User guide

A-2 Cisco 2500 Series Access Server User Guide
Cisco Internetwork Operating System
Note To order UniverCD, Cisco’s technical documentation in CD-ROM format, or paper
documentation, refer to “Ordering Cisco Documents,” DOC-OCD, which is in your
warranty pack.
Cisco Internetwork Operating System
This primer will help you become familiar with using Cisco Internetwork Operating
System (Cisco IOS) software, including the following features:
• Internal memory components
• Cisco IOS operating environments
• Command modes
• Configuration files
Refer to the chapters “Understanding the User Interface,” “Loading System Images and
Configuration Files,” “Configuring Terminal Lines and Modem Support,” and “Managing
the System” in the publication Access and Communication Servers Configuration Guide.
Internal Memory Components
The Cisco 2500 series access server has several kinds of memory—read-only memory
(ROM), Flash memory, nonvolatile random access memory (NVRAM), random access
memory (RAM), and shared-packet memory. System software images, configuration files,
and transient data structures such as routing tables and packets are stored in memory.
Table A-1 lists the different kinds of memory and indicates what they are used for.
Table A-1 Internal Memory Components
Memory Purpose
ROM Stores the ROM Monitor, and boot ROM
Flash memory Stores the system image (Cisco IOS)
NVRAM Stores the configuration file (startup-config)