Juniper Networks G10 CMTS manual Cooling and Fans, Docsis Module

DOCSIS Module

Cooling and Fans	•
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The G10 CMTS has three fan trays. The trays install into the air intake chambers in the bottom	•
of the chassis. Two trays install from the front and one tray installs from the rear. The front	•
trays contain six large fans each and the rear tray contains six smaller fans. The total	•
maximum power consumption of the three fan trays is 165 watts.	•
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Each tray has one LED. If a single fan fails, the LED illuminates red and a warning event is	•
generated (if enabled). If multiple fans fail, a critical event is generated (if enabled). See the	•
JUNOSg Software Configuration Guide: Interfaces, Cable, Policy, and Routing and Routing	•
Protocols for more information on event configuration.	•
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The Chassis Control Module monitors the internal temperature of the chassis in multiple	•
locations. If the temperature is maintained between a lower and an upper threshold, the fans	•
continue to rotate at a nominal speed. If the temperature exceeds the upper threshold, the	•
speed of the fans and the value of the upper threshold are incrementally increased. Likewise,	•
if the temperature drops below the lower threshold, the speed of the fans and the value of the	•
lower threshold are incrementally decreased. This process continues until the temperature	•
and fan speed settle between the latest thresholds.	•
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These temperature thresholds cannot be changed by a user. However, you can set	•
user-defined temperature thresholds by including the temperature-thresholdstatement at the	•
[edit chassis] hierarchy level (see the JUNOSg Software Configuration Guide: Getting Started	•
and System Management for more information).	•
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The chassis directs the air flow upward through the card cage, then past the power supplies	•
and power transition modules. There is a 97-mm high air intake chamber with front and side	•
openings at the bottom of the chassis. Air exits through a 71-mm high chamber at the top of	•
the chassis through a rear opening and through the power transition modules in the rear.	•
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The presence of the various modules is part of the air flow design. In a chassis that is not fully	•
populated, you must install air management modules, air management panels, and power	•
supply filler panels in all unused module slots to maintain proper air flow. You must also	•
install the power supply faceplate to ensure proper air flow.	•
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The G10 CMTS must be installed in an open rack to ensure adequate air flow.	•
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DOCSIS Module	•
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The DOCSIS Module contains the circuits, devices (including the Broadband Cable Processor	•
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ASIC), and code that provide the core functionality and features of the G10 CMTS.
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The DOCSIS Module connects with the HFC Connector Modules or SIMs in the rear of the	•
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chassis through the midplane. This keeps the cabling in back of the chassis. See “HFC
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Connector Module” on page 50 and “Switched I/O Module” on page 53 for more discussion.
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Figure 12 on page 30 shows the DOCSIS Module front panel.	•
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Hardware Component Overview 29