M320 Component Redundancy - Juniper M320 Hardware Manual

M320 Multiservice Edge Router Hardware Guide
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M320 Component Redundancy

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M320 Chassis Description on page 7
M320 Router Physical Specifications on page 86
M320 Environmental Specifications on page 93
M320 Power Requirements on page 96
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.
For information about the effect of taking the host subsystem offline, see
M320 Host Subsystem Offline" on page
features, see the Junos OS High Availability Library for Routing Devices.
Power supplies—A router with a minimum of three AC power supplies or four DC power
supplies is fully power redundant. In the AC configuration, all power supplies share the
load evenly. In the DC configuration, two power supplies share the load to some of the
components, and two other power supplies share the load to the remaining
components. In both configurations, if one power supply fails, the remaining power
supplies can provide full power to the router.
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.
M320 SIB Description on page 79
M320 Host Subsystem Description on page 23
M320 Cooling System Description on page 21
M320 Power System Description on page 73
213. For more information about high availability
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