Assessing Power-Over-Ethernets Near-Term Uses

Industrial automation and building control are likely development areas.

The next probable stage of power-over-ethernet development will be in industrial automation and building control, based on interviews with officials at Cisco Systems Inc., Texas Instruments Inc. and PowerDsine Ltd. Temperature, smoke, heat and other environmental sensors will probably be at the top of the list of near-term future developments and will start appearing sometime in the next several years when integrated chips to control power flow become more widely available.

POE will make network cameras more prevalent, and cutting the AC cord will also make building security monitors such as badge swipe pads easier to implement.

In the next two to five years we might also start to see POE augment batteries in mobile devices. Although the engineering requirements are not trivial, we might see laptops that trickle-charge (charge slowly using a low-power Ethernet cable) from a POE data connection. Cell phones and PDAs could also get in the POE game, making special, expensive power adapters a thing of the past.

Future product development is even more likely because, with the approval of the 802.3af POE standard, the RJ-45 Ethernet jack will become the first worldwide standard power plug.

The groundwork is already laid for POE because the vast majority of businesses have Category 5 LAN cable plants that can accept POE with no changes and because LAN cabling is increasingly available in a number of common work areas such as convention centers and hotels.

In the Immediate Future in the very near term, the conven- ience of having to connect only one cable to any of the devices we tested would likely translate into much lower implementation and operational costs. Several of the new powered devices we looked at illustrated how IT managers could get almost-immediate savings.

For example, our work with Hewlett-Packard Co.s ProCurve 420 WLAN AP (access point) clearly demonstrated both reduced installation and operational costs. The most obvious installation cost savings came when we placed the AP in the most advantageous broadcast location—up near the ceiling. If the AP required AC power, we would have had to compromise between best broadcast location and the nearest AC power outlet. Or, more costly, we would have had to make a facility request for an electrician to rewire parts of our building to run power to the AP.

Weve seen this convenience and cost savings in products such as Trapeze Networks Inc.s WLAN Mobility System, which uses POE to supply electric power to the products APs. (See eWEEK Labs review at Because of POE, the Trapeze system is able to place APs exactly where they provide the desired radio coverage, which is usually above the ceiling tiles and toward the center of the floor plan, places that AC power is very likely not to be found.

In terms of lowering WLAN AP operational costs, the Power Sourcing Equipment can play a significant role. During our tests, we were able to turn the power off and on for specific ports to reset our APs. Before POE, a power reset on a WLAN device would have required sending a technician to the switch to push a reset button. The difference in cost between scheduling and sending a technician to perform this task is hardly even comparable to the very low cost of doing the same thing from the power management system of our PowerDsine 6012 model.

POE will also make it much easier for IT managers to place APs in more secure locations. Because most WLAN implementations cant justify reworking the AC electrical system to place power outlets where the APs need to be, APs often end up in exposed locations. In addition to being physically insecure, exposed APs, with their often tightly stretched AC power cords, are much more susceptible to being unplugged or just ripped off the wall than APs that are placed above the ceiling tiles.

One potential drawback to the adoption of POE is the growing use of wireless networking in the home. Without a data network cable, there is no POE. And, of course, POE jacks will not likely appear outside offices for many years. For this reason, it will likely be quite a while—if ever—before we see consumer devices drawing power from a data cable. One exception: POE is set to rock on in the Gibson guitar (see www.

Senior Analyst Cameron Sturdevant can be contacted at