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What are the differences between non-PoE, PoE, and PoE+?

A non-PoE switch is a switch that provides network connectivity only, and does not supply DC power to connected devices. These switches are suitable when there are a large number of non-powered network devices on the network, such as PCs and laptops. Such switches are commonly deployed in offices, as well as in hotels, student housing, assisted living, and other multi-dwelling unit (MDU) environments where there is a wired Ethernet wall jack in each unit.

Power-over-Ethernet (PoE) switches provide both DC power and data connectivity over a single Ethernet wire. These are extremely useful for connecting powered network devices to a network, as only one cable needs to be run to the device, as opposed to separate cables for data and for power. Per the IEEE standards, switches are able to detect whether a connected device is powered or not, and will therefore only provide power to devices that are not being powered by an alternate power connection. When using managed Power-over-Ethernet switches, the connected device can also be rebooted remotely by turning off and on the power on the Ethernet port, which is very useful when doing network troubleshooting.

A PoE switch conforms to the IEEE 802.3af standard, which provides 48V up to 15.4 W per port. PoE (802.3af) is sufficient for powering older generation access points (i.e. pre-802.11ac) and for most other powered network devices, such as IP cameras, VoIP phones, access control locks, etc.

A PoE+ switch conforms to the IEEE 802.3at standard, which provides 48V up to 30 W per port. PoE+ (802.3at) is required for 802.11ac access points because of the large number of radio chains required for MIMO and MU-MIMO.

It is best practice to not fully load a PoE (802.3af) or PoE+ (802.3at) switch, to ensure that the total power budget of the switch is not exceeded. EnGenius generally recommends a “3/4 rule”, meaning that a network design should plan on only using ¾ of the ports for powered network devices, as follows, with remaining ports being reserved for non-powered network devices, backhaul to other infrastructure (e.g. other switches or routers), or spares:

  • 8 port PoE/PoE+: Only 6 ports should be used for powered network devices
  • 24 port PoE+: Only 18 ports should be used for powered network devices
  • 48 port PoE+: Only 36 ports should be used for powered network devices

Most PoE and PoE+ switch models come with some non-PoE ports for backhaul, consisting of either Ethernet ports and/or SFP ports (for mini-GBIC fiber modules). On EnGenius switches, any standard third party SFP module (1 Gbps) can be used. For a detailed explanation of SFP modules, please read the blog.