Cisco Systems Cisco 12008 manual Switch Fabric in the Cisco

Overview of the Cisco 12008

As a multi-function board, the CSC provides the following system services:

•Provides one plane of switch fabric for the router (see the section below entitled “Switch Fabric in the Cisco 12008”).

•Serves as a switch fabric controller card for the router (see the section below entitled “Switch Fabric Controller Functions of the CSC”).

•Serves as an alarm monitoring facility for the router (see the section below entitled “Housekeeping and Alarm Monitoring Functions of the CSC”).

•Provides onboard power for its own electronic circuitry, as well as power and control functions for the fan trays (see the section below entitled “Board Power and Fan Tray Power Functions of the CSC”).

These functions are described in the following sections.

Switch Fabric in the Cisco 12008

A switch plane in the router consists of one OC-12-rate crossbar in the backplane that enables each line card slot in the router to be connected logically to every other line card slot. Line cards installed in any combination of slots in the upper card cage can communicate with each other by means of the router’s switch fabric.

The switch fabric of the router constitutes the totality of the possible data paths that can be established through the router. The magnitude of the router’s switch fabric (and, hence, its data- carrying capacity) is related directly to the number of switch planes that are made available to the router for data-handling purposes. By installing a second CSC and/or the optional set of three SFCs in the router, you can increase the number of switch planes present in the router, thereby increasing the magnitude of the router’s overall switch fabric.

Table 1-7 outlines the possible configurations of CSCs and SFCs and the router switching capacity that results from these configurations.

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