poor video conferencing quality

Posted on 2007-10-13
Last Modified: 2012-06-21
We have a polycom vx700 unit we use for video conferencing to a single remote location. My company wants "perfect" videoconferencing. We get good video most of the time but the video fades and breaks up during the transmission. We have a T1 line for internet connectivity and are using 512 for the video conferencing. The polycom is attached thru our Cisco 3560 VoIP switch to a Cisco 2800 router. The polycom unit is assigned a public address. I have a couple of questions.

Why would the polycom unit be passed thru the switch to the router instead of directly to the router?

Why would the router connection for the polycom not be in a DMZ?

I have years of experience with networks, routers and switches but I am a complete nubee to video conferencing.  I do not have the problem with the video except when connecting to our Vancouver site. The Vancouver site only has problems with the video when they are connected to us.

I would also be interested in any suggestion of how to get better video conferencing quality.
Question by:jimmylew52
    LVL 16

    Assisted Solution

    the fact that it iso nly the one site and the others are ok would point to something at the vancouver end i would think-is this a branch site or whator how is it connected?
    LVL 4

    Assisted Solution

    We just solved our polycom quality issue.  poweruser32 is right.  Once you can confidently say that the problem is local to one office location, focus your efforts there.  We use our cameras on the DMZ ports of our routers, so that option works.  We just bypass as many latency causing products to ensure the best signal.

    Some settings to check...H323, duplexing is turned on, and the bandwidth at that office.  Our problem was not our T1 at the remote location, but rather we had the camera at our HQ going through the main pipes which were getting hammered by inbound/outbound traffic.  Once we changed the polycom over to the bigger pipes, the audio clipping and jittery video quality went away.

    Try to monitor the remote locations bandwidth usage with counters while you have established a video connection.
    LVL 1

    Author Comment

    I have not been able to  monitor the Vancouver site. However the remote site can establish a video conference with other locations with out poor quality video. While monitoring my own site the only problem I can find is the fluctuation in the bandwidth from my laptop to the Polycom. No report of lost packets or delay just the fluctuation of bandwidth. Running the same test  to Vancouver I do not get the fluctuation in bandwidth.

    I have checked the H232 duplexing at both ends of the connection on the polycom units and everything is OK. Both locations are using 512 bandwidth. The polycom units at both ends are using 100 MB connections. The switch ports are set to auto negotiate both duplex and speed.

    I just received a new switch to expand our network and thought about moving the polycom connection directly to the router port or to the new switch. I am wondering if the load on the old switch might be the problem. The setup we are using now has been working without a problem for about a year prievious to the current problem. The tools I am using (whats up gold) do not give me values for the jitter of a connection or I have not figured out how to measure it..
    LVL 4

    Accepted Solution

    The settings you specify are almost identical to what we have setup between several offices.  If you have a contract with an isp provider, they most likely can provide you with a report on how much bandwidth you are consuming.  If you are able to test this during off hours (when the incoming/outgoing packets would be at their lowest), you may yeild different results.

    I know that the video quality stinks, but if you change the connection to 256kb do you still have the same fluctuations or is the video quality, though poor, remain constant?  If it remains constant, then you most likely have a bandwidth issue.  If you still have fluctuations and are no where near maxing your connection, then it could be hardware related (switch, router, etc.).

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