A company uses a single Direct Connect link to connect its on-premises network to multiple VPCs (each with its own private VIF and VLAN) in the same Region and account. They will soon exceed the VPC and private VIF limits for that connection. What is the most scalable way to add more VPCs with on-premises connectivity?

The most scalable solution is to use a Transit Gateway with a Direct Connect Gateway and a transit VIF. A Transit Gateway acts as a central hub for network connections, allowing you to connect thousands of VPCs and on-premises networks through a single gateway. By attaching all VPCs to the Transit Gateway and then associating the Transit Gateway with a Direct Connect Gateway via a transit VIF, you consolidate all traffic over a single Direct Connect connection, overcoming the VIF and VPC limits per connection. Provisioning a new Direct Connect connection only defers the problem and increases operational overhead. Creating virtual private gateways with Site-to-Site VPNs is a valid solution for some scenarios but introduces VPN overhead and doesn't leverage the existing Direct Connect investment for the new VPCs. Creating a Direct Connect gateway with private VIFs for each VPC still faces the VIF limits and doesn't scale as efficiently as a Transit Gateway.