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Local-first · No real traffic
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DEVELOPER TOOLS / NETWORK SIMULATOR

Computer Network Simulator

Build an IPv4 topology, connect devices, inspect subnets, and follow a simulated packet through switches and routers—one step at a time.

Visual topologyIPv4 / CIDRRoute tracingDownloadable reports

INTERACTIVE WORKSPACE ON DEVICE

Network topology Ready

0 devices · 0 links
02 · NETWORK MAP

Interactive topology

Network topology

Drag nodes to arrange. Select a node or cable to edit. Arrow keys move a focused device. Colored links show packet progress.

03 · PACKET LAB

Trace a simulated packet

Not simulated
Delivery—
Router TTL left—
Link delay—

Choose two endpoints and simulate to see what happens at each hop.

Compare route choices or scan every pair of enabled endpoints to find connectivity problems.

04 · REACHABILITY

Connectivity matrix

Not scanned

Scans use the current routing mode and TTL, with each result showing delivery, drop or same device. A scan does not transmit network traffic.

Choose “Scan all endpoints” above.

Conceptual IPv4 forwarding model: shortest-link-cost discovery is an educational routing abstraction, not OSPF/BGP. No real packets are transmitted.

Local simulation · IPv4 onlyMax 35 devices · 70 links · 300 events

WORKFLOW GUIDE

Learn routing by making changes.

01

Design a topology

Place hosts, servers, switches and routers; connect them and set IPs, gateways and router interfaces.

02

Experiment with delivery

Trace a source-to-destination packet, step through forwarding, disable a cable or reduce TTL to see why it drops.

03

Document your results

Export an SVG network map, a CSV event trace, a printable report, and a ZIP containing the editable model.

Scope: logical IPv4 forwarding over Ethernet-like switched segments, directly connected networks and optional static next-hop routes. No ARP frames, real protocol stack, NAT, firewall, STP, VLANs, TCP retransmission, Wi-Fi radio, DNS/DHCP, or dynamic protocol convergence. Do not use as a production router configuration validator.

Using Computer Network Simulator

Build an educational topology, configure static IPv4 routes, and inspect simplified forwarding, packet paths, and reachability.

Workflow

  1. Add routers, hosts, and links to a topology, then configure the addresses and static next-hop routes.
  2. Trace a simulated packet through the forwarding inspector and review the ordered reachability matrix.
  3. Review warnings and export the full topology, routing, or connectivity report; recompute derived views after topology edits.

Worked example

Create two router-connected IPv4 segments with one host on each side. Add static next-hop routes, trace a simulated packet between the hosts, and inspect the reachability matrix before exporting the topology and route report.

Limits and data handling

This deterministic teaching model does not send real packets, run a complete protocol stack, or diagnose a production network. It simplifies layer-2 segments, next hops, link costs, and TTL. It supports up to 35 nodes and 70 links, with up to 20 routes per router. Route and matrix snapshots become stale after edits; browser storage is best effort. Diagrams export the complete topology regardless of camera zoom.

Frequently asked questions

Does the simulator send packets over my network?

No. Packet paths and reachability are simulated from the topology and static routes you create; no real packets are transmitted.

Do route results update automatically after I edit the topology?

Derived routes and matrices can become stale after edits. Recompute them before using or exporting the results.

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