A company has a Direct Connect private virtual interface (VIF) tied to a Direct Connect gateway from its US on-premises data center. After adding a new European data center with its own Direct Connect connection and private VIF attached to the same Direct Connect gateway, the company wants to enable Direct Connect SiteLink so the two data centers have a private inter-site network. What is the most operationally efficient way to do this?

Enabling SiteLink on the existing private VIFs is the most operationally efficient way because SiteLink is designed to extend connectivity between on-premises networks connected to the same Direct Connect gateway using their existing private VIFs. This avoids creating new infrastructure. Provisioning new public or transit VIFs is unnecessary; public VIFs are for public AWS services, and transit VIFs are for Transit Gateway, neither of which is required for SiteLink between data centers. Creating an AWS Site-to-Site VPN is an alternative for inter-site connectivity but is not Direct Connect SiteLink and adds complexity and cost compared to simply enabling SiteLink on existing VIFs.