ABSTRACT
The real-time audio and video applications are usually sent over Real-Time Transport Protocol (RTP) rather than User Datagram Protocol (UDP) because of suitability of connectionless transport mechanisms; these real-time traffics can tolerate some errors. The support for the RTP and UDP transport protocols are well taken care of in RFC 4566 (see Section 2), and we do not need to address these transport protocols separately here. However, texts and other data applications that are considered nonreal-time applications need connection-oriented transport protocols because they cannot tolerate errors. In this chapter, we discuss the support of connection-oriented media transport (e.g., Transmission Control Protocol (TCP)) in Session Description Protocol (SDP). RFC 4145 describes how to express media transport over TCP using the SDP. It defines the SDP “TCP” protocol identifier, the SDP “setup” attribute, which describes the connection setup procedure, and the SDP “connection” attribute, which handles connection reestablishment.
