Poe Power Budget; Port Prioritization - Allied Telesis IE340 Series Installation Manual

PoE Power
Budget
Port
Prioritization
31
strands. In Alternative A, power is delivered on strands 1, 2, 3, and 6,
which are the same strands that carry the 10/100Base-TX network traffic.
In Alternative B, power is delivered on strands 4, 5, 7, and 8. These are the
unused strands.
The IE340 PoE PSE switches support only Alternative A: They support
PoE and PoE+ powered devices that comply with the IEEE 802.3af and
802.3at standards. The standards require that powered devices support
both Alternatives A and B.
Note
Legacy Powered Devices that are non-standard or were
manufactured before the completion of the standards and support
only one method might not be compatible with the IE340 PoE PSE.
The IE340 PoE PSE switches have a configurable power budget. This is
the total amount of power output that a switch can supply to the powered
devices on its ports. The switches have a maximum allowed budget of
240W. The actual power budget depends on the capabilities of the DC
power supply.
The number of powered devices the switch can support at one time
depends on the switch's PoE budget and the wattage requirements of the
powered devices.
To determine whether the wattage requirements of the PoE devices you
plan to connect to the switch exceed its budget, see their documentation
for their power requirements and add the requirements together. The
switch can power all the devices simultaneously as long as the total is
below its PoE power budget. If the total exceeds the available power
budget, you should consider reducing the number of PoE devices so that
all the devices receive power. Otherwise, the switch powers a subset of
the devices, based on port prioritization.
The switch can handle different power requirements on different ports.
This enables you to connect different classes of PoE equipment to the
ports on the switch.
If the power requirements of the powered devices exceed the switch's
power budget, the switch denies power to some ports based on a system
called port prioritization. You may use this mechanism to ensure that
powered devices critical to the operations of your network are given
preferential treatment by the switch in the distribution of power should the
demands of the devices exceed the available capacity.
Chapter 1: Overview