TCP vs UDP: What’s the Difference?

TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are widely used Internet protocols. They are the different methods that specify how data transmits between 2 entities across the internet. Both TCP and UDP have their own set of functions, advantages, and limitations. In this TCP vs UDP blog, we will understand the key difference between TCP and UDP.

Table of Contents

• What is TCP?
  • Advantages of TCP
  • Disadvantages of TCP
• What is UDP?
  • Advantages of UDP
  • Disadvantages of UDP
• Difference Between TCP vs UDP
• Conclusion

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What is TCP?

TCP (Transmission Control Protocol) is an important protocol of the Internet protocol suite. It is a communications standard that allows the exchange of messages between computing devices in a network. TCP is connection-oriented, which means that a connection is established and maintained until the application/servers at each end finish exchanging the message.

TCP takes messages from an application or server. It divides them into packets that are forwarded by the devices in the network, such as switches and routers to the destination. TCP assigns a number to each packet and reassembles them before delivering them to the recipient.

In simple terms, TCP is designed to send messages (in the form of numbered packets) across the internet and ensure their successful delivery over networks. TCP is reliable and has in-built mechanisms to check for errors and to guarantee the ordered delivery of data.

Also Read: OSI vs TCP/IP Model: What’s the Difference?

Advantages of TCP

The following are some of the benefits of TCP:

• TCP is connection-oriented.
• It establishes a connection between sender and receiver over the network before sending a message.
• It uses a congestion control policy to avoid congestions.
• Supports data retransmission. If the packets get lost failing to reach their destination, they will be sent back to the sender from the receiver. The sender can retransmit the packets.
• Performs in-order delivery by rearranging all packets at the receiving end.
• Error detection, such as corrupted and missing packets is easier. It is done through a three-step mechanism – checksum, retransmission, and acknowledgment.

Disadvantages of TCP

Some of the limitations of using TCP are:

• It does not support broadcast or multicast transmission.
• TCP offers several features that we may not want. These features may result in a waste of bandwidth, time, or effort.
• While establishing a connection, TCP performs a handshake between the sender and the receiver. This slows down the connection establishment. However, this issue can be solved using high latency devices.

Also Read: OSI Model Explained: 7 Layers and Their Functions

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What is UDP?

UDP (User Datagram Protocol) is a connectionless Internet protocol. Error-checking and error recovery services are not required. There is no need for opening a connection, maintaining a connection, or terminating a connection. This is because data is continuously sent to the recipient, whether or not they receive it.

UDP is mainly used for real-time communications and time-sensitive applications, such as playing videos, gaming, or Domain Name System (DNS) lookups. It provides faster data transfer speeds as it does not spend time establishing a firm connection with the destination before sending the data.

UDP divides messages into packets, called datagrams. These packets are forwarded by the devices in the network, such as routers and switches to the destination.

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Advantages of UDP

• UDP is an alternative to TCP.
• It is useful for applications in which we don’t need to put sequences of packets together.
• Helps in establishing low-latency connections between applications and reducing transmissions time.
• It is widely used for time-sensitive or real-time communications, such as broadcast or multi-task network transmission.

Disadvantages of UDP

• It is a less reliable and connectionless protocol.
• Not ideal for sending an email, viewing a webpage, or downloading a file.
• It does not provide Congestion Control.
• Does not provide packet sequencing or error connection support.
• Data packets are likely to get lost during transmission.

What is the difference between TCP and UDP?

In TCP, when the data is transferred, the receiving end sends a signal that it is ready to receive the data. In this way, nothing is lost along the way. It takes more time but results in more consistent transmissions.

But with UDP, the data is forwarded before establishing a firm connection with the receiving end. It can cause the data packets to get lost when data is transferred across the internet. Due to this, hackers also get an opportunity to execute a distributed denial-of-service (DDoS) attack.

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TCP vs UDP Comparison: Difference Between TCP and UDP

Here are the top differences between TCP and UDP:

TCP	UDP
TCP stands for Transmission Control Protocol.	UDP stands for User Datagram Protocol.
It is a connection-oriented protocol in which communicating devices establish a connection before transmitting data. The connection terminates after transmitting the data.	UDP is a connectionless protocol. There is no need to establish, maintain, and terminate a connection.
The data units are called packets.	The data units are called datagrams or packets.
Data is sent following a particular sequence. They are re-arranged in the same order at the receiving end.	There is no sequencing of data. If a specific order is required, it is managed by the application layer.
It is reliable and guarantees the delivery of data to the destination.	It does not guarantee the delivery of data to the destination.
TCP provides an extensive error-checking system.	It only provides a basic error-checking mechanism using checksums.
It performs a retransmission of lost packets.	It does not support the retransmission of lost packets.
TCP is heavy-weight.	UDP is lightweight.
The header size is 20 bytes.	The header size is 8 bytes.
Acknowledgment segment is present.	There is no acknowledgment segment.
TCP uses a three-way handshake to establish a connection. It uses a three-step process – SYN, SYN-ACK, and ACK.	There is no handshake in UDP as it is a connectionless protocol.
It is slower than UDP.	UDP is faster and more efficient.

Conclusion

In this article, we discussed the difference between TCP vs UDP. We learned that TCP is a connection-oriented protocol while UDP is a connectionless protocol. The main difference between TCP and UDP is their speed. UDP is a comparatively faster, simpler, and more efficient protocol. On the other hand, TCP is reliable and provides the advantage of retransmission of lost data packets.

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