1. Dr. John P. Abraham Professor UTPA
25-UDP
Dr. John P. Abraham
Professor
UTPA

2. User Datagram Protocol
A Datagram transport service
IP alone can’t distinguish among multiple application programs running on a given host. Another words, once the datagram is delivered to the computer, how does the computer use it? Is it an datagram? Is it a web datagram?
Transport layer protocols are known as end-to-end protocols (rather than host-to-host), because they deliver to the application on each end.

3. Features of UDP (thin protocol)
End-to-end
Connectionless
Message oriented. Programmers may choose a message size that produces datagrams that fit in a standard MTU (1400 to 1450 octets of data).
Best effort
Arbitrary interaction: allows an application to send to many other applications (1 to many), or many-to-1 or many-to-many, or 1 to 1.
Operating system independent.

4. Position of UDP in the TCP/IP protocol suite

6. UDP communication semantics
UDP uses IP to send messages, as such problems of IP are inherited. An application must be immune to these problems or programmers should take additional steps to handle these problems.

7. Well-known ports used with UDP

8. Endpoint identification with protocol numbers
Protocol port numbers (sockets) are independent of underlying operating system. Each computer that supports UDP must map port numbers and program identifiers that the OS uses.

9. User datagram format

10. Encapsulation and decapsulation