JUNOS Internet Software Network Operations Guide: Hardware
534 ! Understanding Redundant Cooling System Components
Figure 220 shows the M320 router cooling system components.
Figure 220: M320 Router Cooling System Components
The host subsystem monitors the temperature of the router components. When the
router is operating normally, the fans function at lower than full speed. If a fan fails
or the ambient temperature rises above a threshold, the speed of the remaining
fans is automatically adjusted to keep the temperature within the acceptable range.
If the ambient maximum temperature specification is exceeded and the system
cannot be adequately cooled, the Routing Engine shuts down some or all of the
hardware components.
T320 Router Redundant Cooling System Components
The T320 router cooling system includes:
! Two front fan trays
! Front air filter
! Rear fan tray
! Rear air filter
The cooling system components work together to keep all router components
within the acceptable temperature range (see Figure 221 on page 535). All fan trays
and filters are hot-insertable and hot-removable. The two front fan trays are
interchangeable. The front and rear fan trays are not interchangeable.
F
P
C
5
F
A
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O
K
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6
F
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7
F
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4
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3
F
A
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K
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C
2
F
A
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F
P
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1
F
A
I
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F
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C
0
F
A
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Fan tray
Air filter
Fan tray
Air intake
Craft interface
Front Rear
A
M
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E
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A
B
B
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V
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S
VCS
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ACTIVE
OK
FAI
L
S-SIB
ACTIVE
OK
FAIL
S-SIB
ACTIVE
OK
FAI
L
S-SIB
ACTIVE
OK
FAIL
S-SIB
Air exhaust
Air filter
Fan tray
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