Although the prevalence of IP-based security and surveillance systems has exploded in the past two years, there is still a lingering concern among many security professionals that network video systems are unreliable. Most of this stems from a fear of network failure. Security professionals often worry about what would happen to IP video if the network went down, and these fears cause them to cling to analog technology.
However, IP networking architecture has been developed with reliability as a primary requirement. The stability of an IP-based video system depends in large part on the configuration of the network, and most networks today operate with a high percentage of uptime. If even minimal downtime is unacceptable, there are technologies and configurations available that can add even more reliability.
Eliminating Single Points of Failure
With an IP-based security system, points of failure can occur on several levels. The key is to avoid what IT professionals call a single point of failure. A single point of failure is a component whose failure will interrupt the functioning of an entire system. Possible points of failure include:
• Cameras. Network cameras today are just as reliable as their analog counterparts. However, if only one network camera is monitoring a critical area and that camera goes down, the entire surveillance system will stop functioning. This is true for both analog and IP-based environments in which systems rely on a single camera. Therefore, it makes more sense to install multiple cameras so the system will still be usable if one camera happens to go down.
The same concept applies to businesses that rely heavily on desktop PCs for employees. Although a company may require desktops for its day-to-day operations, the failure of any one desktop will not bring down the business as a whole.
Network cameras have other advantages when it comes to reliability. The main advantage is built-in intelligence, which can be used to detect interruptions in the video transmission and determine whether a lens is covered or the camera has been repositioned. Basically, the system can monitor itself and send alerts if any component is faulty.
• Power. Another feature available exclusively in network video systems is power over ethernet (also referred to as PoE or power over LAN). PoE integrates power into a standard LAN infrastructure. It enables a network device, such as an IP phone or a network camera, to receive both data and power over the same cable. PoE is based on an IEEE standard (802.3af), which means that compatible components are available from multiple vendors, increasing choice and lowering costs for the end user. Using PoE and an uninterrupted power supply, network video devices can continue to function even in the case of a power shortage. This is not possible in an analog environment.
• Internet Connectivity. Internet outages are another major concern. Admittedly, the Internet goes down. Everyone knows that e-mails are occasionally lost, Web pages won’t load and modems fail. These same types of outages will cause network video systems to fail if users rely on the Internet to view, share or manage video. However, such connectivity issues can be overcome through what IT professionals call aiming for the “five nines”—meaning that an Internet connection should be 99.999 percent reliable.
Today, there is a buyer’s market for network connectivity, which means that the service is relatively inexpensive. If a security application cannot afford any downtime, then Internet connectivity can be purchased from two Internet service providers (ISPs). If one service fails, the network can seamlessly switch over and connect to the other ISP.
With most ISPs, the probability of an outage is only about one percent. Therefore, if you have connectivity from two 99-percent-reliable networks, the odds of a total service outage will be reduced to 0.01 percent. That equals four nines (99.99 percent) of network uptime. If that is still not reliable enough, connectivity can be purchased from a third provider.