community posts that using OCS relay can cause freezing video and using B2BUA will solve the problem.  can anyone explain to me how using B2BUA would remedy the freezing video or what is going on in the Lync side to cause this? 

Last thing is all VCSC devices are H323 only, so all the calls are interworked, forcing the RTP stream to go through the VCSC.


Martin Koch

Hi Jarrod!

I just did not find it in the documentation, but thats a common issue in between lync and the video

systems. That seems to be related to some packet loss and the video does not recover properly.

You should be able to trigger the issue by shortly unplugging and replugging the cable to

one of the involved endpoints.

Its not enough that the VCS is kept in the media path, its important that its the b2bua.

That one will inject some packets and that will help the video to recover.

You might also want to check why you have packet loss.

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