Skip to content
Subnetter Documentation

Subnetter Documentation

Eliminate IP conflicts with automated, hierarchical CIDR allocation
Get Started View on GitHub

What is Subnetter?

Subnetter is a specialized tool that automates the allocation of IPv4 CIDR blocks across cloud infrastructure environments. It eliminates the complexity and error-prone process of manual IP address management by providing deterministic, hierarchical, and conflict-free subnet allocation.

Multi-Cloud Support

Designed to work across AWS, Azure, GCP, and other cloud providers with consistent subnet allocation patterns.

Deterministic Results

Generate the same IP allocations every time, allowing consistent environment rebuilds and disaster recovery.

Hierarchical Allocation

Allocates IP space logically through accounts → regions → availability zones → subnet types.

No IP Conflicts

Automatically prevents overlapping IP ranges across your entire infrastructure.

Why Subnetter?

Manual allocation is error-prone

Hand-crafting CIDR blocks for hundreds of subnets leads to mistakes and overlaps.

Complex multi-cloud environments

Each cloud provider requires its own network architecture but needs to integrate with others.

Growing organizations need planning

Without proper IP allocation strategy, organizations need painful re-IP projects as they scale.

Documentation becomes outdated

Network diagrams and spreadsheets quickly become outdated as infrastructure evolves.

How It Works

Subnetter takes a hierarchical approach to IP allocation, dividing your IP space systematically across multiple cloud providers:

flowchart TD BaseCIDR["Base CIDR 10.0.0.0/8"] --> AWS["AWS 10.0.0.0/12"] BaseCIDR --> Azure["Azure 10.16.0.0/12"] BaseCIDR --> GCP["GCP 10.32.0.0/12"] %% AWS branch AWS --> AWSProd["Account: Production 10.0.0.0/16"] AWS --> AWSDev["Account: Development 10.1.0.0/16"] AWS --> AWSStage["Account: Staging 10.2.0.0/16"] %% AWS Production Account AWSProd --> AWSUsEast["Region: us-east-1 10.0.0.0/20"] AWSProd --> AWSUsWest["Region: us-west-2 10.0.16.0/20"] AWSUsEast --> AWSUsEast1a["AZ: us-east-1a 10.0.0.0/22"] AWSUsEast --> AWSUsEast1b["AZ: us-east-1b 10.0.4.0/22"] AWSUsWest --> AWSUsWest2a["AZ: us-west-2a 10.0.16.0/22"] AWSUsWest --> AWSUsWest2b["AZ: us-west-2b 10.0.20.0/22"] AWSUsEast1a --> AWSPublic1["Subnet: Public 10.0.0.0/24"] AWSUsEast1a --> AWSPrivate1["Subnet: Private 10.0.1.0/24"] %% Azure branch Azure --> AzureProd["Account: Production 10.16.0.0/16"] Azure --> AzureDev["Account: Development 10.17.0.0/16"] Azure --> AzureStage["Account: Staging 10.18.0.0/16"] %% Azure Production Account AzureProd --> AzureEastUS["Region: eastus 10.16.0.0/20"] AzureProd --> AzureWestUS["Region: westus 10.16.16.0/20"] AzureEastUS --> AzureEastUS1["AZ: eastus-1 10.16.0.0/22"] AzureEastUS --> AzureEastUS2["AZ: eastus-2 10.16.4.0/22"] AzureWestUS --> AzureWestUS1["AZ: westus-1 10.16.16.0/22"] AzureWestUS --> AzureWestUS2["AZ: westus-2 10.16.20.0/22"] AzureEastUS1 --> AzurePublic1["Subnet: Public 10.16.0.0/24"] AzureEastUS1 --> AzurePrivate1["Subnet: Private 10.16.1.0/24"] %% GCP branch GCP --> GCPProd["Account: Production 10.32.0.0/16"] GCP --> GCPDev["Account: Development 10.33.0.0/16"] GCP --> GCPStage["Account: Staging 10.34.0.0/16"] %% GCP Production Account GCPProd --> GCPUsEast["Region: us-east1 10.32.0.0/20"] GCPProd --> GCPUsWest["Region: us-west1 10.32.16.0/20"] GCPUsEast --> GCPUsEast1b["AZ: us-east1-b 10.32.0.0/22"] GCPUsEast --> GCPUsEast1c["AZ: us-east1-c 10.32.4.0/22"] GCPUsWest --> GCPUsWest1a["AZ: us-west1-a 10.32.16.0/22"] GCPUsWest --> GCPUsWest1b["AZ: us-west1-b 10.32.20.0/22"] GCPUsEast1b --> GCPPublic1["Subnet: Public 10.32.0.0/24"] GCPUsEast1b --> GCPPrivate1["Subnet: Private 10.32.1.0/24"] %% Styling classDef baseCidr fill:#f5f5f5,stroke:#333,stroke-width:2px classDef awsProvider fill:#FFEBEE,stroke:#D32F2F,stroke-width:2px classDef azureProvider fill:#E3F2FD,stroke:#1976D2,stroke-width:2px classDef gcpProvider fill:#E8F5E9,stroke:#388E3C,stroke-width:2px classDef account fill:#F3E5F5,stroke:#7B1FA2,stroke-width:2px classDef region fill:#FFF3E0,stroke:#E65100,stroke-width:2px classDef az fill:#E8EAF6,stroke:#3F51B5,stroke-width:2px classDef subnet fill:#FFFDE7,stroke:#FBC02D,stroke-width:2px class BaseCIDR baseCidr class AWS,AWSProd,AWSDev,AWSStage,AWSUsEast,AWSUsWest,AWSUsEast1a,AWSUsEast1b,AWSUsWest2a,AWSUsWest2b,AWSPublic1,AWSPrivate1 awsProvider class Azure,AzureProd,AzureDev,AzureStage,AzureEastUS,AzureWestUS,AzureEastUS1,AzureEastUS2,AzureWestUS1,AzureWestUS2,AzurePublic1,AzurePrivate1 azureProvider class GCP,GCPProd,GCPDev,GCPStage,GCPUsEast,GCPUsWest,GCPUsEast1b,GCPUsEast1c,GCPUsWest1a,GCPUsWest1b,GCPPublic1,GCPPrivate1 gcpProvider

