OPINION
`Power over Ethernet: One cable fits all
`
`* What is Power over Ethernet?
`
`By Currid & Company and Michael Day 
`Network World  |  Jul 19, 2004 1:00 AM PT
`
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`Until now, the thought of adding an IP-enabled camera to an existing cabled
`network meant consideration of not only camera placement, but knowing
`where the nearest 110-volt outlet was as well - unless you are outside of North
`America, in which case you would be searching for the nearest 220-volt supply.
`
`To help solve the problem the IEEE last year ratified 802.3af, one of the latest in
`the 802.xx series of Ethernet standards, which has the potential to make the
`power dilemma go away. The 802.3af standard specifies how switches, routers,
`and hubs should deliver power over standard Ethernet cabling to devices like IP
`phones, security systems and wireless LAN access points. In fact, Power over
`Ethernet, or PoE, will work with existing cable, including Category 3, 5, 5e or 6.
`
`Like many good ideas that are executed before being standardized, PoE started
`off with custom implementations as varied as the companies implementing
`them. The RJ-45 connectors' pin-outs varied from manufacturer to
`manufacturer.  And if that weren't dangerous enough, the voltages being
`pumped over those little wires ranged from as little as 3.3 volts to as much as
`48 volts. Now that there is an industry standard, consumers will be able to buy
`off-the-shelf equipment and be assured that the different manufacturers'
`products will interact with each other.
`
`The standard dictates that over the maximum recommended run of Ethernet
`cabling, there will be a guaranteed continuous power of up to 12.95 watts at
`each node, taking into account power loss due to leakage. (As a point of
`reference, IP phones and wireless access points consume anywhere from 3.5 to
`10 watts.)
`
`This also means that an entire network segment can be served by a single
`uninterruptible power supply, since the power requirements are so minimal.
`The cost savings in back-up power systems alone could easily justify
`implementing such an architecture.
`
`SONY EXHIBIT 1018
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`A major concern might be the ability to safely mix legacy and PoE-compatible
`devices on the same network. The standard addresses such an issue by
`specifying that only PoE-enabled devices receive power through network
`power controllers, known as "injectors," by blocking power to incompatible
`legacy devices. The complement to an injector is the "tap," or "picker," as some
`call it. The tap sits inline, before any connected legacy device, and removes the
`power, piping it to the device requiring it and at the same time preventing any
`legacy device from receiving the potentially damaging charge.
`
`To date, PoE has been deployed in two very different ways: as end-of-run
`devices where the technology is actually embedded into new hubs or switches,
`or as stand-alone midspan hubs.  The latter allows existing networks to
`implement the PoE standard without upgrading existing switches or hubs. With
`such a large base of wired networks already installed, retrofitting existing LANs
`with midspan devices makes up about 90% of the implementations in
`existence. 
`
`In less than a year, the PoE market is already pretty well established.  Some
`estimates suggest that over 20 million ports have already shipped worldwide.
`And the application of this technology won't be limited to wireless access
`points and IP phones. Other applications already in the works include:
`
`* Keypads.
`
`* Security devices, like retinal scanners or fingerprint readers.
`
`* Point-of-sale systems.
`
`* Lighting control.
`
`* Home automation systems.
`
`* Factory floor monitoring networks.
`
`* Security cameras.
`
`The list is almost endless now that the industry can unite around an
`international specification.  And because it is an international standard, PoE
`could become the universal power jack that continent-hopping travelers have
`yearned for.
`
`Michael Day is an emerging technology analyst for Currid & Company.  You can
`write to him at mailto:michael.day@currid.com
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`Page 2 of 4
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`Learn more about this topic
`
`Network World Fusion Encyclopedia: PoE (http://www.nwfusion.com/details/4681.html)
`
`Power over Ethernet generates buzz
`(http://www.nwfusion.com/news/2003/1124infrapoe.html)
`
`Network World, 11/24/03
`
`803.3af powers new switches (http://www.nwfusion.com/weblogs/routers/004207.html)
`
`Network World Fusion 02/23/04
`
`What is Power-over-Ethernet (PoE)?
`(http://www.hyperlinktech.com/web/what_is_poe.php)
`
`PoE resources on the Web (http://www.poweroverethernet.com/)
`
`PowerDsine (claims to be the PoE "pioneers") (http://www.powerdsine.com/) New
`server chips carry hidden cost
`(http://www.nwfusion.com/news/2004/071904multicore.html)
`
`Network World, 07/19/04
`
`Cisco buys earn mixed reviews
`(http://www.nwfusion.com/news/2004/071904infcisco.html)
`
`Network World, 07/19/04
`
`Healthcare braces for federal IT czar
`(http://www.nwfusion.com/news/2004/071904brailer.html)
`
`Network World, 07/19/04
`
`Currid & Company
`
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