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The IP protocol deployed in the Internet today provides a best-effort service to all the datagrams it
carries. In other words, the Internet makes its best effort to move each datagram from sender to receiver as quickly
as possible, but it does not make any promises whatsoever about about the end-to-end delay for an individual packet.
Nor does the service make any promises about the variation of packet delay within a packet stream. Because TCP and UDP
run over IP, it follows that neither of these transport protocols makes and delay guarantees to invoking applications.
Due to the lack of any special effort to deliver packets in a timely manner, it is an extremely challenging problem to
develop successful multimedia networking applications for the Internet. Multimedia over the Internet has achieved significant
but limited success.
Internet phone and real-time interactive video had been less successful than streaming stored audio/video. Real-time
interactive vioce and video impose rigid constraints on packet delay and packet jitter. Packet jitter
is the variability of packet delays within the same packet stream. Real-time voice and video can work well in regions
where bandwidth is plentiful, and hence delay and jitter are minimal.
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