VPN over Direct Connect with Direct Connect Gateway

If someone wants to run a VPN appliance (or two - for redundancy) in each VPC then this will work. But it's an expensive way to go (many virtual appliances required; potentially significant network resources on premises also required; probably lots of configuration as VPCs come and go) so I'm not sure I'd recommend it.

Another alternative is to use a Direct Connect Public VIF (which removes the requirement for Direct Connect Gateway) and have a VPN connection to Transit Gateway. This has the advantage of using a managed service at the AWS end but has a disadvantage of limiting flows to 1.5 Gb/s and overall bandwidth to 10 Gb/s.

Is using Direct Connect Gateway a requirement?

In summary: This is probably an area where I would dive deeper into the requirements for encryption and the best way to achieve connectivity - as it's going to be different for every customer.

Edit in 2022:

Customers should now consider using Private Site-to-Site VPN or Transit Gateway Connect.