Power Redundancy; Limitations Of The 1+1 Redundancy Mode - Cisco WS-C4003 - Catalyst 4000 Chassis Switch Software Configuration Manual

Power Management
In systems with redundant power supplies, both power supplies must be of the same wattage. The
Catalyst 4000 family switches allow you to mix AC-input and DC-input power supplies in the same
chassis. For detailed information on supported power supply configurations for each chassis, refer to the
Catalyst 4000 Family Installation Guide.
Catalyst 4000 family modules have different power requirements; thus, some switch configurations
require more power than 1+1 redundancy mode (a single power supply) can provide. In those
configurations, redundancy requires three power supplies. Redundant and nonredundant power
configurations are discussed in the following sections.

Power Redundancy

The Catalyst 4006 switch contains holding bays for up to three power supplies. You need two primary
power supplies to operate a fully loaded Catalyst 4006 chassis. You can set the power redundancy to two
primary plus one redundant power supply (2+1 redundancy mode) or to one primary plus one redundant
power supply (1+1 redundancy mode). The 1+1 redundancy mode does not support a fully loaded
chassis.
If your switch has only two power supplies and is in 2+1 redundancy mode (the default mode), there is
no redundancy. You can create redundancy with only two power supplies by setting the power
redundancy to operate in 1+1 redundancy mode (one primary plus one redundant power supply).
However, 1+1 redundancy will not support all configurations.
The 1+1 redundancy mode is designed and optimized for a specific hardware configuration: a
Catalyst 4006 chassis with a WS-X4013 supervisor engine and four WS-X4148-RJ or WS-X4148-RJ21
modules. Although other configurations are possible, we do not recommend that you use them without
careful consideration of the power usage in the system. For example, other similar and possible
configurations can consist of four modules, where each module consumes 65W or less (for a total of
265W), or more generally, where the total module power usage does not exceed the absolute maximum
module usage of 265W.
The supervisor engine uses 110W and the fan box uses 25W, for a system total of 400W (modules +
supervisor + fan). The 1+1 redundancy mode cannot support a fully loaded chassis, regardless of the
module configuration, and, therefore, one slot of the chassis must be empty. Any attempt to use five
modules guarantees an oversubscription of available power.
If you opt to use the 1+1 redundancy mode, the type and number of modules supported are limited by
the power available from a single power supply. To determine the power consumption for each module
in your chassis, see the
To choose a 1+1 redundancy configuration, you must change the system configuration from the default
2+1redundancy mode to 1+1 redundancy mode by using the set power budget command. The set power
budget 1 command sets the power budget to accommodate a 1+1 redundancy mode. In the 1+1
redundancy mode, the nonredundant power available to the system is the power of a single 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 redundancy mode, and you have more modules
installed in the chassis than a single power supply can handle, the system will prevent you from enabling
the1+1 redundancy mode.
If you are already operating in 1+1 redundancy mode with a valid module configuration 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
Software Configuration Guide—Catalyst 4000 Family, Catalyst 2948G, Catalyst 2980G, Releases 6.3 and 6.4
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"Power Consumption of Modules" section on page
Chapter 26 Administering the Switch
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