Private virtual interface routing example - AWS Direct Connect

Private virtual interface routing example

Consider the configuration where the AWS Direct Connect location 1 home Region (east) is the same as the VPC home Region. There is a redundant AWS Direct Connect location 2 in a different Region (west). There are two private VIFs from AWS Direct Connect location 1 to the Direct Connect gateway. There is one private VIF from AWS Direct Connect location 2 to the Direct Connect gateway. To have AWS route traffic over VIF B before VIF A, set the AS_PATH attribute of VIF B to be shorter than the VIF A AS_PATH attribute.

The VIFs have the following configurations:

  • VIF A (in us-east-1) advertises 172.16.0.0/16 and has an AS_PATH attribute of 65001, 65001, 65001

  • VIF B (in us-east-1) advertises 172.16.0.0/16 and has an AS_PATH attribute of 65001, 65001

  • VIF C (in us-west-1) advertises 172.16.0.0/16 and has an AS_PATH attribute of 65001


                Private VIF Routing no AS_PATH

If you change the CIDR range configuration of VIF C, routes that fall in to the VIF C CIDR range use VIF C because it has the longest prefix match.

  • VIF C (in us-west-1) advertises 172.16.0.0/24 and has an AS_PATH attribute of 65001


                Private VIF Routing