Mx480 Component Redundancy - Juniper MX480 Hardware Manual

MX480 3D Universal Edge Router Hardware Guide
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MX480 Component Redundancy

4
Control plane—Gigabit Ethernet links between the combined SCBs/Routing Engines
and each DPC, FPC, or MPC. All board-to-board information is passed over Ethernet
except for low-level status and commands.
Management signals—Provide for low-level status diagnostic support.
MX480 Component Redundancy on page 4
MX480 Chassis Description on page 7
MX480 Host Subsystem Description on page 20
MX480 Craft Interface Description on page 28
MX480 Power System Description on page 32
MX480 Cooling System Description on page 38
MX480 Router Physical Specifications on page 265
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.
If the Routing Engines are configured for graceful switchover, the backup Routing Engine
automatically synchronizes its configuration and state with the master Routing Engine.
Any update to the master Routing Engine state is replicated on the backup Routing
Engine. If the backup Routing Engine assumes mastership, packet forwarding continues
through the router without interruption. For more information about graceful switchover,
see the
Junos OS System Basics Configuration Guide
Power supplies—In the low-line (110 V) AC power configuration, the router contains
three or four AC power supplies, located horizontally at the rear of the chassis in slots
through (left to right). Each AC power supply provides power to all
PEM0 PEM3
components in the router. When three power supplies are present, they share power
almost equally within a fully populated system. Four AC power supplies provide full
power redundancy. If one power supply fails or is removed, the remaining power supplies
instantly assume the entire electrical load without interruption. Three power supplies
provide the maximum configuration with full power for as long as the router is
operational.
In the high-line (220 V) AC power configuration, the router contains two or four AC
power supplies located horizontally at the rear of the chassis in slots
.
through
PEM0
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