Cisco Carrier Routing System CRS-1 Installation Manual page 16

Chassis Components
A chassis midplane that connects line cards to their associated PLIMs. The midplane design allows
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a line card to be removed from the chassis without having to disconnect the cables that are attached
to the associated PLIM. The midplane distributes power, connects the line cards to the switch fabric
cards, and provides control plane interconnections. The midplane is not field replaceable by the
customer.
One or two route processor cards (RPs). The RPs function as the Cisco CRS 4-slot line card chassis
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system controller and provide route processing.
Only one RP is required for system operation. For redundant operation, you can order a second RP
as an option (CRS-4-RP/R). When two RPs are used, only one RP is active at a time. The second
RP acts as a "standby" RP, serving as a backup if the active RP fails.
The RP also monitors system alarms and controls the system fans. LEDS on the front panel indicate
active alarm conditions.
A Performance Route Processor (PRP) is also available for the Cisco CRS 8-slot line card chassis.
Two PRPs perform the same functions as RPs, but provide enhanced performance for both route
processing and system controller functionality.
Note
Fan tray. The fans pull cool air through the chassis. A removable air filter is located below the PLIM
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card cage at the front of the chassis. The fan tray has four fans that provide n+1 redundancy.
Four switch fabric cards (SFCs). These cards provide the three-stage Benes switch fabric for the
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routing system. The switch fabric performs the cross-connect function of the routing system,
connecting every line card (and its associated PLIM) with every other line card (and its associated
PLIM) in the system.
The switch fabric receives user data from one line card and PLIM pair and performs the switching
necessary to route the data to the appropriate egress line card and PLIM pair. The switch fabric is
divided into eight logical planes (four physical planes) that are used to evenly distribute the traffic
across the switch fabric. Each switch fabric card implements two planes of the switch fabric.
A power system that provides redundant power to the chassis. The power system consists of an AC
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power shelf, which contains four AC rectifier modules, or a DC power shelf, which encloses four
DC power supplies. The power shelf (AC or DC as ordered) is pre-installed in the chassis when you
receive the routing system.
The PLIM side of the chassis is considered the front of the chassis, where user data cables attach to the
PLIMs and cool air enters the chassis. The switch fabric card side, which is where warm air is exhausted,
is considered to be the rear of the chassis.
Cisco CRS Carrier Routing System 4-Slot Line Card Chassis Installation Guide
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A chassis may not be populated with a mix of RP and PRP cards. Both route processor cards
should be of the same type (RP or PRP).
Chapter 1 Overview
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