Why TCP is not suitable for interactive multimedia traffic, while UDP is?
1 Answer
  • In real time interactive audio/video, people communicate with one another in real time.
  • The internet phone or voice over IP and video conferencing are the examples of this type of application.
  • Real time data on a packet-switched network require the preservation of the time relationship between packets of a session.
  • There is a gap between the first and second packets and between the second and the third as the video is viewed at the remote site.
  • This phenomenon is called jitter. One solution to jitter is the use of a timestamp.
  • If each packet has a timestamp that shows the time it was produced relative to the first (or previous) packet. Then the receiver can add this time to the time at which it starts the playback.
  • To be able to separate the arrival time from the playback time, we need a buffer to store the data until they are played back. The buffer is referred to as a playback buffer.
  • The traffic can be heavy and the data are distributed using multi casting methods. Sometimes real time traffic needs translation.
  • If there is more than one source that can send data at the same time (video or audio), the traffic is made-up of multiple streams.
  • To encourage the traffic to one stream, data from different sources can be mixed. TCP is not suitable for interactive traffic as it has no provision for time stamping and it does not support multi casting.
  • One feature of TCP that makes it particularly unsuitable for interaction traffic is its error control mechanism.
  • In interactive traffic, we cannot allow the re-transmission of a lost or corrupted packet.If a packet is lost or corrupted in interactive traffic, it must be ignored.
  • Re-transmission upsets the whole idea of time stamping and playback. UDP is more suitable for multimedia traffic as it supports multi-casting and has no re-transmission strategy. However, we need the services of RIP to makeup for the deficiencies of UDP.
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