Administrator Guide

Power over Ethernet (PoE)
The PoE feature supports electrical power and transmission of data on Ethernet cabling. A single cable can provide both data connection
and electrical power to the attached devices such as wireless access points or IP cameras.
Power over Ethernet (PoE), as described by IEEE 802.3af specifies that a maximum of 15.4 watts can be transmitted to Ethernet devices
over the signal pairs of an unshielded twisted pair (UTP) cable. PoE is useful in networks with IP phones and wireless access points
because separate power supplies for powered devices (PD) are not needed. Power over Ethernet Plus (PoE+), as described by IEEE
802.3at, supplies a maximum of 30.0 watts. This provides sufficient power for devices that require 12.95W to 25.5W, such as pan-tilt-
zoom (PTZ) security cameras, 802.11n Wi-Fi Access Points, and IP phones with advanced features, such as video conferencing.
The following table describes the classes of powered devices defined by IEEE 802.3af and 802.3at:
Table 55. Classes of Powered Devices
Class Power Range (Watts) Classification Current (MA)
0 0.44 to 12.95 <5.0
1 0.44 to 3.84 10.5
2 3.84 to 6.49 18.5
3 6.49 to 12.95 28
PoE+ Only
4 12.95 to 25.5 40
NOTE: Class 4 is meant for IEEE802.3at compliant devices which require >12.95 Watts. Class 4 devices will be
supported by PoE card, but the maximum power is limited to 15W.
In the S3100 series, the platforms S3124P and S3148P support PoE/PoE+ with the following power options:
• S3124P PSU: 715W, DC output 54V/13.24A or 1100W, DC output 54V/20.37A
• S3148P PSU: 1100W, DC output 54V/20.37A,
Topics:
• Configuring PoE or PoE+
• Manage Ports using Power Priority and Power Budget
• Manage Legacy Devices
• Suspend Power Delivery on a Port
• Restore Power Delivery on a Port
• Display the Power Details
Configuring PoE or PoE+
Configuring PoE/PoE+ is a two-step process:
1. Connect the IEEE 802.3af/802.3at -compliant powered device directly to a port.
2. Enable PoE/PoE+ on the port.
Enable PoE/PoE+
PoE/PoE+ is disabled by default.
You can enable PoE/PoE+ on a port by using the power inline command in the INTERFACE mode.
• To manage the inline power in a stack unit, use the Class or Static mode. See Manage Inline Power.
• To limit the maximum amount of power available to a powered device and to set the priority of power access by the ports, use the
power inline {[max_milliwatts] | priority {critical | high | low}} command.
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Power over Ethernet (PoE) 581