How does BBR congestion control differ from traditional algorithms?

BBR (Bottleneck Bandwidth and RTT) models the network path instead of reacting to packet loss. Estimates bottleneck bandwidth (BtlBw) and minimum RTT, targeting sending at BtlBw with inflight data of BtlBw*RTT. Doesn't interpret loss as congestion (critical for wireless, shallow buffers). Four phases: Startup (exponential search), Drain (reduce inflight), ProbeBW (steady with bandwidth probing), ProbeRTT (periodic RTT measurement). Benefits: higher throughput on lossy links, lower latency. BBRv2 improves fairness.