Chapter 2. What Makes Junos So Special?

Back when Juniper Networks set out to create the world’s best routers, it needed to design a new hardware platform to handle extremely fast router speeds. The hardware architecture included line cards that contained a series of application-specific integrated circuits (ASICs), processors, and interfaces, with each card designed to act as a client within the chassis. The main component that could control these line cards, the route engine, was also created, and it is the hardware component that runs Junos.

Although this may not seem like such a big deal, it is; it was a huge advancement in the state of router technology in the 1990s and it still is today. This design creates the clear physical separation of the control and data planes; separating these two elements allows the components to operate at their full capacity without interrupting each other. The data plane can pass traffic at 100% of capacity while leaving the route engine (RE) to calculate routes and manage the device. It’s at the heart of enabling extremely fast router speeds.

Just as the forwarding and control planes were once intertwined, so, too, was the control and data plane software. All processes operated in kernel space and very little prioritization was done. With Junos, the network operating system game changed. Having a separate RE allowed for the running of a more robust underlying operating system, and Junos, unlike previous network operating systems, enabled the restarting ...

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