16 March, 2024 by Ashley

What is UDP and why is it used?

UDP is a data transport protocol, the part of the Internet Protocol suite (UDP/IP) that is known as the simplest way to send data.

As a networking protocol, UDP does not require previous communication to establish communication channels or data pathways.

It helps create network connections that are loss-tolerant and low latency.

User Datagram Protocol (UDP) is widely used for real-time services and other below targets:

Online Gaming.
Live Video Conferences.
Video/Voice Communications.
IPTV.
Online Radio.
VoIP services (Skype and WhatsApp)
As the transport protocol on OpenVPN.
Saving Bandwidth.
DNS Lookups.
Speed up Data transferring.

Table of Contents

How UDP Works and Speeds Up Communications

UDP is a lightweight Transport Layer protocol that is used in VPNs. Here is How UDP works in detail:

It provides high performance by removing delayed packets instead of processing them.
Packets are units of data transmission, and the UDP packets are referred to as ”datagrams”.
A datagram is sent to the user by UDP, which attaches its header and transfers it from the Network Layer. Thus, it operates quickly.
Also, because UDP doesn’t take time to establish a strong connection with the destination before sending the data, it facilitates faster communication.
UDP transfers data from one computer to a target computer directly without first formally establishing a link in a network.
UDP accomplishes this process without previously making a connection, specifying the packets’ order, or confirming that the packets arrived as intended.

What is UDP Used for?

When you need to use an unreliable protocol, UDP must be your choice. Let’s check out the most important reasons to use UDP:

UDP is used in situations where the packets require a significant quantity of bandwidth in addition to the essential data.
It’s frequently employed in time-sensitive applications where speed trumps accuracy, such as real-time video streaming and video gaming.
RIP (Routing Information Protocol) is one of the routing update protocols that uses UDP.
UDP is used to ensure quick and effective data transmission since packet delays caused by congestion control might be visible in voice communication.
DNS requests are usually brief and demand a fast response. So, UDP is an appropriate protocol to be used by DNS for query and response communications.
UDP is used by DHCP to assign IP addresses to networked devices dynamically. Due to the tiny size of DHCP messages, packet loss or retransmission delays are usually not an issue for this application.
UDP is used for implementations where it is a useful transport layer protocol, such as NTP, NNP, DHCP, BOOTP, RTSP, TFTP, QOTD, DNS, and RIP.
Because it allows packet switching, UDP is the best protocol for multicasting applications.
Applications that require dependable information exchange can also use UDP, but they should have their protocols for responding to packets.
UDP is useful for applications that demand lossless data delivery, such as an application set up to control the process of retransmitting dropped packets.

How UDP is Used in VPNs?

In VPNs, UDP is crucial and offers efficiency and speed, making it appropriate for particular use cases.

Here is the way UDP plays its role in VPNs:

Because UDP is lightweight and faster than TCP, VPNs frequently use it for data delivery.
During a connection, unlike TCP, UDP doesn’t wait for acknowledgments or retransmissions.
For real-time applications like streaming, VoIP, and online gaming, this speed is quite helpful.
Users of OpenVPN and other VPN protocols have the option to select between TCP and UDP.
Because of its speed, OpenVPN is recommended over UDP, particularly in steady network conditions.
For streaming services, where speed is more important than dependability, VPNs frequently employ UDP.
UDP is used to encapsulate the encrypted data packets within the tunnel between the user’s device and the VPN server.
The encrypted data is sent to the VPN server by the VPN client on the user’s device as UDP packets.
UDP packets (datagrams) are transferred one after the other without waiting for a reply. It is effective for VPNs since there is no connection overhead.
Many VPNs use UDP by default, which typically functions without any problems unless there are particular network constraints in place.

Why to Use UDP in VPNs?

Because UDP does not create a formal connection and does not incur the burden of error-checking and retransmitting missing packets, VPNs utilizing UDP are typically faster than those using TCP.

This leads to faster and more efficient data transfer, which is particularly helpful for real-time activities like streaming and online gaming.

UDP Advantages

Compared to TCP, UDP uses smaller packet sizes, which can reduce network congestion and enhance network performance in general.
UDP is helpful for online gaming and video streaming applications since it allows broadcasting to numerous recipients and supports multicast transmission.
In terms of latency and bandwidth, UDP is more effective.
Because almost all devices and network configurations accept UDP, it’s a suitable option for interoperability across many networks and systems.
While UDP comes with no connection establishment, a lower latency and a faster response time is guaranteed.
Because UDP does not have the overhead of connection establishment and dependable data transmission, it is faster than TCP and requires fewer resources.
The simpler protocol design of UDP makes it easier to implement and manage than TCP.

UDP Disadvantages

A site is especially vulnerable to DDoS attacks since UDP does not require a handshake between the source and the destination, leaving the receiver open to attack.
Applications like file transfers and email that need dependable data delivery cannot use UDP.
Due to UDP’s lack of certainty over packet delivery or delivery sequence, data may be missed or duplicated.
UDP is less secure than TCP because of its unreliability, which makes it impossible to ensure that all data has been received and processed appropriately.
Because UDP lacks congestion management, it can transmit packets at a rate that may lead to network congestion.
Due to the lack of flow control in UDP, an excessive number of packets may reach the receiver and overload it.
UDP isn’t available with IKEv2, L2TP, SSTP, or PPTP protocols.

UDP vs TCP

Let’s check the differences between UDP and TCP in detail to understand why UDP is an alternative to TCP.

Protocol	UDP	TCP
Design	Connectionless.	Connection-oriented.
Data Transmission	Packets do not arrive in order.	At the recipient's end, the data packets arrive in the desired order.
Speed	Faster than TCP	Slower than UDP
Efficiency	More efficient than TCP	Less Efficient than UDP
Data Delivery Guarantee	Regarding data transmission to the destination receiver/router, UDP makes no guarantees.	Data transmission to the intended receiver/router is guaranteed by TCP.
Header Size	8 bytes	20 bytes
Reliability	Only minimal error checking utilizing the checksum data blocks is supported by UDP. In addition, unlike TCP, it does not ensure that data will reach its destination.	TCP provides error-checking support in addition to guaranteeing data delivery to the destination path. As a result, it is more dependable than the UDP protocol.
Use Case	DNS, VoIP, media streaming, video conferencing systems, gaming, etc.,	HTTP, HTTPS, POP, SMTP, FTP, etc.
Weight	Light-weight	Heavy-weight
Use a handshake protocol	No	Yes

What is the Main difference between UDP and TCP?

UDP sends data continuously to any recipient, regardless of whether they get it or not.

Its benefit over Transmission Control Protocol (TCP) is that programs can use the quickest possible transfer speeds due to its lack of activity.

Using UDP, it doesn’t matter when a packet gets lost. There will be a millisecond pause in real-time communication that goes unnoticed.

Why does OpenVPN Use UDP?

While TCP is an option for customers who would choose, OpenVPN uses UDP by default as the transport protocol for VPN connections.

Although this can be adjusted if needed, OpenVPN normally uses UDP port 1194 by default when using UDP.

When it comes to real-time applications like VoIP, online gaming, and video conferencing, OpenVPN favors UDP because of its efficiency and speed.

When does OpenVPN Use TCP?

Because UDP is unreliable, it may not be the best option for some applications where data integrity is crucial.

TCP can be used in these circumstances instead. TCP port 443 is usually utilized by OpenVPN when utilizing TCP.

This port is frequently used for HTTPS transmission.

Does WireGuard Use UDP or TCP?

By default, UDP is already used by WireGuard. It can’t even use TCP, in actuality.

When to Use UDP?

Although there is no guarantee of a datagram’s arrival, transmission time, or content integrity, UDP can be used in the below situations:

If it’s necessary to minimize latency.
If it is not a problem, packets will get lost or arrive in a different order than how users transmitted them.
Appropriate for applications like DNS, TFTP, and SNMP that can provide reliability or do not require high dependability.

So, setups with many connected clients where real-time error correction is not a problem, are perfect for using UDP.

Why is UDP Used in Online Gaming?

UDP is usually employed for real-time applications that cannot stand inconsistent message delays between segments.

It is frequently used in online gaming, where fast transmission and low latency are necessary for enjoyable gameplay.

Due to its speed and lightweight nature, UDP is an excellent choice for the short, frequent data packets that game servers transmit to clients.

Why is UDP Unreliable?

Although UDP offers a method for identifying corrupted or out-of-order packets, it does not attempt to address other packet-related issues.

UDP is frequently referred to as the Unreliable Data Protocol because of this.

How Does Google Use UDP?

In May 2021, the Google Quick UDP Internet Connection (QUIC) protocol was formally included in the Internet Engineering Task Force’s (IETF) standard.

QUIC is an encrypted transport protocol running on UDP that is tailored for HTTPS. The main benefits of TCP and UDP are combined by QUIC:

Low latency.
Fewer errors.
Lighter data streams.

Final Notes

Using UDP, you will have an establishing, maintaining, or ending a connection with no overhead.

It continuously distributes data to any recipient, regardless of whether they receive it or not.

UDP works well in situations when guaranteed data delivery and error recovery are not as crucial as real-time communication, low overhead, and lower latency.