IPSim is a lightweight, Java-based network simulator (.jar) originally developed at the University of Salford to help computer science students practice and master subnetting and static routing skills.
The “IPSim Tutorial: How to Simulate and Test Routed Networks” is a step-by-step educational guide that teaches users how to visually manipulate hardware, assign IP addresses, configure routing logic, and verify data pathways. 🛠️ Core Capabilities of IPSim
Visual Topology Builder: Users drag and drop endpoints (PCs), Ethernet network interface cards (NICs), cables, and hubs to build physical network architectures.
IP Configuration: Supports custom network mask configurations (e.g., 255.255.255.0) and unique host IP assignments to map out boundaries.
Algorithmic Grading: It features a built-in grading engine across three difficulty levels. It compares your active configuration against a randomly generated networking problem to score your layout and path accuracy. 💻 Step-by-Step Tutorial: Simulating a Network
A foundational tutorial tracking a multi-subnet routed network generally follows these stages: 1. Assemble the Physical Layout
Place at least two computers (or separate local segments) on the digital canvas. Install Ethernet cards into each computer.
Connect the computers to central hubs or switches using virtual Ethernet cables.
Bridge the disparate subnets together by connecting the switches to an intermediary router. 2. Configure Subnets and Netmasks
Select the leftmost network host and alter its IP address (e.g., 1.1.1.1).
Set the target subnet mask (e.g., changing from a blank default 0.0.0.0 to a defined 255.255.255.0).
Replicate this step for the rightmost network host using a completely different subnet range. 3. Establish the Default Gateways
Access the target operating system settings or routing interfaces inside the simulation.
Manually input the Router’s interface IP address as the default gateway for each local PC segment.
Note: Hosts cannot send packets outside their local subnet without pointing to this service gateway. 4. Populate the Routing Table
Program the router with explicit static routes or subnet IDs so it knows how to handle traffic traveling to remote networks.
Define target paths using dotted-decimal syntax. For example, pointing specific host queries directly to a single destination link requires utilizing a strict host mask like 255.255.255.255. 🧪 Methods for Testing Connectivity
Once your routing tables are populated, you must test the data transmission paths to catch configuration errors:
Ping Command: Send an Internet Control Message Protocol (ICMP) echo request from a computer on Subnet A to an IP address on Subnet B. A successful echo response confirms full, bidirectional reachability.
Trace Route Command: Execute a traceroute to follow the hop-by-hop path of a packet. This reveals exactly which router interface discards your packets if a misconfigured static route breaks the link. Configure Your Network’s Routing – OpenClassrooms