The Universal Fat Tree - network standard for data centre networks

Have you ever wondered why spine-and-leaf networks are the “standard” for data centre networks? While the answer has a lot to do with trial and error, it turns out there is also a mathematical reason the fat-tree spine-and-leaf is is used almost universally. There often is some mathematical reason for the decisions made in engineering, although we rarely explore those reasons. If it seems to work, there is probably a reason.

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