The edges take the load until a purge, a deploy or a cold region sends every one of them to the origin at once. Hit-ratio arithmetic, the cache headers that are the whole contract, and which machine to actually build.
The port sets the ceiling; disk, TLS and connection state decide the number you actually reach. Bitrate arithmetic for every tier, a worked 10 Gbps live example, and the three resources that run out before the network card does.
Port tiers are sold in Gbps, but workloads arrive in viewers, backup windows and downloads per hour. The arithmetic that turns one into the other, with no rounding in our favour.
Unmetered is not unlimited-with-an-asterisk. It means you pay for the port speed and never for the bytes that cross it — here is what that changes in practice.