In this lab, you will implement the following architecture to connect four VPCs via AWS Transit Gateway:
In lesson lab Setting up VPC Peering, you have been practicing setting up a Peering Connection between two VPC. Now imagine you have four VPCs that want to connect, how many Peering Connection? do you need?**
Answer: You need up to 6 Peering Connection to connect 4 VPCs. Imagine you need to connect six, eight, or even ten VPCs together. From that, you realize that the Peering Connection connection method is not highly scalable.
To work around the limitation of Peering Connection, AWS Transit Gateway is used to connect VPCs and on-premises networks through a central hub. This simplifies the network and ends complex routing relationships. It acts as a cloud router - each new connection is made only once.
AWS Transit Gateway Attachment is a tool to assign subnets of each VPC to be connected to an already initialized TGW. Transit Gateway Attachment operates on the scale of Availability Zone (AZ-level). In VPC, when a subnet in one AZ has a Transit Gateway Attachment with a TGW, other subnets in the same AZ can connect to that TGW.
This lab will result in fees for your AWS account. The instance will run all t3.nano. In addition, the lab has fees associated with Transit Gateway. Therefore, you will have to delete the lab template at the end of the lab to avoid additional costs.