Cisco Systems Cisco 12008 manual Switch Fabric Cards

Overview of the Cisco 12008

Switch Fabric Cards

The SFCs increase the switching capacity of the Cisco 12008. By adding three SFCs to a router equipped with a single CSC, you increase the bandwidth of each line card slot in the router from an OC-12 rate to an OC-48 rate.

By adding three SFCs to a router equipped with two CSCs, you not only increase the bandwidth of each line card slot to an OC-48 rate, but you also provide a fifth (redundant) switch plane so that the router’s OC-48 data rate can be maintained even if a switch plane should fail.

In a router with full switch plane redundancy (that is, a router with five available switch planes), five parallel 1.25 Gbaud serial data streams can be transmitted across the backplane to and from the router’s line cards. However, only four of the data streams are required for data transmission purposes; the fifth data stream carries error correction information. If an error occurs on one of the parallel data streams, data in error can be recovered through use of the four remaining correct data streams.

You need not install the optional SFCs in a router that uses line cards having an aggregate bandwidth rate of OC-12 or less. In such a system, a single CSC can provide sufficient bandwidth to accomplish all the router’s switching and routing functions. Thus, a minimally configured router does not require the optional switching capacity provided by the SFCs. To increase the switching capacity of the Cisco 12008 to the full OC-48 rate, however, you must install the three optional SFCs.

Each SFC is mounted on its own card carrier and incorporates an onboard power supply that takes the –48 VDC supplied by the backplane and converts it into the 3.3 VDC operating voltage required by the card.

1-70Cisco 12008 Gigabit Switch Router Installation and Configuration Guide