Network Documentation Best Practices for IT Teams

Network Documentation Best Practices

Good documentation is the difference between a 2-hour fix and a 2-day outage. These are the essentials.

What to Document

Network topology diagrams (L1, L2, L3)
IP address management (IPAM)
Device inventory with firmware versions
Configuration baselines
Change log
Runbooks for common procedures

Topology Diagram Layers

Layer 1 (Physical):

Which cable goes where
Patch panel numbering
Rack diagrams with U positions

Layer 2 (Logical):

VLAN assignments
Switch port to device mapping
Trunk links

Layer 3 (IP):

Subnets and gateway IPs
Routing protocols and neighbors
Static routes

Use draw.io (free), Visio, or Lucidchart. Export as SVG for version control.

IPAM in Spreadsheet Format

TEXT

| Network       | VLAN | Gateway      | Purpose     | DHCP Range               |
|---------------|------|--------------|-------------|--------------------------|
| 10.10.0.0/24  | 10   | 10.10.0.1    | Management  | Static only              |
| 10.10.1.0/24  | 20   | 10.10.1.1    | Corporate   | 10.10.1.100-10.10.1.200  |
| 10.10.2.0/24  | 30   | 10.10.2.1    | Guest WiFi  | 10.10.2.10-10.10.2.250   |
| 10.10.3.0/24  | 40   | 10.10.3.1    | Servers     | Static only              |
| 10.10.4.0/24  | 50   | 10.10.4.1    | VoIP        | 10.10.4.10-10.10.4.100   |

Device Inventory

TEXT

| Hostname | IP          | Type    | Model          | Firmware | Location    | Notes        |
|----------|-------------|---------|----------------|----------|-------------|--------------|
| rtr-hq   | 10.10.0.1   | Router  | RB4011iGS+RM   | 7.14.2   | HQ-Rack1-U1 | Core router  |
| sw-core  | 10.10.0.2   | Switch  | CRS354-48G     | 7.14.2   | HQ-Rack1-U2 | Core switch  |
| fw-hq    | 10.10.0.3   | Firewall| FG-200F        | 7.4.3    | HQ-Rack1-U4 | Edge FW      |

Change Log Format

MARKDOWN

## 2025-06-15 — VLAN 50 Added for VoIP

**Changed by:** H. Habibazar  
**Approved by:** IT Manager  
**Ticket:** IT-1234  

**Changes made:**
- Added VLAN 50 on all switches (sw-core, sw-access-1, sw-access-2)
- Configured DHCP scope 10.10.4.10-100 on rtr-hq
- Updated IP phones to receive VLAN 50 LLDP-MED config
- Added QoS markings for DSCP EF on VoIP traffic

**Rollback procedure:**
- Remove VLAN 50 from all switches
- Delete DHCP scope

Tools Recommendation

Free: draw.io + GitHub/GitLab for version control
IPAM: phpIPAM (self-hosted, free)
Wiki: Outline, Notion, or Confluence
Network config backup: Oxidized (free, auto-backup via SNMP/SSH)