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2.5 Power over Ethernet
There are two components in Power over Ethernet (PoE):
Power Sourcing Equipment (PSE), the Ethernet Routing Switch (ERS) that provides the PoE.
Powered Device (PD), the end device that uses the power such as IP Phones, Wireless access
points, security cameras, and security card readers.
PoE ports provide power and data simultaneously to network devices over a standard Ethernet cable.
This eliminates the need for separate power supplies for each powered device, which reduces cabling
and management costs for equipment additions, moves or changes. Because a switch that offers PoE
has the ability to power IP Phones centrally from the Ethernet, IP Telephony is the leading user of PoE.
There are two standards for PoE:
IEEE 802.3af for PoE, available on Ethernet Routing Switch PWR models
IEEE 802.3at for PoE+, available on Ethernet Routing Switch PWR+ models
The newer of the two standards, PoE+, increases the amount of power that the PSE can supply.
When you connect a powered device to the switch through a PoE or PoE+ port, PoE-capable switches
automatically detect the network device power requirements and dynamically supply the required DC
voltage, at a set current, to the device.
Under the standards, the switch can provide power over the used or unused pairs in a UTP copper cable.
Avaya Ethernet Routing Switches provide power over the used pairs.
Note –
You must use a four-pair Category 5e or higher UTP cable for PoE. A standard two-pair UTP
Cable does not support PoE
The Avaya Ethernet Routing Switches do not use power classification to provide PoE to the PDs. The
Ethernet Routing Switches use a pool of power per switch or per module. As devices come online and
begin to use power, the overall pool of power decreases.
Features, such as Power Management and Power Priority, are available within the Ethernet Routing
Switches to control PoE across the switch. Power Management can enable, disable, or limit the PoE on a
per-port basis or on a per-module basis. In configurations where there is not enough PoE available,
Power Priority sends power to designated ports before lower priority ports. This ensures that critical PoE
devices always have power. See the next section,
important power consumption management feature.
Avaya created a PoE Calculator tool to help you determine your PoE needs. In the tool you select the
number of Avaya IP phones and wireless access points, or enter information for third party PoE devices,
then the calculator provides information for the power required, number of switches, and, if necessary,
the amount of redundant power required. The PoE Calculator tool helps you confidently streamline the
design of the PoE infrastructure. You can find the PoE Calculator (NN48500-520) on the Avaya Web site
at http://www.avaya.com/support.
October 2012
Avaya Inc. – External Distribution
IP Office & Ethernet Switching Technical Configuration Guide
Avaya Energy
Saver, for information about another
avaya.com
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