Chapter 2 M320 Hardware Components; M320 Component Redundancy - Juniper M320 Hardware Manual

CHAPTER 2
M320 Hardware Components

M320 Component Redundancy

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M320 Component Redundancy on page 5
M320 Chassis Description on page 6
M320 Midplane Description on page 9
M320 Flexible PIC Concentrator (FPC) Description on page 11
M320 FPCs Supported on page 14
M320 PIC Description on page 15
M320 Switch Interface Board (SIB) Overview on page 16
M320 Host Subsystem Overview on page 18
M320 Connector Interface Panel (CIP) Overview on page 25
M320 Craft Interface Overview on page 27
M320 Power System Overview on page 33
M320 Cooling System Description on page 37
M320 Cable Management System Description on page 38
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:
Switch Interface Boards (SIBs)—A fully configured router has four SIBs. Each FPC has
a dedicated ASIC with four high-speed links that connect to the SIBs (one link per SIB).
In the event of a complete SIB failure, the traffic is forwarded across the remaining
three planes with a slight degradation in performance. When the failed SIB is replaced,
the router regains full forwarding capacity.
Host subsystem—The host subsystem consists of a Routing Engine functioning together
with a CB. To operate, each host subsystem requires a Routing Engine installed in an
adjacent slot to 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 or is taken
offline, the backup can take over as the master.
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