RTP & Media Transport Flashcards

What does RTP stand for?

Answer: Real-Time Transport Protocol

RTP stands for Real-Time Transport Protocol, defined in RFC 3550, and is used to deliver audio and video over IP networks.

Which transport layer protocol does RTP primarily use?

Answer: UDP

RTP uses UDP because its low overhead and tolerance for occasional packet loss suits real-time media better than TCP's reliable, ordered delivery.

Which RFC defines the RTP protocol?

Answer: RFC 3550

RFC 3550 defines RTP and its companion RTCP protocol, obsoleting the earlier RFC 1889.

What is the purpose of the SSRC field in an RTP header?

Answer: It uniquely identifies the synchronization source of the stream

SSRC (Synchronization Source) is a randomly chosen 32-bit value that uniquely identifies a single RTP stream source within a session.

What does the sequence number field in an RTP packet enable?

Answer: Detecting packet loss and reordering out-of-order packets

The sequence number increments by one for each RTP packet sent, allowing receivers to detect missing packets and resequence packets that arrive out of order.

What is the typical UDP port range used for RTP media streams in VoIP systems?

Answer: 16384-32767

RTP commonly uses even-numbered UDP ports in the range 16384-32767, with the adjacent odd port reserved for RTCP.

What field in the RTP header provides timing information for correct media playback?

Answer: Timestamp

The RTP timestamp reflects the sampling instant of the first byte in the packet, enabling the receiver to play back media at the correct rate and synchronize multiple streams.