Power Priority - ProCurve 2626 Management And Configuration Manual

Note
Power Over Ethernet (PoE) Operation for the Series 2600-PWR Switches
Disconnecting a PD from a port causes the switch to stop providing PoE power
to that port and makes the power available to other ports configured for PoE
operation. If the PoE demand becomes greater than the available power, the
switch transfers power from lower-priority ports to higher-priority ports.
(Ports not currently providing power to PDs are not affected.)
15.4 watts of available power is required for the switch to begin delivering
power to a port, such as when a newly connected PD is detected or when
power is released from higher priority ports. Depending on power demands,
lower-priority ports on a switch with high PoE power demand may
occasionally lose power due to the demands of higher-priority ports. (Refer
to "Power Priority" for further details.)

Power Priority

In the default configuration PoE power priority is determined by port number,
with the lowest numbered port having the highest priority.
When Does the Switch Prioritize Power Allocations? If the switch can
provide power for all existing PD demands, it does not use its power priority
settings to allocate power. However, if the PD power demand oversubscribes
the available power, then the switch prioritizes the power allocation to the
ports that present a PD power demand. This causes the switch to remove
power from one or more lower-priority ports to meet the power demand on
other, higher-priority ports. (This operation occurs, regardless of the order in
which PDs connect to the switch's PoE-configured ports.)
How Does the Switch Prioritize Power Allocations? The switch
simultaneously uses two priority methods:
The priority class method enables port PoE priority class assign­
■
ments of Low (the default), High, and Critical.
The port-number priority method gives a lower-numbered port
■
priority over a higher-numbered port within the same configured
priority class.
On the Switch 2650-PWR, the ports configured with the highest priority of
either bank (1-24 or 25-48) will receive PoE power, regardless of position.
There is also an option to provision ports 1-24 with 406 watts of internal power
and ports 25-48 with 408 watts of external power by adding an external power
supply. For more information on using external power supplies with
PoE-capable switches, refer to the PoE Planning and Implementation Guide.
Power Availability and Provisioning
11-5