[Editor's Note: This is the seventh in a series of articles that is being published jointly between Security Technology & Design and SecurityInfoWatch.com. This article originally appeared in the August issue of Security Technology & Design; earlier articles appear on the website and are linked at the bottom of this article.]
Networks allow devices such as network cameras, servers and PCs to communicate with each other, sharing information and, in some cases, a common Internet connection. Network designs can take many forms and vary in terms of performance and security.
It is useful to think of building a network as a layering process, beginning with the physical cabling configuration and connections. The number of cameras, the physical environment, the sensitivity of the application, and the protocols and software will impact the operation of the IP surveillance network.
Types of Networks
Networks can be local area networks (LANs), metropolitan area networks (MANs) or wide area networks (WANs). Each network covers a progressively larger area. For example, LANs exist within a building or company, while MANs could cover a campus or city center. WANs cover the largest areas-anything from multiple distant areas to the entire world. WANs often connect several smaller networks, such as LANs and MANs. The largest WAN is the Internet.
Basic Network Layout
Networks are made up of cabling such as Ethernet or fiber, and equipment such as servers, routers and hubs. There are many ways to physically lay out networks, but the main four designs are bus, ring, star and mesh. You can determine the right layout for any IP surveillance system by considering requirements such as redundancy, cost and number of cameras.
Bus: A bus network connects each device to a main cable or link called "the bus," creating a simple and reliable network configuration. If one device fails, the rest can still communicate with each other, unless the bus itself is broken. This setup is most often found in older LANs.
Star: Star is the most popular topology used in LANs today. In star networks, all devices are directly connected to a central point. If one device is disconnected or crashes, none of the others will be affected. However, if the central switch goes offline, the entire network could fail. This makes it important to build redundancy into the system.
Ring: In a ring network, devices are connected in a closed loop, meaning that adjacent devices are directly and indirectly connected to other devices. MANs and WANs often use ring configurations, but this design can be used for LANs as well.
Mesh: Mesh networks come in two varieties: full and partial mesh. In a full mesh network, devices are connected directly to each other. In partial mesh, some devices are connected to all the others, while some are connected only to those with which they exchange the most data. Mesh networks are becoming popular as the use of wireless technologies grows.
Wired and Wireless Options
Network devices can be connected over wires or wirelessly. Ethernet cabling provides a fast network at a reasonable cost and is the primary medium for most existing IT infrastructures. Ethernet connections-which resemble phone jacks-are usually integrated into network cameras and video servers, making it easy to connect them to the network.
Fast Ethernet is the most common standard used in computer networks today. It supports a transfer rate of 100 megabits per second (Mbit/s). Gigabit Ethernet (1000 Mbit/s) is the current standard endorsed by network equipment vendors and is used primarily in backbones between network servers and network switches. The upcoming standard is 10 Gigabit Ethernet (10,000 Mbit/s), which will soon be incorporated into network backbones. IP surveillance systems work with all of these standards, so as networks become faster, they will be able to support higher-quality video.