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Cisco 12404 Internet Router Installation and Configuration Guide
OL-11636-01
Chapter 1 Product Overview
Route Processors
SDRAM
The SDRAM on the PRP stores routing tables, protocols, and network accounting
applications. It also runs the Cisco IOS software. The default PRP SDRAM
configuration is 512 megabytes (MB) of SDRAM, which you can increase up to
1 GB maximum, through DIMM upgrades. You cannot mix memory sizes. If two
DIMMs are installed, they must be the same memory size.
Caution
We recommends that you use only Cisco approved memory. To prevent memory
problems, SDRAM DIMMs must be +3.3VDC, PC133-compliant devices. Do not
attempt to install other devices in the DIMM sockets.
DIMM
The Dual In-line Memory Module (DIMM) with 168 pins is a small circuit board
that holds memory chips and doubles the number of circuit paths to and from a
module by using independent pins on each side of the edge connector. You can
install DIMM memory modules one at a time.
SRAM
The principle function of SRAM is to act as a staging area for routing table update
information to and from the line cards. SRAM also provides secondary CPU
cache memory. The standard PRP configuration is 2 MB. SRAM cannot be
upgraded or configured.
NVRAM
Non-Volatile Random Access Memory (NVRAM) cannot be upgraded or
configured. The system configuration, software configuration register settings,
and environmental monitoring logs are contained in the 2 MB NVRAM, which is
backed up with built-in lithium batteries that retain the contents for a minimum of
five years.
Caution
Before you replace the RP in the system, back up the running configuration to a
Trivial File Transfer Protocol (TFTP) file server or an installed Flash memory
card so you can retrieve it later.
todd.book Page 15 Tuesday, November 27, 2007 6:02 PM
