Elephant flow
Beginner
One very large, long transfer of data, as opposed to many tiny ones.
Novice
A flow that carries a large amount of data for a long time, often at the full speed of the link. AI training produces a few elephant flows per NIC rather than thousands of small ones.
Expert
Long-lived, high-rate flows. Hash-based balancing assumes many small flows that average out; a handful of elephants per link turns every hash collision into a lasting bottleneck.