POE Planning

By Cameron Sturdevant  |  Posted 2003-11-24 Print this article Print

POE Planning

IT managers in or-ganizations large and small should start planning now to accommodate the changes POE will foment, both in the number of devices that will come on the data network and in the amount of electrical energy that LAN infrastructure equipment will consume.

Power reliability in outlying wiring closets is going to move from a nice-to-have checklist item to an infrastructure requirement similar to the resilient power required in data centers today. This will likely mean an extensive review of the UPSes (uninterruptible power supplies) currently installed in wiring closets. In some cases, these UPSes will need to increase in capacity and reliability (which usually means buying premium systems) to support POE.

Most Ethernet cable already installed in businesses around the country should support POE with no modification.

However, IT managers should start figuring out now how to provision wall power to POE PSE. One complicating factor is that not all devices—and especially not all VOIP telephone handsets—draw the same amount of power during normal use. For example, basic Cisco Systems Inc. VOIP telephone handsets typically use less than 2 watts of power while idle; they use the most electricity for the short period of time that they ring; and they use a more moderate amount of power during talk time. It is also likely that badge readers and fire sensors will use far less power than, for example, WLAN APs and network cameras.

These wide-ranging power needs will likely play a big role in determining how to provision PSE in the wiring closet. Extreme Networks Inc., Cisco and other equipment vendors have indicated that their chassis-based systems will allow a mix-and-match arrangement of powered and unpowered line cards. This is a good thing because the typical LAN is certain to have a mix of PDs and PCs, which will always need a separate AC power supply that cant be met by POE.

Will my existing wiring support POE? Heres what to look for to support 802.3af in the network:
  • Ensure Category 5 Ethernet cable is installed to exact specifications.

  • Inventory the amount of power running to wirring closets; 15-20-amp circuits with 110 voltage are typical. Large installations of VOIP telephones may mean running more 220-volt circuits.

  • Check to see if the UPS can support this increased load. Factor UPS upgrades into the cost of supporting POE.
  • Our testing and research showed a wide range of management features in PSE. Vendors are clearly thinking about managing power usage so that just enough power is reserved to support PDs.

    However, there is still a long way to go in terms of managing PSE during a power outage.

    None of the vendors we interviewed is currently working with UPS makers to handle selective shutdown of devices. Wed like to see much more policy-driven control of how PSE will behave in a power outage. For example, wed like to be able to specify that essential services, such as the phone at the front desk, are powered even if that means shutting down the wireless APs in all the conference rooms.

    For now, IT managers will have to learn the quirks of each PSE. For example, PowerDsines 6012 prioritizes the first 10 ports over the next 10, and so on. All the vendors with which we spoke indicated that, with experience, more management capability would be added.

    Senior Analyst Cameron Sturdevant can be contacted at cameron_sturdevant@ziffdavis.com.

    Cameron Sturdevant Cameron Sturdevant has been with the Labs since 1997, and before that paid his IT management dues at a software publishing firm working with several Fortune 100 companies. Cameron also spent two years with a database development firm, integrating applications with mainframe legacy programs. Cameron's areas of expertise include virtual and physical IT infrastructure, cloud computing, enterprise networking and mobility, with a focus on Android in the enterprise. In addition to reviews, Cameron has covered monolithic enterprise management systems throughout their lifecycles, providing the eWEEK reader with all-important history and context. Cameron takes special care in cultivating his IT manager contacts, to ensure that his reviews and analysis are grounded in real-world concern. Cameron is a regular speaker at Ziff-Davis Enterprise online and face-to-face events. Follow Cameron on Twitter at csturdevant, or reach him by email at csturdevant@eweek.com.

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