FACT: Today, PoE ports represent one quarter of all enterprise Ethernet ports. As with any evolving technology, its true worth to business must be weighed as it ultimately determines its long term success. Not being a spring chicken myself, this is not unlike the days of Frame Relay. Though it was slow to be adopted, it became a big hit until newer technology offerings became available- like MPLS (Multi Protocol Label Switching). I digress.
PoE is very much the same thing, but with much farther reaching potential. In a nutshell, PoE is where low voltage DC power is pushed over a CAT5E or better Ethernet cable. As many of you know, pins 1, 2, 3, & 6 are used for Ethernet data transmission. Pins 4 & 5 are blank so as to not conflict with someone plugging in a legacy phone line RJ11 plug into an RJ45 jack and blowing up an expensive network switch. The power of PoE goes over pins 7 & 8, aka THE BROWN PAIR .This prevents you from having to run electrical outlets to every device, as the power comes over the Ethernet cable. The costs savings here can be quite substantial.
Understanding the standards and options is key here as you may already have some PoE switches, but they may be older. It is important to know their capability before buying equipment. Older switches simply cannot power the newer and higher demand PoE devices due to their lower wattage restriction.
802.3af is the original 2003 standard that supplies up to 15W of DC power, though only about 12.5 watts is assured.
802.3at aka PoE+ is the current standard and takes it up to 30W (25 adjusted for power loss). With the greater power, many more applications are possible!
As with any Ethernet cable run, the standard 300 foot distance limitation applies here as well.
PoE Devices. Although the most common uses for PoE today are forIP phones and wireless access points, this is a rapidly expanding field. There is significant growth in the areas of surveillance, which includes encompassing video up to HD standards and building access control. Rounding off some of the current PoE device offerings includes digital signage, IP paging, school clock systems, video phones and many others. New devices will emerge being able to utilize PoE power thus creating a more powerful and useful network. Simply put, this is where we're headed. So, when looking to move and re-cable, you may want to rethink where to add cable drops as to ensure you don’t fall short and have to end up paying for expensive piecemeal cabling to fill your needs.
PoE switches. A number of outfits make these switches, including the likes of Juniper, HP, Cisco and many others. Our favorite switch is Juniper’s EX3300 series for a number of reasons. First, the price point is attractive. Second, it has “virtual chassis technology”. What this means is that the virtual switch (made up of many physical switches) only uses one IP address and all switches within the virtual switch can be viewed in a single interface, greatly simplifying management. Another benefit here is that individually, these are all 1U (1.75”) units that will make it simple to swap out old switches and put in new switches without having to re-manage patch cables. Finally, we love the DAC cable because for $100, it gives you a sweet 10Gb interface to other switches that are in close proximity and to servers that adhere to the SFP DAC standard. This way, you don’t have to use expensive fiber to get 10Gb within the same room. It's a win-win as the DAC cable saves cost and is less fragile than fiber.
In summary, if you’re changing out your data switches, consider popping for a few extra dollars to go for PoE to future-proof your dollars and being to save even more downstream.