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M320 Router Redundant Cooling System Components
The M320 router includes the following cooling system components:
- Two front fan trays
- Front air filter
- Rear fan tray
- Rear air filter
The cooling system components work together to keep all router components within the acceptable temperature range. All fan trays and filters are hot-insertable and hot-removable. The two front fan trays are interchangeable. The front and rear fan trays are not interchangeable.
Figure 1 shows the M320 router cooling system airflow.
Figure 1: M320 Router Cooling System and Airflow

Figure 2 shows the M320 router cooling system components.
Figure 2: M320 Router Cooling System Components

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.