Cisco XR 12404 - Manual (Page 37)

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Cisco XR 12404 Router Installation Guide
OL-13830-02
Chapter 1 Cisco XR 12404 Router Overview
Power Entry Modules
Switch Fabric Functionality
Switch fabric circuitry provides up to 40 Gbps (full duplex) of synchronized speed
interconnections that carries user traffic between line cards or between the route
processor and the line cards.
Clock and Scheduler Functionality
The fabric card generates and distributes system-wide clock and cell time
synchronization signaling. System clock generation is delivered to the system
through the backplane and local clock functions are derived from the system
clock.
• System Clock—The system clock synchronizes data transfers between line
cards or between the route processor and a line card through the CSF. The
system clock signal is sent to all line cards and the route processor.
• Scheduler—The scheduler handles requests from the line cards for access to
the CSF. When the scheduler receives a request from a line card for CSF
access, the scheduler determines when to allow the line card access to the
CSF.
Power Entry Modules
The Cisco XR 12404 router chassis supports two hot swappable AC or DC PEMs.
The router must be populated with 2 PEMs to meet EMI standards.
Caution Do not mix PEM types in the router. PEMs must be the same type; either both
AC PEMs, or both DC PEMs and PDUs.
todd.book Page 23 Monday, March 16, 2009 2:47 PM