Network documentation: what to record and how to keep it current
What network documentation should include — inventory, racks, cabling, IP addressing, topology and configs — and how to keep it accurate with automation. Includes a checklist.
It's 2 a.m. and a third-floor switch is down. The on-call engineer needs to know which rack it's in, which core port it uplinks to, which VLANs cross it and where its credentials are. If those answers live in one person's head, or in a spreadsheet last touched six months ago, the network isn't really documented.
What is network documentation?
Network documentation is a structured record of everything needed to design, operate, troubleshoot and extend the network: devices, physical locations, connections, addressing, configuration and ownership. Good documentation is complete, searchable and — above all — matches the real network.
What to document
Device inventory
For each device: name, type, vendor and model, serial number, firmware, management IP, MAC, location, owner, purchase date and warranty end.
Physical location
Building, floor, room, rack and rack unit. Rack elevations show where each device sits and where there's space without a trip to the server room.
Cabling and connections
Which port connects to which, and through which patch panel. Without it, a simple re-patch can become hours of troubleshooting.
IP addressing and VLANs
Subnets, VLANs, DHCP ranges, reservations and which device owns each IP — the job of an IPAM system. See our IPAM guide.
Logical topology
How devices connect at layers 2 and 3: core, distribution, access, WAN links and redundant paths.
Configuration and changes
Config versions and the history of who changed what, and when. See our config backup guide.
Why documentation always goes stale
The hard part isn't writing documentation; it's keeping it. Manual documentation starts decaying the day it's saved. After a few months nobody trusts it, and everyone goes back to relying on memory.
The golden rule: anything that can be read from the network should be read automatically. People should only record what a machine can't see — physical location and ownership.
What can be discovered automatically?
- Discovery scans reveal new and missing devices.
- LLDP/CDP builds the layer-2 topology from each device's neighbours.
- SNMP reads model, serial, interfaces and port state.
- DHCP and ARP show which IPs are really in use.
- Config backups replace “the config we think it has” with the real one.
Checklist to get started
- List your sites, rooms and racks.
- Run discovery across every IP range and register the devices.
- Enable SNMP so specs and interfaces are read automatically.
- Record each device's rack position and attach QR labels.
- Record core links and cable paths first.
- Load subnets and VLANs into IPAM.
- Move credentials into an encrypted vault.
- Turn on automatic config backups.
- Schedule recurring scans with change reports so the record stays current.
Conclusion
Documentation is a process, not a project. BehMon's documentation module combines inventory, racks, cabling, topology, IPAM and QR labels in one live record that updates with every scan.