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Key Points
- TCP is slower than UDP for packet transmission.
- UDP does not support end-to-end connections.
- TCP allows for services to create secure connections making it ideal for subscription services like Netflix, Hulu, YouTube, and HBO.
- Both TCP and UDP are TCP/IP transport layer protocols.
- HTTP, HTTPS, FTP, and SMTP are some of the more well-known TCP Protocols.
- BOOTP, DHCP, DNS, and TFTP are some of the more well-known UDP Protocols.
Computing programming is full of protocols. Everything your computer needs to do is handled by them. Most tasks even have a set of different protocols to handle specific portions of a task. The most common example of this is an internet connection. Many may assume that IP, or internet protocol, is an all-encompassing protocol for handling internet traffic and connections. However, there are many different protocols taking place at one time. In the example of a computer connecting to the internet, there is also TCP/IP and UDP.
Think of TCP and UDP as underlying protocols that the client, or users computer, needs to determine the best method for interacting with networked connections. These protocols first sort out how the computer should connect to a server or another client then it begins to transfer information. While UDP and TCP may achieve similar goals, they are not the same.
UDP vs. TCP: Side by Side Comparison
| UDP | IDP | |
| What it is | TCP/IP transport layer | TCP/IP transport layer |
| Primary Use | dictate computer network transmission | dictate computer network transmission |
| Name | User Datagram Protocol | Transmission Control Protocol |
| Conceived | 1980 | 1970 |
| Initial release | 1980 | 1970 |
| Technical committee | RFC768 | DARPA |
| Influential developers | David P. Reed | Vint Cerf, Bob Kahn |
| open format | yes | yes |
| Technologies influenced | BOOTP, DNS, DHCP, TFTP, IP | HTTP, HTTPs, FTP, SMTP, IP, VPN |
What is TCP?
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Transmission Control Protocol/Internet Protocol, or TCP/IP, is a subset of connection protocols that help your computer to define a stable connection with other network-connected devices. TCP uses a three-way handshake that helps to verify the integrity and authenticity of a connection as well as the consistency of full form data exchanges with error-checking.
TCP was designed specifically to offer reliable end-to-end byte streams over an unreliable network to ensure that the full form of each data transmission is received along with better connection security. The security TCP offers is among the main reasons it is used for subscriptions services or VPNs. While It’s bandwidth intensive nature makes it perform worse for multi-player gaming.
How Does TCP Work?
When your computer starts the process of connecting to a networked device, it first determines whether to use TCP or UDP. TCP is a common default. When TCP is selected, the client computer will send a signal that needs a specific response. The connected device and the client computer will trade packets or keys to establish authenticity. Once the connection is established, data can transmit between devices. This can mean downloading programming, video chat, music streaming, video streaming, or any of the now countless ways to transmit data across the internet.
Once the task is complete, the connection is severed by the client computer by closing the virtual pathway on the client-side. Out of many thousands of examples of TCP connections, VPNs are make the features of TCP more abundantly clear. The reliable connection and tunneling of information through discrete routed pathways requires a reliable and solid connection be maintained to the VPN provider.
The main features of TCP are its superior delivery acknowledgements, its ability to re-transmit data, its error detection features, and the way that it can control transmission to moderate network congestion.
Pros and Cons of TCP
| Pros | Cons |
|---|---|
| It establishes connections between different types of computers. | It can’t be used for broadcast or multicast transmission. |
| It operates independently of the operating system. | There are no block boundaries. |
| It supports multiple routing protocols. | It is a resource intensive protocol that uses more bandwidth and time than UDP. |
| TCP enables internet working between organizations. | The transport layer doesn’t guarantee delivery of packets. |
| It has high scalability for client-server architecture. | Replacing TCP protocol is difficult. |
| It can be operated independently. | TCP can’t conclude a transmission without all data in motion being explicitly asked. |
| It can be used for multi-connection transmissions, such as connections between more than two computers. | It doesn’t have a clear separation from services, interfaces, and protocols. |
What is UDP?
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User Datagram Protocol, or UDP, is an IP protocol set used for broadcast and multicast network transmissions. (Side note: A datagram is a transfer unit associated with a packet-switched network.) It works very similarly to how TCP performs with data transmission without the authentication of a handshake or decent error-checking.
