Cisco IOS (originally Internetwork Operating System) is a family of software used on most Cisco Systems routers and current Cisco network switches. (Earlier switches ran CatOS.) IOS is a package of routing, switching, internetworking and telecommunications functions integrated into a multitasking operating system. Cisco IOS: 1- Allows enterprises to build resilient, cost-effective standards-based infrastructures end to end 2- Delivers thousands of features network-wide to meet the unique needs of evolving enterprises 3- Supports the increasing demand for service orchestration, application awareness, and simplicity