Table of Contents
Advertisement
Overview of the Cisco 12008
•
Fan tray power—The Cisco 12008 router contains two fan trays (see Figure 1-2).
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 DC-DC converter on the CSC provides +20 VDC for slow fan
operation and +25 VDC for fast fan operation when an overtemperature condition is
sensed in the router.
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 current-limiting feature in the faulty fan prevents it from interfering with
the operation of other fans.
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:
•
Quad OC-3c/STM-1c POS—4 ports
•
OC-12c/STM-4c POS—1 port
•
OC-12c/STM-4c ATM—1 port
1-54
Cisco 12008 Gigabit Switch Router Installation and Configuration Guide
Advertisement
Table of Contents
Troubleshooting
