Chassis Components And Descriptions; Mx240 Component Redundancy - Juniper MX240 Hardware Manual

CHAPTER 3

Chassis Components and Descriptions

MX240 Component Redundancy

Copyright © 2017, Juniper Networks, Inc.
MX240 Component Redundancy on page 7
MX240 Chassis Description on page 8
MX240 Router Hardware and CLI Terminology Mapping on page 10
MX240 Craft Interface Overview on page 12
MX240 Alarm Relay Contacts on the Craft Interface on page 13
MX240 Alarm LEDs and Alarm Cutoff/Lamp Test Button on page 13
MX240 Component LEDs on the Craft Interface on page 14
The MX240 chassis provides redundancy and resiliency. The hardware system is fully
redundant, including power supplies, Routing Engines, and SCBs.
A fully configured router is designed so that no single point of failure can cause the entire
system to fail. Only a fully configured router provides complete redundancy. All other
configurations provide partial redundancy. The following major hardware components
are redundant:
Host subsystem-The host subsystem consists of a Routing Engine functioning together
with an SCB. The router can have one or two host subsystems. If two host subsystems
are installed, one functions as the master and the other functions as the backup. If the
master host subsystem (or either of its components) fails, the backup can take over
as the master. To operate, each host subsystem requires a Routing Engine installed
directly into in an SCB.
In the high-line (220 V) AC power configuration, the MX240 router contains one or two
AC power supplies, located horizontally at the rear of the chassis in slots
(left to right). The high-line configuration requires one power supply, with the
PEM2
second power supply providing redundancy. Each AC power supply provides power to
all components in the router. When two power supplies are present, they share power
almost equally within a fully populated system. If one power supply fails or is removed,
the remaining power supply assumes the entire electrical load without interruption.
One power supply can provide the maximum configuration with full power for as long
as the router is operational.
and
PEM0
7