This document discusses the industry standard methodologies of calculating, for purposes of comparison, various underlay element types. It compares single form factor switching elements at the Leaf, Spine and Super-Spine Layers with their chassis-based counterparts, and identifies the mean-time-between-failures (MTBFs), Mean-time-between-repairs (MTTR), and their relation to element and network availability. It also provides availability measurements and the unavailability calculations based upon the elements placement in the network, and the number of port connections between compute and application services platforms.
