ACCE - Reading

Week One: Reading (pages 22 - 43)

Due: Aug 28, 2020 by 12:59am

Points: 40

This assignment is open until Aug 28, 2020 at 12:59am

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Traditional OS Software Architecture


•Most Arista Competitors began building networking products 2-3 decades ago.

•Most of their operating systems (OS) were proprietary and based on generic UNIX practices. This worked fine then when the devices were doing very simplistic routing and switching and the code was small.

•As the industry progressed this became more problematic as the features became inter-mingled. The industry joke was when they fixed one bug they generally created three more. A BGP code issue could impact STP.

•As they moved to Linux kernels they only solved a portion of the problem because they still added hooks into the kernel, it was not a true separation if Linux updated then they would have to start from scratch.

Silo’d Operating Systems


Operating so many different Operating Systems is not efficient

Certification/testing/validation of interactions

Consistency of features


Impact of bugs to production

Constant change and churn- change windows every weekend so to maintain normal

New code versions released forces you to start all over or not implement a much needed new feature

EOS: Software Driven Foundation Like No Other


Arista solved this problem by launching the company with a completely fresh approach. We left the kernel alone. Arista EOS was coded to work with the untouched and protected kernel, this meant and update to EOS didn’t impact the Linux kernel and vice versa. We also changed to a more modern software architecture approach which created a state database referred to as SYSDB. Instead of BGP and STP being inter-mingled they each now existed in their own space. The messaging communications between hardware and software components were no longer tied together. This meant simpler and faster code revisions, bug fixes and HW and SW failure recoveries. 

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Instructor Comments:

I think you'll find this interesting reading!