It's good practice to back up your iOS images, especially as your network grows.
You're going to want to have a central place to back up and store your iOS images and configuration
files.
So it's good practice to back up your iOS files to a central TFTP server or FTP server.
This is useful,
for example, if an iOS image gets accidentally deleted or erased or becomes corrupted, you're going
to want to be able to restore your iOS from a TFTP server.
So good practice to copy from the Flash to a TFTP server and have that available.
If you need to restore an image or perhaps when you upgrade a router, you encounter issues and may
need to downgrade back to an older version of operating system.
So good practice to have your iOS images backed up to a central location.
Now, what about iOS images that have these cryptic names that may be difficult initially to understand?
So when looking at an iOS image, the first part such as C2900 is the platform.
This is an image for a 2900 Cisco router.
The universal canine option means that this image is universal, so it's a single image set that includes
the IP base, security, unified communications, and data feature sets.
Each router is activated for an IP based feature set.
However, for other feature sets, you'll need to activate those features by loading a license onto
the router and we'll discuss that in a separate video.
So in this example, the platform is a Cisco 2900 series integrated services router.
The third part, M Zed or M Z, indicates where the image runs and if the file is compressed. In this example,
In this example, the image is run in RAM.
So M indicates runs in RAM and Z or Zed indicates a compressed image.
Digitally signed Cisco iOS images identified by a three-character extension in the image name. S stands
for digitally signed software POS stands for production or special development image.
So P in the name indicates that it's a production image that is approved for general release.
A
S indicates a special image that is development software and should only be used in special circumstances.
The A indicates the key version that is used to digitally sign the image.
A key version is identified by an alphanumeric character such as A, B or C, the fifth part 152-
4.M1 indicates the software version number and the final part bin is the file extension.
This indicates that the file is a binary executable file.
Just be aware that the Cisco iOS naming conventions do change.
The best place to look for information is on the Cisco website.
For example, on the Cisco software downloads, Help and FAQ page.
You'll find a lot of information.
For example, the Cisco iOS software release naming convention is explained.
So in this example, we have a major release of 12.1 the maintenance release enterprise designator
a sixth build of the release and first rebuild release date.
Have a look at documents such as the following for instructions on how to download software and how
to discover more information about the different options available with regards to the Cisco iOS.