Depending on your ISP and or co-location provider the way that your AWS Direct Connect is implemented and how you configure it in you AWS account can vary.
If you go full steam ahead to the Direct Connect section of your AWS console and ‘create a connection’, essentially you are requesting that AWS allocate a physical port on their core switch in your co-location datacenter for your use. This requires that there be an existing AWS Direct Connect location in your co-location datacenter. Once this is done you are presented with an authorization letter (LOA-CFA), you give that to your co-location provider and they connect from your core switch to the AWS core switch. These can be 1Gbps or 10Gbps connections. There is a 72 hour lead time between creating this connection in your AWS account and receiving the authorization letter. This connection is owned by you. All in all this is a very comfortingly manual process for those of us who have spent long days in co-location datacenters locked in cages, racking hardware and connecting cables. When complete you then create a virtual interface (VIF) in the AWS console to begin using your AWS Direct Connect connection.
The more likely scenario for most of us is that our ISP is providing you with a hosted connection (NNI) or a hosted virtual interface (VIF) connection.
Hosted Connection, also referred to as a Network-Network-Interconnect (NNI) can be used where your network is not co-located with an existing AWS Direct Connect location. Instead you can request a sub-physical or child connection from your ISP, you own the child connection but the actual physical connection is owned by your ISP. This appear automatically in Virtual Interfaces under Direct Connect in your AWS console in a ‘pending acceptance’ state. You accept the connection and create virtual interfaces (VIF) to begin using your AWS Direct Connect connection. In this case, the bandwidth will be dedicated based on your agreement with the ISP.
Hosted Virtual Interface (VIF) also can be used where your network is not co-located with an existing AWS Direct Connect location, you can request a hosted virtual interface from your ISP, assuming they own a physical connection. Once the hosted VIF is created for you, it appears in your AWS console in a ‘pending acceptance’ state. You accept the connection and begin using the AWS Direct Connect connection. There can and most likely will be multiple customers with VIFs sharing a single physical connection. The bandwidth will be shared across all the VIFs and customers.
The above description of NNI and VIF assumes that your ISP is providing a link back to your MPLS cloud or similar extended network.It is also assumed in this article that your ISP is an AWS Direct Connect partner.
… thanks to Guru K. in AWS Support Service for clarifying information around this.