3.5. Other Upper-Layer Protocols
Various other upper-layer protocols play an important role in the success of the TCP/IP protocol suite as a flexible, well-rounded, self-contained group of protocols:
3.5.1. User Datagram Protocol (UDP)
User Datagram Protocol (UDP) is a Transport layer connectionless protocol that does not provide the reliability services available with TCP but instead provides best effort transmission services to application protocols. UDP gives applications a direct interface with IP and the ability to address a specific application protocol running on a host via a port number without setting up an end-to-end virtual circuit or connection. UDP, like TCP, uses IP to deliver its packets.
Figure 3.4 shows how some ...