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Cisco Redundant Power System Hardware Installation Guide
OL-3654-01
Chapter 1 Overview
Supported Devices and Configurations
Note
If you use this configuration, always power up the external device before
powering up the Cisco RPS to ensure correct operation. If the Cisco RPS powers
up first, the LEDs might not indicate the actual state.
After power up, a sense circuit in the Cisco RPS reads that the device has its AC
power connected and shuts the Cisco RPS output off, preventing competition
between the power supplies.
Normally, the external device internal power supply always provides power. If the
internal power system of the hub or switch fails, the device powers down briefly
(for approximately 30 seconds) until the Cisco RPS begins supplying power.
When the device comes back up, the Cisco RPS is the main power source.
In this configuration, if the Cisco RPS fails or is disconnected, the external device
does not power cycle, because its internal power supply has not been disturbed.
When both the Cisco RPS and internal power supply are powered, the RPS LED
on the external device blinks green, and the LED on the Cisco RPS front panel is
off because the Cisco RPS is not supplying power.
Despite 30 seconds of downtime that occur when using redundancy with reboot,
this configuration does provide additional redundancy and extends the capacity of
the Cisco RPS.
Note
Cisco recommends that you do not use the redundant-with-reboot configuration
with the hub or switch connected to both the Cisco RPS and to the AC power plug,
because of the 30-second reboot and downtime. If you do use the
redundant-with-reboot configuration, always power up the external device before
you power up the Cisco RPS to ensure correct operation. When the Cisco RPS
powers up first, the LEDs might not indicate the actual state.
Quasi- and Fully Redundant Mixed Configuration
You can mix quasi-redundant and fully redundant configurations for supported
devices. For example, two devices can be in quasi-redundant mode while one is
in fully redundant mode (see
Figure 1-4
).
