The two primary protocols used in the transport layer of the internet protocol suite are TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
TCP (Transmission Control Protocol)
TCP is a connection-oriented protocol, meaning it establishes a dedicated connection between the sender and receiver before transmitting data. This connection ensures reliable data delivery through features like:
- Error checking: TCP verifies the integrity of received data and requests retransmission if errors are detected.
- Sequencing: Data packets are numbered to ensure they arrive in the correct order.
- Flow control: TCP adjusts the transmission rate to prevent overwhelming the receiver.
TCP is ideal for applications requiring reliable data transfer, such as:
- Web browsing (HTTP)
- Email (SMTP)
- File transfer (FTP)
UDP (User Datagram Protocol)
UDP is a connectionless protocol. It transmits data packets without establishing a prior connection. This makes it faster but less reliable than TCP because:
- No error checking: UDP does not guarantee delivery or order of packets.
- No sequencing: Packets are not numbered.
- No flow control: UDP transmits data at the sender's rate, potentially overwhelming the receiver.
UDP is suitable for applications where speed is prioritized over reliability, such as:
- Online gaming
- Video streaming
- DNS lookups
Multiple sources confirm TCP and UDP as the two dominant transport layer protocols. For example, GeeksforGeeks states, "The two protocols that make up the transport layer are TCP and UDP." (https://www.geeksforgeeks.org/transport-layer-protocols/) Similarly, an O'Reilly book on Windows NT TCP/IP Network Administration highlights TCP and UDP as the "two most important protocols in the Transport Layer." (https://www.oreilly.com/library/view/windows-nt-tcpip/1565923774/ch01s06.html) Other sources (https://www.cbtnuggets.com/blog/technology/networking/what-are-transport-layer-protocols) reinforce this conclusion.
