Key choices in AWS network design: VPC peering vs Transit Gateway and beyond

This blog post discusses Ably's journey in building the next iteration of their global network and the design decisions they faced. The company operates a global network spanning 8 AWS regions with hundreds of additional points-of-presences, providing unrivaled realtime messaging and data streaming performance, availability, and reliability. They decided to use VPC peering instead of Transit Gateway due to its cost-effectiveness and scalability. Multi-account support was achieved by creating a prod and nonprod VPC per region, with 3 public and private subnets per VPC each in a different availability zone. The company also chose to purchase a block of IPv6 space and will provision all VPCs and subnets as dual stack for easier routing between regions.