SDP (Session Description Protocol) is a set of rules that defines how multimedia sessions can be set up to allow all end points to effectively participate in the session. In this context, a session consists of a set of communications end points along with a series of interactions among them. The session is initiated when the connection is first established and is terminated when the all of the end points have stopped participating. An example is a videoconference conducted by a large corporation that includes participants from multiple departments in diverse geographic locations.
In SDP, session parameters include information such as the session name, the date and time at which the session is scheduled to begin, the purpose of the session, the addresses or ports of all end points, the data formats to be used and the bandwidth requirements for effectively exchanging the session data. SDP is intended primarily for use in large WANs (wide-area networks) including the Internet. As such, it is designed to function in a many-to-many environment. Nevertheless, SDP can also be employed in proprietary LANs (local area networks) and MANs (metropolitan area networks).