Networking Across Clouds

# AWS: Create a VPC
aws ec2 create-vpc \
  --cidr-block 10.0.0.0/16 \
  --tag-specifications 'ResourceType=vpc,Tags=[{Key=Name,Value=my-vpc}]'

# Create subnets in different AZs
aws ec2 create-subnet \
  --vpc-id vpc-12345 \
  --cidr-block 10.0.1.0/24 \
  --availability-zone us-east-1a

aws ec2 create-subnet \
  --vpc-id vpc-12345 \
  --cidr-block 10.0.2.0/24 \
  --availability-zone us-east-1b

# Azure: Create a VNet
az network vnet create \
  --name my-vnet \
  --resource-group my-rg \
  --address-prefixes 10.0.0.0/16 \
  --location eastus

# Create subnets
az network vnet subnet create \
  --name web-subnet \
  --vnet-name my-vnet \
  --resource-group my-rg \
  --address-prefixes 10.0.1.0/24

az network vnet subnet create \
  --name app-subnet \
  --vnet-name my-vnet \
  --resource-group my-rg \
  --address-prefixes 10.0.2.0/24

# GCP: Create a custom VPC with subnets in multiple regions
gcloud compute networks create my-vpc \
  --subnet-mode=custom

gcloud compute networks subnets create web-subnet \
  --network=my-vpc \
  --region=us-central1 \
  --range=10.0.1.0/24

gcloud compute networks subnets create app-subnet \
  --network=my-vpc \
  --region=europe-west1 \
  --range=10.0.2.0/24
# These subnets can communicate directly - no peering needed!

# OCI: Create a VCN
oci network vcn create \
  --compartment-id COMPARTMENT_OCID \
  --cidr-blocks '["10.0.0.0/16"]' \
  --display-name my-vcn

# Create a subnet
oci network subnet create \
  --compartment-id COMPARTMENT_OCID \
  --vcn-id VCN_OCID \
  --cidr-block 10.0.1.0/24 \
  --display-name web-subnet

# AWS: Create VPC Peering
aws ec2 create-vpc-peering-connection \
  --vpc-id vpc-11111 \
  --peer-vpc-id vpc-22222 \
  --peer-region us-west-2

# Accept the peering connection
aws ec2 accept-vpc-peering-connection \
  --vpc-peering-connection-id pcx-12345

# AWS: Create Transit Gateway (hub-and-spoke)
aws ec2 create-transit-gateway \
  --description "Hub for all VPCs"
aws ec2 create-transit-gateway-vpc-attachment \
  --transit-gateway-id tgw-12345 \
  --vpc-id vpc-11111 \
  --subnet-ids subnet-11111

# Azure: Create VNet Peering (bi-directional, two commands)
az network vnet peering create \
  --name vnet1-to-vnet2 \
  --resource-group rg1 \
  --vnet-name vnet1 \
  --remote-vnet /subscriptions/SUB_ID/resourceGroups/rg2/providers/Microsoft.Network/virtualNetworks/vnet2 \
  --allow-vnet-access

az network vnet peering create \
  --name vnet2-to-vnet1 \
  --resource-group rg2 \
  --vnet-name vnet2 \
  --remote-vnet /subscriptions/SUB_ID/resourceGroups/rg1/providers/Microsoft.Network/virtualNetworks/vnet1 \
  --allow-vnet-access

# GCP: VPC Peering (VPC is global, but peering connects separate VPCs)
gcloud compute networks peerings create vpc1-to-vpc2 \
  --network=vpc1 \
  --peer-network=vpc2 \
  --auto-create-routes

gcloud compute networks peerings create vpc2-to-vpc1 \
  --network=vpc2 \
  --peer-network=vpc1 \
  --auto-create-routes

# Example: AWS-to-GCP VPN tunnel
# Step 1: Create HA VPN gateway on GCP
gcloud compute vpn-gateways create aws-gcp-gateway \
  --network=my-vpc \
  --region=us-central1

# Step 2: Create Cloud Router for BGP
gcloud compute routers create aws-gcp-router \
  --region=us-central1 \
  --network=my-vpc \
  --asn=65001

# Step 3: Get GCP gateway IPs, create customer gateway on AWS
aws ec2 create-customer-gateway \
  --type ipsec.1 \
  --bgp-asn 65001 \
  --public-ip GCP_GATEWAY_IP_0

# Step 4: Create VPN connection on AWS
aws ec2 create-vpn-connection \
  --type ipsec.1 \
  --customer-gateway-id cgw-12345 \
  --vpn-gateway-id vgw-12345

# Step 5: Create VPN tunnels on GCP with AWS PSK
gcloud compute vpn-tunnels create aws-tunnel-0 \
  --region=us-central1 \
  --vpn-gateway=aws-gcp-gateway \
  --peer-external-gateway-interface=0 \
  --peer-external-gateway=aws-peer-gw \
  --shared-secret=AWS_GENERATED_PSK \
  --router=aws-gcp-router \
  --ike-version=2 \
  --interface=0