As far back as the 1980s network engineers have relied on command-line interface (CLI) to configure, manage and fix anything from local area networks (LAN) to wide area carrier networks.

By dominating the networking space, Cisco Systems Inc. has provided the de facto industry standard for CLI which was adopted by network engineers issuing commands to gears such as routers and switches.

Command-line interface is a way to interact with software by typing lines of commands just as computer users did when during the disk operating system (DOS) era.

Now software-defined networking (SDN) offers a new alternative.

SDN and the recent trend to network automation employ a layer of software to control networks in a more abstract way.

SDN separates the control plane of the network from the forward plane which is comprised of equipment that pushes the packets. With SDN, engineers now interact with applications rather than ports.

Joe Skorupa, analyst for Gartner research believes SDN has the potential to replace CLI. This he said “scares the living daylights” out of a majority of Cisco Certified Internetwork Experts (CCIE).

He said Gartner is seeing some groups of CCIE’s “doing everything they can” to block SDN deployment in their companies.

Despite the benefits that SDN provide, some industry watchers don’t see SDN as a threat to CLI.

SDN does not go deep enough to analyze and fix all the flaws in a network, according to Alan Mimms, senior architect for F5 Networks.

He compares SDN to driving a car and CLI to inspecting and working under the hood of the vehicle. Mimms said a network engineer still needs to use CLI to diagnose and solve network problems.

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  1. The CLI will always be required for troubleshooting, and if for some reason the SDN controllers are down, you still need a way in and be able to push or reverse changes.

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