Week 23: IP Transport Protocols

TCP (Transmission Control Protocol)

TCP: is a connection-oriented protocol, it requires the establishment of the transmission parameters before the exchange of data, it also provides error-recovery and rate control services.

UDP (User Datagram Protocol)

This transport protocol, commonly referred to as a fire and forget, is a connectionless protocol with no prior connection between the sender and receiver, used most commonly for sending audio and video streams.

UDP has no connection establishment stage. A UDP sender just blasts the packets out without any regard for the receiver. The UDP header adds 8 bytes to the underlying IP  header's 20 bytes, creating a combined overhead of 28 bytes (Church and Pizzi, 2010).

In general, UDP is a much faster and more efficient method of sending media over IP.

RTP over UDP sometimes has a higher priority than TCP in the network routers.

RTP (Real-time Transport Protocol)

RTP has been designed to transport real-time multimedia streams over IP networks. It is a standardised packet format for sending audio and video data streams and ensures consistency in the delivery order of voice data packets.

RTP is layered on top of UDP.

RTP divides multimedia data streams into packets and transmits them over an IP network.

In order to handle and meet the necessary Quality of Service parameters during the transfer, RTP uses Real-Time Control Protocol (RTCP).

“RTP is a flexible standard which can transport almost anything, but in order to transport a particular format of data a supplementary "payload format" is needed. RTP payload formats exist for a variety of common video and audio formats (such as Uncompressed Video, or H.264).”

An IP Packet consists of two parts:

A header: which contains instructions about the data contained within the packet; and
The Payload: which is the actual data that is being sent to the destination.

References

Church, S. and Pizzi, S. (2010). Audio over IP. Burlington, MA: Focal Press.
https://www.bbc.co.uk/rd/blog/2019-01-ip-production-standards-interoperability-facilities
https://www.bbc.co.uk/rd/blog/2018-10-rfc8450-vc2-rtp
https://github.com/bbc/rfc8450-vc2-dissector