In a push protocol the sender opens a TCP or UDP session to a known endpoint at the receiver and writes media into it. The receiver is passive — it advertises an URL or an SRT IP/port and waits. Push is the natural fit for contribution from the field, because the field unit might sit behind NAT or change IP, and the receiver in the data centre is stable and reachable. Almost all OBS, vMix and broadcast encoder workflows are push.
Push is contrasted with pull, where the receiver opens a connection to a sender and reads media (RTSP from an IP camera is the canonical example). Push has the advantage of NAT traversal — the sender's outbound connection passes through home and corporate NATs naturally — and the disadvantage of needing the receiver to be addressable. For internet-wide contribution, the standard pattern is a load-balanced public ingest endpoint accepting RTMP/SRT/WHIP from anywhere.
Push protocols differ in retransmission and security. RTMP runs on TCP and gets reliability for free but pays in head-of-line latency. SRT runs on UDP with ARQ and adjustable latency window. RIST is similar to SRT but with multipoint distribution and stronger compliance with broadcast standards. WHIP is push-WebRTC over HTTP signalling, ideal for browsers. The choice depends on round-trip distance, packet loss profile, and whether the source is hardware or software.
