IPv4 Fragmentation with Dijkstra Routing

This program simulates IPv4 packet fragmentation and routes each fragment using Dijkstra's algorithm to find the shortest path through a network.

Features

• Create and visualize network topologies (predefined or custom)
• Generate IPv4 packets with custom payload sizes
• Fragment packets based on MTU constraints
• Calculate shortest paths for each fragment using Dijkstra's algorithm
• Support for dynamic network topology changes between fragment transmissions
• Detailed display of fragmentation and routing information

Project Structure

• src/main.c: Main program logic and workflow
• src/network.c & include/network.h: Network topology representation and management
• src/ipv4.c & include/ipv4.h: IPv4 packet structures and fragmentation functions
• src/dijkstra.c & include/dijkstra.h: Implementation of Dijkstra's shortest path algorithm
• src/ui.c & include/ui.h: User interface functions
• Makefile: Compilation instructions

Compilation

Use the provided Makefile to compile the program:

make

This will create an executable named network_sim in the build directory.

Usage

Run the compiled program:

./build/network_sim

Follow the interactive prompts to:

1. Choose or create a network topology
2. Specify source and destination nodes
3. Set MTU and payload size
4. View the fragmentation results and routing paths

Docker Support

You can also run the application using Docker, which ensures consistent execution across different systems:

Building the Docker Image

docker build -t ipv4-router .

Running the Application in a Docker Container

docker run -it ipv4-router

The -it flags ensure you can interact with the program's interface.

Module Details

Network Module

• Represents the network as an adjacency matrix
• Supports directed graphs with weighted edges
• Allows dynamic modification of the topology

IPv4 Module

• Creates IPv4 packets with proper headers
• Fragments packets according to IPv4 standards
• Handles fragment offset calculation in 8-byte units

Dijkstra Module

• Implements Dijkstra's algorithm for shortest path finding
• Constructs the complete path from source to destination
• Detects unreachable destinations

UI Module

• Provides user interface for input and visualization
• Displays network topology in multiple formats
• Shows detailed information about packets and fragments

Limitations

• Does not implement actual packet transmission
• Uses simplified addressing (node numbers instead of IP addresses)
• Does not handle IPv4 options
• Simplified checksum calculation

Extension Possibilities

• Add fragment reassembly at the destination
• Implement actual network simulation with packet transmission
• Add support for network failures and fault tolerance
• Extend with alternative routing algorithms