Pd Support - HP ProCurve 6400cl Series Management And Configuration Manual

Power Over Ethernet (PoE) Operation for the Series 5300xl Switches
General PoE Operation
Note
11-6
The ports on a PoE module support standard networking links and PoE links.
Thus, you can connect either a non-PoE device or a PD to a PoE-enabled port
without reconfiguring the port.

PD Support

An xl PoE module must have a minimum of 15.4 watts of unused PoE power
available when you connect an 802.3af-compliant PD, regardless of how much
power the PD actually uses. Depending on the amount of power the EPS
device delivers to a specific xl PoE module, there may or may not always be
enough power available to connect and support 802.3af PoE operation on all
24 10/100-TX ports. For example, if an EPS device is supporting only one xl
PoE module and no other PSEs, then there will be sufficient power available
for all ports on the module. However, if the same EPS is supporting both an
xl PoE module and another HP PSE device then, depending on the power
demand placed on the module by the PDs you connect, it is possible to
oversubscribe the available PoE power on the module. In this case, one or
more PDs connected to the module will not have power. That is:
Sufficient PoE Power Available: When a new PD connects to an xl
■
PoE module in the switch, and if the module has a minimum of 15.4
watts of unused PoE power available, the module supplies power to
the port for that PD.
Insufficient PoE Power Available: When a new PD connects to an
■
xl PoE module, and if the module does not have a minimum of 15.4
watts of unused PoE power already available:
• If the new PD connects to a port "X" having a higher PoE priority than
another port "Y" that is already supporting another PD on the same
module, then the module removes PoE power from port "Y" and
delivers it to port "X". In this case the PD on port "Y" loses power and
the PD on port "X" receives power.
• If the new PD connects to a port "X" having a lower priority than all
other PoE ports currently providing power to PDs on the same
module, then the module does not deliver PoE power to port "X" until
one or more PDs using higher priority ports are removed.
Note that once a PD connects to a PoE port and begins operating, the port
retains only enough PoE power to support the PD's operation. Unneeded
power becomes available for supporting other PD connections. Thus, while
15.4 watts must be available for an xl PoE module on the switch to begin
supplying power to a port with a PD connected, 15.4 watts per port is not
continually required if the connected PD requires less power. For example,