At first, UDP can seem to be a less useful protocol than TCP until you consider the smaller amount of bandwidth and resources a UDP connection requires. Error-checking and authenticity checks require that a data log be kept and transmitted between the connected devices at the same time as the primary data transmission. For some smaller transmissions, this can double the transmission size. For applications that require multiple user connections like video streaming, the doubling of transmissions per user becomes unwieldy and less preferable. A very common use of UDP is for multi-player gaming. Packet loss is less important than the speed of the connection and the open access for clients and servers to constantly send packets back and forth.
How Does UDP Work?
UDP assumes that data integrity, authentic connections, and error checking are not important for the task the connection is performing. As stated in the “What is UDP?” section, this is incredibly useful for streaming services or broadcasts that allow for thousands of client-side connections to be made at once.
It is important to remember that broadcast and multicast are networking protocol terms. While UDP is meant for broadcast and multicast types of connections, this does not mean that streaming services make use of it.
Some of the features of UDP including its ability to support bandwidth-intensive applications with high pack-loss tolerance, the way that it allows small transactions, and its short delay.
Pros and Cons of UDP
| Pros | Cons |
|---|---|
| There is no connection-based communication model restriction. | Packet delivery order and confirmation are mixed bags. Packets can be undelivered, delivered twice, or delivered in the wrong order. |
| The recipient of UDP packets receives them unmanaged. | Routers will not retransmit UDP packets if the connection collides with another. |
| Broadcast and multicast transmission are supported. | There is no congestion control. |
| Data loss can be made. | There is high probability of packet loss. |
| It allows for DNS lookup. |
The Difference Between TCP and UDP
Here’s a quick breakdown of the differences between TCP and UDP:
| TCP | UDP | |
|---|---|---|
| Protocol | Connection-oriented protocol. | Connectionless protocol. |
| Packets | Reads data as streams of bytes, messages are transmitted to segment boundaries. | Does not require connections for packets to be sent from program to program. |
| Messages | Messages move from one computer to another. | Messages contain packets that were sent individually. Checks for integrity on arrival. |
| Order | Rearranges packets in a specific order. | It has no fixed order. |
| Transmission speed | Slower transmission speed. | Faster transmission speed due to no error recovery. |
| Header size | Header size is 20 bytes. | Header size is 8 bytes. |
| Weight | Heavy-weight. Needs three packets to set up a socket connection. | Lightweight, no tracking connections. |
| Error checking | Performs error checking and error recovery. | It performs light error checking, but discards broken packets. |
| Acknowledgement segments | Acknowledgement segments. | No acknowledgement segments. |
| Handshake | Uses SYN, SYN-ACK, ACK, and other handshake protocols. | No handshake. |
| Transmission delivery | Reliable transmission delivery. | No delivery guarantee. |
| Error checking | Extensive error checking. | Single error checking used for checksums. |
TCP, or Transmission Control Protocol, is a connection-oriented protocol. This means that when a computer uses TCP it establishes a verified, stable connection with network devices. This is often achieved with a three-way handshake. TCP also prioritizes full form delivery of data and requires that all data in motion be explicitly asked to conclude for the connection to be closed.
UDP, or User Datagram Protocol, is used for broadcast and multicast network transmissions. This allows for more connections to be established, but with less security. Some transmissions need to find their way to multiple locations at once. This requires that new receivers be able to pick up a transmission without interrupting any previously established transmissions. In order to achieve this, UDP removes the handshake methods used in TCP as well as error-checking and back-and-forth communication.
One or both of these protocols are always in use when the internet or network is connected. A quick way to remember the difference is to think of TCP as stable, secure connection protocols for more sensitive information and checks against packet loss and UDP as an open broadcast like a data concert. Both protocols can be used for almost any connection, but TCP is widely considered to be the better option even if it has more overhead.
When to use UDP or TCP
For the average user, TCP is the ideal choice. No user wants to deal with broken downloads or packet loss. UDP is more often used for multimedia applications like VoIP (Voice over Internet Protocol) or where both the client and server are sending packets separately with no delay like online gaming.
However, UDP is a lighter-weight protocol that can help ease the strain of resources like bandwidth when performing broadcast or multicast connections. It is also helpful when speed is more important than data integrity or connection security.
Examples of Applications for UDP:
- Online gaming connections
- Voice over Internet Protocol (VoIP)
- Media Streaming(Discord, Twitch)
Examples of Applications for TCP:
- File Transfer, or FTP
- HyperText Transfer Protocol, HTTP
- Simple Mail Transfer Protocol, SMTP
