Power over Ethernet (POE) is a new and rapidly emerging technology that is strongly supporting the deployment of voice over IP (VOIP), wireless networking and other applications. Graham Duxbury, CEO of Duxbury Networking, looks at the role of this technology in today`s organisations and its impact on the communications process.
POE technology allows VOIP telephones, wireless local area networking (LAN) access points and other appliances to receive power - as well as data - over existing Ethernet LAN cabling.
POE is one of the newest and most effective means of increasing the efficiency of communications across the enterprise-wide network, without the need to the change the existing cabling infrastructure.
It was discovered in 1999 by engineers keen to improve the distribution of power to the growing numbers of network devices that were becoming common to most LANs at this time.
A key requirement was the need to ensure interoperability among these devices - so the establishment of a standard was imperative before POE could be widely adopted.
The 802.3af standard for POE was recently ratified by the Institute of Electrical and Electronics Engineers (IEEE). This has highlighted an important achievement for the information technology (IT) industry: The ubiquitous Ethernet RJ-45 plug and outlet are the first universally accepted, worldwide power connectors.
No other industry has managed to standardise power delivery across countries and continents to this extent - if at all.
Broad functionality
From a technical perspective, POE extends the already broad functionality of Ethernet by supplying reliable DC power over the same Category 5/5e twisted-pair cable that currently carries Ethernet data.
POE is based on the technology used by the telecommunications industry to supply reliable power to telephones.
Because of its simplicity, it is seen by many as a technology that will have wide ranging advantages for IP telephone systems as well as many other low power Ethernet network devices, particularly wireless access points and security cameras.
POE will impact on a number of other commercial product offerings, including security access systems, vending and gaming machines, point-of-information systems, EPOS systems, time and attendance systems - even electronic shavers.
For POE designers, the market is open and its horizons will be determined only by their ingenuity and design abilities.
IT industry
Within the IT industry, it can be expected that the uptake of POE will be rapid and broadly based as there are many advantages for the user.
Most significantly, from a cost perspective, new infrastructure investments will be minimised as many existing LANs will be capable of supporting POE.
Even greater cost saving can be realised in new LAN implementations - as POE does away with the need to run both data and power wires to each network device.
This means that, for example, wireless access points and security cameras can be installed without the additional expense of contracting electricians to install AC outlets where these devices are deployed.
Already the marketplace is flooding with stories of large corporates saving tens of thousands of rand in new installations simply by obviating electrical plug points.
POE is also forward and backward compatible with other Ethernet protocols, so integration with legacy devices and systems will not present any hurdles to be overcome.
Efficiency is a major selling point for POE technology. Because they are Simple Network Management Protocol (SNMP) manageable, POE devices can be remotely controlled, enabling cameras and other devices to monitor, manage and even troubleshoot a variety of other devices associated with mission-critical systems. These include remote robot monitoring on production lines and assembly plants, for instance.
Flexibility is another key advantage. POE powered network devices can be easily installed and re-located when necessary as they are not linked to an AC outlet.
This is a boon for devices such as wireless access points - which often have to be installed in difficult-to-reach places in order to achieve the broadest coverage on the network.
Technically speaking
There are two basic components in a standard POE network. There is the Power Sourcing Equipment (PSE) a device that supplies power, and a device that receives and uses the power, known as the Powered Device (PD).
With safety being a high priority, upon connection of any network device to a PSE, the PSE must first determine whether the device is a PD or not.
This is done to ensure power is not supplied to older-generation Ethernet devices that cannot make use of it or will probably be damaged by it.
The PSE checks this by applying two small current-limited voltage signals across the cable.
If checks are positive, then 48 volts of power are provided to the device. Safety is ensured because no high, mains-type voltages (usually 110 or 220 volts) are involved.
The future
At present POE is not designed to power desktop computers, servers or printers. However, this could be in the pipeline for the future, along with a host of new devices that are sure to increase the role of IT in providing cost-effective services.
Undoubtedly the big winner will be IP telephony, as POE technology will accelerate its adoption as companies look to reap the substantial - and immediate - cost saving benefits associated with the coupling of POE and VOIP technologies.
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