LanTopoLog: Visual Network Mapping with Switch-Level Insight
LanTopoLog is a niche but practical tool for Windows admins who want to visualize their LAN topology — not just by IP range or ping response, but by actual switch port connectivity. It queries SNMP-enabled switches, matches MAC addresses to hosts, and builds a live topology diagram with port-to-device resolution.
While the interface is dated, the underlying idea is still rare among free tools: physical layer visibility without expensive NMS platforms.
What It Can Do
| Feature | Purpose |
| Switch port discovery | Uses SNMP to identify which MAC addresses are plugged into which switch ports. |
| Layer 2 topology mapping | Builds a visual diagram of how devices are physically linked. |
| Host identification | Maps IP, hostname, and MAC to switch ports. |
| Device tracking | Monitors when endpoints connect/disconnect from the network. |
| Scheduled scans | Runs periodic polling to detect topology changes. |
| CSV/XML export | Outputs device inventory or port maps for documentation. |
| No agents required | Works with SNMP-enabled switches only. |
| Freeware license | Fully functional for single-site environments. |
When It’s Useful
– Troubleshooting who’s plugged into what — in a mess of unmanaged desktops
– Mapping out Layer 2 topology during infrastructure audits
– Tracking device moves in office relocations
– Documenting port-to-host assignments for switch configs
– Replacing manual diagrams with auto-generated network maps
Installation and Setup
1. Download the installer
Official site: http://www.lantopolog.com
2. Install on a Windows host
The tool runs as a GUI application. No server-side service needed.
3. Configure SNMP community strings
Add read-only community credentials for switches under “SNMP Settings.”
4. Add switches manually
Specify switch IPs or import from a list. Automatic discovery is limited.
5. Run scan
LanTopoLog will walk each switch, read MAC tables, and correlate them with ARP data.
6. View the map
Devices are displayed as icons linked to switch ports. Hover or click to see IP, MAC, host, and port data.
7. Export data
Save maps, host tables, or port assignments in CSV or XML for reference.
Known Limitations
– Windows-only
– SNMP v1/v2c only — no v3 support
– Interface is functional but outdated
– Doesn’t track wireless or virtual infrastructure
– Switches must support SNMP and provide complete MAC tables
– Best used in small or mid-sized networks with known switch inventory
Why It’s Still Useful
LanTopoLog solves a very specific problem: mapping physical switch ports to connected devices. Most network monitoring tools don’t go there, or they require full-stack NMS solutions with licensing fees. For wired networks with SNMP-enabled gear, this tool gives visibility where it’s often lacking — at the cabling layer.
It’s not flashy, but when you need to answer “who’s using port 23 on that closet switch,” LanTopoLog gives a clear, no-nonsense answer.
