Busy night here! We've now launched AWS Transit Gateway aws.amazon.com/blogs/aws/new-… I think TGWs are going to be a really neat primitive for customers who are building big cloud foot prints. Here's some things you can do with them ...
First, you can use a Transit Gateway to interconnect two or more VPCs transitively .. it's a slot-in placement for the "Transit VPC" design pattern, without the need to use VPN tunnels.
Second, you can use a TGW to build a managed "border" network. You can, with a console or some API calls, build a border that can do things that often take million dollar routers! It's got support for routing domains for example.
Third, you can use a TGW to build a DMZ - insist that all traffic goes through a firewall or a VPS. It's now much easier to do this in general, and especially across several VPCs.
Fourth, you can use TGW as a VPN and Direct Connect concentrator. Land all your links in one place. Physical and virtual ones, including the ability to balance traffic across several!
Really brings it home for me: my first job was at an ISP where we spent maybe a year planning for 3 year build-outs of big transit networks. I can now replicate the same flexible configurations in a few minutes with some API calls. SDN for borders!!
