vpc-design

# Skill: VPC / Network Design > **Expertise:** CIDR planning, zone-redundant subnets, routing tables, NAT, VPN/peering — AWS, GCP, Hetzner, and bare-metal. ## When to load When designing a new network for a cloud environment or bare-metal cluster, planning subnets, or diagnosing routing issues. ## CIDR Allocation Strategy ``` Organization supernet: 10.0.0.0/8 Environment blocks: production: 10.10.0.0/16 (65,534 addresses) staging: 10.20.0.0/16 dev: 10.30.0.0/16 Per-environment subnet layout (/16 → four /18 zones): Zone A (eu-west-1a): 10.10.0.0/18 (16,382 IPs) Public subnet: 10.10.0.0/20 (4,094 IPs — load balancers, NAT GW) App subnet: 10.10.16.0/20 (4,094 IPs — K8s nodes) Data subnet: 10.10.32.0/20 (4,094 IPs — databases, Redis) Zone B (eu-west-1b): 10.10.64.0/18 (same subdivision pattern) Zone C (eu-west-1c): 10.10.128.0/18 (same subdivision pattern) Reserved / Management: 10.10.192.0/18 Management subnet: 10.10.192.0/24 (jump hosts, CI runners) Future expansion: 10.10.193.0/18 ``` ## Terraform: AWS VPC Module ```hcl module "vpc" { source = "git::https://git.example.com/infra/modules//vpc?ref=v2.1.0" project = var.project environment = var.environment cidr = "10.10.0.0/16" azs = ["eu-west-1a", "eu-west-1b", "eu-west-1c"] public_subnets = ["10.10.0.0/20", "10.10.64.0/20", "10.10.128.0/20"] private_subnets = ["10.10.16.0/20", "10.10.80.0/2...