Cisco Gigabit Switch Router 12008 Installation And Configuration Manual page 82

Overview of the Cisco 12008
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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 in making 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 POS Line Card
The OC-12c/STM-4c POS line card provides the Cisco 12008 with a single 622-Mbps
Packet-Over-SONET (POS) interface. The card provides one OC-12c/STM-4cc 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 1-18 shows a high-level block diagram of the OC-12c/STM-4c POS line card;
Figure 1-19 shows a front view of the card.
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Cisco 12008 Gigabit Switch Router Installation and Configuration Guide