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.
• Storage. In most security applications, video is recorded and stored for later use. Storing video allows users to review incidents, isolate interesting video and distribute the information in an appropriate manner. Instead of relying on VCRs and videotapes for recordings, networked video images can be recorded on hard disks attached to standard servers. For added reliability, video can also be recorded and stored in multiple off-site locations, which is not possible with a DVR system.
One of the most common ways to back up storage systems is with a redundant array of independent disks (RAID). RAID basically arranges standard, off-the-shelf hard drives so that the operating system sees them as one large, logical hard disk. Data is divided over multiple hard drives, each with enough redundant data on all disks so that the data can be recovered from the remaining disks in case of a failure. Most common RAID systems offer full hot swappable mirrored solutions, where there is no disruption to the system and no lost data in the event of a failure.
• Servers. In order to back up servers, it is common to have two servers work with the same storage device, commonly a RAID system. When one server fails, the other identically configured server takes over the application. These servers regularly share the same IP address, making the so-called fail-over completely transparent to the user.
A network video system uses standard server and network equipment, so replacing faulty hardware takes much less time and costs less than it does with analog or DVR solutions. Replacement parts can generally be procured from any electronics distributor, reseller or retailer, because IP-based surveillance is based on open standards that allow for the use of products from different manufacturers. Components such as switches, routers and servers can all be purchased off the shelf, which significantly lowers costs and increases choices. Of course, these options are up to the network designer. A small network will not deploy all of these safety measures, but choosing high-quality IT components from the start will make for a more reliable solution than a CCTV/VCR or DVR system.
In the Real World
Today, IP-based systems have proven that they are more reliable than their analog counterparts. Network video systems are successfully deployed in some of the most sensitive and demanding locations, including airports, banks, train stations and prisons. In many cases, the cameras can function for years without being touched. Both network and PC reliability have also come a long way. Banks, government agencies and Fortune 100 companies all rely on IT equipment for e-mail, data, and increasingly for voice and video.
For example, a federal penitentiary in California installed a network video system to monitor inmates and provide evidence in the criminal prosecution of inmate crimes. The network cameras and video servers allow high-quality digital images to be recorded throughout the prison on a 24-hour basis, which enables the prison to maintain a greater level of security and surveillance within prison grounds. In the private sector, a New York casino selected an IP-based surveillance system to monitor its hotel, garden, restaurants, parking garages and exhibition hall. The casino’s existing analog surveillance system needed to be upgraded, so the company turned to network video and PoE to provide uninterrupted surveillance.
Ultimately, the reliability of a network video system can be as simple or as sophisticated as you want it to be. IP networks are flexible, and they are the key to wide-ranging possibilities in system design, applications and solutions. Using the benefits of IP networks, network video systems offer many advantages over analog-based CCTV systems. The answer to creating a reliable system is making well-informed decisions during the installation process and properly configuring the network.
About the author: Fredrik Nilsson is general manager for Axis Communications. He oversees the company’s operations in North America. Mr. Nilsson can be reached at firstname.lastname@example.org.
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