RTP (Real-time Transport Protocol)
RTP is the IETF real-time media transport framework used to carry audio, video, and related payloads with sequence numbers, timestamps, source identifiers, and companion RTCP reporting. For IT/firewall purposes, the main answer is that there is no one universal "RTP port". RFC 3551 defines 5004 as a default media port for the classic AV profile and the traditional adjacent RTCP convention makes 5005 common, but real AV systems usually negotiate or configure their media ranges through SDP, SIP, RTSP, WebRTC, AES67, ST 2110, or a vendor control plane.
Scope: RTP (Real-time Transport Protocol) — select the deployed product/version; optional services require separate selection.
protocol · Catalog reviewed 2026-09-27
Infrastructure Requirements
- A complete session context, not just raw packet carriage: matching codec and payload-format support
- an agreed RTP profile (RTP/AVP, RTP/AVPF, RTP/SAVP, RTP/SAVPF, or another explicitly supported profile)
- session description/signalling such as SDP (rtpmap, fmtp, direction, transport, profile name)
- port policy
- jitter buffering
- and usually a companion control/signalling layer such as RTSP, SIP, WebRTC, AES67, ST 2110, or a vendor-specific control plane. If the path is multicast, it also needs correct multicast design. If the path crosses untrusted or NATed networks, it usually needs SRTP, ICE / STUN / TURN, or an SBC / gateway strategy. If multiple streams must line up cleanly, the wider timing design matters too
- RTP timestamps alone are not a whole plant-sync answer.
Network & Physical Requirements
| Port / allocation | Transport | Connection / signal flow | Feature and requirement | Evidence |
|---|---|---|---|---|
| Negotiated | UDP | Media sender / RTCP participant → Media receiver / RTCP participant | Profile requirement · Core RTP media and companion RTCP RTP/RTCP over UDP Classic even/odd RTP/RTCP pairing is a convention; negotiate actual ports. 5004/5005 are not universal. | Source checked 2026-09-27 RFC 3550, Section 11: RTP over Network and Transport Protocols |
| Negotiated | UDP | Media peer → Media peer | Optional · RTCP mux RTP/RTCP multiplexing Negotiated rtcp-mux | Source checked 2026-09-27 RFC 5761, Section 5: Multiplexing RTP and RTCP on a Single Port |
| Negotiated | TCP | Connection initiator → Listening media peer | Optional · TCP carriage Connection-oriented RTP framing RFC 4571 carrier | Source checked 2026-09-27 RFC 4571, Sections 2 and 4: framing method and session descriptions |
Gotchas & IT Notes
- ⚠Use negotiated destinations, actual payload format, codec and clock rates. Multicast group allocation is separate from UDP port allocation.
- ⚠A stateful return path is not a requirement to expose a new listening service. RTCP feedback and independent reverse streams still need the appropriate roles.