Unlike small installations, enterprise-level deployments cannot always plug directly into an existing network. These extensive installations require that users take additional steps to ensure that IP surveillance technology will not tax the network.
If the decision is made to use the existing network, then it is best to define the minimum and maximum bandwidth available for the network video system. Enterprise networks consist of multiple segments of different speeds; a connection to a switch may be anywhere from 10 to 100 Mbps, while the backbone communicating between the two switches may range from 1 to 10 Gbps (gigabits per second). A 1 GBps network can transmit video from hundreds of network cameras, even at full frame rate, over a single network connection.
If the network video system is large enough, a separate network to handle the video transmissions will be required. This is similar to rail transportation: once the existing track becomes too congested, you simply must build another set of tracks. However, because network video operates with standard networking equipment such as switches and routers, separating networks is typically an easy and inexpensive process.
In addition to mapping out potential bottlenecks or building a separate network, enterprise users can rely on some of the following methods to better manage bandwidth consumption:
Switched networks: If many devices are connected to the same network, the network should be divided into segments with switches or routers placed in between. Switches sometimes have built-in router functions. Network switching - a common networking technique - separates one network into two autonomous networks. Even though these networks remain physically connected, the network switch divides them into two virtual and independent networks: one for data and one for video. By designing the system wisely and splitting the number of cameras between different sections or links, the user gains the benefits of higher reliability and improved performance.
Efficient compression: At high continuous frame rates, above 15 fps, considerable bandwidth savings can be achieved by using MPEG-4 compression, rather than Motion JPEG. The two formats usually target different applications, and MPEG-4 is not expected to replace Motion JPEG. However, MPEG-4 is recommended for live viewing and for applications where bandwidth and storage limitations are important factors.
Faster networks: As the price of networking equipment continues to fall, Gigabyte networks become increasingly affordable. Having a faster network alleviates bandwidth concerns, and a faster network increases the value of running security and surveillance applications over networks.
Event-driven frame rate: Full frame rate, 30 frames per seconds (fps), on all cameras at all times is more than enough for most security and surveillance applications. With the configuration capabilities and built-in intelligence of network cameras and video servers, frame rates under normal conditions can be set lower, at approximately 1-3 fps, to dramatically decrease bandwidth consumption. In the event of an alarm, the recorded frame rate speed can be automatically increased to a higher frame level.
Ultimately, a network's ability to handle the demands of a network video system depends on its configuration. It is important to take the time to consider how your network will operate when video is added and ensure that you are properly equipped to handle the extra bandwidth requirements. Although it seems intimidating at first, bandwidth issues can be easily be overcome with a little bit of advanced planning and proper configuration.
About the author: As the general manager for Axis Communications, Fredrik Nilsson oversees the company's operations in North America. He can be reached at firstname.lastname@example.org.