iPerf3 Network Performance Testing Tool

Table of Contents

• Overview
• Installation
• Basic Syntax
• Common Use Cases
• Advanced Options
• Best Practices
• Troubleshooting

Overview

iPerf3 is a tool for active measurements of the maximum achievable bandwidth on IP networks. It supports tuning various parameters related to timing, buffers, and protocols (TCP, UDP, SCTP).

Key Features

• Measure bandwidth, loss, and jitter
• Support for IPv4 and IPv6
• Client and server functionality
• Multiple simultaneous connections
• TCP window size adjustment
• UDP bandwidth specification

Installation

Ubuntu (22.04/24.04)

sudo apt update
sudo apt install iperf3

MacOS

brew install iperf3

Basic Syntax

Server Mode

# Basic server
iperf3 -s
 
# Server on specific port
iperf3 -s -p 5201
 
# Server with detailed output
iperf3 -s -V

Client Mode

# Basic client test
iperf3 -c SERVER_IP
 
# Client with specific duration (in seconds)
iperf3 -c SERVER_IP -t 30
 
# Client with specific port
iperf3 -c SERVER_IP -p 5201

Common Use Cases

1. TCP Bandwidth Test

# Server
iperf3 -s
 
# Client
iperf3 -c SERVER_IP -t 30 -i 1

• -t 30: Run for 30 seconds
• -i 1: Output interval every 1 second

2. UDP Bandwidth Test

# Server
iperf3 -s
 
# Client
iperf3 -c SERVER_IP -u -b 100M

• -u: Use UDP
• -b 100M: Set bandwidth target to 100 Mbits/sec

3. Multiple Parallel Streams

# Test with 10 parallel streams
iperf3 -c SERVER_IP -P 10

4. Reverse Mode Test

# Server sends, client receives
iperf3 -c SERVER_IP -R

Advanced Options

TCP Window Size

# Set TCP window size
iperf3 -c SERVER_IP -w 256K

JSON Output

# Output results in JSON format
iperf3 -c SERVER_IP -J

Bidirectional Test

# Run bidirectional test
iperf3 -c SERVER_IP --bidir

Best Practices

1. Testing Methodology

   • Always run multiple tests
   • Test at different times of day
   • Use consistent test durations
   • Monitor system resources during tests

2. Security Considerations

   # Bind to specific IP
   iperf3 -s --bind SERVER_IP
    
   # Set authentication
   iperf3 -s --rsa-private-key-path /path/to/private_key

3. Performance Tips

   • Disable system sleep during tests
   • Close unnecessary applications
   • Monitor CPU usage
   • Consider network conditions

Troubleshooting

Common Issues and Solutions

1. Connection Refused

   # Check if server is running
   ps aux | grep iperf3
    
   # Verify port is open
   ss -tulpn | grep 5201

2. Poor Performance

   # Check CPU usage
   top -n 1
    
   # Monitor network interface
   ifconfig INTERFACE_NAME

3. Permission Issues

   # Check firewall rules
   sudo ufw status
    
   # Check port availability
   sudo lsof -i :5201

Debug Mode

# Run with debug output
iperf3 -s -d
iperf3 -c SERVER_IP -d

Example Test Scenarios

1. Network Baseline Test

# Run a 5-minute test with 1-second intervals
iperf3 -c SERVER_IP -t 300 -i 1

2. Maximum Performance Test

# Multiple streams with maximum buffer size
iperf3 -c SERVER_IP -P 10 -w 2M

3. Network Stability Test

# Long duration test with JSON output
iperf3 -c SERVER_IP -t 3600 -J > network_test.json

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Quick Reference

Essential Commands

# Start server
iperf3 -s
 
# Basic client test
iperf3 -c SERVER_IP
 
# UDP test
iperf3 -c SERVER_IP -u
 
# Reverse mode
iperf3 -c SERVER_IP -R
 
# JSON output
iperf3 -c SERVER_IP -J
 
# Multiple streams
iperf3 -c SERVER_IP -P 4

Common Flags

• -s: Server mode
• -c: Client mode
• -p: Port number
• -t: Time duration
• -i: Interval timing
• -u: UDP mode
• -b: Bandwidth target
• -R: Reverse mode
• -P: Parallel streams
• -J: JSON output
• -V: Verbose output