Cisco Systems Cisco 12008 manual Dram

Overview of the Cisco 12008

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
Total DRAM	Product Numbers	DRAM Sockets		Number of DIMMs
64 MB1	MEM-GRP/LC-64(=)	U39	(bank 1)	1 64-MB DIMM
128 MB	MEM-GRP/LC-64(=)	U39	(bank 1) and	2 64-MB DIMMs
		U42	(bank 2)
128 MB	MEM-GRP/LC-128(=)	U39	(bank 1)	1 128-MB DIMM
256 MB	MEM-GRP/LC-256(=)	U39	(bank 1) and	2 128-MB DIMMs
		U42	(bank 2)

1. 64 MB is the standard (default) DRAM configuration for the GRP.

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.

1-30Cisco 12008 Gigabit Switch Router Installation and Configuration Guide