Cisco IOS (Cisco Internetwork Operating System)

Contributor(s): Jessica Scarpati

Cisco IOS (Internetwork Operating System) is a proprietary operating system that runs on most Cisco Systems routers and switches.

The core function of Cisco IOS is to enable data communications between network nodes. In addition to routing and switching, Cisco IOS offers dozens of additional services that an administrator can use to improve the performance and security of network traffic. Such services include encryption, authentication, firewall capabilities, policy enforcement, deep packet inspection, Quality of Service, intelligent routing and proxy capability. In Cisco's Integrated Services Routers (ISRs), IOS can also support call processing and unified communications services. 

There are three variants of the operating system: IOS XE, IOS XR and Nexus OS. IOS XE runs on enterprise-grade Cisco ISRs, Aggregation Services Routers and Catalyst switches. IOS XR runs on Cisco's service provider products, such as its Carrier Routing System routers. Nexus OS runs on Cisco's Nexus family of data center switches.

This was last updated in December 2013

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I've been in IT Desktop Support for a few years. I've now gotten the opportunity to apply for a LAN Supervisor position in a large, multi-building Facility.

I'm a beginner when it comes to Cisco IOS switch configuration Commands. I'm trying to find a listing of Basic IOS commands, and their meaning. Can you provide a beginners list of some of the common commands for ex. in a Cisco catalyst 3560 PoE 48 Port switch? Thank you, LAN wanna-be



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