Brocade FastIron Ethernet Switch Administration Guide - Manual (Page 263)

• 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 figure below. 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 illustrated in the illustration below.
FIGURE 9 PoE Endspan delivery method
PoE midspan method
The PoE Midspan method uses an intermediate device, usually a PD, to inject power into the network.
The intermediate device is positioned between the switch and the PD and delivers power over the
network using the spare pairs of wires (Alternative B). The intermediate device has multiple channels
(typically 6 to 24), and each of the channels has data input and a data-plus- power RJ-45 output
connector.
PoE endspan method
FastIron Ethernet Switch Administration Guide 263
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