Cisco 6503 - Catalyst Firewall Security Sys Installation Manual page 382

Power Supply Redundancy
Table A-42 Power Supply Redundancy
If you have two and redundancy is
power supplies of
Equal wattage Enabled
Unequal wattage Enabled
Equal or unequal Disabled
wattage
Table A-43 Effects of Power Supply Configuration Changes
Configuration Change
Redundant to combined
Combined to redundant
Equal wattage power
supply is inserted with
redundancy enabled
Catalyst 6500 Series Switches Installation Guide
A-74
Then
The total power drawn from both supplies is never greater than the
capability of one supply. If one supply malfunctions, the other supply
can take over the entire system load. Each power supply provides
approximately half of the required power to the system. Load sharing
and redundancy are enabled automatically; no software configuration is
required.
Both power supplies initially come online. For the Catalyst operating
system, if the difference between the two power supply's output
wattage is less than 10 percent of the higher output wattage power
supply, redundancy is enabled. If the difference is greater than
10 percent, the lesser wattage power supply is disabled.
For Cisco IOS, both power supplies come on. The total available
wattage is the output wattage of the higher wattage power supply.
The total power available to the system is approximately 167 percent of
the lower-wattage power supply. The system powers up as many
modules as the combined capacity allows. If the higher-wattage power
supply fails, the lower-wattage supply might also shut down due to
overcurrent protection to prevent damage to the lower-wattage power
supply.
Effect
System log and syslog messages are generated.
•
System power is increased to approximately 167 percent of the
•
lower-wattage power supply.
The modules marked as power-deny in the show module Status field
•
are powered up if there is sufficient power.
System log and syslog messages are generated.
•
System power is the power capability of the higher-wattage supply.
•
• If there is not enough power for all previously powered-up modules,
some modules are powered down and marked as power-deny in the
show module Status field.
System log and syslog messages are generated.
•
• System power equals the power capability of one supply. (Both
supplies provide approximately one half of the total current.)
No change in the module status because the power capability is
•
unchanged.
Appendix A Power Supply Specifications
OL-5781-08