CCIE 400-101: Network Principles

When TCP flows are combined with UDP flows within a single traffic class and the class experiences congestion, TCP flows continually lower their transmission rates (global synchronization), potentially giving up their bandwidth to UDP flows that are oblivious to drops.
This effect is called TCP starvation/UDP dominance.
The best way to resolve this is to classify UDP and TCP streams separately as much as possible.

Latency is the end to end delay.
Jitter is the variance in latency.
UDP is connectionless, the real effect of the latency on the UDP stream is that there would be a great delay between the sender and the receiver.
Jitter causes problems with UDP streams if packets arrive in the wrong order.
Jiffer can be smoothed by buffering.

UDP is the preferred protocol for real-time data transport like voice and video.
However, UDP does not have any data flow management mechanisms like datagram sequencing or other "missing pieces".
These functions are handled by RTP instead.
For example, to help guarantee that datagrams are played back in the right order, RTP has a 16-bit sequence number field in its packet header, which allows the receiving device to ensure that the packets are correctly sequenced.
Simply put, RTP carries the actual data, such as voice or video. RTCP carries information about that data – information such as jitter and delay statistics, or information about QoS mechanisms involved with these conversations.

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