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PTX10003 Cooling System Description and Airflow

The PTX10003 is cooled front to back with five fan modules (PTX10003-160C) or three fan modules (PTX10003-80C). Located in the rear of the chassis, the 98.4-W fan modules operate at 164 cubic feet per minute (CFM) at full speed under zero static pressure. Each fan module is a redundant unit containing dual counter-rotating fans. The fan modules can be hot-swapped and hot-inserted, meaning that you can replace a fan module without powering off the router or disrupting the router function.

The fan modules pull air through the front panel around the gaps between the optical transceivers. Cooling for the power supplies is also front to back, utilizing fans inside the power supplies. A separate air plenum provides air circulation to the power supplies in the entrance at the top of the chassis. There are no air filters in the PTX10003. Fans are field replaceable. Access to the fans is from the Field Replaceable Units (FRU) end of the chassis. Each fan module is composed of two individual fans per tray (10 fans per PTX10003-160C chassis and six fans per PTX10003-80C chassis). The power requirements of the PTX10003 do not allow for redundant fan modules.

PTX10003 Fan Modules

The PTX10003 fan modules are hot-removable and hot-insertable FRUs designed for front-to-back airflow. For the PTX10003-160C, the fan modules are numbered 0 through 4. For the PTX10003-80C, the fan modules are numbered 1 through 3. Fan modules are installed in fan trays located below the power supplies. Each fan tray has a fan icon label on the handle.

Figure 1 shows a PTX10003 fan module.

Figure 1: PTX10003 Fan ModulePTX10003 Fan Module

You remove and replace a fan module from the FRU end of the chassis. The router continues to operate for a limited period of time during the replacement of the fan module without thermal shutdown. See PTX10003 Cooling System Shutdown.


All fan modules must be installed for optimal operation of the router.


If a fan module fails and the remaining fan modules are unable to keep the PTX10003 within the desired temperature thresholds, chassis alarms are raised and the PTX10003 might shut down.

PTX10003 Chassis Airflow

In data center deployments, position the router in such a manner that the AIR OUT labels on router components are next to the hot aisle. Figure 2 shows the airflow through the chassis.

Figure 2: Front-to-Back Airflow Through the PTX10003 ChassisFront-to-Back Airflow Through the PTX10003 Chassis

Fan Module Status and LED Description

You can check the status of fan modules by using the show system alarms or show chassis fan commands or by looking at the LEDs next to each fan module. For example:

Each router has a status LED (labeled ST) for each fan module on the left of the corresponding fan module slot. The LED indicates the fan module status.

Figure 3 shows the location of the LED next to the PTX10003-80C and PTX10003-160C fan modules.

Figure 3: PTX10003 Fan Module LEDsPTX10003 Fan Module LEDsPTX10003 Fan Module LEDs

Fan module LEDs


Table 1 describes the fan module LED states.

Table 1: PTX10003 Fan Module LED





On steadily

The fan module is operating normally. The system has verified that the module is engaged, and that the fan is operating correctly.



An error has been detected in the fan module. Replace the fan module as soon as possible. Either the fan has failed or it is seated incorrectly. To maintain proper airflow through the chassis, leave the fan module installed in the chassis until you are ready to replace it.

PTX10003 Temperature Sensor Behavior

Under normal operating conditions, the fan modules operate at a moderate speed. Temperature sensors in the chassis monitor the temperature within the chassis.

The system raises an alarm if a fan module fails or if the ambient temperature inside the chassis rises above the acceptable range. If the temperature inside the chassis rises above the threshold temperature, the router shuts down automatically.

PTX10003 Cooling System Shutdown

The PTX10003 cooling system will immediately shut down if:

  • A single fan tray is out of the chassis for more than 240 seconds. The cooling system will shut down regardless of the temperature of the chassis or chassis components.

  • More than one fan is out of the PTX10003 chassis. The cooling system will shut down regardless of the temperature of the chassis or chassis components.