This article describes the meaning of the power redundancy configuration shown on EX series switches and the configuration of the power supply redundancy.

When running the command >show chassis power-budget-statistics you will get an output like the one below:

user@switch> show chassis power-budget-statistics

    PSU 0   (EX6200-PWR-AC2500)         :  2500 W  Online

    PSU 1   (EX6200-PWR-AC2500)         :  2500 W  Online

    PSU 2   (EX6200-PWR-AC2500)         :  2500 W  Online

    PSU 3   (EX6200-PWR-AC2500)         :  2500 W  Online

    Total Power supplied by all Online PSUs :  10000 W

    Power Redundancy Configuration      :   N+1

    Power Reserved for the Chassis      :   500 W

 Fan Tray Statistics      Base power  Power Used

 FTC 0             :   300 W   43.04 W

 FPC Statistics         Base power  Power Used  PoE power  Priority

 FPC 1  (EX6200-48P)     :   220 W   49.47 W   1440 W    1

 FPC 2  (EX6200-48P)     :   220 W   47.20 W    800 W    2

 FPC 3  (EX6200-48P)     :   220 W  1493.57 W   1440 W    0

 FPC 4  (EX6200-SRE64-4XS)  :   100 W   51.38 W     0 W    0

 FPC 5  (EX6200-SRE64-4XS)  :   100 W   50.28 W     0 W    0

 FPC 6  (EX6200-48P)     :   220 W   49.38 W    800 W    6

 FPC 8  (EX6200-48P)     :   220 W   61.41 W   1440 W    9

 FPC 9  (EX6200-48T)     :   150 W   12.49 W     0 W    9

    Total (non-PoE) Power allocated     :  1750 W

    Total Power allocated for PoE      :  5920 W

    Power Available (Redundant case)     :  5750 W

    Total Power Available          :  2515 W

As highlighted on the output shared, the power redundancy configuration might show N+1 or N+N, this statement might generate some confusion on what does it mean and how it changes the power redundancy on the switch.

The default power redundancy configuration is set to N+1, indicating that one power supply is kept in reserve as a backup in case any of the other power supplies is removed or fails. In this configuration, only one power supply is actively providing power to the system.

Alternatively, the configuration can be changed to N+N. In this setup, the power management system allocates half of the online power supplies for normal operating power and the other half for redundant power. This means that all available power supplies are actively providing power to the system. It's important to note that if you have an odd number of online power supplies, the power management system allocates one additional power supply to normal operating power than to redundant power.

To implement N+N redundancy, use the following command:

user@switch# set psu redundancy n-plus-n

If you wish to revert to the default N+1 configuration, use the following command:

user@switch# delete chassis psu redundancy n-plus-n

https://www.juniper.net/documentation/us/en/software/junos/high-availability/topics/task/power-management-power-supply-redundancy-ex-series-cli.html

https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/command/show-chassis-power-budget-statistics-ex-series.html