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Cisco ASR 903 Router Hardware Installation Guide
OL-25178-04
Chapter 1 Cisco ASR 903 Router Overview
Cisco ASR 903 Router Features
• AC Power Specifications, page 1-5
Redundancy
The Cisco ASR 903 Router chassis includes a slot for an optional redundant power supply. The
redundant power supply option provides a second, identical power supply to ensure that power to the
chassis continues uninterrupted if one power supply fails or input power on one line fails. The
Cisco ASR 903 Router supports current sharing between the power supplies.
If you install a redundant power supply on the Cisco ASR 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 Cisco ASR 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 uses a three-position terminal block-style connector with labeled connections for
ground, -24/48 V, and +24/48 V. 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.
Table 1-2 summarizes the input power specifications for the Cisco ASR 903 Router DC power supply.
Table 1-2 DC Power Supply Specifications
Part number A900-PWR550-D
Input power specification +24/-48 VDC
Input voltage -48/-60 VDC
Minimum input voltage -19.2 VDC
Maximum input voltage -72 VDC