Product Overview 1-27
Overview of the Cisco 12008
The GRP communicates with the line cards either through the switch fabric or through a
maintenance bus (MBus). The switch fabric connection is the main data path for routing
table distribution as well as for packets that are sent between the line cards and the GRP.
The MBus connection allows the GRP to download a system bootstrap image, collect or
load diagnostic information, and perform general, internal system maintenance operations.
The GRP plugs into any slot in the upper card cage in the Cisco 12008 except the rightmost
slot, which is reserved for the alarm card.
The GRP contains the following components:
•IDT R5000 Reduced Instruction Set Computing (RISC) processor used for the CPU.
The CPU runs at an external bus clock speed of 100 MHz and an internal clock speed
of 200 MHz.
•Up to 256 megabytes (MB) of parity-protected, extended data output (EDO) dynamic
random-access memory (DRAM) on two, 60-nanosecond (ns), dual in-line memory
modules (DIMMs); 64 MB of DRAM is the minimum shipping configuration.
•512 kilobytes (KB) of static random-access memory (SRAM) for secondary CPU cache
memory functions (SRAM is not user configurable or field upgradeable).
•512 KB of NVRAM (NVRAM is not user configurable or field upgradeable).
•Most of the additional memory components used by the system, including onboard
Flash memory (8-MB) and up to two PCMCIA-based Flash memory cards. The default
GRP PCMCIA Flash memory is 20 megabytes (MB).
•Air-temperature sensors for environmental monitoring.
The Cisco IOS software images that run the Cisco 12008 reside in Flash memory, which is
located on the GRP in the form of a single in-line memory module (SIMM), and on up to
two Personal Computer Memory Card International Association (PCMCIA) cards (called
Flash memory cards) that insert in the two PCMCIA slots (slot 0 and slot 1) on the front of
the GRP. (See Figure1-9.) Storing the Cisco IOS images in Flash memory enables you to
download and boot from upgraded Cisco IOS images remotely or from software images
resident in GRP Flash memory.
Note EIA/TIA-232 was previously known as recommended standard RS-232 before its
acceptance as a standard by the Electronic Industries Association (EIA) and the
Telecommunications Industry Association (TIA).