Cisco CRS 8-slot LCC contains the following components:

• As many as eight modular services cards (MSCs) or forwarding processor (FP) cards (both types are also called line cards), and eight physical layer interface modules (PLIMs). The MSC or FP and PLIM are an associated pair of cards that mate through the chassis mid-plane. The MSC or FP provides the forwarding engine for Layer 3 routing of user data, and the PLIM provides the physical interface and connectors for the user data.

Each MSC or FP can be associated with several different PLIMs, which provide different interface speeds and technologies. Some of the available PLIMs are:

Note	For a complete list of available PLIMs, consult your Cisco sales representative or visit http:/​/​www.cisco.com.

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 two RPs, but provide enhanced performance for both route processing and system controller functionality.

Note	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).

• 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. Each fan tray contains four fans.
• Four half-height switch fabric cards (SFCs). These cards provide the three-stage Benes switch fabric (S1/S2/S3) 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 (or FP) and PLIM pair and performs the switching necessary to route the data to the appropriate egress MSC (or FP) and PLIM pair. The switch fabric is divided into eight planes that 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. Two types of power systems are available: fixed configuration power and modular configuration power. Both power configurations use either AC or DC power. The fixed configuration power solution contains two power distribution units (PDUs), with either one AC rectifier or one DC power entry modules (PEM) per PDU. Each DC PEM and AC rectifier contains a removable air filter, located on the back of the module. The modular configuration power solution contains two power shelves with either up to four DC power modules (PMs) or up to three AC PMs per power shelf.

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.

This section identifies the location and slot numbers for major cards and modules (primarily the field-replaceable units) that plug into the chassis.

The following figure shows the slot numbers on the front (PLIM) side of the Cisco CRS 8-slot line card chassis.

Figure 6. Cisco CRS 8-Slot Line Card Chassis Slot Numbers—Front (PLIM) Side

As shown, the front (PLIM) side of the chassis has the following card slots:

• Eight PLIM slots (left to right: 0, 1, 2, 3...4, 5, 6, 7)
• Two route processor card slots (RP0 and RP1)

The following figure shows the slot numbers on the rear (MSC) of the chassis.

Figure 7. Cisco CRS 8-Slot Line Card Chassis Slot Numbers—Rear (MSC) Side

The rear (MSC) side of the chassis has the following card slots:

• Eight MSC slots (left to right: 7, 6, 5, 4...3, 2, 1, 0)
• Four half-height switch fabric card slots (SM0, SM1, SM2, and SM3)

The MSC slot numbers are reversed from the PLIM slot numbers on the other side of the chassis. Because an MSC mates with its associated PLIM through the midplane, MSC slot 0 is on the far right side of the chassis looking at it from the rear (MSC) side.

PLIM slot 0 is on the far left side of the chassis, looking at if from the front (PLIM) side. MSC slot 0 and PLIM slot 0 mate with each other through the midplane, and so do all other MSC and PLIM slots (0 through 7).