Managing Cisco IOS Software

From Mycomputer Notes

A Cisco router cannot operate without the Cisco IOS. Each Cisco router has a predetermined bootup sequence for locating and laoding the IOS. The startup routines main purpose is to startup the router operations in a relaible manner. To accomplish this the router must:

• Test the router's hardware.
• Find and load the Cisco IOS Software.
• Find and apply configuration statements such as protocol functions and interface addresses.

Locating and loading the IOS

Cisco IOS software image from:

• Flash memory - A system image can be loaded from flash memory. Information stored in flash memory is not vulnerable to network failures that can occur when system images are loaded from TFTP servers.
• Network server - If flash memory is corrupted, a system image can be loaded from a TFTP server.
• ROM - The final bootstrap option is to boot from ROM. However, a system image in ROM is usually a subset of the Cisco IOS that lacks the protocols, features, and configurations of the full Cisco IOS. Also, if the software has been updated, a router may have an older version stored in ROM