Power Over Ethernet, PoE Plus and the Weather Channel

In light of the recent weather conditions, I thought I would write up a short take for Journey to the Cloud on Power over Ethernet (PoE).  Over the last decade there have been several variations of PoE – starting with the proprietary (heard this story before) and moving to a standards-based solution.  This doesn’t mean that the confusion has gone away.  

The original standards-based PoE was classified under the 802.3af specification.  These devices (mostly switches) provided power for end-devices such as IP-phones, access points, web cams and more.  There are varying levels of devices within this standard based upon the wattage required to run the device. 

There are three classes of PoE devices within this spec; classes 1, 2 and 3 – which maxes out at 15.4 Watts.  This has been sufficient for quite some time, but in 2009 a new, enhanced standard was ratified which provides more power – Power over Ethernet Plus or 802.3at can provide up to 30 Watts for what is now known as a class 4 device.

The delta between PoE and non-PoE switches is still significant – especially if you are considering a Power over Ethernet plus capable switch.  If you only require PoE for a few access points or a camera or two it might not be advantageous to spend the extra money for a fully-loaded, PoE capable switch.

That being said, if you have VoIP in your near-future plans and are already considering upgrading your access switches, you might want to consider that before you upgrade.  If you are looking at just a few devices though you may be better off getting some PoE injectors, which reside in your data closet and providing Power over Ethernet for the few devices that need it.  They are somewhat kludgy though, and we all have seen messy wiring closets – these add to the chaos.

What about the weather?  Well as we are moving towards a converged infrastructure there are some additional considerations to keep in mind. The PoE switches that are powering your phones and providing data connectivity for your hose devices are becoming more and more critical from a system uptime perspective.  If your voice and data is running over the same infrastructure and you lose power due to – let’s say a hurricane – you had best prepare yourself from an Uninterruptable Power Supply (UPS) perspective. 

If your business can’t tolerate having the phones and the network down, then a UPS or a generator is an oft-neglected requirement.  The UPS needs to be sized appropriately based on the Power over Ethernet switches you are using and the end-devices you are powering.  Lastly – all of this is going to incur more of a demand on your electrical system which feeds your wiring closets.  Quite possibly you will have to upgrade the electrical system and have some 30Amp circuits brought in – depending on the switches you have and the UPSes backing them up.

 

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