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Cisco 12006 and Cisco 12406 Router Installation and Configuration Guide
OL-11497-03
Chapter 1 Product Overview
Multigigabit Crossbar Switch Fabric
• System clock—The system clock synchronizes data transfers between line
cards or between the RP and a line card, through the switch fabric. In systems
with redundant CSCs, the two system clocks are synchronized so that if one
system clock fails, the other clock takes over. The system clock signal is sent
to all line cards, the RP, and switch fabric cards.
• Scheduler—The scheduler handles requests from the line cards for access to
the switch fabric. When the scheduler receives a request from a line card for
switch fabric access, the scheduler determines when to allow the line card
access to the switch fabric.
• Switch fabric—The switch fabric carries the user traffic between line cards or
between the RP and the line cards. The switch fabric card contains only the
switch fabric circuitry and receives scheduling information and system clock
information from the CSC.
The SFC contains only the switch fabric circuitry, which carries user traffic
between line cards or between the RP and the line cards. The SFC receives
scheduling information and the system clock sent from the CSC.
Nonredundant and Redundant System Configurations
Cisco 12006 and Cisco 12406 routers are available in two system configurations:
1. Nonredundant configuration that includes one CSC and one power supply.
When you order a Cisco 12006 or Cisco 12406 Router, the nonredundant
configuration is shipped by default.
2. Redundant configuration that includes two CSCs and two power supplies.
For the redundant configuration, EMI compliance and cooling requirements are
met by having two CSCs and two power supplies installed in the system.
For the nonredundant configuration, EMI compliance and cooling requirements
are met only when blank fillers are installed in place of either (or both) the second
(unused) CSC slot or the second (unused) power supply bay.
Note When operating your router with a single CSC, the second CSC slot must have a
CSC blank filler (MAS-GSR6-CSCBLNK=) installed to ensure EMI compliance.