Linux as a Switch Operating System: Five Lessons Learned. This is what Arista says:
- It’s okay to leave the door unlocked - get net admin access to the underlying Linux operating system tools
- Preserve the integrity of the Linux core - keep your product specific changes as small as possible to allow integration with already existing software out there
- Focus on state, not messages - being only maybe an average programmer I will not comment on this as this is clearly not my area of expertise
- Keep your hands out of the kernel - why to complicate your code if it doesn't bring any revolutionary benefit; besides it is much easier to find developers who know how to program in linux/libc than in Linux kernel.
- Provide familiar interfaces to ease adoption - everyone knows the IOS CLI so why to invent something new.
The company success would not be possible without a clear and consistent OS and tools set design. From my experience they are the second company (I saw this first on BigIP - F5 load balancers).