Multi-Cloud Hierarchical Allocation

Subnetter allows you to manage your IP space across different cloud providers with a hierarchical approach:

  1. Base CIDR: Start with a single large CIDR block (e.g., 10.0.0.0/8)

  2. Cloud Providers: Divide the base CIDR into non-overlapping blocks for each cloud provider

    • AWS: 10.0.0.0/12
    • Azure: 10.16.0.0/12
    • GCP: 10.32.0.0/12

  3. Accounts: Allocate provider-specific CIDRs to different accounts

    • Production: 10.0.0.0/16 (AWS), 10.16.0.0/16 (Azure), 10.32.0.0/16 (GCP)
    • Development: 10.1.0.0/16 (AWS), 10.17.0.0/16 (Azure), 10.33.0.0/16 (GCP)
    • Staging: 10.2.0.0/16 (AWS), 10.18.0.0/16 (Azure), 10.34.0.0/16 (GCP)

  4. Regions: For each account and provider, allocate CIDRs to regions

    • us-east-1: 10.0.0.0/20 (AWS)
    • eastus: 10.16.0.0/20 (Azure)
    • us-east1: 10.32.0.0/20 (GCP)

  5. Availability Zones: Divide region CIDRs among AZs

    • us-east-1a: 10.0.0.0/22 (AWS)
    • eastus-1: 10.16.0.0/22 (Azure)

  6. Subnets: Finally, create subnet CIDRs in each AZ based on type

    • Public: 10.0.0.0/24 (AWS), 10.16.0.0/24 (Azure)
    • Private: 10.0.1.0/24 (AWS), 10.16.1.0/24 (Azure)
    • Data: 10.0.2.0/24 (AWS)

Each step of this process is automated by Subnetter, ensuring consistent, non-overlapping CIDR allocation across your entire multi-cloud environment.

Quick Start

Terminal window
# Install globally
npm install -g subnetter


# Generate allocations
subnetter generate --config config.json --output allocations.csv

Documentation Overview

User Guide

Comprehensive guide covering installation, configuration, usage examples, and best practices.

Read the User Guide

API Documentation

Reference for developers using Subnetter programmatically in their Node.js applications.

Browse API Docs

Key Resources

CIDR Primer

Learn about CIDR notation and IP subnetting concepts.

Read CIDR Primer

Architecture

Understand Subnetter’s technical design and components.

View Architecture

Developer Guide

Guidelines for contributing to the Subnetter codebase.

Developer Guide

Error Handling

Detailed information about error types, codes, and handling.

Error Handling