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Understanding the difference in IOS that are either .bin or .image

I'm using GNS3 to study for CCNA and I'm have a number of IOSs, which have the following extentions:  .md5, .bin and .image.

I know that .bin allows the CPU to "read" what the contents of the file is, but I'm still not really clear on what the difference is between .bin and .image is when it portains to IOS files.

Also are all of these IOS files uncompressed?  Do I have to worry about uncompressing them before trying to use them or will the router/swtich take care of that for me?


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Re: Understanding the difference in IOS that are either .bin or

Hi Chris,

The .bin file is the compressed version of the IOS and .image is the opposite.

If you've downloaded and install the latest GNS3 copy, the first time you'll put an IOS, it will prompt you to decompress the IOS file and use the image whenever you bootup you virtual device. Both .bin and .image are located on the same folder you've chosen.

You can alternatively decompress using third party software such as Winzip or Winrar. Good luck in your studies!

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Re: Understanding the difference in IOS that are either .bin or


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As John already noted, a .bin image is compressed and an .image is not.  Although a router in GNS will decompress a .bin image to run it (just as would a real device), the .image file saves the time it takes to decompress the image (i.e. the device boots much faster in GNS).

BTW, the reason for compressed IOS files is just to save flash space. The 2500s used decompressed IOS files which they executed directly out of flash.

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