Managing Cisco IOS Software
From Mycomputer Notes
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==Locating and loading the IOS == | ==Locating and loading the IOS == | ||
| + | The default source for Cisco IOS Software starup depends on the hardware platform. Most routers use the boot system commands saved in NVRAM. Cisco IOS software allows several alternatives to be used. Other sources can be specified for the software, or the router can use its own fallback sequence to load the software | ||
| - | + | Router own's fallback sequence: | |
*'''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. | *'''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. | *'''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 | *'''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 | ||
Revision as of 21:50, 8 May 2006
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
The default source for Cisco IOS Software starup depends on the hardware platform. Most routers use the boot system commands saved in NVRAM. Cisco IOS software allows several alternatives to be used. Other sources can be specified for the software, or the router can use its own fallback sequence to load the software
Router own's fallback sequence:
- 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
