AWS vs. GCP VPC architecture deep dive

Summary

Introduction: Modern cloud-native companies (e.g. Airbnb, Netflix) operate complex virtual networks to support global, large-scale services. Achieving scalable, secure, and highly available networking in the cloud requires careful VPC architecture design. This report compares AWS and GCP best practices for Virtual Private Cloud (VPC) networks at enterprise scale. We focus on VPC structure, subnet segmentation, multi-account/project design, shared VPC strategies, cross-region connectivity, service isolation, and secure access patterns, with high-level ASCII diagrams illustrating key topologies. AWS VPC Architectures at Scale AWS’s Virtual Private Cloud provides an isolated networking environment per AWS account and region. Large organizations like Netflix and Airbnb leverage multiple AWS accounts and VPCs to achieve isolation, scalability, and resilience. This section covers standard AWS VPC layouts, multi-VPC/multi-account designs, transit connectivity, service isolation mechanisms, and security patterns in large AWS environments. Standard AWS VPC Layout and Subnet Segmentation A standard AWS VPC typically spans an entire AWS region (one VPC per region per account), divided into subnets (per Availability Zone) for different tiers (public, private, database, etc.). Subnets allow segmenting resources and controlling access via route tables and network ACLs. A common pattern is a 3-tier network: public subnets for front-end load balancers or bastions, private subnets for application servers, and isolated subnets for databases. Internet Gateways (IGW) attach to the VPC to allow outbound internet access from public subnets, while NAT Gateways in public subnets enable instances in private subnets to reach out to the internet securely (for updates, external API calls) without exposing those instances to inbound traffic. Security Groups (stateful instance-level firewalls) and Network ACLs (stateless subnet-level ACLs) enforce inbound/outbound rules for defense in depth. The...