User Datagram Protocol (UDP)

User Datagram Protocol (UDP)
- UDP is a connectionless, unreliable transport protocol.
- If UDP is so powerless, why would a process want to use it?
With the disadvantages come some advantages.
UDP is a very simple protocol using a minimum of overhead.
Using UDP takes much less interaction between the sender and receiver than using TCP.
USER DATAGRAM
UDP packets, called user datagrams, have a fixed-size header of 8 bytes.
Question:
The following is a dump of a UDP header in hexadecimal format. CB84000D001C001C
1. What is the source port number?
2. What is the destination port number?
3. What is the total length of the user datagram?
4. What is the length of the data?
5. Is the packet directed from a client to a server or vice versa?
6. What is the client process?
UDP SERVICES
Process-to-Process Communication
Several port numbers used by UDP are shown in the below Table.
Connectionless Services
- One of the ramifications of being connectionless is that the process that uses UDP cannot send a stream of data to UDP and expect UDP to chop them into different related user datagrams. Instead each request must be small enough to fit into one user datagram.
- Only those processes sending short messages, messages less than 65,507 bytes (65,535 minus 8 bytes for the UDP header and minus 20 bytes for the IP header), can use UDP.