Work out switch capacity instantly with clear inputs, formula shown and shareable results.
Vendors quote switching capacity as the sum of all port speeds counted in both directions, so a 48-port 25G switch with six 100G uplinks needs 3,600 Gbps of fabric to be non-blocking. The separate forwarding rate in millions of packets per second is what limits small-frame traffic, and it is derived from 64-byte frames plus the 20-byte preamble and inter-frame gap.
Switch capacity
aggregate = ports x port speed + uplinks x uplink speed; switching capacity = aggregate x 2 (full duplex); forwarding rate = aggregate bits / (64 x 8 + 160) bits per minimum frame
Because each port can send and receive simultaneously at line rate. The marketing figure counts both directions.
Forwarding rate, for traffic dominated by small packets such as voice or DDoS floods. Bandwidth binds for bulk transfer traffic.