M120 Dc Power Supply Leds; M120 Cooling System Description - Juniper Networks Hardware Manual

M120 Multiservice Edge Router Hardware Guide

M120 DC Power Supply LEDs

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M120 Cooling System Description

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The LED on each power supply faceplate indicates the status of the power supply (see
Table 14 on page 30, which applies to the AC and DC power supply). The power supply
status is also reflected in two LEDs on the craft interface (see Table 13 on page 28). In
addition, a power supply failure triggers the red alarm LED on the craft interface.
M120 DC Power Supply Description on page 31
M120 Router Power Requirements on page 237
Connecting Power to a DC-Powered M120 Router on page 91
Maintaining the M120 Power Supplies on page 115
Replacing an M120 DC Power Supply on page 177
M120 DC Power, Connection, and Cable Specifications on page 234
The cooling system consists of the following components:
Two front fan trays
Two rear fan trays
Front air filter
The cooling system components work together to keep all router components within the
acceptable temperature range (see Figure 16 on page 33, Figure 17 on page 33, and Figure
18 on page 33). The router cooling system comprises two front and two rear fan trays
(see Figure 1 on page 7 and Figure 2 on page 7). Both the front and rear fan trays install
horizontally above and below the front and rear card cages. Each fan tray contains eight
fans. The two front fan trays are interchangeable, the two rear fan trays are
interchangeable, but the front and rear fan trays are not interchangeable. The fan trays
are hot-insertable and hot-removable. The front fan trays cool the components installed
in the front card cage (the FPCs, CFPCs, PICs, and craft interface). The rear fan trays cool
the components installed in the rear card cage (the Routing Engines, CBs, power supplies,
and FEBs). Figure 16 on page 33 shows the airflow through the router.
An air filter in the front in the chassis located beneath the lower fan tray helps keep dust
and other particles from entering the cooling system. To function properly, the entire
cooling system requires an unobstructed airflow and proper clearance around the site,
as described in "M120 Clearance Requirements for Airflow and Hardware Maintenance"
on page 41.
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