Brocade FastIron Ethernet Switch Administration Guide - Manual (Page 274)

Enabling the detection of PoE power requirementsadvertised
through CDP
Many power consuming devices, such as Cisco VoIP phones and other vendors’ devices, use the
Cisco Discovery Protocol (CDP) to advertise their power requirements to power sourcing devices,
such as Brocade PoE devices. Brocade power sourcing equipment is compatible with Cisco and other
vendors’ power consuming devices; they can detect and process power requirements for these
devices automatically.
NOTE
If you configure a port with a maximum power level or a power class for a power consuming device,
the power level or power class will take precedence over the CDP power requirement. Therefore, if
you want the device to adhere to the CDP power requirement, do not configure a power level or power
class on the port.
Command syntax for PoE power requirements
To enable the Brocade device to detect CDP power requirements, enter the following commands.
device# configure terminal
device(config)# cdp run
Syntax: [no] cdp run
Use the no form of the command to disable the detection of CDP power requirements.
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 will supply 15.4 watts of power at the RJ-45 jack, minus any power loss through
the cables. A PoE+ device will supply 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. For example, a PoE port with a
default maximum power level of 15.4 watts will receive 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, will 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
will supply at the RJ-45 jack.
Setting power levels configuration note
Consider the following when enabling this feature:
• There are two ways to configure the power level for a PoE or 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 275. For each PoE port, you can
Enabling the detection of PoE power requirementsadvertised through CDP
274 FastIron Ethernet Switch Administration Guide
53-1003075-02