Cisco IOS software features

Cisco IOS software features
2.1.4 This page will introduce some IOS images that are provided by Cisco for devices that span a wide range of network product platforms.


Cisco continues to develop different IOS software images to optimize the Cisco IOS software that these various platforms require. Each image represents a different feature set that serves the various device platforms, available memory resources, and customer needs.

Although there are numerous IOS images for different Cisco device models and feature sets, the basic configuration command structure is the same. The configuration and troubleshooting skills that are acquired for any device will apply to a wide range of products.

The naming convention for the different Cisco IOS releases contains three parts:

• The platform on which the image runs
• The special features supported in the image
• Where the image runs and whether it has been zipped or compressed

One of the main considerations when selecting a new IOS image is compatibility with the router flash and RAM memory. In general, the newer the release and the more features that it provides, the more flash and RAM memory it requires. Use the show version command on the Cisco device to check the current image and available flash.

The Cisco support site has tools available to help determine the amount of flash and RAM required for each image. For example, specific IOS features can be selected using the Cisco Software Advisor, which is available to registered Cisco.com users. The Cisco Software Advisor is an interactive tool that provides the most current information and allows users to select options that meet network requirements.

Before installing a new Cisco IOS software image on the router, check to see if the router meets the RAM memory and flash requirements for that image. To see the amount of RAM, issue the show version command:

…

…

cisco 2620 (MPC860) processor (revision 0x102) with 59392K/6144K bytes of memory

This line shows how much main and shared memory is installed in the router. Some platforms use a fraction of DRAM as shared memory. The memory requirements take this into account, so both numbers have to be added together to find the amount of DRAM installed on the router.

To find out the amount of flash memory, issue the show flash command:

Router>show flash

…

…

[12655376 bytes used, 4121840 available, 16777216 total] 16384K bytes of processor board System flash (Read/Write)

The next page will discuss the three operating environments that are available for Cisco IOS devices.