Tech Tips: Keep in Mind a Few PoE Rules

Power over Ethernet (PoE) is a twisted-pair Ethernet cabling technology that allows for power and data to be transmitted via a single cable. Here are a few elements of PoE that might elude security pros:

• Any device that’s PoE-compatible will conform with one of the IEEE 802.3 standards — there are four as of publication — which guarantees the device can be connected to other PoE-compatible devices. The standards define how PoE equipment should behave, including with noncompatible devices.
• When powered, a PoE switch, which allows PoE products to work when there isn’t nearby power, will perform a signature detection check to confirm whether a device is PoE. If it’s compatible, the PoE switch or injector then will determine how much power the device should receive. The check also allows non-PoE data cables to be used with PoE network switches, with no risk of damaging the device at the other end of the cable. Network switches also monitor the current of all connected devices, which allows the switch to power down one of the channels, should a device draw too much power.
• Through the use of PoE, cabling can become a straightforward process, because PoE access points can be positioned in more-convenient locations when compared with power outlets. Many security products sit on the edge, and the length of a PoE cable run typically is limited to about 300 feet. However, many newer PoE switches feature an “extended” mode, which allows you to increase this range for when longer runs are necessary.
• The power draw provided by PoE is relatively low. This isn’t an issue for low-power products. If there isn’t enough power, then the device could be prone to fail. For example, for a maglock that’s set up as fail-safe, it could cause the door to remain unlocked and allow unauthorized entry. It’s important to check the specification of any device you wish to power via PoE and the other devices that might be connected to the same PoE switch to ensure the load can be handled.
• Most modern buildings have existing network infrastructure in place that can be reused to aid in the setup of a PoE electronic access control (EAC) system. This isn’t always the case, of course. When you install networked security products and then include them in an existing network, it’s important to ensure that the security of the network isn’t compromised. IT professionals are increasingly conscious of network security, but having third-party EAC products freely communicating across a network isn’t always welcomed with open arms. It’s common and sometimes necessary for IT teams to be involved in the installation process to ensure that all equipment is separated onto its own virtual network to minimize any security vulnerabilities.

— Paxton Access