Mx2020 Component Redundancy - Juniper MX2020 Hardware Manual

MX2020 3D Universal Edge Router Hardware Guide
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MX2020 Component Redundancy

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and one lower signal and power backplane located at the bottom of the chassis. The
Switch Fabric Boards (SFBs) connect both upper and lower backplanes. The adapter
cards (ADCs) are carrier cards used to house the MPCs. The MPCs install into the top
and bottom card cage backplanes from the front of the chassis and mate to the signal
backplanes. The SFBs and CB-REs install into the middle from the front of the chassis.
The PSMs and PDMs install into the top and bottom power backplanes from the rear of
the chassis. The cooling system components also connect to the top and bottom
backplanes.
The backplane performs the following major functions:
Data path—Data packets are transferred across the backplane between the MPCs
through the fabric ASICs on the SFBs.
Power distribution—The router PDMs relay power from the feeds to the input of the
PSMs through the power midplane. In addition, the output power from PSMs is
distributed to the components of the chassis (MPCs, SFBs, and CB-REs), using the
power backplane.
Control/Management path—The backplane provides management and control path
connectivity among the various system components.
MX2020 Router Overview on page 3
MX2020 Chassis Description on page 5
MX2020 Modular Port Concentrator Description on page 68
MX2020 Switch Fabric Board Description on page 64
MX2020 Host Subsystem Description on page 57
MX2020 Modular Interface Card Description on page 73
MX2020 Power Subsystem Description on page 83
MX2020 Power Midplane Description on page 85
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 combined Control Board and
Routing Engine (CB-RE) functioning together. 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.
DC power subsystem—The MX2020 DC power system is made up of two subsystems.
Each subsystem provides power to ten line card slots, one local fan tray and critical
FRUs. These critical FRUs consist of two CB-REs, eight SFBs located in the center of
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