UDP & TCP

Master the fundamental transport layer protocols that power internet communication

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Protocol Performance Calculator

Protocol Type

Packet Size (bytes)1024 bytes

Data Rate (MB/s)10 MB/s

Network Latency (ms)50 ms

Packet Loss Rate (%)0.1%

Concurrent Connections100 connections

Performance Metrics

Protocol Overhead:3.91%

Effective Data Rate:10 MB/s

Packets/Second:10656

Total Latency:200 ms

Protocol Features

Guaranteed Delivery:Yes

Ordered Delivery:Yes

Flow Control:Yes

CPU Overhead:High

Resource Usage

Memory Usage:6.25 MB

Connection Overhead:400 KB

Window Size:64 KB

Transport Layer Protocols

TCP and UDP are the fundamental transport layer protocols that enable communication between applications across networks. Understanding their trade-offs is crucial for designing performant distributed systems.

TCP (Transmission Control Protocol)

Reliable, connection-oriented protocol with guaranteed delivery, ordering, and flow control. Higher overhead but ensures data integrity.

UDP (User Datagram Protocol)

Fast, connectionless protocol with minimal overhead. No delivery guarantees but excellent for real-time applications.

TCP: Reliable Communication

Connection Management

Three-Way Handshake

Client → Server: SYN

Server → Client: SYN-ACK

Client → Server: ACK

# Connection established

Connection Termination

Client → Server: FIN

Server → Client: ACK

Server → Client: FIN

Client → Server: ACK

Flow Control & Congestion Control

Sliding Window

Controls how much data can be sent before receiving acknowledgment.

Window Size: Dynamic (up to 64KB)

Purpose: Prevent receiver overflow

Congestion Algorithms

Slow Start: Exponential growth

Congestion Avoidance: Linear growth

Fast Recovery: Quick adaptation

TCP Header Structure

Source Port

Dest Port

Sequence Number

Acknowledgment Number

Window Size

+ Control Flags, Checksum, Options

Minimum 20 bytes, Maximum 60 bytes

UDP: Fast Communication

Connectionless Design

UDP sends data without establishing a connection, making it much faster but less reliable than TCP.

✓ Advantages:

Low latency (no handshake)
Minimal protocol overhead
No connection state
Multicast/broadcast support

# UDP communication

socket.sendto(data, address)

# No handshake needed

# Immediate transmission

data = socket.recvfrom(1024)

UDP Header Structure

Source Port

Dest Port

Length

Checksum

Fixed 8 bytes

Simple & Efficient

Only 8 bytes of overhead vs TCP's 20+ bytes

Maximum Datagram

65,507 bytes (64KB - IP/UDP headers)

Checksum

Optional error detection (not correction)

Use Cases for UDP

🎮

Gaming

Low latency position updates, some packet loss acceptable

📺

Video Streaming

Real-time media where speed > perfect quality

🌐

DNS Queries

Simple request-response, fast lookups

TCP vs UDP Comparison

Feature	TCP	UDP
Connection	Connection-oriented	Connectionless
Reliability	Guaranteed delivery	Best effort
Ordering	Ordered	No guarantee
Error Detection	Yes + Correction	Basic checksum
Flow Control	Yes	No
Congestion Control	Yes	No
Header Size	20-60 bytes	8 bytes
Speed	Slower	Faster
Broadcasting	No	Yes
Use Cases	Web, Email, File Transfer	Gaming, Video, DNS, IoT

Real-World Protocol Usage

TCP Applications

HTTP/HTTPS

Web browsing requires reliable delivery of complete pages

Database Connections

SQL queries must be delivered completely and in order

File Transfers

FTP, SFTP ensure every byte is transferred correctly

Email (SMTP)

Message delivery must be guaranteed and complete

UDP Applications

Online Gaming

Player positions updated 60+ times per second

Live Video Streaming

Netflix, YouTube Live prefer current frames over old ones

Voice over IP (VoIP)

Real-time audio where slight drops are acceptable

IoT Sensors

Temperature readings sent frequently, occasional loss OK

Implementation Examples

TCP Server (Python)

import socket

# Create TCP socket

server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

server.bind(('localhost', 8080))

server.listen(5)

while True:

client, addr = server.accept()

# Reliable connection established

data = client.recv(1024)

client.send(b"HTTP/1.1 200 OK\\r\\n")

client.close()

UDP Server (Python)