Cisco Gigabit Switch Router 12008 Installation And Configuration Manual page 87

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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-4c ATM 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
Packet
Input
receive
interface
(Rx)
Forwarding
processor
Packet
Output
transmit
interface
(Tx)
Block Diagram of the OC-12c/STM-4c ATM Line Card
Burst
Reassembly
buffer
L3 switching
accelerator
Burst
Segmen-
buffer
tation
Overview of the Cisco 12008
MBus
module
Buffer
memory
Silicon
queuing
engine
Switch
fabric
interface
Silicon
queuing
engine
Buffer
memory
MBus
interface
Switch
fabric
Product Overview 1-65