Setting the maximum power level for a PoE power-consuming device
When PoE is enabled on a port to which a power-consuming device, or PD, is attached, by default, a
Brocade PoE device supplies 15.4 watts of power at the RJ-45 jack, minus any power loss through the
cables. A PoE+ device supplies either 15.4 or 30 watts of power (depending on the type of PD
connected to the port), minus any power loss through the cables. A PoH device supplies 15.4, 30, or
95 watts of power (depending on the type of PD connected to the port), minus any power loss through
the cables.
As an example, a PoE port with a default maximum power level of 15.4 watts receives a maximum of
12.95 watts of power after 2.45 watts of power loss through the cable. This is compliant with the IEEE
802.3af and 802.3at specifications for delivering inline power. Devices that are configured to receive
less PoE power, for example, 4.0 watts of power, experience a lower rate of power loss through the
cable.
If desired, you can manually configure the maximum amount of power that the Brocade PoE device
supplies at the RJ-45 jack.
Considerations for setting power levels
Consider the following when enabling this feature:
• There are two ways to configure the power level for a PoE, PoE+, or High PoE power-consuming
device. The first method is discussed in this section. The other method is provided in the section
Setting the power class for a PoE power-consuming device
on page 355. For each PoE port, you
can configure either a maximum power level or a power class. You cannot configure both. You can,
however, configure a maximum power level on one port and a power class on another port.
• The Brocade PoE, PoE+, or High PoE device adjusts the power on a port only if there are available
power resources. If power resources are not available, the following message is displayed on the
console and in the Syslog:
PoE: Failed power allocation of 30000 mwatts on port 1/1/21. Will retry when more
power budget.
• If you are not using High PoE or PoH devices in any of the first 8 ports of the ICX7450-48P or
ICX7450-24P, Brocade recommends that you limit the power on those ports using the
inline power
power-limit
command. Limiting power with the
inline power power-by-class 4
command does not
work for the ICX7450 because Class 4 encompasses 30-95W. However, Class 4 on units that do
not support PoH or High Power is still 30W.
• FastIron devices pre-allocate power as per the configured maximum power for a physically
operational PoE, PoE+, or High PoE configured port. However, in an ICX 6450-C12 device that is
operational without direct power supply and that has pass-through power, there is no pre-allocation
of power. Instead, power is allocated only when a powered device is connected to the port.
Configuring power levels command syntax
To configure the maximum power level for a power-consuming device, use the
inline power power-
limit
command as shown in the following example.
device# configure terminal
device(config)# interface ethernet 1/1/1
device(config-if-e1000-1/1/1)# inline power power-limit 14000
These commands enable inline power on interface ethernet 1 in slot 1 of unit 1 and set the PoE power
level to 14,000 milliwatts (14 watts).
Syntax:
inline power
power-limit
power-level
Setting the maximum power level for a PoE power-consuming device
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FastIron Ethernet Switch Administration Guide
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