SAP / SDP
SDP describes sessions, media formats and transport destinations; it is a document format without its own port. SAP distributes session announcements over multicast when supported.
Scope: SAP / SDP — requirements depend on the selected profile.
protocol · Catalog reviewed 2026-09-27
Infrastructure Requirements
- A supported session-description workflow
- SAP multicast reachability when selected
- compatible media and clock parameters from each SDP.
Network & Physical Requirements
| Port / allocation | Transport | Connection / signal flow | Feature and requirement | Evidence |
|---|---|---|---|---|
| 9875 | UDP Multicast: 239.255.255.255 (scope dependent) | Session announcer → Session listeners | Profile requirement · Core SAP session announcements SAP IPv4 administratively scoped example Actual announcement group follows SAP scope. SDP may instead be obtained through RTSP, SIP, NMOS, HTTP or configuration. | Source checked 2026-09-27 RFC 2974, Section 3: Session Announcement (destination and port) |
Physical, link and configuration requirements
configuration · Profile requirement · Core
Read each SDP media address/port, payload type, clock and format parameters. SDP is not a TCP/UDP service.
SDP session descriptions
Source checked 2026-09-27
RFC 8866, Sections 5.7 and 5.14: Connection Data and Media Descriptions
Gotchas & IT Notes
- ⚠SDP is a description format, not a service port. Use its declared addresses, ports and media parameters.
- ⚠SAP is one optional announcement mechanism; not all endpoints use it.