Reloading and Upgrading
A system restart on Cisco routers is called a reload. If the router needs to be reloaded for any reason, the reload command needs to be entered from privileged mode, as shown in Example 4-4. The reload command also allows a time to be set so that the system restarts after the specified time expires.
Example 4-4 System Reload Options
IOS# reload ? LINE Reason for reload at Reload at a specific time/date cancel Cancel pending reload in Reload after a time interval <cr>
The system can also be reloaded by switching it off and then back on again.
The configuration register is used to specify the router's behavior during the reloading process. It determines whether the IOS image should be loaded, determines whether terminal access parameters are provided, and enables or disables the Esc key. The configuration register can be modified in configuration mode using the config-register command.
Use the config-register command only if you completely understand its effects. Incorrect use of this command can make the system inaccessible.
By default, the router first tries to boot from the first image in the onboard system Flash, if available, and then it tries the PCMCIA Flash cards. The user may also specify which images or locations to attempt booting from and the order using the boot system command in configuration mode:
IOS(config)# boot system slot0
This causes the system to attempt booting from an image in the Flash memory in PCMCIA slot 0 before going to the onboard system Flash.
To upgrade the Cisco IOS software version running on a router, you must first determine the right image to upgrade to using the upgrade planners available on http://www.cisco.com.
Attempting to load an incorrect image for your system might leave the system inaccessible. Ensure that you have the correct software image and meet the RAM and Flash memory requirements to run and store the image before installing.
The copy command copies an image into Flash memory. There are many ways to do this, as demonstrated in Example 4-5.
Example 4-5 Options for Copying an IOS Image into Flash Memory
IOS# copy ? /erase Erase destination file system. flash: Copy from flash: file system ftp: Copy from ftp: file system null: Copy from null: file system nvram: Copy from nvram: file system pram: Copy from pram: file system rcp: Copy from rcp: file system running-config Copy from current system configuration slot0: Copy from slot0: file system slot1: Copy from slot1: file system startup-config Copy from startup configuration system: Copy from system: file system tftp: Copy from tftp: file system xmodem: Copy from xmodem: file system ymodem: Copy from ymodem: file system
The most common methods are TFTP and FTP. After the file has been placed on your TFTP or FTP server, enter the copy command from privileged mode and answer the questions on server IP address and source and destination filenames. After you specify which image the system should load using the boot system command, a reload is required for the new version of IOS to be booted.