Networking

VPC Peering vs Transit Gateway Scaling

Network Design diagram · made in Skemio

Hierarchical network diagram showing public internet leading to an enterprise firewall, transit router, and multiple connected application and database VPC subnets.
Hierarchical network diagram showing public internet leading to an enterprise firewall, transit router, and multiple connected application and database VPC subnets.
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What it shows

  • Direct VPC peering scales at N*(N-1)/2, quickly hitting route table limits
  • AWS Transit Gateway acts as a central hub, cutting links from O(N^2) to O(N)
  • Centralized routing simplifies cross-VPC inspection and security policies

The takeaway

Replace full-mesh peering with a transit gateway the moment your architecture grows beyond 4 or 5 VPCs.

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