UDP

User Datagram Protocol

USP is not connection-oriented.

• The sending host does not establish a connection with the destination host before sending data. The data is simply sent.

USP does not provide reliable communication.

• When UDP is used, acknowledgments are not sent to received segments. If a segment is lost, UDP has no mechanism to re-transmit it. Segments are sent 'best-effort'.

UDP does not provide sequencing.

• There is no sequence number field in the UDP header. If segments arrive out of order, UDP has no mechanism to put them back in order.

UDP does not provide flow control.

• UDP has no mechanism like TCP's window size to control the flow of data.