Consider the configuration where the AWS Direct Connect location 1 home Region is the same as the VPC home Region. There is a redundant AWS Direct Connect location in a different Region There are two private VIFs (VIF A and VIF B) from AWS Direct Connect location 1 (us-east-1) to the Direct Connect gateway. There is one private VIF (VIF C) from AWS Direct Connect location (us-west-1) 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:
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VIF A (in us-east-1) advertises 172.16.0.0/16 and has an AS_PATH attribute of 65001, 65001, 65001
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VIF B (in us-east-1) advertises 172.16.0.0/16 and has an AS_PATH attribute of 65001, 65001
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VIF C (in us-west-1) advertises 172.16.0.0/16 and has an AS_PATH attribute of 65001
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 length.
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VIF C (in us-west-1) advertises 172.16.0.0/24 and has an AS_PATH attribute of 65001
