Cisco WS-C4003 - Catalyst 4000 Chassis Switch Software Configuration Manual page 351

Chapter 26 Administering the Switch
has been inserted and 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.
Both of these scenarios initiate the five minute evaluation countdown timer. When this timer runs out,
the system attempts to resolve this power usage limitation by evaluating the type and number of modules
installed. The evaluation process may require several cycles to stabilize the chassis' power usage.
During the evaluation cycle, the modules are in effect removed and reinserted thus causing disruption of
network connectivity; the switch reactivates only the modules it is able to support with the limited power
available and leaves the remaining modules in reset mode. The supervisor engine always remains
enabled. Modules placed into reset mode still consume some power. If the chassis module combination,
including the modules in reset, still require more power than is available, the five-minute evaluation
countdown timer starts for another evaluation cycle, and additional modules are placed into reset mode
until the power usage is stable.
If the power requirement of the active modules, along with the modules in reset, does not exceed the
available power, the system is stable and no more evaluation cycles are run, until something again causes
insufficient power usage. One, possibly two cycles, are required to stabilize the system. If you configure
the chassis correctly, the system will not enter the evaluation cycle.
If you have all three power supplies installed and you still choose to operate in 1+1 redundancy mode
Note
but later add additional modules which exceed the power available, the five-minute evaluation timer
starts again. The switch may require several evaluation cycles to stabilize the system. To correct this
power situation caused by the additional modules, you can either remove the extra modules or change
the power budget to 2+1 redundancy mode. If you choose to return to the 2+1 redundancy mode, each
module held in reset mode is brought up one by one to an operational state.
A module in reset continues to draw power as long as it is installed in the chassis; however, the module
is not shown in the show module command output, because the system considers it removed.
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 modules you wish to use.
A single power supply provides 400W, and two power supplies provide 750W. For 1+1 redundancy
mode, verify that the total is less than 400W.
For example, the following configuration requires a minimum of 395W:
WS-X4013 supervisor engine—110W
•
Four WS-X4148-RJ modules—65W each (260W total—the optimized module configuration)
•
Fan box—25W
•
This is 5W less than the maximum that a single power supply can provide in 1+1 redundancy mode.
The following configuration, however, requires more power than a single power supply can supply:
• WS-X4013 supervisor engine—110W
• Two WS-X4148-RJ modules in slots 2 and 3—65W each (130W total)
• Two WS-X4448-GB-LX modules in slots 4 and 5—90W each (180W total)
• Fan box—25W
78-12647-02
Software Configuration Guide—Catalyst 4000 Family, Catalyst 2948G, Catalyst 2980G, Releases 6.3 and 6.4
Power Management
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