T4000 Cooling System Description; Airflow; Figure 10: Airflow Through The Chassis - Juniper T4000 Hardware Manual

T4000 Cooling System Description

Airflow

Copyright © 2013, Juniper Networks, Inc.
The cooling system components work together to keep all router components within the
acceptable temperature range. The host subsystem monitors the temperature of the
router components. When the router is operating normally, the fans function at normal
speed. If a fan fails or the ambient temperature rises above a threshold, the speed of the
remaining fans is set to full speed. 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.
In additions to the fans, the front fan trays are equipped with a fan tray controller (FTC)
board. The FTC board is a transition board that distributes the fan-related signals between
the Routing Engine and the fans, and controls the speed as required.
Airflow on page 21
Fan Trays on page 22
Air Filters on page 22
Power Supply Cooling System on page 22
Figure 10 on page 21 shows the airflow through the router.

Figure 10: Airflow Through the Chassis

Chapter 3: T4000 Hardware Components Overview
21