The battle between JUNOS and IOS

Despite marketing claims, are Juniper and Cisco's operating systems really that different?

  • Monolithic vs. modular: Monolithic OSes -- like IOS -- tightly couple processes like file systems, procedure calls and device drivers, to the OS kernel; a modular system, like JUNOS, decouples them.

  • JUNOS vs. IOS: Cisco's 20+ year leadership position in routing has been challenged by Juniper over the past 10 years. Juniper has swiped about a quarter of Cisco's share of the service provider router market and is also coming after Cisco in the enterprise. Juniper credits its JUNOS operating system strategy for much of its success while criticizing Cisco's IOS software direction as fragmented. Here's a comparison of both OSes.

  • The Incumbent: Cisco's IOS is a monolithic operating system that's been in networks for over 20 years.

  • The Challenger: JUNOS is a modular operating system that provides a single code base across most of Juniper's platforms.

  • The IOS command hierarchy: A schematic diagram of some common IOS commands.

  • The JUNOS CLI: The JUNOS command line interface is intended to be friendly and easy to use for engineers steeped in years of IOS.

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