How is the RouterLink port created between a Tier-1 Gateway and Tier-O Gateway?

The RouterLink port is automatically created when a Tier-1 Gateway is connected with a Tier-0 Gateway from the NSX UI1. The RouterLink port is a logical interface that is assigned an IP address and is associated with a physical or virtual interface. The RouterLink port acts as an end point of the IPSec tunnel and routes traffic between the Tier-1 Gateway and the Tier-0 Gateway2. The other options are incorrect because they involve manual creation of logical switches or segments, which are not required for RouterLink port creation. References: Configure NSX for Virtual Networking from vSphere Client, Virtual Private Network (VPN)

https://docs.vmware.com/jp/VMware-NSX/4.0/administration/GUID-3F163DEE-1EE6-4D80-BEBF-8D109FDB577C.html