Difference Between TCP and UDP

In internet networking, multiple protocols are being used for the transmission of data. The standard protocols in vogue include TCP and UDP.

Both of them transit data over the internet.

Though both terms may be used synonymously due to their use of IP protocol, there is a strong difference between these two concepts as they transmit data differently from a networking perspective.

Key Takeaways

1. TCP (Transmission Control Protocol) is a connection-oriented protocol that ensures reliable and accurate data transmission by establishing a connection, verifying data delivery, and retransmitting lost packets.
2. UDP (User Datagram Protocol) is a connectionless protocol that offers faster data transmission without error-checking and connection-establishing processes, leading to possible inaccuracies in the delivered data.
3. The main difference between TCP and UDP is their approach to data transmission, with TCP prioritizing reliability and accuracy. At the same time, UDP emphasizes speed and efficiency at the expense of potential data inaccuracies.

TCP vs UDP

The difference between TCP and UDP is that TCP is a protocol based on connection, i.e. it sets up a connection between the sender and receiver before sending the data, while UDP is a protocol based on no connection, i.e. it does not form a connection before sending data.

However, the above is not the only difference. A comparison between both the terms on specific parameters can shed light on subtle aspects:

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Comparison Table

Parameter of Comparison	TCP	UDP
What does the acronym mean?	Transmission Control Protocol	User Datagram Protocol
Basis of connection	Connection based	Not based on connection
Does it establish a connection between the sender and receiver of data?	Yes	No
Is this a handshake protocol?	Yes	No, i.e. no connection
Is it the most commonly used protocol?	Yes	No, but it depends on the suitability for certain areas
How does it work?	Messages based on TCP are transmitted from one system/computer to another on the internet.	One program can send multiple packets of data to another program.
Can the delivery of data be guaranteed?	Yes	No
Which one is more reliable?	TCP is more reliable as the sender receives an acknowledgement	Less reliable
Are the data packets arranged in any specific order?	The yes, sequential order	No specific order
Does it enable data packets to be sent in sequential order?	Yes	No, the data packets are sent in any fashion
From a weight perspective?	Heavy-weight due to the requirement of multiple ports for connections setup	Lightweight because there is no sequential ordering of messages and no connection tracking.
Are there any acknowledgement segments?	Yes	No
From Speed perspective	It is slower than UDP as it performs multiple activities such as connection setup, checking errors and sequential sending.	Faster than TCP
What is the header size?	20 bytes	8 bytes
Is error recovery performed?	Yes, error checking and recovery.	Not much
Does it provide an extensive error-checking mechanism?	Yes	No, only a single machine is available
Can it be used for broadcast transmission?	No	Yes
Does it enable flow control management?	Yes	No, as packets are sent continuously
Suitability	Used in cases of FTP (file transfer protocol) internet, email, cases where client and server transmit data packets independently	Used in case of live broadcasting, VOIP (Voice over Internet Protocol), video streaming, online gaming, DNS

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What is TCP?

TCP means Transmission Control Protocol or Internet Protocol. TCP is a connection-based protocol and one commonly used protocol for transmitting internet data.

TCP works in a simple way enabling a two-way communication mechanism in which one party seeks information, and the other party/system sends the data or acknowledges the receipt.

For example, once we load an internet page, the system sends TCP packets to a specific web server asking to send the concerned web page or information. That specific web page will respond by sending a set of TCP packets.

TCP is a reliable protocol meaning there is a tracking of data packets and no loss or corruption of data during transit, and it provides for acknowledgement by the recipient. TCP further provides error-checking, and guarantees delivery of data and packets are delivered in the order they are sent.

TCP functions separately from the operating system. TCP has a highly upgradable client-server model.

TCP supports creating a virtual network in case of the connection of multiple system networks. TCP also supports generating a connection between systems and assists multiple routing protocols.

TCP provides an effective flow control management mechanism as it implements flow control by organizing network traffic and congestion

TCP cannot be used for broadcasting transmission. TCP replacement is fraught with challenges.

Also, TCP may have hanging issues, such as the hanging of web pages, unless reloaded again.

 

What is UDP?

UDP stands for User Datagram Protocol. Datagram, in simple terms, means a packet of information.

UDP is a protocol that is not based on connection.

UDP works the same way as TCP but does not ensure data delivery. Simply put, the recipient will continue receiving data packets, and the sender may not be able to validate if the recipient is receiving data.

It is quite possible that recipients may miss receiving certain packets but cannot ask for them, but all this happens at a fast speed. So the most significant benefit of UDP is the high speed with which packets are transferred.

UDP supports packet broadcasting of network transmission. UDP is commonly used in the case of time-sensitive applications.

UDP can also be used in the case of DNS (i.e. domain name system) and internet gaming. UDP can be used when speed is critical, but error correction is not essential.

UDP does not guarantee the delivery of packets, and also there is a possibility of packet/data loss. UDP protocol may support the detection of errors, but this can lead to discarding the packets with further retransmission not being attempted.

Further, data packets may be delivered incorrectly or receive duplicate packets multiple times.

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Main Differences Between TCP and UDP

1. TCP stands for Transmission Control Protocol.  UDP stands for User Datagram Protocol.
2. TCP is a connection-based protocol, i.e. sets up a connection between a sender and receiver before sending the data. UDP is a connection-less protocol and does not require a set-up connection for data movement.
3. TCP provides error-checking techniques. UDP does not provide for such techniques, and recipients may receive erroneous data or corrupt data or may not even receive data that may not be asked for again.
4. TCP is slower and heavyweight as it needs to perform multiple tasks such as connection setup, checking of errors, and sequential ordering. UDP is faster as it does not perform such tasks and is a lightweight protocol.
5. TCP is reliable, and data delivery is guaranteed, combined with an acknowledgement of data loss recovery in practice. UDP is not reliable as it doesn’t ensure data delivery, and there remains a possibility of data corruption or loss in transit.
6. TCP provides sequential ordering when sending data and a flow control technique to maintain smooth traffic flow and not irritate the receivers with too many packets. UDP does not provide for such a protocol nor any specific order for sending data packets and will send packets in any fashion and does not provide for any flow control mechanism.

References

1. https://ieeexplore.ieee.org/abstract/document/751376/
2. https://smartech.gatech.edu/bitstream/handle/1853/12301/MANIACS_40.pdf?sequence=1&isAllowed=y