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AT-9000 Switch Command Line User’s Guide
217
The AT-9000/12POE switch has a power budget of 125 watts. The
AT-9000/28POE switch has a power budget of 370 watts. These are the
maximum amounts of power the switches can provide at one time to the
powered devices.
The AT-9000/28POE switch has two power supplies. Each power supply
is responsible for providing 185 watts, or half, of the power budget. Both
power supplies must be connected to AC power sources for the switch to
provide the full 370 watts. The power budget is reduced to 185 watts if only
one power supply is connected to a power source.
Port
Prioritization
As long as the total power requirements of the PDs is less than the total
available power of the switch, it can supply power to all of the PDs.
However, when the PD power requirements exceed the total available
power, the switch denies power to some ports based on a process called
port prioritization.
The ports on the PoE switch are assigned to one of three priority levels.
These levels and descriptions are listed in Table 19.
Without enough power to support all the ports set to the same priority level
at one time, the switch provides power to the ports based on the port
number, in ascending order. For example, when all of the ports in the
switch are set to the low priority level, and the power requirements are
exceeded on the switch, port 1 has the highest priority level, port 2 has the
next highest priority level and so forth.
Table 19. PoE Port Priorities
Priority
Level
Description
Critical This is the highest priority level. Ports set to the Critical
level are guaranteed to receive power before any of the
ports assigned to the other priority levels.
High Ports set to the High level receive power only when all
the ports assigned to the Critical level are already
receiving power.
Low This is the lowest priority level. Ports set to the Low level
receive power only when all the ports assigned to the
Critical and High levels are already receiving power. This
level is the default setting.