Prior to Cisco IOS Software Release 15.0, Cisco IOS Software Packaging consisted of eight packages for Cisco routers, as shown in the figure. This packaging scheme was introduced with the Cisco IOS Software 12.3 mainline train and was later used in other trains. The image packaging consists of eight IOS images, three of which are considered premium packages.

The five non-premium packages are:

Note: Starting with the Cisco IOS Software 12.4 release family SSH is available in all images.

Three other premium packages offer additional IOS software feature combinations that address more complex network requirements. All features merge in the Advanced Enterprise Services package. This package integrates support for all routing protocols with Voice, Security, and VPN capabilities:

Note: The Cisco Feature Navigator is a tool used to find the right Cisco operating system depending on the features and technologies needed.