AWS Quick Notes — AWS Transit Gateway
When there are multiple VPCs need to be connected to each other and also there may be connections such as Direct Connect.
The transit gateway serves as a hub and spoke connection facilitator for VPCs.
Also a Direct Connect connection from a on premise data center to an AWS VPC can be brokered through a transit gateway.
This way you can connect your on prem data center to one or more VPCs.
Route tables are used to manage what VPCs can talk to others or not.
Transit Gateway supports IP Multicast.
Site to Site VPN ECMP
To increase the bandwidth of a connection to AWS, multiple site to site VPN connections can be used. This is where routing strategies such as ECMP(Equal cost, multiple paths) are used to forward the packet over multiple paths, choosing the best path, etc.
VPN to transit gateway can allow for multiple VPNs connecting into it.
Sharing Direct Connect between accounts
A transit gateway also lets you share direct connect connection across AWS accounts.
- A direct connect connection is first set up between the on-premises data center and AWS Direct Connect endpoint.
- A transit gateway is setup that connects into multiple VPCs into multiple different accounts.
- The Direct Connect Endpoint then connects into the transit gateway.
