Understanding the Cooling System ! 263
Chapter 19: Monitoring the Cooling System
Figure 116 shows the M320 router airflow.
Figure 116: M320 Router Cooling System and Airflow
T320 Router and T640 Routing Node Cooling Systems
The T320 cooling system consists of the following components:
! Two front fan trays—The front fan trays each contain six fans and are
interchangeable. The fan trays in the front of the chassis, each with six fans,
cool the components installed in the FPC card cage (the FPCs, PICs, CIP, and
midplane).
! Rear fan tray—The rear fan tray contains five fans and is not interchangeable
with the front trays. It cools the components installed in the rear card cage (the
Routing Engines, Control Boards, PCGs, and 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—The power supplies each have a fan that cools that power
supply.
During normal operation, the fans in each fan tray function at less than full
capacity. Temperature sensors on the midplane and the host subsystem control the
speed of the fans. A fan failure triggers the red alarm LED on the craft interface. If
the temperature passes a certain threshold, the JUNOS software turns off the power
supplies.
Air intake cover
Front view
Air flow (front boards)
Card cage
g003459
Rear
Rear view
Air intake and filter
Left
Right
Air exhaust
Air flow (back boards)
Front
Fan tray
Fan tray
Air filter
Card cage
Side view
Air flow (front boards)
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