T320 Component Redundancy - Juniper Core Router T Series Hardware Manual

T320 Core Router Hardware Guide
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T320 Component Redundancy

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T320 Chassis Description on page 13
T320 Physical Specifications on page 92
T320 Environmental Specifications on page 93
T320 Power Requirements on page 96
The T320 Core Router is designed so that no single point of failure can cause the entire
system to fail. The following major hardware components are redundant:
Switch Interface Boards (SIBs)—The router has three SIBs. Each Type 1 FPC and Type
2 FPC has a dedicated ASIC with five high-speed links that connect to the SIBs (one
link per SIB). A Type 3 FPC has two dedicated ASICs, and each ASIC has five high-speed
links that connect to the SIBs (a total of 10 links). One of the three SIBs—usually
—acts as a backup to the remaining two SIBs. In the event of a SIB failure, the
SIB0
backup SIB becomes active and traffic forwarding continues without any degradation.
When the failed SIB is replaced, it becomes the new backup.
Host subsystem—The host subsystem consists of a Routing Engine functioning together
with a control board. 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 in an adjacent slot to a control board.
SONET Clock Generators (SCGs)—The router has a standard configuration of one
SCG, but a second can be purchased to function as backup. If one SCG fails, the other
becomes the master SCG. Mastership of the SCGs is independent of the host subsystem,
so routing functions are not affected.
Power supplies—The router has two power supplies, which share the load evenly. If
one power supply fails, the other power supply can provide full power to the router
indefinitely.
Cooling system—The cooling system has redundant components, which are controlled
by the host subsystem. If one of the fans fails, the host subsystem increases the speed
of the remaining fans to provide sufficient cooling for the router indefinitely.
T320 Router Description on page 3
T320 Switch Interface Boards (SIBs) Description on page 85
T320 Host Subsystem Description on page 29
T320 SONET Clock Generator (SCG) Description on page 19
T320 Power System Description on page 83
T320 Cooling System Description on page 25
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