Cisco Systems Cisco 12008 manual OC-12c/STM-4cATM Line Card

Overview of the Cisco 12008

Input interface

Output interface

•Cisco Express Forwarding (CEF) memory table—Each line card maintains CEF tables. These tables, derived from routing tables maintained by the GRP, are used by the line card processor to make forwarding decisions.

Large networks may require more DRAM to support large CEF tables. For information on adding memory to a line card, see the document entitled Cisco 12000 Series Gigabit Switch Router Memory Replacement Instructions.

OC-12c/STM-4cATM Line Card

The OC-12c/STM-4c ATM line card provides the Cisco 12008 with a 622-Mbps ATM interface. The card interfaces to the router’s switch fabric, supports from 10 to 40 Gbps, and provides one OC-12c/STM-4c SC duplex single-mode or multimode SONET/SDH connection. This connection is concatenated, which provides for increased efficiency by eliminating the need to partition the bandwidth.

Figure 1-20 shows a high-level block diagram of the OC-12c/STM-4c ATM line card; Figure 1-21 shows a front view of the card.

Figure 1-20 Block Diagram of the OC-12c/STM-4c ATM Line Card

					MBus	MBus
Packet				Buffer	module	interface
			Burst
	Reassembly			memory
receive
			buffer
(Rx)
				Silicon
				queuing
				engine	Switch
Forwarding		L3 switching				Switch
					fabric
processor		accelerator		Silicon	interface	fabric
				queuing
				engine		H7695
Packet	Segmen-		Burst
transmit				Buffer
	tation		buffer
(Tx)
				memory

Product Overview 1-65