T640 Cooling System Description
The cooling system components work together to keep all router components within the acceptable temperature range. Figure 1 shows the airflow through the router.
Figure 1: Airflow Through the Chassis
The host subsystem monitors the temperature of the router components. When the router is operating normally, the fans function at lower than full speed. If a fan fails or the ambient temperature rises above a threshold, the speed of the remaining fans is automatically adjusted to keep the temperature within the acceptable range. If the ambient maximum temperature specification is exceeded and the system cannot be adequately cooled, the Routing Engine shuts down some or all of the hardware components.
The cooling system consists of the following components:
- Two front fan trays—The front fan trays each contain six fans and are interchangeable. The front fan trays cool the components installed in the front card cage (the FPCs, PICs, CIP, and midplane).
- Front air filter.
- Rear fan tray—The rear fan tray contains eight fans or five blowers, and cools the components installed in the rear card cage (the Routing Engines, Control Boards, SCGs, and the SIBs). The rear fan tray is not interchangeable with the front trays.
- Rear air filter.
- Each power supply contains one fan that cools that power supply.
All fan trays and filters are hot-insertable and hot-removable.
