M320 Router Cooling System
The M320 cooling system consists of the following components (see Figure 115):
- Two front fan trays—The front fan trays each contain four fans and are interchangeable. The front fan trays cool the components installed in the FPC card cage (the FPCs, PICs, Connector Interface Panel [CIP], and midplane).
- Rear fan tray—The rear fan tray contains seven fans and is not interchangeable with the front trays. The rear fan tray cools the components installed in the rear card cage (the Routing Engines, Control Boards, and the Switch Interface Boards [SIBs]).
- Front and rear air filter—Air filters for both the front and rear fan trays help keep dust and other particles from entering the cooling system.
- Power supply fans—Each power supply has two fans that cool that power supply.
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.
Figure 116 shows the M320 router airflow.
