Brocade FastIron Ethernet Switch Administration Guide - Manual (Page 198)

enables an Endpoint to communicate a more precise required power level, thereby enabling the
device to allocate less power to the Endpoint, while making more power available to other ports.
The LLDP-MED Power-via-MDI TLV advertises an Endpoint IEEE 802.3af power-related information,
including the following:
• Power type - indicates whether the LLDP-MED device transmitting the LLPDU is a power sourcing
device or a powered device:
‐ Power sourcing device/equipment (PSE) - This is the source of the power, or the device
that integrates the power onto the network. Power sourcing devices/equipment have
embedded POE technology. In this case, the power sourcing device is the Brocade POE
device.
‐ Powered device (PD) - This is the Ethernet device that requires power and is situated on
the other end of the cable opposite the power sourcing device.
• Power source - The power source being utilized by a PSE or PD, for example, primary power
source, backup power source, or unknown.
For Endpoint devices, the power source information indicates the power capability of the Network
Connectivity Device it is attached to. When the Network Connectivity device advertises that it is using
its primary power source, the Endpoint should expect to have uninterrupted access to its available
power. Likewise, if the Network Connectivity device advertises that it is using backup power, the
Endpoint should not expect continuous power. The Endpoint may additionally choose to power down
non-essential subsystems or to conserve power as long as the PSE is advertising that it is operating
on backup power.
NOTE
Brocade devices always advertise the power source as "unknown".
• Power priority - The in-line power priority level for the PSE or PD:
‐ 3 - low
‐ 2 - high
‐ 1 - critical
‐ unknown
• Power level - The total power, in tenths of watts, required by a PD from a PSE, or the total power a
PSE is capable of sourcing over a maximum length cable based on its current configuration.
If the exact power is not known for a PSE or PD, it will advertise the power level associated with its
802.3af power class listed in the following table.
802.3af power classes TABLE 24
Power class Minimum power level output at the PSE Maximum power levels at the PD
0 15.4 watts 0.44 - 12.95 watts
1 4.0 watts 0.44 - 3.84 watts
2 7.0 watts 3.84 - 6.49 watts
3 15.4 watts 6.49 - 12.95 watts
For a PD (Endpoint device), the power level represents the maximum power it can consume during
normal operations in its current configuration, even if its actual power draw at that instance is less than
the advertised power draw.
LLDP and LLDP-MED
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