Table of Contents
Advertisement
Preparing the Site
For example, if you are installing a switch with two Supervisor 2 modules (2 x 265 W), 16 48-port 10-Gigabit
Ethernet I/O modules (PID: N77-F248XP-23E) (16 x 500 W), six fabric modules (6 x 300 W) and three fan
trays (3 x 900 W), the power requirements for this switch would be 13,030 W.
Note
Step 2
Determine the number of power supplies needed for the available power requirement by dividing the power
requirement amount (see Step 1) by the output wattage of the power supplies installed in the switch.
For 3-kW power supplies, round up a fractional result to the nearest ones digit to determine the number of
power supplies needed.
For example, if you are installing a switch with 3-kW power supplies and have a consumption of 13,030 W,
you need five power supplies (13,030 W / 3000 W = 4.34 or 5 power supplies) to operate the switch and all
of its modules.
Step 3
Select one of the following power modes to determine the number of additional power supplies required for
reserve power:
• Combined power—Do not add any power supplies to the number of power supplies calculated for the
available power in Step 2. This power mode does not provide power redundancy, so no extra power
supplies are needed.
• Power supply redundancy (n+1 redundancy)—Add one power supply (reserve power supply). This form
of power redundancy provides a reserve power supply that can replace any active power supply that
goes offline.
• Input source redundancy (grid redundancy)—Add enough power supplies (reserve power supplies) to
at least equal the total output of the active power supplies (number of power supplies calculated in Step
2). Typically, you would double the number of power supplies. You must plan for a second power source
for the reserve power supplies. For example, if you calculate that you need two 3-kW power supplies
for 6 kW of available power, you need another two 3-kW power supplies for 6 kW of reserve power
(for a total of four 3-kW power supplies used for available and reserve power).
• Full redundancy (n+1 and grid redundancy)—Add enough power supplies (reserve power supplies) to
at least equal the output of the active power supplies (number of power supplies calculated in Step 2).
For power supply (n+1) redundancy, ensure that you have at least one extra power supply. For input-source
(grid) redundancy, you will probably double the number of power supplies. You must plan for a second
power source with at least the same amount of input power for the reserve power supplies. For example,
if you calculate that you need two 3-kW power supplies for 6 kW of active power, then you need another
two 3-kW power supplies for 6 kW of reserve power (for a total of four 3-kW power supplies used for
active and reserve power). Either one of the reserve power supplies can replace any of the active power
supplies.
Step 4
Be sure that the power source circuits are dedicated to the switch and not to other electrical equipment.
For combined power mode (no power redundancy) or power supply (n+1) redundancy, you need only one
dedicated circuit. For input-source (grid) or full redundancy, you must have two dedicated power circuits,
each circuit powering half of the 3-kWor 3.5-kW power supplies. The requirements for each circuit are listed
in the following table.
OL-30453-01
Maximum power values are used for calculating the power
requirements.
Cisco Nexus 7718 Switch Site Preparation and Hardware Installation Guide
Planning for Power Requirements
13
Advertisement
Table of Contents
