M40E System Redundancy - Juniper M40E Hardware Manual

M40e Multiservice Edge Router Hardware Guide

M40e System Redundancy

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The M40e Multiservice Edge Router is designed so that no single point of failure can
cause the entire system to fail. The following hardware components contribute to system
redundancy:
Cooling system—When the temperature inside the router is below the acceptable
maximum, the cooling system's components function at less than full speed. If the
temperature becomes excessive—for example, because a cooling system component
is removed—the MCS automatically increases the speed of the remaining components
to reduce the temperature. The cooling system can function at the higher speed
indefinitely. For more information, see "M40e Cooling System Description" on page 48.
FPC—Each FPC has two I/O Manager ASICs, one that interacts with the active SFM
and the other in standby mode. If two SFMs are installed and the active one stops
functioning, the standby I/O Manager ASIC automatically becomes active when the
standby SFM boots and becomes the active SFM. For more information, see "M40e
Flexible PIC Concentrators (FPCs) Description" on page 13.
Host module (Routing Engine and MCS functioning together)—The router can have
one or two host modules. If two host modules are installed, one (the master) is active
and the other is in standby mode. If the master host module (or either of its
components) is removed from the chassis, the standby host module becomes active.
The Routing Engine and MCS must reside in adjacent slots and be fully operational for
the host module to function. For more information, see "M40e Host Module Description"
on page 23.
PCG—The router has two PCGs. Both PCGs send their clock signals to the other Packet
Forwarding Engine components, along with a signal that indicates which clock is the
master. If one PCG fails, the other PCG becomes the master system clock. For more
information, see "M40e Packet Forwarding Engine Clock Generators (PCGs) Description"
on page 18.
Power supply—The router has two load-sharing, fully redundant power supplies to
distribute either AC or DC power to the other components. If one power supply fails,
the second power supply can provide full power to the router's components indefinitely.
For more information, see "M40e Power System Description" on page 42.
SFM—The router can have one or two SFMs. If two SFMs are installed, one is active
and the other is in standby mode. If the active SFM fails or is removed from the chassis,
the standby SFM automatically boots and becomes the active SFM. For more
information, see "M40e Switching and Forwarding Module (SFM) Description" on
page 20.
In the base configuration, the router has one host module and SFM, and multiple PCGs,
power supplies, and cooling system components.
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