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Cisco CRS-1 Carrier Routing System 8-Slot Line Card Chassis Installation Guide
OL-6256-08
Chapter 1 Overview
Chassis Slot Numbers
• A chassis midplane that connects MSCs to their associated PLIMs. The midplane design allows an
MSC 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 MSCs 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 provide the intelligence of the system by
functioning as the Cisco CRS-1 8-slot line card chassis system controller (serving as part of the
control plane in multi-chassis systems) and providing route processing. Only one RP is required for
system operation. For redundant operation, you can order a second RP as an option (CRS-8-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.
• Upper and lower fan trays. The fans pull cool air through the chassis. A removable air filter is located
below the PLIM card cage at the front of the chassis.
• Four half-height switch fabric cards. These cards provide the three-stage Benes switch fabric for the
routing system. The switch fabric performs the cross-connect function of the routing system,
connecting every MSC (and its associated PLIM) with every other MSC (and its associated PLIM)
in the system.
The switch fabric receives user data from one MSC and PLIM pair and performs the switching
necessary to route the data to the appropriate egress MSC and PLIM pair. The switch fabric is
divided into eight 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 two
AC
or DC power distribution units (PDUs) and two AC rectifier modules or two DC power entry
modules (PEMs), one per PDU. Each PDU supplies input power to a rectifier or PEM, which in turn
provides processed power to the chassis. Each DC and AC power module contains a removable air
filter, located on the front of the module.
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 MSC side, which is where warm air is exhausted, is
considered the rear of the chassis.
Chassis Slot Numbers
This section identifies the location and slot numbers for major cards and modules (primarily the
field-replaceable units) that plug into the chassis.
Figure 1-3 shows the slot numbering on the front (PLIM) side of the Cisco CRS-1 8-slot line card
chassis.