Difference Between Tcp And Udp Protocol


What is TCP?

The Transmission Control Protocol (TCP) is a communications standard that enables application programs and computing devices to exchange messages over a network. It is designed to send packets across the internet and ensure the successful delivery of data and messages over networks.

TCP is one of the basic standards that define the rules of the internet and is included within the standards defined by the Internet Engineering Task Force (IETF). It is one of the most commonly used protocols within digital network communications and ensures end-to-end data delivery.

TCP organizes data so that it can be transmitted between a server and a client. It guarantees the integrity of the data being communicated over a network. Before it transmits data, TCP establishes a connection between a source and its destination, which it ensures remains live until communication begins. It then breaks large amounts of data into smaller packets, while ensuring data integrity is in place throughout the process.

As a result, TCP is used to transmit data from high-level protocols that need all data to arrive. These include peer-to-peer sharing protocols like File Transfer Protocol (FTP), Secure Shell (SSH), and Telnet. It is also used to send and receive email through Internet Message Access Protocol (IMAP), Post Office Protocol (POP), and Simple Mail Transfer Protocol (SMTP), and for web access through the Hypertext Transfer Protocol (HTTP).

An alternative to TCP is the User Datagram Protocol (UDP), which is used to establish low-latency connections between applications and speed up transmissions. TCP can be an expensive network tool as it includes absent or corrupted packets and protects data delivery with controls like acknowledgments, connection startup, and flow control. 

UDP does not provide error connection or packet sequencing nor does it signal a destination before it delivers data, which makes it less reliable but less expensive. As such, it is a good option for time-sensitive situations, such as Domain Name System (DNS) lookup, Voice over Internet Protocol (VoIP), and streaming media.

The Transmission Control Protocol is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol. Therefore, the entire suite is commonly referred to as TCP/IP.


What is User Datagram Protocol (UDP/IP)?

The User Datagram Protocol, or UDP, is a communication protocol used across the Internet for especially time-sensitive transmissions such as video playback or DNS  lookups. It speeds up communications by not formally establishing a connection before data is transferred. This allows data to be transferred very quickly, but it can also cause packets to become lost in transit — and create opportunities for exploitation in the form of DDOS Attack

How does UDP work?

Like all networking protocols UDP is a standardized method for transferring data between two computers in a network. Compared to other protocols, UDP accomplishes this process in a simple fashion: it sends packets (units of data transmission) directly to a target computer, without establishing a connection first, indicating the order of said packets, or checking whether they arrived as intended. (UDP packets are referred to as ‘datagrams’.)

UDP is faster but less reliable than TCP another common transport protocol. In a TCP communication, the two computers begin by establishing a connection via an automated process called a ‘handshake.’ Only once this handshake has been completed will one computer actually transfer data packets to the other.

UDP communications do not go through this process. Instead, one computer can simply begin sending data to the other:

In addition, TCP communications indicate the order in which data packets should be received and confirm that packets arrive as intended. If a packet does not arrive — e.g. due to congestion in intermediary networks — TCP requires that it be re-sent. UDP communications do not include any of this functionality.

These differences create some advantages. Because UDP does not require a ‘handshake’ or check whether data arrives properly, it is able to transfer data much faster than TCP.

However, this speed creates tradeoffs. If a UDP datagram is lost in transit, it will not be re-sent. As a result, applications that use UDP must be able to tolerate errors, loss, and duplication.

(Technically, such packet loss is less a flaw in UDP than a consequence of how the Internet is built. Most network routers do not perform packet ordering and arrival confirmation by design, because doing so would require an unfeasible amount of additional memory. TCP is a way of filling this gap when an application requires it.)

What Kind Of Services Rely On UDP?

UDP is commonly used in time-sensitive communications where occasionally dropping packets is better than waiting. Voice and video traffic are sent using this protocol because they are both time-sensitive and designed to handle some level of loss. For example VOIP (voice over IP), which is used by many internet-based telephone services, operates over UDP. This is because a staticy phone conversation is preferable to one that is crystal clear but heavily delayed.

This also makes UDP the ideal protocol for online gaming. Similarly, because DNS servers both need to be fast and efficient, they operate though UDP as well.



  • TCP is a connection-oriented protocol, whereas UDP is a connectionless protocol.
  • The speed for TCP is slower while the speed of UDP is faster
  • TCP uses handshake protocol like SYN, SYN-ACK, ACK while UDP uses no handshake protocols
  • TCP does error checking and also makes error recovery, on the other hand, UDP performs error checking, but it discards erroneous packets.
  • TCP has acknowledgment segments, but UDP does not have any acknowledgment segment.
  • TCP is heavy-weight, and UDP is lightweight.

Differences between TCP and UDP

Here, are the differences between TCP and UDP

011720 0714 TCPvsUDPWha1
It is a connection-oriented protocol.It is a connectionless protocol.
TCP reads data as streams of bytes, and the message is transmitted to segment boundaries.UDP messages contain packets that were sent one by one. It also checks for integrity at the arrival time.
TCP messages make their way across the internet from one computer to another.It is not connection-based, so one program can send lots of packets to another.
TCP rearranges data packets in the specific order.UDP protocol has no fixed order because all packets are independent of each other.
The speed for TCP is slower.UDP is faster as error recovery is not attempted.
Header size is 20 bytesHeader size is 8 bytes.
TCP is heavy-weight. TCP needs three packets to set up a socket connection before any user data can be sent.UDP is lightweight. There are no tracking connections, ordering of messages, etc.
TCP does error checking and also makes error recovery.UDP performs error checking, but it discards erroneous packets.
Acknowledgment segmentsNo Acknowledgment segments
Using handshake protocol like SYN, SYN-ACK, ACKNo handshake (so connectionless protocol)
TCP is reliable as it guarantees delivery of data to the destination router.The delivery of data to the destination can’t be guaranteed in UDP.
TCP offers extensive error checking mechanisms because it provides flow control and acknowledgment of data.UDP has just a single error checking mechanism which is used for checksums.

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