Rockwell Automation 1783-Mxxx Stratix 8000 and 8300 Ethernet Managed Switches User Manual - Manual (Page 64)

64 Rockwell Automation Publication 1783-UM003I-EN-P - March 2014
Chapter 3 Switch Software Features
• Static—The module pre-allocates power to the port even when no
powered device is connected and guarantees that power is available for the
port. The module allocates the port-configured maximum wattage, and
the amount is never adjusted through the IEEE class or by CDP messages
from a powered Cisco end device. Because power is pre-allocated, any
powered device that uses less than or equal to the maximum wattage is
guaranteed to be powered when it is connected to the static port. The port
no longer participates in the first-come, first-served model.
However, if the powered-device IEEE class is greater than the maximum
wattage, the module does not supply power to it. If the module learns
through CDP messages that a powered Cisco end device needs more than
the maximum wattage, the powered device is shut down.
If you do not specify a wattage, the module pre-allocates the maximum
value. The module powers the port only if it discovers a powered device.
Use the static setting on a high-priority interface.
• Off—The module disables powered-device detection and never powers
the PoE port, even if an unpowered device is connected. Use this mode
only when you want to make sure power is never applied to a PoE port,
making the port a data-only port.
Maximum Power Allocation (cutoff power) on a PoE Port
The module determines the cutoff power on a PoE port in this order.
1. Manually when you configure the power level that the module budgets for
the port
2. Manually when you configure the power level that limits the power
allocated to the port
3. Automatically when the module sets the power usage of the device by using
the IEEE classification and LLDP power negotiation or CDP power
negotiation
If you do not manually configure the cutoff-power value, the module can
automatically determine the value by using CDP power negotiation when
connected to a Cisco end device. If the switch cannot determine the value by
using one of these methods, it uses the default value of 15.4 W.