Power over Ethernet (PoE) is a new technology that allows networking equipment to operate without a power adapter. The electrical power is delivered through a standard Ethernet cable, without affecting the data transfer speed in any way. There is no need to replace existing cables or equipment, unless they happen to be really old and not compatible with Category 5 Ethernet. A PoE switch has all the features of a regular network switch and can be used in the same roles without any modifications. Many other PoE devices are also available, including webcams and VOIP telephones. As always, there are plenty of features to check when shopping for a PoE switch, such as the number of Ethernet ports.
Ethernet cables contain several twisted pairs of copper wire. The wires and their insulation are all very thin, which limits how much power they can carry. Ethernet cable was not designed to carry alternating current (AC) from a mains socket. Power over Ethernet uses direct current (DC) at voltages less than fifty volts. The standard version has a power limit of fifteen watts for each device, but the new PoEPlus version can go as high as twenty-five watts. A device called a PoE Injector is used to get power into an Ethernet cable. Power over Ethernet should not be confused with Ethernet over Power, which is a different technology that uses regular power cables to carry data.
Power over Ethernet slightly increases the price of networking equipment, but the advantages it provides are certainly worth the extra cost. Fewer power adapters are needed which frees up mains sockets for other equipment. Travelers no longer have to carry lots of power adapters around with them. Networking equipment can be installed in remote spots that do not have mains power. Point-of-sale terminals can be used in busy areas where mains power might be a safety hazard. Power over Ethernet can even be used for wall clocks that are connected to a computer network. So long as the connection is wired and not wireless, you can power most networking devices with this amazing technology.
In simple terms, a network switch connects computers and other devices to a network. It is better than a hub at directing network traffic but it does not have the advanced features of a router. If the network needs to be connected to other networks or the internet, a router can be used separately or alongside a switch. A typical switch is housed in a rectangular metal box, which is usually placed in a rack along with other networking equipment. Desktop models are also available that are good for small networks around the home or office. There are many brands to choose from including familiar names like Cisco, D-Link, Linksys, and Netgear.
Before buying or using a PoE switch, check that it meets either the 802.3af standard or the newer 802.3at standard, which is known as PoEPlus. Be careful when buying old or second-hand equipment as it may not be compatible with these standards. An unmanaged switch requires minimal setup and works straight out of the box in most cases. A managed switch takes longer to setup but is more flexible than an unmanaged switch. The other main feature to look for in a PoE switch is the number of Ethernet ports. The smallest models have as few as four ports while the largest models have nearly one hundred. Ensure that all the ports are able to accept PoE devices, and that they can automatically detect crossover cables (MDI/MDI-X detection).
Other features to look in a PoE switch include auto-sensing ports, mini-GBIC slots, security measures, remote management, and fanless cooling. Auto-sensing is important for a network that contains a lot of different Ethernet equipment which operates at different speeds. Mini-GBIC slots allows optical fiber, copper wires, and other physical connectors to be connected to the switch. The security measures should include port authentication, MAC filtering, and denial-of-service (DOA) protection. Remote management. If the server room is quite small, it may be worthwhile getting a fanless model to keep noise to a minimum.