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Software Configuration Guide—Release 12.2(25)SG
OL-7659-03
Chapter7 Environmental Moni toring and Power Management
Power Management
To choose a 1+1 redundancy configuration, you must change the system configuration from the default
2+1 redundancy mode to 1+1 redundancy mode by using the power supplies required 1 command. The
power supplies required 1 command sets the power redundancy to 1+1 redundancy mode. In the 1+1
redundancy mode, the nonredundant power available to the system is the power o f the single weakest
power supply. The second power supply installed in your switch provides full redundancy.
Limitations of the 1+1 Redundancy Mode
If you attempt to configure the system to operate in 1+1 redund ancy mode, and you have more modules
installed in the chassis than a single power supply can handle, the system displays the following error
message:
Insufficient power supplies for the specified configuration
This message will also appear in the show power command output.
If you are already operating in 1+1 redundancy mode with a valid module configu ration and you attempt
to insert additional modules that require more power than the single power supply provides, the system
immediately places the newly inserted module into reset mode and issues these error messages:
Module has been inserted
Insufficient power supplies operating
Additionally, if a chassis that has been operating in 1+1 redundancy mode with a valid module
configuration is powered down, and you insert a module or change the module configuration
inappropriately and power on the switch again, the module(s) in the chassis (at boot up) that require more
power than is available, are placed into reset mode.
A module in reset mode continues to draw power as long as it is inst alled in the chassis and as long as
the show module command output indicates that there is not enough power for the module to be brought
out of reset mode.
A single power supply provides 400 W or 650 W. Two 400 W power supplies provide 725 W. Two 650W
power supplies supply only 750 W. The 750 W limit is a restriction on the power supply cooling capacity
for the Catalyst 4006 switches.
If you mix a 400 W power supply and a 650 W power supply, the switch performs as if there were two
400 W power supplies. If you have one 400 W power supply and one 650 W power supply in 1+ 1
redundancy mode, and a second 650 W power supply is set as the backup, the syst em performs as if there
were 400 W. If the 400 W power supply fails, the backup 650 W power supply comes into service;
however, the switch still has only 400 W available. You need to remove the failed 400 W power supply
for the switch to make use of the 650 W available.
To compute the power requirements for your system and verify that your system has enough power, add
up the power consumed by the supervisor engine module, the fan box, and the installed modules. (See
the “Powering Down a Module” section on page 7-19 for more information on the power consumption
for the various components of your switch.) For 1+1 redundancy mode, verify that the total is less than
400 W or 650 W, depending on the power supplies installed in your switch. The following examples are
provided to further explain the use of power supplies.
The following configuration requires a minimum of 395 W:
•WS-X4014 supervisor engine—110 W
•Four WS-X4148-RJ modules—65 W each (260 W total—the optimized m odule configuration)
•Fan tray—25 W
This configuration requires less than the maximum that a single power supply can provide in 1+1
redundancy mode.