IP video conferencing tips

Here is some information that may be useful when you set up your local network and codecs for IP video conferencing.

Hardware

• Ensure all switches the IP video path will follow through the network are set to 100 mbps or full duplex.
• All cables between Ethernet devices must be at least Category 5.
• Avoid cable lengths of more than 300 feet (100 meters) on any Ethernet segment. If a segment requires more than 300 feet, we recommend a fiber connection between the switch and codec. A fiber to copper converter can be used to terminate the connection to the codec.
• Using a repeater will induce latency into the video conferencing stream. Multiple repeaters will multiply the amount of latency in the video conferencing stream.We recommend they not be used
• Don’t use a 10 mbps or half-duplex hub. As a shared device, a hub will split the available bandwidth to connected devices, decreasing bandwidth to the codec.

Codec

• Ensure the NIC card is set to 100 mbps / full duplex (PC) before moving IP desktop or room system codecs from one location to another. If the codec is an appliance, make sure the port it is plugged into is also set to 100 mbps / full duplex.
• If your codec sits behind a firewall, you will need a gatekeeper to perform proxy services. Do contact the IHETS Help Desk for configuration assistance with your firewall and proxy services.
• IHETS video conferencing only works with the following firewalls: Cisco Pix 6.1 and up, and Checkpoint Firewall-1. Do contact the IHETS Help Desk (317.263.8999 or 1.800.556.7612) if you have any questions concerning firewalls or proxies.

Quality of Service (QoS) parameters

Depending upon network traffic, it is possible to have two successful IP video calls at the same time on a T1 WAN connection; however, only one call at a time is guaranteed. The second call, while fully connected, may experience freezing video/audio and jitter. The freezing and jitter may extend to the first call already in progress thus affecting both video calls. Once the second call has disconnected, the first call will resume with the same quality that it had before the second call was initiated.

IP codecs connected directly into the Netgear switch will have QoS. If there are two codecs on a single T1 connection, overall bandwidth utilization, including data, must be below 70 percent of the total capacity for optimum performance.

If your codec sits outside your firewall, it can be connected directly into the IHETS Netgear switch.

IHETS cannot provide QoS if:

• Your IP codec is connected to a 10 mbps hub
• You are using anything lower than Category 5 cables
• You are running anything other than a certified H.323 firewall and gatekeeper
• Your codec is not on the list of recommended codecs