UDP

User Datagram Protocol (UDP) is part of the Transport Layer of the TCP/IP suite. UDP provides a connectionless communication method for sending data between devices. Unlike TCP, UDP does not guarantee data delivery, ordering, or error recovery. Instead, it offers a simpler, faster way to transmit data with minimal overhead.

When sending data over the network from the Application layer, we create a UDP socket. To send and receive data using this socket, we use the socket programming APIs provided by the operating system. These APIs include system calls like sendto() and recvfrom(), which facilitate the transmission of data between the Application layer and the Transport layer.

Here’s how UDP handles data:

1. Socket Creation:
   • UDP Socket: An application creates a UDP socket using the socket() system call, specifying the UDP protocol.
2. Data Transmission:

• Sending Data: When data is sent via a UDP socket, the data is provided to the sendto() system call. The data is then encapsulated in UDP packets (datagrams).
• Receiving Data: The recvfrom() system call is used to receive data from the socket. The received UDP datagram is then passed up to the application layer.

3. UDP Datagram Structure:
   • Datagram Format: A UDP datagram consists of a UDP header and the data payload. The UDP header includes fields such as:
     • Source Port: The port number of the sending application.
     • Destination Port: The port number of the receiving application.
     • Length: The length of the UDP header and payload.
     • Checksum: Used for error checking, but it's optional in IPv4.