Detection And Reporting Of Power Problems - Cisco ASR 9000 series Reference Manual

Chapter 3 High Availability and Redundant Operation

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 shelf. 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 will always have 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 will always have two fans operating to compensate for the air speed.
If only one fan tray is installed in the system, one single point of failure will not cause all fans to stop.
Caution
However, the system cannot operate without a fan tray. The system shuts itself off if all fan trays are
removed.
Cooling Failure Alarm
Temperature sensors are installed in all cards and fan trays. These sensors detect and report any fan
failure or high temperature condition, and raise an alarm. Fan failure can be a fan stopping, fan controller
failure, power failure, or a failure of a communication link to the RSP card.
Every card has temperature measurement points in the hottest expected area to clearly indicate a cooling
failure. The line cards have two sensors, one at the inlet and one near the hottest devices on the card. The
RSP card also has two sensors.
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D R A F T — C I S C O C O N F I D E N T I A L
Cisco ASR 9000 Aggregation Services Router Overview and Reference Guide
Cooling System Redundancy
3-5