Figure 167: M320 Router Cooling System And Airflow - Juniper M Series Monitoring And Troubleshooting Manual

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Figure 167: M320 Router Cooling System and Airflow

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

Figure 168 on page 330

shows the M320 router airflow.

Chapter 11: Monitoring the Cooling System