1. Sources of Cisco IOS Honolulu Community College Cisco Academy Training Center Semester 2 Version 2.1

2. Overview n 1. Cisco IOS software can be loaded from: u Flash u TFTP server u ROM (not full Cisco IOS) n 2. Configuration Register: u In NVRAM. u Used to set where the router boots from. n 3. TFTP Server u Used to store backup copies of the IOS, and the configuration files.

3. Locating Cisco IOS Software n Default source for Cisco IOS: u depends on specific hardware platform. u most commonly is NVRAM. n Configuration Register (16bits) - in NVRAM. u Indicates from where to boot a default system image. u Set with boot system commands. n Fallback u Use default Cisco IOS in Flash. u Next is TFTP (network server).

5. Configuration Register Values n Determine the order in which the router looks for system bootstrap information. n Config-register command specifies a hex value.

6. Show Version command n Displays information about the IOS version that is currently running on the router. n Information includes: u Boot field setting u Cisco IOS version & description u System image name u Type of platform u Configuration register values

8. Bootstrap Options n Flash Memory u Flash memory is not vulnerable to network failure, as may occur when downloading from a server. n Network Server (TFTP) u Gives backup such flash memory become corrupted. n ROM u Generally final option if both Flash and network server fails. u Not a full IOS

9. Show Flash command n Used to verify that you have sufficient memory on your system for the Cisco IOS.

11. Summary n Cisco IOS sources: u Flash u Network server (TFTP) u ROM (limited image) n Configuration register can be used to select where router boots from. u Config-register command n Show Version Command u boot filed setting u IOS version & description u system image name, platform

12. Summary (2) n Show Flash command u to check amount of flash memory n Backup and Download of IOS u copy flash tftp - backup copy to tftp server. u copy tftp flash - download IOS from tftp server.