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The Cisco IOS Software Binary Image Naming Convention

Cisco has a Cisco IOS image naming convention for identifying the platform or board for which the binary software is built, the package feature content of the image, and the area of memory used by the image at run time. As shown in the figure, the image name follows a three-part format, where:

PPPPP = Platform
FFFF = Features
MM = Run-time memory and compression format

Figure: Cisco IOS Image Naming Convention

Cisco IOS Image Naming Convention

Platform Identifiers:
PPPPP indicates the platform. For this image is a Cisco 7200 Series Router.

Cisco IOS images that run on boards are named according to a scheme that identifies the board and the platform that supports the board. The names have three parts, separated by dashes (PPPPP-FFFF-MM). Example: dsc-as5800-mz.

Feature Content of Cisco IOS Images:
FFFF identifies the feature content of the image (also referred to as the Cisco IOS feature set). Example: c7200-ajs56-mz.

Here "a" stands for Advanced Peer-to-Peer Networking (APPN) features, "j" is for enterprise features (desktop plus all routing protocols), "s" is for the plus features such as NAT, Inter-Switch Link (ISL), L2F, and VPDN, and "56" stands for 56-bit encryption.

Cisco IOS Run-Time Memory Space:
MM in the figure is composed of two letters. The first letter identifies the memory area where the Cisco IOS image is executed at run time. The second letter indicates the method used to compress the Cisco IOS binary image.

Cisco IOS Execution Area:
F Image runs in Flash
m Image runs in RAM
R Image runs in ROM
L Image will be relocated at run time




Cisco IOS Image Compression Identifiers:
Z Image is Zip compressed
x Image is Mzip compressed
w Image is "Stac" compressed



As far as users are concerned, they only need to get the image into the router Flash or ROM. At run time, the image automatically unzips itself and relocates to the area of memory from where it is intended to run.