Overview of the Cisco 12008
•Fan tray
Control of fan power is initiated at system startup, with the fans running at a slow rate for normal operations. Such operation minimizes fan noise, wear, and power consumption. A
Periodically, the master MBus module on the GRP polls the MBus module on each circuit board to determine whether router components are cool enough to warrant keeping the fans running at their minimum rate. If they are not, the master MBus module directs the MBus module on the CSC to increase the operating voltage being delivered to the fan trays, causing the fans to run faster, thus increasing the volume of air being circulated through the router.
Each fan is monitored separately for failure. A failed fan is not “shut off” in the usual sense; rather, a
On failure of a fan in either the card cage fan tray or the power supply fan tray, the CSC increases the voltage being delivered to the surviving fans, causing them to run faster to compensate for the failed fan.
Cisco 12000 Series Line Cards
The Cisco 12008 comes equipped with the number and type of line cards that you ordered already installed. Up to seven Cisco 12000 series line cards can be installed in the router to support a variety of physical network media.
The line cards can be installed in upper card cage slots 0 through 3 and slots 4 through 7. Note, however, that it is recommended that the GRP be installed in slot 0. Line cards interface to each other and the GRP through the router’s switch fabric.
The following types of line cards are available for use with the Cisco 12008:
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Quad
