All commands are assigned a privilege level, from 0 to 15, and can only be accessed by users with the necessary privilege. 'Global configuration mode' provides commands to change the system's configuration, and 'interface configuration mode' provides commands to change the configuration of a specific interface. The set available is determined by the 'mode' and the privilege level of the current user. The IOS command-line interface (CLI) provides a fixed set of multiple-word commands. For the Nexus switches Cisco developed NX-OS, which is similar to IOS, except that it is Linux-based. Cisco eventually introduced the native mode for chassis, so that they only run one operating system. In early modular chassis network switches from Cisco, modules with layer 3 routing functionalities were separate devices that ran IOS, while the layer 2 switch modules ran CatOS.

The Cisco Catalyst series would for some time run the CatOS. The company acquired a number of young companies that focused on network switches, such as the inventor of the first Ethernet switch Kalpana, and as a result Cisco switches did not run the IOS. When IOS was developed, Cisco Systems' main product line were routers. Through modular extensions IOS has been adapted to increasing hardware capabilities and new networking protocols. The IOS network operating system was developed in the 1980s for routers that had only 256 kB memory and low CPU processing power. Notable exceptions include ASA security products, which run a Linux-derived operating system, carrier routers which run IOS-XR and Cisco's Nexus switch and FC switch products which run Cisco NX-OS. Although the IOS code base includes a cooperative multitasking kernel, most IOS features have been ported to other kernels such as QNX and Linux for use in Cisco products. IOS is a package of routing, switching, internetworking and telecommunications functions integrated into a multitasking operating system. ( February 2015) ( Learn how and when to remove this template message)ġ5.9(3)M / August 15, 2019 2 years ago ( )Ĭisco Internetwork Operating System ( IOS) is a family of network operating systems used on many Cisco Systems routers and current Cisco network switches.

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