What’s the Difference Between TCP and UDP Protocols?

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TCP Vs UDP

TCP and UDP are two protocols that are part of the transport layer in a TCP/IP model of data transmission. Both share the same core function – transmitting data packets from the client to the server and vice versa.

But it is the difference between TCP and UDP protocols which make them appropriate for specialized requirements. In this tutorial, we will attempt to understand TCP and UDP before proceeding to highlight their differences.

Differences Between TCP and UDP Protocol

Both the protocols serve completely different purposes and usually aren’t interchangeable. Though TCP can easily perform all the functionality that the UDP protocol performs at the moment, it will slow down things to an unacceptable level.

For a quick background, think of the online gaming industry where missing out on a single data packet doesn’t make much of a difference. In this case, if TCP is implemented instead of UDP, it will verify the delivery of the packet and resend it if undelivered.

But games drop a lot of packets and frames when streamed online and retransfer of dropped packets will make the game unplayable!

So, when we wish to understand the difference between TCP and UDP protocols, we need to start by learning these TCP/IP protocols one by one.

What is the TCP?

TCP is short for Transmission Control Protocol. This data transfer protocol is connection-oriented i.e. it waits for a proper connection to be established between the communicating devices.

  • The connection is closed once the data transfer is complete.
  • These connections are verified using a three-way handshake.
  • It ensures the proper delivery of data between the two devices.

To do the above three things, TCP employs its thorough error-checking mechanisms through flow control and data acknowledgement.

  • TCP uses data sequencing to ensure that all the data packets arrive at the receiver in the order they were sent.
  • In the case of packet loss, the specific data packets can be transferred again using TCP. 

While it is a heavy-weight protocol, TCP compromises on speed and doesn’t allow broadcasting. With its variable header length of 20 to 80 bytes, TCP finds itself being used in HTTP, FTP, SMPT, and Telnet.

Applications for TCP

TCP allows a person to establish a connection between systems that may or may not be similar to each other. Its support for a variety of networking protocols makes it a popular choice for inter-networking between two or more parties.

TCP allows easy identification of errors and delays data transfer in case the network is congested. This ensures that packet loss is minimized greatly.

Hence, it is used for instances when a delay is acceptable while packet loss is not.

What is the UDP?

UDP is short for User Datagram Protocol. This data transfer protocol is connectionless and oriented with user datagrams.

  • A datagram is a unit for data transfer in the case of packet-switched networks.
  • While its functioning is broadly similar to TCP, UDP doesn’t wait for the receiver to be ready to receive the data.
  • It doesn’t wait for a properly established connection or use handshake protocols to check the same. 

This, coupled with UDP’s basic checksum-based error checking mechanisms, increase the possibility of data packet loss.

  • If packet loss occurs during a UDP transfer, the specific lost packets cannot be sent again.
  • UDP doe not offer any data sequencing either, which means that ordering the data packets has to be done by an application.
  • Unlike TCP, UDP offers a lightweight alternative for data transfer.
  • It’s simpler, faster than TCP and efficient.
  • It allows things like broadcasting which isn’t possible through TCP.

With its fixed header length of 8 bytes, UDP finds itself being used in DNS, TFTP, RIP, SNMP and VoIP.

Applications for UDP

UDP removes the need for an established connection. This helps cut down the latency during startup. UDP allows for broadcasting and multicast data transfer. It is a popular choice for multimedia transmissions such as VoIP.

To ensure maximum speed, it uses only checksums to identify errors. This makes the data transfer speed to be enhanced at the cost of risking data packet loss.

As there is no need for a connection to be established, delays aren’t an issue in UDP. Hence it is used for instances where packet loss can be tolerated, but delay can’t.

Summarizing the differences between TCP and UDP protocols

Now that we have an idea about both these protocols, we can move on to the difference between TCP and UDP protocols.

These differences play a big role in helping you choose the correct protocol for your needs. Both TCP and UDP offer a variety of pros and cons in terms of functionality. 

Here is a table that contains an overview of the difference between TCP and UDP protocols.

Transmission control protocol (TCP)User datagram protocol (UDP)
TCP is a connection-oriented data transfer protocolUDP is a datagram-oriented data transfer protocol
Data is guaranteed to safely reach the receiverData is not guaranteed to safely reach the receiver
Uses data acknowledgment and flow control to perform an in-depth error checkUses checksums to search for basic errors in transmission
Data sequencing is handled by TCPData sequencing needs to be handled by an application
TCP works slower than UDP and is a heavyweight protocolUDP works faster than TCP and is a lightweight protocol
HTTPs, SMPT, FTP and Telnet use TCP for data exchangeDNS, DHCP, TFTP, VoIP and RIP utilise UDP for data exchange
TCP does not allow broadcastingUDP allows broadcasting
The header length can vary between 20 to 80 bytesThe header length is fixed at 8 bytes

This difference between TCP and UDP protocols make each better at handling specific kinds of use.

Hence, while TCP is great for general use, choosing UDP would be the right decision when speed is more essential than the risk of packet loss.

Wrapping up

There is a lot of differences between TCP and UDP protocols. These differences mean that irrespective of your data transfer needs, you always have one protocol which will optimally meet your requirements.

  • TCP is designed to handle load efficiently and ensure packet losses don’t occur.
  • On the other hand, UDP is based on ensuring maximum speed in data transmission.

Despite the difference between TCP and UDP protocols, both are widely used to transfer data over the network.

It’s critical to know the differences between TCP and UDP protocols when you’re working with developing applications that communicate over the network.

I hope this tutorial has been useful to you.

If you have any feedback, queries or suggestions, feel free to reach out to us in the comments below.

Comments

  1. Johny says:

    Nicely written article. However, Adding working examples would have make this article much better.

    1. Ninad says:

      Thanks for commenting Johny! I’ll add some interesting examples and update the article sometime soon… Appreciate it, have a good day mate! 🙂

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