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Cat 6500: why 42 V input for all modules

Hi Expert,

I am trying to understand the power efficiency of Catalyst 6500 and I can see that all modules and cards take 42 V on input for all IO Modules, Sups, PFCs and DFCs Cards. I don't think such implementation is power efficient enough as you need multiple DC-DC converters on the Modules and Cards. Am I missing the point? Any comments?




Re: Cat 6500: why 42 V input for all modules

HI Alex,

can you send me the output of the following command

show power

You can display power supply input fields by specifying the power supply number in the command. A new power-output field with operating mode is displayed for power supplies with more than one output mode. Enter the

show env status power-supply

# show env status power-supply 1

# show env status power-supply 2

The Catalyst 6500 series switches allow you to use both AC-input and DC-input power supplies in the same chassis.

The modules have different power requirements, and some configurations require more power than a single power supply can provide. The power management feature allows you to power all installed modules with two power supplies. However, redundancy is not supported in this configuration because the total power drawn from both power supplies is at no time greater than the capability of one supply. Redundant and nonredundant power configurations are described in the following sections.

There are two types of configuration:

1. Non-redundant

2. Redundant

In a nonredundant configuration, the power available to the system is the combined power capability of both power supplies. The system powers up as many modules as the combined capacity allows. However, if one power supply fails and there is not enough power for all of the previously powered-up modules, the system powers down those modules.

In a redundant configuration, the total power drawn from both power supplies is not greater than the capability of one power supply. If one supply malfunctions, the other supply can take over the entire system load. When you install and power up two power supplies, each concurrently provides approximately half of the required power to the system. Load sharing and redundancy are enabled automatically; no software configuration is required.

To enable redundancy, use the redundant keyword.

To disable or enable redundancy (redundancy is enabled by default) from global configuration mode, enter the

power redundancy-mode combined | redundant


You can change the configuration of the power supplies to redundant or nonredundant at any time.