Hello from Tallahassee, FL

[F16Viper68]

My name is Dave Whiting and I work in Tallahassee, FL. For the past two years I've been working as a District Technology Manager for North Florida. One of the programs I recently took over is our video conferencing system. We have 16 Polycom Viewstation FX's all connected by dedicated AT&T MIS T-1's (the only thing on the network is the endpoint). The endpoints are spread throughout the United States.

While we are happy with Polycom’s, we've been experiencing problems when using the units as MCU's. They work great with two or three endpoints but when we add the fourth site we are getting a lot of "lighting bolts", freezes, dropped calls, etc. Since I'm relatively new to video conferencing I was wonder if this was normal with 384Kbps multipoint calls?

Dave...

[tom9933]

Dave,
We do this all the time with the Polycom endpoints and if you have dedicated bandwidth you shouldn’t be seeing a problem. Are the links IP or V.35? If they are V.35 then you might have a clocking issue. If they are IP then it depends on the network topology. You may or may not know this yet, but a 384k call on IP actually takes about 460k of bandwidth. The reason for this is that the network transport adds another 20% or so to the call bandwidth. So if you had 4 calls on a single T-1 you would be over the capacity of the link. Normally you would see PVEC and Dynamic Bandwidth take care of this type of problem but it may be possible that those features are disabled or you may be running an older version of the software. 6.03 is the latest but 6.01 has been out a lot longer and it looks like there may be a few issues with 6.03.