6.Working with Software Images

The system can store up to two software images in flash. The image selected for bootup is termed the Active image, while the other is termed the Alternate image.

It is possible to swap the Active and the Alternative image, and it is possible to upgrade to a new Active image. A swap simply switches the Active and Alternate designation on each image and reboots the system.

A firmware upgrade performs these steps:

  • Download new firmware using TFTP/HTTP/HTTPS/FTP and verify suitability for the system

  • Overwrite the current Alternate image with the newly downloaded image

  • Swap Active and Alternate and reboot

The result is that the old Active build becomes the Alternate, and the newly downloaded image Active. The relevant commands are:

show version

firmware swap

firmware upgrade protocol tftp://server[:port]/path_to_file

show version lists various details about the system, including the images in flash.

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