Switch Fabric; Switch Fabric Overview - Cisco CRS-1 System Description

Switch Fabric

This chapter describes the Cisco CRS 8-Slot Line Card Chassis Enhanced router switch fabric.
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Switch Fabric
This chapter describes the Cisco CRS 8-Slot Line Card Chassis Enhanced router switch fabric. It includes the
following topics:

Switch Fabric Overview

The switch fabric is the core of the Cisco CRS routing system. The switch fabric is implemented through
switch fabric cards installed in the chassis. The switch fabric uses a cell-switched, buffered three-stage Benes
switch fabric architecture. The switch fabric receives user data from a modular services card (MSC) and
performs the switching necessary to route the data to the appropriate egress MSC.
The switch fabric is divided into eight planes (plane 0 to plane 7) that are used to evenly distribute traffic
across the switch fabric. Each switch fabric plane is independent and not synchronized with one another. Each
cell traverses the switch fabric using a single switch fabric plane. (Cells are not bit sliced across the switch
fabric.) And unlike the Cisco CRS 16-Slot Line Card Chassis Enhanced router the Cisco CRS 8-Slot Line
Card Chassis Enhanced router has only 4 physical switch fabric cards
There are four types of switch fabric cards used in the Cisco CRS 8-Slot Line Card Chassis Enhanced router:
CRS-8-FC/S, CRS-8-FC-140/S, CRS-8-FC-400/S and the CRS-8-FC-400/M fabric card. Each fabric card
implements all three stages of the switch fabric.
The following figure shows the basic path of IP data packets through the Cisco CRS routing system switch
fabric. Note that the figure shows a single-shelf system, in which all three stages of the switch fabric are
provided by switch fabric cards in the Cisco CRS 8-Slot Line Card Chassis Enhanced router. In a multishelf
system, Stage 2 of the switch fabric is provided by S2 fabric cards in the fabric card chassis.
Switch Fabric, on page 39
Cisco CRS Carrier Routing System 8-Slot Line Card Chassis Enhanced Router System Description
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