28-3
Catalyst 4500 Series, Catalyst 2948G, Catalyst 2948G-GE-TX, and Catalyst 2980G Switches Software Configuration Guide
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Release 8.2GLX
78-15908-01
Chapter 28 Power Management
Understanding How Power Management Works on the Catalyst 4500 Series Switches
Redundant Mode Guidelines
This section describes the guidelines for using redundant mode in the Catalyst 4500 series switches:
•
By default, the power supplies in a Catalyst 4500 series switch are set to redundant mode.
•
The two power supplies must be the same type.
Caution
Do not use the 1400 W DC power supply with any other power supply, even for a hot swap or other
short-term emergency, because you can seriously damage your switch.
•
If you set your switch to redundant mode and only one power supply is installed, your switch accepts
the configuration but operates without redundancy.
Note
If you use power supplies with different types or wattages in your switch, the switch uses
the power supply in power supply bay 1 (PS1) and ignores the power supply in power supply
bay 2 (PS2). If you use different wattages, your switch will not have power redundancy.
•
When using fixed power supplies, choose a power supply that can support the switch configuration.
•
When using variable power supplies, choose a power supply that supplies enough power so that the
chassis and Power over Ethernet (PoE) [inline power] requirements are less than the maximum
available power for the chassis and PoE for the power supply. Variable power supplies automatically
adjust the power resources to accommodate the chassis and PoE requirements when a system boots.
Modules are brought up first, followed by powered devices.
•
See
Table 28-1 on page 28-4
for a list of the maximum available power for chassis and PoE for each
power supply.
Combined Mode Guidelines
This section describes the guidelines for using combined mode in the Catalyst 4500 series switches:
•
The two power supplies must be the same type.
•
If you use power supplies with different types or wattages, the switch uses only one power supply.
Your switch will have no power redundancy.
•
The 1400 W DC power supply does not support combined mode. If you set the power budget to 2,
the switch ignores this setting. For more information about the 1400 W DC power supply, see the
“1400 W DC Power Supply Guidelines and Restrictions” section on page 28-5
.
•
When you set your switch to combined mode and only one power supply is installed, your switch
continues to operate in combined mode.
•
When using variable power supplies, choose a power supply that supplies enough power so that the
chassis and PoE requirements are less than the maximum available power for the chassis and PoE
for the power supply. Variable power supplies automatically adjust the power resources to
accommodate the chassis and PoE requirements.
•
When your switch is set to combined mode, the total available power is not the mathematical sum
of the individual power supplies. The power supplies have a predetermined current sharing ratio.
The total power available is P + (P * ratio).
•
See
Table 28-1 on page 28-4
for a list of the maximum available power for chassis and PoE for each
power supply.