Switch radix
Beginner
How many cables one switch can plug in at once.
Novice
The number of ports on a switch. A higher radix lets each switch reach more servers or more other switches, so the network needs fewer layers.
Expert
Port count at a given lane speed. Total capacity is fixed by the SerDes, so one chip can be run as fewer fast ports or more slow ones (for example 64 × 800G or 128 × 400G). Reach grows as for two tiers and for three.