An operating system software that runs on Cisco routers and switches comprising the majority of the Internet. IOS was first developed by William Yeager at Stanford University’s Knowledge Systems Laboratory. Yeager licensed the code to Cisco in 1987. IOS brought together a comprehensive collection of routing, switching, internetworking, and telecommunications functionality running on top of a full fledged multitasking operating system. Triple Fiber Networks. [Online, 2006.] 3Fn Website. http://www.3fn.net/ cisco.php.