M120 Router Chassis Description - Juniper M120 Hardware Manual

M120 Multiservice Edge Router Hardware Guide
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M120 Router Chassis Description

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CAUTION: Mixing AC and DC power supplies is not supported. The first
power supply powered on will electrically disable the second power supply
without damaging any components in the system.
Cooling system—The cooling system has redundant components, which are controlled
by the host subsystem. If one of the fans fails, the host subsystem increases the speed
of the remaining fans to provide sufficient cooling for the router indefinitely.
M120 Router Chassis Description on page 6
M120 Host Subsystem Description on page 18
M120 AC Power Supply Description on page 29
M120 DC Power Supply Description on page 31
M120 Cooling System Description on page 32
The router chassis is a rigid sheet metal structure that houses all the other router
components (see Figure 1 on page 7, Figure 2 on page 7, and Figure 3 on page 8). The
chassis measures 20.75 in. (52.71 cm) high, 17.43 in. (44.3 cm) wide, and 24.3 in. (61.7 cm)
deep (from the front-mounting flanges to the rear of the chassis). The chassis installs
in standard 800-mm (or larger) enclosed cabinets, 19-in. equipment racks, or telco
open-frame racks. Up to four routers can be installed in one standard (48-U) rack if the
rack can handle their combined weight, which can be greater than 900 lb (408.4 kg).
The chassis includes three electrostatic discharge points (banana plug receptacle). Two
are located in the front of the chassis and one in the rear of the chassis.
CAUTION: Before removing or installing components of a router, attach an
ESD strap to an ESD point and place the other end of the strap around your
bare wrist. Failure to use an ESD strap can result in damage to the router.
WARNING: The router must be connected to earth ground during normal
operation.
Copyright © 2010, Juniper Networks, Inc.