Connecting an Amazon EC2 instance to an Amazon Neptune cluster in a different VPC

An Amazon Neptune DB cluster can only be created in an Amazon Virtual Private Cloud (Amazon VPC), and its endpoints are only accessible within that VPC, usually from an Amazon Elastic Compute Cloud (Amazon EC2) instance running in that VPC.

When your DB cluster is in a different VPC from the EC2 instance you are using to access it, you can use VPC peering to make the connection:

A VPC peering connection is a networking connection between two VPCs that routes traffic between them privately, so that instances in either VPC can communicate as if they are within the same network. You can create a VPC peering connection between VPCs in your account, between a VPC in your AWS account and a VPC in another AWS account, or with a VPC in a different AWS Region.

AWS uses the existing infrastructure of a VPC to create a VPC peering connection. It is neither a gateway nor an AWS Site-to-Site VPN connection, and it does not rely on a separate piece of physical hardware. It has no single point of failure for communication and no bandwidth bottleneck.

See the Amazon VPC Peering Guide for more information about how use VPC peering.