1. NVRAM (check config-register)
2. FLASH (load IOS)
3. TFTP (boot IOS from tftp if FLASH fails)
4. ROM (If TFTP fails, load "mini" IOS from ROM
Booting up the router and locating the Cisco IOS
1. POST (power on self test)
2. Bootstrap code executed 3. Check Configuration Register value (NVRAM) which can be modified using
the config-register command
0 = ROM Monitor mode
1 = ROM IOS
2 - 15 = startup-config in NVRAM
4. Startup-config file: Check for boot system commands (NVRAM)
If boot system commands in startup-config
a. Run boot system commands in order they appear in startup-config to locate
the IOS
b. [If boot system commands fail, use default fallback sequence to locate the
IOS (Flash, TFTP, ROM)?]
If no boot system commands in startup-config use the default fallback
sequence in locating the IOS:
a. Flash (sequential)
b. TFTP server (netboot)
c. ROM (partial IOS) or keep retrying TFTP depending upon router model
5. If IOS is loaded, but there is no startup-config file, the router
will use the default fallback sequence for locating the IOS and then it will
enter setup mode or the setup dialogue. 6. If no IOS can be loaded, the router will get the partial IOS version
from ROM
Default (normal) Boot Sequence
Power on Router - Router does POST - Bootstrap starts IOS load - Check
configuration register
to see what mode the router should boot up in (usually 0x2102 to read
startup-config in NVRAM / or 0x2142 to start in "setup-mode") -
check the startup-config file in NVRAM for boot-system commands - load IOS
from Flash.
Boot System Commands
Router(config)# boot system flash IOS filename - boot from FLASH memory
Router(config)# boot system tftp IOS filename tftp server ip address - boot
from a TFTP server
Router(config)# boot system rom - boot from system ROM
This post has been edited by spacyfreak: Apr 2 2006,
03:46 PM
Booting
up the Router
Cisco routers can boot Cisco IOS software from
1. Flash memory
2. TFTP server
3. ROM (not full Cisco IOS)
Normally its booted from Flash RAM. But if it fails, it trys to load IOS from
tftp server.
If this also fails, it boots a "small" ios which is in ROM.
Default
boot sequence for Cisco IOS software:
1. NVRAM (check config-register)
2. FLASH (load IOS)
3. TFTP (boot IOS from tftp if FLASH fails)
4. ROM (If TFTP fails, load "mini" IOS from ROM
Booting up the router and locating the Cisco IOS
1. POST (power on self test)
2. Bootstrap code executed 3. Check Configuration Register value (NVRAM) which can be modified using
the config-register command
0 = ROM Monitor mode
1 = ROM IOS
2 - 15 = startup-config in NVRAM
4. Startup-config file: Check for boot system commands (NVRAM)
If boot system commands in startup-config
a. Run boot system commands in order they appear in startup-config to locate
the IOS
b. [If boot system commands fail, use default fallback sequence to locate the
IOS (Flash, TFTP, ROM)?]
If no boot system commands in startup-config use the default fallback
sequence in locating the IOS:
a. Flash (sequential)
b. TFTP server (netboot)
c. ROM (partial IOS) or keep retrying TFTP depending upon router model 5. If IOS is loaded, but there is no startup-config file, the router
will use the default fallback sequence for locating the IOS and then it will
enter setup mode or the setup dialogue. 6. If no IOS can be loaded, the router will get the partial IOS version
from ROM
Default (normal) Boot Sequence
Power on Router - Router does POST - Bootstrap starts IOS load - Check
configuration register
to see what mode the router should boot up in (usually 0x2102 to read
startup-config in NVRAM / or 0x2142 to start in "setup-mode") -
check the startup-config file in NVRAM for boot-system commands - load IOS
from Flash.
Boot System Commands
Router(config)# boot system flash IOS filename - boot from FLASH memory
Router(config)# boot system tftp IOS filename tftp server ip address - boot
from a TFTP server
Router(config)# boot system rom - boot from system ROM
این وبلاگ به دور از هر گونه حاشیه تنها به مباحث فناوری اطلاعات و ارتباطات می پردازد. برخی مطالب به عنوان نکات قابل توجه از سایتهای دیگر در این وبلاگ درج میشود که حتما از نویسنده اصلی با ذکر منبع تقدیر و تشکر خواهد شد.
این وبلاگ به دور از هر گونه حاشیه تنها به مباحث فناوری اطلاعات و ارتباطات می پردازد. برخی مطالب به عنوان نکات قابل توجه از سایتهای دیگر در این وبلاگ درج میشود که حتما از نویسنده اصلی با ذکر منبع تقدیر و تشکر خواهد شد.