Port Power Priority - Nortel 4500 Series Overview-System Configuration

power each device requires and supply the required DC voltage at a set
current based on the load conditions and current availability. The switches
support both PoE and standard LAN devices.
The power detection function of the Nortel Ethernet Routing Switch 4500
Series 4550T-PWR and the 4548-GT-PWR operate independently of the
data link status. A device that is already operating the link for data or a
device that is not yet operational can request power. That is, the switches
provide power to a requesting device even if the data link for that port is
disabled. The switches monitor the connection and automatically disconnect
power from a port when you remove or change the device, as well as when
a short occurs.
The switches automatically detect devices that require no power connections
from them, such as laptop computers or other switching devices, and send
no power to those devices. You control the supply of power to specific ports
by setting the maximum allowed power to each port in 1 W increments,
from 3 W to 16 W.

Port power priority

You can configure the power priority of each port by choosing low, high, or
critical power priority settings.
The switch automatically drops low-priority ports when the power
requirements exceed the available power budget. When the power
requirements becomes lower than the switch power budget, the power
returns to the dropped port. When several ports have the same priority,
one of them must be dropped. In this case, the port with the highest port
number is dropped.
For example, assume the following scenario:
•
•
•
The devices connected to the ports consume the available Nortel Ethernet
Routing Switch 4500 Series 4550T-PWR and 4548-GT-PWR switch power.
The device connected to port 41 requests power from the 4550T-PWR or
the 4548-GT-PWR. The switch provides the required power as port 41 is
configured as high priority. However, to maintain the power budget, the
Copyright © 2007, Nortel Networks
.
Note: Allow 30 seconds between unplugging and replugging an IP
device to the switch to enable the IP device to discharge. If you attempt
to connect earlier, the switch may not detect the IP device.
Ports 1 to 40 are configured as low priority.
Port 41 is configured as high priority.
Ports 1 to 40 are connected to powered devices.
Nortel Ethernet Routing Switch 4500 Series
Overview — System Configuration
NN47205-500 02.01 Standard
5.0 23 February 2007
Port power priority 149
Nortel Networks Confidential