Friday, June 26, 2009

Designing your networks for IP video

So you've made the decision to go with an IP Video Management system. How do you design your network to handle all of the video from the IP cameras? Here's what to think about:

A. Bandwidth available: If you're installing the new camera system on an existing network (not recommended), how much overhead do you have to devote to the new system?
Some common guidelines include:
1. A maximum of 5 Mbps on each network port
2. Not more than 100 Mbps per uplink
3. Not more than 500 Mbps per NVR server port
Remember that to transmit IP video images that are measured in bytes per second across networks that are measured in bits per second, you have to multiply by 8.

B. Power and signal feeds: CAT 5e and CAT6 cabling, already installed in the building, has distinct advantages. Connecting a Power over Ethernet (POE) switch port to an IP camera allows both the signal and the power to be transmitted across the cable. This can result in saving thousands of installation dollars since the additional power cable does not have to be run. Next, determine what the powered device will require from the switch. This is referred to as a POE class, and there are four classes, zero through three, each requiring a different amount of power draw in watts. The design engineer can also figure in uninterrupted power supplies (UPS) back in the data room. When the power is lost, the camera is still recording and video is still available from PCs with UPS backup. It is now easy to figure the power budget by using the following formula:
Number of cameras x power class (in watts) = power budget

C. Traffic Segmentation: There are two different ways to divide or segment traffic on an Ethernet network. One is to physically separate the IP camera network from the company’s production network by running separate network cables and installing new switches. This is by far the most expensive way to segment traffic. The other way is to program Virtual Local Area Networks (VLANs). This method utilizes the existing switch and separates specific ports into their own smaller networks.

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