Differences between TCP and UDP



Prerequisite – Transport Layer responsibilities, TCP, UDP

Transmission control protocol (TCP) User datagram protocol (UDP)
TCP is a connection-oriented protocol. Connection-orientation means that the communicating devices should establish a connection before transmitting data and should close the connection after transmitting the data. UDP is the Datagram oriented protocol. This is because there is no overhead for opening a connection, maintaining a connection, and terminating a connection. UDP is efficient for broadcast and multicast type of network transmission.
TCP is reliable as it guarantees delivery of data to the destination router. The delivery of data to the destination cannot be guaranteed in UDP.
TCP provides extensive error checking mechanisms. It is because it provides flow control and acknowledgment of data. UDP has only the basic error checking mechanism using checksums.
Sequencing of data is a feature of Transmission Control Protocol (TCP). this means that packets arrive in-order at the receiver. There is no sequencing of data in UDP. If ordering is required, it has to be managed by the application layer.
TCP is comparatively slower than UDP. UDP is faster, simpler and more efficient than TCP.
Retransmission of lost packets is possible in TCP, but not in UDP. There is no retransmission of lost packets in User Datagram Protocol (UDP).
TCP header size is 20 bytes. UDP Header size is 8 bytes.
TCP is heavy-weight. UDP is lightweight.
TCP is used by HTTP, HTTPs, FTP, SMTP and Telnet UDP is used by DNS, DHCP, TFTP, SNMP, RIP, and VoIP.


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