SDP is an IETF
standard that allows a
multimedia device to describe the kinds of media that has to offer
or that it wishes to accept. As part of this description, the
device will indicate the type of media (audio, video, text, etc.),
the ▲IP ports used, the protocols used (e.g., ▲T.120),
and other information necessary for a device to receive the
specified media and understand how to handle that media.
SDP is defined in RFC 2327. There are additional RFCs that document
extensions or enhancements to SDP.