Both power supplies must be the same type. Do not mix AC, DC, and HVAC/HVDC power supplies in
the same chassis.
Note
For
n
+1 redundancy, you can use one or two power sources for the two power supplies. For
n
+
n
redundancy,
you must use two power sources and connect each power supply to a separate power source.
Note
The power supplies are rated to output up to 650 W (AC power supplies), up to 1200 W (HVAC/HVDC power
supplies), or up to 930 W (DC power supplies), but the switch requires less than those amounts of power from
the power supply. To operate the switch you must provision enough power from the power source to cover
the requirements of both the switch and a power supply. Typically, this switch and a power supply require
about 232 W of power input from the power source, but you must provision as much as 455 W power input
from the power source to cover peak demand.
Some of the power supply modules have Underwriter Labs (UL) rating capabilities that exceed the switch
requirements. When calculating power requirements, use the switch requirements to determine the amount
of power required for the power supplies.
Note
To minimize the possibility of circuit failure, make sure that each power-source circuit used by the switch is
dedicated to the switch.
For the power cables to use with the power supplies, see
Power Cord Specifications, on page 54
.
Note
Airflow Requirements
The switch is designed to be positioned with its ports in either the front or the rear of the rack depending on
your cabling and maintenance requirements. Depending on which side of the switch faces the cold aisle, you
must have fan and power supply modules that move the coolant air from the cold aisle to the hot aisle in one
of the following ways:
•
Port-side exhaust airflow
—
Coolant air enters the chassis through the fan and power supply modules in
the cold aisle and exhausts through the port end of the chassis in the hot aisle.
•
Port-side intake airflow
—
Coolant air enters the chassis through the port end in the cold aisle and exhausts
through the fan and power supply modules in the hot aisle.
•
Dual-direction airflow
—
Airflow direction is determined by the airflow direction of the installed fan
modules.
You can identify the airflow direction of each fan and power supply module by its coloring as follows:
•
Blue coloring indicates port-side exhaust airflow.
•
Burgundy coloring indicates port-side intake airflow.
•
White coloring on HVAC/HVDC power supplies indicates dual-direction airflow.
Cisco Nexus 9396PX NX-OS Mode Switch Hardware Installation Guide
10
Preparing the Site
Airflow Requirements
