1-4
Cisco ASR 903 Router Hardware Installation Guide
OL-25178-05
Chapter1 Cisco ASR 903 router Overview
CiscoASR 903 router Features
Redundancy
The Cisco ASR 903 router chassis includes a slot for an optional redundant power supply. The redundant
power supply option provides a second power supply to ensure that power to the chassis continues
uninterrupted if one power supply fails or input power on one line fails. Redundancy is supported either
with identical power supplies or a combination of AC and DC power supply. The CiscoASR 903 router
supports current sharing between the power supplies.
If you install a redundant power supply on the CiscoASR 903 router, we recommend that you connect
each power supply to a separate input power source in order to ensure that the router maintains power in
the event of a power interruption caused by an electrical failure, a wiring fault, or a tripped circuit
breaker.
Dying Gasp
The Cisco ASR 903 router DC power supply supports the Dying Gasp feature, which allows the router
to provide an input power loss notification to the RSP so that the RSP can send appropriate SNMP traps
or OAM messages and update log files on the router. With the DC power supply, the router supports a
minimum input power loss detection time of 2 milliseconds (DC) and continued operation of at least 6
milliseconds (DC) after the notification.
Note Continued DC power supply operation may vary for voltages other than +24/-48V.
Status LEDs
LEDs are also provided on each power supply to indicate the status of the input power and the health of
the power supply. For more information about the LEDs on the CiscoASR 903 router, see Chapter 5,
“Troubleshooting.”
DC Power Specifications
The Cisco ASR 903 router uses a +24/-48 Volts Direct Current (VDC) (-19 to -72 VDC supply
tolerance) power supply. The power supply provides 550 W output power for system 12 V power. The
power supply is field replaceable, hot-swappable, and operates separately from the fan tray. The power
supply contains a front panel with mounting screws, a handle for insertion and removal, and two status
LEDs. No ON/OFF switch is provided.
The two DC PEM models supported on the router are:
•A900-PWR550-D—Uses a euro-style three-position terminal block connector, Figure1-2
•A900-PWR550-D-E—Uses a T-shaped connector, Figure1-3