AWS Transit Gateway is used to simplify your AWS network architecture (topology) by allowing to have transitive peering between hundreds and thousands of VPC and on-premise data centers.
- A transit gateway implements a hub-and-spoke network topology.
- It can be used across multiple AWS accounts using Resource Access Manager (RAM).
- It can use route tables to control access among VPCs.
- It works with VPN and Direct Connect.
- It supports IP multicast.
- A transit gateway scales elastically based on the volume of network traffic. Routing through a transit gateway operates at layer 3, based on their destination IP addresses.