Consolidate 100G ports into 400G: port count saved, capacity delivered and power per gigabit improvement.
A 400G port carries four 100G lanes, so four existing links collapse onto one port and one trunk. Because a 400G optic draws roughly 12 W against 4.5 W for 100G, the per-gigabit power falls by about a third even though each module draws more. Switch port count and optical power are the two limits in a modern spine rack, and 400G consolidation relieves both without new fibre if MPO-16 trunks are already in place.
100G to 400G Upgrade
400G ports = ceil(100G ports ÷ 4) when each 400G port breaks out to 4 × 100G; power per gigabit = 400G optic power ÷ 400.
400G ports = ceil(100G ports ÷ 4) when each 400G port breaks out to 4 × 100G; power per gigabit = 400G optic power ÷ 400. A 400G port carries four 100G lanes, so four existing links collapse onto one port and one trunk. Because a 400G optic draws roughly 12 W against 4.5 W for 100G, the per-gigabit power falls by about a third even though each module draws more.
Switch port count and optical power are the two limits in a modern spine rack, and 400G consolidation relieves both without new fibre if MPO-16 trunks are already in place.
This calculator takes 4 inputs: 100G ports in service, 400G breakout mode, Power per 100G optic, Power per 400G optic. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.