11.1 TCP/IP Transport Layer  
  11.1.8 User Datagram Protocol (UDP)  
User Datagram Protocol (UDP) is the connectionless transport protocol in the TCP/IP protocol stack. UDP is a simple protocol that exchanges datagrams, without acknowledgments or guaranteed delivery. Error processing and retransmission must be handled by higher layer protocols.

UDP uses no windowing or acknowledgments so reliability, if needed, is provided by application layer protocols. UDP is designed for applications that do not need to put sequences of segments together.

The protocols that use UDP include:

  • TFTP (Trivial File Transfer Protocol)
  • SNMP (Simple Network Management Protocol)
  • DHCP (Dynamic Host Control Protocol)
  • DNS (Domain Name System)

The following are the definitions of the fields in the UDP segment:

  • Source port – Number of the calling port
  • Destination port – Number of the called port
  • Length – Number of bytes including header and data
  • Checksum – Calculated checksum of the header and data fields
  • Data – Upper-layer protocol data

 

Web Links

User Datagram Protocol

http://www.webopedia.com/TERM/U/ User_Datagram_ Protocol.html