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Overview of the Cisco 12008
Cisco 12008 Gigabit Switch Router Installation and Configuration Guide
1-30
DRAM
The extended data output (EDO) dynamic random-access memory (DRAM) on the GRP
stores routing tables, protocols, and network accounting applications, and runs the
Cisco IOS software. The standard (default) GRP DRAM configuration is 64 megabytes
(MB) of EDO DRAM, which you can increase up to 256 MB through DRAM upgrades.
The Cisco IOS software runs from within GRP DRAM.
Two DRAM DIMM sockets are incorporated into the GRP, as shown in Figure 1-10. These
sockets, labeled U39 (P4 DRAM bank 1) and U42 (P4 DRAM bank 2), enable you to
configure DRAM in increments ranging from 64 MB to 256 MB. Table 1-3 lists the
available upgrade configurations for DRAM on the GRP.
Table 1-3 DRAM Configurations
Caution
To prevent memory problems, DRAM DIMMs must be 3.3 V, 60-nanosecond
(ns) devices. Do not attempt to install memory devices in the DIMM sockets that do not
meet these requirements.
SRAM
SRAM provides secondary CPU cache memory. The standard GRP configuration is
512 KB. Its principle function is to act as a staging area for routing tables update
information to and from the line cards. SRAM is not user configurable or field-upgradeable.
Total DRAM Product Numbers DRAM Sockets Number of DIMMs
64 MB
1
1. 64 MB is the standard (default) DRAM configuration for the GRP.
MEM-GRP/LC-64(=) U39 (bank 1) 1 64-MB DIMM
128 MB MEM-GRP/LC-64(=) U39 (bank 1) and
U42 (bank 2)
2 64-MB DIMMs
128 MB MEM-GRP/LC-128(=) U39 (bank 1) 1 128-MB DIMM
256 MB MEM-GRP/LC-256(=) U39 (bank 1) and
U42 (bank 2)
2 128-MB DIMMs