What is the MOST cost-effective solution to connect these VPCs?
Implement AWS Transit Gateway to connect the VPCs. Update the route tables of each VPC to use the transit gateway for inter-VPC communication.
Implement an AWS Site-to-Site VPN tunnel between the VPCs. Update the route tables of each VPC to use the VPN tunnel for inter-VPC communication.
Set up a VPC peering connection between the VPCs. Update the route tables of each VPC to use the VPC peering connection for inter-VPC communication.
Set up a 1 GB AWS Direct Connect connection between the VPCs. Update the route tables of each VPC to use the Direct Connect connection for inter-VPC communication.
Explanations:
AWS Transit Gateway is a scalable and highly available option for connecting multiple VPCs and on-premises networks. However, it is generally more expensive than VPC peering and may not be cost-effective for just two VPCs with relatively low data transfer requirements.
AWS Site-to-Site VPN is suitable for securely connecting on-premises networks to AWS, but it incurs additional costs related to VPN usage and may introduce latency. It is typically not the most cost-effective solution for direct VPC-to-VPC communication.
VPC peering allows for direct communication between two VPCs within the same region, and there are no data transfer costs for traffic within the same region when using peering connections. This makes it the most cost-effective solution for the required 500 GB data transfer between the two VPCs.
AWS Direct Connect provides a dedicated network connection from on-premises to AWS, which is costly and unnecessary for VPC-to-VPC communication. The cost of establishing and maintaining a Direct Connect connection is typically higher than other options for this scenario.
I rank that the answer is:
Set up a VPC peering connection between the VPCs. Update the route tables of each VPC to use the VPC peering connection for inter-VPC communication.