UDP Packets

UDP is a "connectionless" protocol. Unlike TCP, it does not check to make sure that data arrived at the receiving host. Instead, UDP takes the message received from the application layer and formats it into UDP packets. UDP attaches a header to each packet, which contains the sending and receiving host ports, a field with the length of the packet, and a checksum.

The sending UDP process attempts to send the packet to its peer UDP process on the receiving host. The application layer determines whether the receiving UDP process acknowledges that the packet was received. UDP requires no notification of receipt. UDP does not use the three-way handshake.