Chapter 2 M120 Hardware Components; M120 Component Redundancy - Juniper Networks Hardware Manual

CHAPTER 2
M120 Hardware Components

M120 Component Redundancy

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M120 Component Redundancy on page 5
M120 Router Chassis Description on page 6
M120 Midplane Description on page 8
M120 Flexible PIC Concentrators (FPCs) Overview on page 9
M120 Compact FPCs (CFPCs) Overview on page 12
M120 FPCs and CFPCs Supported on page 14
M120 PICs Description on page 15
M120 Forwarding Engine Boards (FEBs) Overview on page 16
M120 Host Subsystem Description on page 18
M120 Routing Engine Overview on page 18
M120 Control Board (CB) Overview on page 21
M120 Craft Interface Overview on page 23
M120 Power Supplies Overview on page 28
M120 Cooling System Description on page 32
M120 Cable Management System Description on page 34
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 requires a Routing Engine to be installed directly
into the CB. 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.
Power supplies-A router with two AC power supplies or two DC power supplies is fully
power redundant. In both AC and DC configurations, the power supplies share the load
almost evenly.
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