Cisco IOS routers and switches perform functions that network professionals depend upon to make their networks operate as expected. Major functions performed or enabled by Cisco routers and switches include:
- Providing network security
- IP addressing of virtual and physical interfaces
- Enabling interface-specific configurations to optimize connectivity of the respective media
- Routing
- Enabling quality of service (QoS) technologies
- Supporting network management technologies
Each feature or service has an associated collection of configuration commands that allow a network technician to implement it.
The services provided by the Cisco IOS are generally accessed using a CLI.