🧮 Subnetting Mastery
9 min de lecture
IP Addressing Plan Template
A complete IP addressing plan template for enterprise networks, covering documentation standards, allocation strategies, and IPAM best practices.
Why Document Your IP Plan?
An IP addressing plan is the single most important network document. Without it, teams make conflicting assignments, subnets overlap, and troubleshooting becomes guesswork.
A good IP plan answers:
- What subnets exist and where?
- Who owns each allocation?
- What is reserved for growth?
- How do sites interconnect?
Plan Structure
An enterprise IP plan should have four sections:
1. Site Summary
| Site | Supernet | Location | Contact |
|---|---|---|---|
| HQ | 10.1.0.0/16 | New York | [email protected] |
| DC-East | 10.2.0.0/16 | Virginia | [email protected] |
| Branch-EU | 10.3.0.0/16 | London | [email protected] |
| VPN Pool | 10.255.0.0/16 | N/A | [email protected] |
2. Subnet Detail
For each site, document every subnet:
Site: HQ (10.1.0.0/16)
------------------------------------------------------
Subnet VLAN Name Hosts Gateway
10.1.1.0/24 10 Corporate 254 10.1.1.1
10.1.2.0/24 20 Engineering 254 10.1.2.1
10.1.3.0/24 30 VoIP 254 10.1.3.1
10.1.4.0/24 40 Guest-WiFi 254 10.1.4.1
10.1.10.0/24 100 Servers 254 10.1.10.1
10.1.11.0/24 101 Database 254 10.1.11.1
10.1.254.0/28 999 Management 14 10.1.254.1
10.1.255.0/30 -- WAN to DC 2 10.1.255.1
3. Reserved Ranges
Always document what is intentionally unallocated:
10.1.5.0/24 -- 10.1.9.0/24 Reserved for future VLANs
10.1.12.0/24 -- 10.1.253.0/24 Reserved for growth
10.0.0.0/16 Reserved (do not use)
4. Allocation Policy
Define rules before anyone starts assigning:
- Gateways always use .1 in every subnet
- Static servers use .10 -- .49
- DHCP pools start at .50
- Point-to-point WAN links use /30 or /31
- New sites get a /16 from the 10.x.0.0 range
- VPN pools must not overlap with any site
IPAM Tools
For organizations beyond 5 subnets, a spreadsheet becomes error-prone. Use an IP Address Management (IPAM) tool:
| Tool | Type | Best For |
|---|---|---|
| phpIPAM | Open source, self-hosted | Small/medium orgs |
| NetBox | Open source (DigitalOcean) | Network automation |
| Infoblox | Commercial | Large enterprise |
| AWS VPC IPAM | Cloud-native | AWS environments |
| SolarWinds IPAM | Commercial | Multi-vendor |
Versioning and Reviews
Treat your IP plan like code:
- Store it in version control (Git)
- Require peer review for changes
- Run automated validation to catch overlaps
- Review the full plan quarterly