•
PoH
- Covered by IEEE 802.3at 2009 and sometimes called power over HDBaseT, provides up to
95 Watts of power to power-consuming devices.
•
Power-sourcing device
or
Power-sourcing equipment (PSE)
- The source of the power, or the
device that integrates the power onto the network. Power sourcing devices and equipment have
embedded PoE technology. The Brocade FastIron PoE device is a power sourcing device.
Methods for delivering Power over Ethernet
There are two methods for delivering Power over Ethernet (PoE) as defined in the 802.3af and 802.3at
specifications:
•
Endspan
- Power is supplied through the Ethernet ports on a power-sourcing device. With the
Endspan solution, power can be carried over the two data pairs (Alternative A) or the two spare
pairs (Alternative B).
•
Midspan
- Power is supplied by an intermediate power-sourcing device placed between the switch
and the PD. With the Midspan solution, power is carried over the two spare pairs (Alternative B).
With both methods, power is transferred over four conductors, between the two pairs. 802.3af- and
802.3at-compliant PDs are able to accept power from either set of pairs.
Brocade PoE devices use the Endspan method, compliant with the 802.3af and 802.3at standards.
The Endspan and Midspan methods are described in more detail in the following sections.
NOTE
All 802.3af- and 802.3at-compliant power-consuming devices are required to support both application
methods defined in the 802.3af and 802.3at specification.
PoE endspan method
The PoE Endspan method uses the Ethernet switch ports on power-sourcing equipment, such as a
BrocadeFastIron PoE switch, which has embedded PoE technology to deliver power over the network.
With the Endspan solution, there are two supported methods of delivering power. In Alternative A, four
wires deliver data and power over the network. Specifically, power is carried over the live wire pairs
that deliver data as illustrated in the following figure. In Alternative B, the four wires of the spare pairs
are used to deliver power over the network. Brocade PoE devices support Alternative A.
The Endspan method is shown in the following illustration.
Methods for delivering Power over Ethernet
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FastIron Ethernet Switch Administration Guide
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