Session Announcement Protocol (SAP) is an experimental protocol for broadcasting multicast session information. SAP was published by the IETF as RFC 2974. Session Announcement Protocol (SAP) is an experimental protocol for broadcasting multicast session information. SAP was published by the IETF as RFC 2974. SAP typically uses Session Description Protocol (SDP) as the format for Real-time Transport Protocol session descriptions. Announcement data is sent using IP multicast and User Datagram Protocol. Under SAP, senders periodically broadcast SDP descriptions to a well-known multicast address and port. A SAP listening application can listen to the SAP multicasts and construct a guide of all advertised multicast sessions.