The best option for a cloud administrator who wants to deploy a VMware Cloud software-defined data center (SDDC) on a cloud provider and requires a consistent 4.5 Gbps bandwidth from applications to communicate from on-premises to the SDDC is a Route-Based Virtual Private Network (VPN). This type of connection offers enhanced performance [1][2], flexibility, scalability, and security compared to other options, such as Policy-Based Virtual Private Network (VPN), Private L2 Virtual Private Network (VPN), or Private Line.

According to the VMware official site, "Route-based VPN enables a secure connection between two or more sites, or between a site and a mobile user, and provides better performance and scalability than a policy-based VPN. Route-based VPNs are also more secure than policy-based VPNs, because the traffic is encrypted with a unique encryption key for each tunnel, rather than relying on a shared key for all tunnels. This allows for secure and reliable connections for devices and applications located in different physical locations." [1]

[1] https://docs.vmware.com/en/VMware-NSX-Data-Center/2.4/com.vmware.nsx.admin.doc/GUID-D6B7B9E9-E134-4C8A-8F2E-1C60A2FEDC1A.html