Cisco Systems Cisco 12008 manual Switch Fabric Controller Functions of the CSC

Overview of the Cisco 12008

Table 1-7	Switch Planes Provided by Switch Cards
		Number
		of Switch
Switch Card Type Availability		Planes	Description
One CSC	Standard	1	A single CSC supports an OC-12 data rate
			for the router, but provides no redundancy
			in the router’s switch fabric.
Second CSC	Optional	1	A second CSC supports an OC-12 data
			rate for the router and also provides a
			redundant plane of switch fabric. If one of
			the CSCs fails, a fault recovery cutover to
			the surviving CSC occurs, not only to
			maintain the router’s OC-12 data rate, but
			also to preserve the system services
			peculiar to the CSC.
Three SFCs	Optional	3	The optional set of three SFCs enables the
			router to support an OC-48 data rate. In an
			OC-48 rate1 system, no redundancy exists

in the switch fabric. However, if a switch plane failure occurs in a fully-redundant2system, a CSC can take over the functions of either a failed CSC or a failed SFC, not only to maintain the router’s OC-48 data rate, but also to preserve the essential CSC system services.

1.Router equipped with one CSC and three SFCs.

2.Router equipped with two CSCs and three SFCs.

Switch Fabric Controller Functions of the CSC

In addition to providing one plane of switch fabric for the router, the CSC provides numerous other functions and services essential to router operations. Figure 1-13 illustrates the primary functional elements of the CSC.

1-46Cisco 12008 Gigabit Switch Router Installation and Configuration Guide