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Cisco ASR 9000 Series Aggregation Services Router Overview and Reference Guide
OL-17501-09
Chapter 3 High Availability and Redundant Operation
Cooling System Redundancy
Figure 3-12 DC System Power Redundancy for the Cisco ASR 9912 Router—Version 2
Note The Cisco ASR 9000 Series Routers are capable of operating with one power module. However, such a
configuration does not provide any redundancy.
Redundant –48 VDC power feeds are separately routed to each power tray. For maximum diversity, the
power entry point to each tray is spatially separated to the left and right edges of the tray. Each feed can
support the power consumed by the entire tray. There is load sharing between the feeds. Each power
module in the tray uses either feed for power, enabling maintenance or replacement of a power feed
without causing interruption.

Detection and Reporting of Power Problems

All –48 VDC feed and return lines have fuses and are monitored. Any fuse blown can be detected and
reported. The input voltages are monitored against an over and under voltage alarm threshold. The
controller area network (CAN) monitors the power output voltage levels.
Cooling System Redundancy
The Cisco ASR 9000 Series Routers are configured in such a way that a fan failure or its subsequent
replacement does not cause a significant outage. During either a fan replacement or a fan failure, the
airflow is maintained and no outage occurs. Also, the fan trays are hot swappable so that no outage
occurs during replacement.
The Cisco ASR 9010 Router has two fan trays at the bottom of the card tray. Each fan tray has 12 fans
arranged in three groups of four fans each. Two fans of each group share a fan controller. The power
supplied to the fan controller is 1:3 protected. A single fan failure has no impact on air flow because the
other 11 fans will compensate for it. If the fan controller fails, there is a possibility of up to two fans
failing; however, the design always has two fans operating in a row (three rows of fans) to compensate
for the air speed.
The Cisco ASR 9006 Router has two fan trays at the top left of the chassis. Each fan tray has six fans
arranged in three groups of two fans each. The two fans in a group share a fan controller. The power
supplied to the fan controller is 1:3 protected. A single fan failure has no impact on air flow because the
other five fans will compensate for it. If the fan controller fails, there is a possibility of up to two fans
failing; however, the design always has two fans operating to compensate for the air speed.
350775
2100WDC 2100WDC 2100WDC 2100WDC 2100WDC 2100WDC 2100WDC 2100WDC
2100WDC 2100WDC 2100WDC 2100WDC
2100WDC 2100WDC 2100WDC 2100WDC
6,300W DC system
3+1 min power redundancy
23,100W DC system
11+1 max power redundancy