Ever wondered how your messages, videos, or game data travel across the internet? The answer lies in two major protocols: TCP and UDP. But here’s the catch: they work totally differently! Why does that matter to you? Let’s dive in and find out how choosing the right one could mean the difference between a smooth video call and a laggy game session.
What is TCP?
Imagine you’re sending an important package — you want to make sure it gets to the right place, safely, and in the right order. TCP is like that reliable courier service that will confirm the delivery and make sure everything is in perfect condition.
Connection-Based: Before sending anything, TCP ensures both the sender and receiver are ready. It’s like a handshake — both sides say, “Okay, we’re ready to start.”
How TCP Sets Up a Connection: The 3-Way Handshake
Before TCP can send data, it establishes a connection between the sender and the receiver using a special process called the 3-Way Handshake. Here’s how it works:
SYN: The sender sends a request to the receiver to establish a connection (SYN = Synchronize).
SYN-ACK: The receiver acknowledges the request and sends a response back (SYN-ACK = Synchronize Acknowledgement).
ACK: The sender acknowledges the response and the connection is established, ready to transmit data.
Even if packets get lost along the way. Thanks to sequence numbers, acknowledgments TCP is able to track every packet and ensure nothing is missing. If a packet is lost, the sender simply resends it until it’s successfully received, so the recipient gets the correct data in the right order.
What’s UDP?
But wait! What if speed is more important than making sure every little detail is perfect? That’s where UDP comes in.
UDP is a connectionless protocol. This means that it doesn't require a connection to be established between the sender and receiver before sending data. It simply sends packets (called datagrams) of data to the destination without checking if they are received correctly.
No Handshake: Unlike TCP, UDP doesn't perform a 3-way handshake (SYN, SYN-ACK, ACK) to establish a connection.
No Acknowledgement: UDP does not wait for an acknowledgment from the receiver, which means it doesn't know if the data arrived successfully or not.
No Resend: If a UDP packet is lost during transmission, it is not resent. There’s no retry mechanism like in TCP.
This makes UDP much faster than TCP because there are fewer overheads involved. However, it also means that data can be lost or arrive out of order, which is acceptable in certain situations but problematic in others.
Key Differences:
| Feature | TCP | UDP |
| Connection | Requires a connection | Doesn’t need a connection |
| Reliability | Very reliable, resends lost data | Not reliable, no retransmission |
| Speed | Slower because of checks | Faster with less overhead |
| Order | Makes sure data arrives in order | No guarantee on order |
| Use Cases | File transfers, web browsing | Live streaming, online gaming |
Now Think: We Have to Use Both Protocols – Yes, It’s Possible!
When it comes to online communication, especially for platforms like Zoom, you might think it’s one protocol or the other. But what if I told you Zoom uses both UDP and TCP at the same time to keep everything running smoothly? Sounds interesting, right? Let’s dive into how this works!
Imagine you’re on a Zoom call. There are different participants – hosts and viewers. Both of them need to be connected for the meeting to happen, but the way Zoom handles their connections is slightly different. Let’s break it down step by step.
Zoom Hosts: Connected via UDP
When two hosts are on a Zoom call, Zoom uses UDP for their connection. Why? It’s simple – UDP is great for fast, real-time communication.
Speed: Since video and audio need to be transmitted quickly with minimal delay, UDP is the best choice. It doesn’t wait for acknowledgment or retransmit lost packets – it just sends the data as fast as possible.
Real-time Performance: Video and audio streaming need to happen with low latency (delay). Any lag can break the flow of conversation. UDP ensures minimal delay, so everything stays in sync.
Zoom Viewers: Connected via TCP
But wait – what if you're just a viewer in the Zoom meeting? Do you still get the same fast connection? Not exactly. Viewers, or participants who aren’t speaking or sharing their screen, are connected to Zoom using TCP.
Reliability: Unlike video and audio, chat messages and file transfers need to be reliable. TCP ensures that the data reaches its destination correctly and in the right order. Viewers receive meeting content (like the video feed, text chat, and shared files) through TCP, which guarantees accuracy and delivery.
Error Handling: If there’s any packet loss or corruption in the data, TCP will retransmit the data until it’s successfully delivered. This is perfect for things like receiving chat messages or documents shared during the meeting.
Why Both?
it might seem odd to use two protocols in a single Zoom meeting, but the combination of UDP and TCP gives Zoom the best of both worlds. Here’s how:
Hosts’ Data (UDP): Video and audio streaming need to be fast and smooth. UDP is perfect here because it doesn't worry about retransmitting lost data. A slight glitch in video or audio is acceptable as long as the conversation keeps flowing.
Viewers’ Data (TCP): For viewers, getting the correct content is more important than speed. Messages, files, and meeting details need to be delivered properly, without any errors. TCP ensures that happens, even if it takes a bit longer.
Switching from TCP to UDP
Now here’s the coolest part: What if a viewer decides to speak or share their screen? Does Zoom just leave them connected via TCP, or does something change?
Zoom seamlessly switches from TCP to UDP when a viewer wants to speak or share their screen. Here's how:
Viewer Requests to Speak or Share Screen: When a viewer decides they want to speak or share their screen, Zoom immediately recognizes this and switches their connection to UDP for real-time, low-latency communication.
Viewer Starts Speaking or Sharing Screen (UDP): Once the switch happens, the viewer’s audio and video data are transmitted via UDP. This ensures their voice or screen share is sent quickly, with minimal delay, so everyone else can see and hear them in real-time.
Viewer Stops Speaking or Sharing (Switch Back to TCP): After the viewer finishes speaking or sharing their screen, Zoom automatically switches them back to TCP for receiving content like chat messages and video feeds
When to Use TCP?
Reliable delivery: TCP ensures data arrives correctly and in the right order.
Best for: Downloading files, sending emails, and browsing the web where accuracy is key.
When to Use UDP?
Fast delivery: UDP prioritizes speed over reliability. Some data loss is okay.
Best for: Online gaming, live streaming, and voice calls where speed is more important than perfect delivery.
in Nutshell:
TCP = Reliable but slower.
UDP = Faster but less reliable.
So, next time you're using the internet, you can now think about whether TCP or UDP is behind the scenes, helping send all that data your way!
Conclusion
In short, TCP is perfect for tasks that need reliable, ordered data delivery, like file transfers and emails. On the other hand, UDP is ideal when speed matters more than accuracy, such as in gaming or live streaming. So, it all comes down to whether you prioritize reliability (TCP) or speed (UDP) for your application.