Adaptive routing
Beginner
Switches that steer traffic away from busy routes as they see them, instead of following a fixed rule.
Novice
Choosing each packet’s or flowlet’s output port from the current load on the candidate ports, so traffic moves to less busy paths as conditions change.
Expert
Load-aware path selection in the switch (local queue depth, or remote congestion state), per packet or per flowlet. Common in InfiniBand and HPC fabrics and offered on recent Ethernet switch chips; like spraying, per-packet variants need reordering tolerance at the receiver.
Explained in Scale-out networking (Systems).
See also: Packet spraying, ECMP (equal-cost multipath).