User guide

Internetworking Primer A-3
Cisco Internetwork Operating System
The show version command displays the capacity of each kind of memory.
Proper operation of the access server requires the following memory configuration:
• The correct system image (Cisco IOS) is loaded and running in Flash memory. See the
following section “Cisco IOS Operating Environments.”
• The proper configuration file is loaded into RAM. See the section “Configuration Files”
later in this appendix.
Cisco IOS Operating Environments
The access server has three distinct operating environments (see Table A-2).
Table A-2 Cisco IOS Operating Environments
The startup process of the access server normally loads and executes each of the operating
environments in turn.
RAM Stores the operating configuration (for example,
running-config), routing tables, caches, queues, packets, and
so forth
Shared packet memory Stores incoming and outgoing packets
Operating
Environment Prompt
Configuration
Register Usage
ROM monitor > 0x0 Failure or password recovery
Boot ROM Router(boot)> 0x1 Flash image upgrade
Cisco IOS Router> 0x2102 Normal operation
Memory Purpose