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Chapter 1 Product Overview
Route Processors
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Cisco 12006 and Cisco 12406 Router Installation and Configuration Guide
OL-11497-03
Caution To prevent memory problems, DRAM DIMMs must be 3.3-volt (V),
60-nanosecond (ns) devices. Do not install other devices in the DIMM sockets.
Cisco recommends that you use the Cisco-approved memory options listed in
Table 1-2.
SRAM
SRAM provides secondary CPU cache memory. The standard GRP configuration
is 512 KB. Its principal function is to act as a staging area for routing table
updates and for information sent to and received from line cards. SRAM is not
user configurable and cannot be upgraded in the field.
NVRAM
NVRAM provides 512 KB of memory for system configuration files, software
register settings, and environmental monitoring logs. This information is backed
up with built-in lithium batteries that retain the contents for a minimum of five
years. NVRAM is not user configurable and cannot be upgraded in the field.
Flash Memory
Flash memory allows you to remotely load and store multiple Cisco IOS software
and microcode images. You can download a new image over the network or from
a local server and then add the new image to Flash memory or replace the existing
files. You then can boot the routers either manually or automatically from any of
the stored images.
Table 1-2 GRP DRAM Configurations
Total DRAM Product Numbers DRAM Sockets Number of DIMMs
128 MB
1
1. 128 MB is the standard (default) DRAM configuration for the GRP.
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