Session announcements are handled by two protocols, SDP and SAP. These two protocols display multicast session names and correlate the names with multicast traffic.
SDP is a session directory protocol that is used for multimedia sessions. As such, it assists in advertising multimedia conference sessions and in communicating setup information to participants who want to join the session. SDP simply formats the session description; it does not incorporate a transport protocol. SDP commonly is used by a client to announce a conference session by periodically multicasting an announcement packet to a well-known multicast address and port using SAP.
SAP is a session directory announcement protocol that is used by SDP as its transport protocol.
This chapter discusses the following topics that provide information about SAP and SDP: