TCP vs UDP: What is the Difference Between Both Protocols?

TCP and UDP are two commonly used protocols that netizens interact with on a daily basis that determine how data is transferred over the Internet. While they’re similar in many ways, their differences make them useful for different purposes.

In this TCP vs UDP comparison, we’ll go over what these protocols are, the main differences between them, as well as some examples of their uses:

What is TCP?

TCP, or Transmission Control Protocol, is a connection-oriented protocol that devices use to communicate on the Internet. It’s one of the main protocols in the TCP/IP protocol suite and provides error detection and correction. Furthermore, TCP guarantees reliable delivery of data and ensures that packets will arrive in the same order they were sent.

What is UDP?

UDP, or User Datagram Protocol, is a connection less protocol that functions much like TCP but without error detection and correction services. Instead, packets are continuously sent to the recipient whether they have been received or not. This allows for devices to communicate with one another more quickly and with less overhead.

Difference Between TCP and UDP

Now, let’s take a look at some key differences between TCP and UDP:

Speed

UDP is faster than TCP because it has less to do. TCP not only has to establish a connection but also handle error control and guarantee that files arrive in order. UDP, on the other hand, doesn’t guarantee delivery of transferred packets and just sends data without establishing a connection.

Flow and Congestion Control

TCP’s flow and congestion control mechanism ensures that a sender doesn’t overwhelm a receiver by transmitting too much data too quickly. UDP doesn’t offer flow and congestion control as packets are received in a continuous sequence or they’re dropped.

Connection-Oriented & Connectionless

As stated earlier, UDP is a connectionless protocol whereas TCP is a connection-oriented protocol. In TCP, a connection is established between a sender and receiver before sending data. Here, the three way handshake is used, which involves the exchange of SYN (synchronize) and ACK (acknowledge) packets. When it comes to UDP, though, it doesn’t require an explicit connection to send data.

Reliability

TCP is known for being reliable. When you send data via TCP, it’s guaranteed to arrive at your intended destination without errors. Even if data is corrupted or lost in transit, it will recover and resend it. TCP also tracks if packets go missing or are in the wrong order.

UDP, on the contrary, is an unreliable protocol and doesn’t guarantee data delivery. Due to this, datagrams might become lost or corrupt during transit. Moreover, UDP doesn’t track packets between the sender and receiver.

Ordering

With TCP, ordering and sequencing is done to ensure packets are delivered in the same order in which they were sent. UDP, however, sends datagrams in any random order.

TCP vs UDP Comparison Table

	TCP	UDP
Type	Connection-oriented	Connection-less
Speed	Slower	Faster
Error Detection & Correction	Yes	No
Reliability	Higher	Lower
Flow & Congestion Control	Yes	No
Weight	Heavyweight	Lightweight
Acknowledgement	Yes	No
Method of Transfer	Packets are delivered in order	Datagrams are delivered in a continuous stream

 

When to Use TCP vs UDP?

UDP is well suited for applications where efficiency and speed is more critical than reliability. Some examples include:

• Trivial File Transfer Protocol (TFTP)
• Domain Name System (DNS)
• VPN tunneling
• Voice over Internet Protocol (VoIP)
• Online games
• Media streaming

TCP is well suited for applications where reliability is a bigger concern than timing. Some examples include:

• Email (POP, SMTP, and IMAP)
• Secure Shell (SSH)
• Web browsing (HTTP and HTTPS)
• File Transfer Protocol (FTP)

Advantages of TCP

Here are some pros of TCP:

• Provides error checking and recovery mechanisms
• Support for many routing protocols
• Operates independently

Disadvantages of TCP

Here are some cons of TCP:

• Offers slower speeds than UDP
• Connections are heavyweight
• Isn’t compatible with broadcasting

Advantages of UDP

Here are some pros of UDP:

• Availability of broadcast and multicast transmissions
• Offers faster speeds than TCP
• Connections are lightweight

Disadvantages of UDP

Here are some cons of UDP:

• Doesn’t perform any error recovery
• Packets are sent out of order
• Susceptible to data loss

OpenVPN over TCP vs UDP

Many VPN providers support OpenVPN in their apps and allow users to select between the TCP and UDP protocol. It’s important to note that neither of them are superior to the other and the difference isn’t even noticeable to most end users. Generally, UDP offers better speeds, but it can vary on a scenario-by-scenario basis.

In some cases, either one of the protocols might be needed to circumvent a firewall. Both TCP and UDP are capable of running on different ports. However, since OpenVPN uses UDP port 1194 by default, it’s common for firewalls to blacklist it. If your OpenVPN connection is blocked, your best bet is to switch to TCP, which is more NAT and firewall-friendly.

FAQs

The following are some questions people ask about TCP and UDP protocols:

Is UDP or TCP better?

To be fair, neither one is particularly better than the other. Both TCP and UDP are suitable for different purposes. If speed is of utmost significance to you, then you should use UDP. If data integrity is your main priority, then you should use TCP.

Is TCP or UDP Better for Streaming?

As far as streaming (video and audio) is concerned, UDP is the far better protocol due to faster speeds and low overhead. In fact, most streaming applications use UDP rather than TCP because of this very reason.

Should I Use TCP or UDP for VPN?

Once again, it depends on what exactly your needs are. OpenVPN over UDP is typically preferred for bandwidth-intensive activities like streaming and downloading. On the flip side, OpenVPN over TCP is excellent for circumventing firewalls and geo-blocking.

Wrapping Things Up

Now that you understand the differences between TCP and UDP, you’ll be able to make sound decisions when setting up your router, configuring a firewall, or choosing a VPN protocol.

If you have any questions or confusions about TCP and UDP, feel free to voice them via the comments section below. We’ll get back to you as soon as we can!