Chapter 8. Introduction to EOS

The operating system for Arista switches is called the Extensible Operating System, or EOS for short. Arista describes EOS as “...the interface between the switch and the software that controls the switch and manages the network.” This is sort of like Apple’s macOS in that what you see is actually a kind of Unix (actually a derivative of FreeBSD in OS X) shell; Unix is doing all the heavy lifting behind the scenes. Arista switches run Unix (actually Fedora Core Linux) natively, but to make them easier for nonprogrammers to understand, EOS makes them look more like industry-standard networking devices.

The word extensible means “capable of being extended,” and EOS was designed from the ground up to allow third-party development of add-ons. This is a first in the networking world and is a big departure from traditional proprietary operating systems.

Arista is a big believer in open standards, and there are no proprietary protocols found in EOS that I am aware of. Even features such as Multi-Chassis Link Aggregation Group (MLAG) and Virtual Address Resolution Protocol (VARP), both Arista developments, use behaviors found in existing open-standard protocols, the details of which we cover later in Chapter 18 and Chapter 19.

Perhaps even more impressively, Arista allows the user to access the underlying Linux operating system (OS) and even to write Python and Bash scripts that can control the switch. This is a significant difference from other vendors ...

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