Cisco Systems 12006 series, 12406 series manual Sdram, 1-29, Sram, Nvram, Flash Memory

Chapter 1 Product Overview

Route Processors

SDRAM

SDRAM stores routing tables, protocols, and network accounting applications, and runs the Cisco IOS software. The default PRP configuration includes 512 MB of error checking and correction (ECC) SDRAM. DIMM upgrades of 512 MB and 1 GB are available. You cannot mix memory sizes. If two DIMMS are installed, they must be the same memory size.

Caution Cisco Systems strongly recommends that you use only Cisco-approved memory. To prevent memory problems, SDRAM DIMMs must be +3.3 VDC, PC133-compliant devices. Do not attempt to install other devices in the DIMM sockets.

SRAM

SRAM provides 2 MB of parity-protected, secondary CPU cache memory. It acts 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 2 MB of memory for system configuration files, software configuration register settings, and environmental monitoring logs. This information is backed up with built-in lithium batteries that retain the contents for a minimum of 5 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.

Flash memory also functions as a TFTP server to allow other servers to boot remotely from stored images or to copy them into their own Flash memory. The onboard Flash memory (called bootflash) contains the Cisco IOS boot image, and

	Cisco 12006 and Cisco 12406 Router Installation and Configuration Guide
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