PoE / Power over Ethernet

Do you think Alexander Graham Bell thought his “vocal telegraph” invention would ever be the source of new technologies over the last 100 years? Telephones have spurred numerous trends and inventions from voicemail to mobile devices to text messaging to voice documentation, just to name a few. One technology that came out of the IP version of telephones was Power over Ethernet (PoE) technology.

Traditional TDM or digital phones are connected back to a phone system using copper wiring. This copper wiring is used to send the digital signal from the port card in the TDM telephone system. This signal powers the telephone set and it’s LED lights. When using TCP/IP to send data and voice, as IP phones do, those signals cannot use the same pairs as power. When VoIP telephones, using TCP/IP to communicate, first came out there was a question of how do we power these new devices? One solution was to add a power brick to each phone and plug it into an outlet. This seemed a bit over-kill for power consumption as well as, “just one more thing to buy and worry about.” This is where PoE took shape. To solve the problem manufacturers began sending power over the unused wire pairs in the Ethernet cables.

Today most common PoE set ups are comprised of a PoE switch(es), powered by a centralized power unit. There is then an Ethernet cable running from the switch to the device that will be Powered over Ethernet. This allows for a couple newer developments into the IT and telecom world. We can now run one network for both voice and data using one cable, or run separate networks using one cable depending on your switch’s capability (there is then a patch cord from the phone to the computer connecting both back to the switch). With IP phones working so well over PoE and the culmination of both networks using only one cable it lead to a thought. If we can power these phones this way what else can we power this way and what benefits does it give?

PoE can currently be used for:
· IP telephones
· IP security cameras
· Wireless access points
· Radio frequency identification (RFID) tag readers
· Print servers
· Bar code scanners
· Building automation system; including thermostats, smoke detectors, alarm systems, security access, industrial clocks/timekeepers, and badge readers

Benefits of PoE:
· Lower install costs (those magic words again…lower costs)
· Going Green…reduction of costs as well as a reduction of energy consumption
· Space saver…consolidation of wiring saves precious space in ordinarily cramped and full data rooms

As with everything in the telecom and IT industry, PoE is going through an upgrade and change. Soon there will be a new form of PoE that will have increased power allowing us to power even more devices using PoE and open up many more opportunities for PoE benefits. Stay tuned, the next post will be on PoE+, the next generation of PoE.

This was Mike Martin's last conversation with Bill Taylor and Dean Reskevich