The correct answers are B and C . During a migration from a legacy WAN, such as MPLS Layer 3 VPN, to Versa Secure SD-WAN, an SD-WAN gateway is used to allow communication between SD-WAN-enabled branches and legacy WAN sites. Versa SD-WAN design guidance states that an SD-WAN gateway allows sites connected to the SD-WAN VPN network to communicate with sites connected to a legacy MPLS VPN network. It also explains that this gateway facilitates route exchange between the MPLS underlay network and the SD-WAN VPN network, typically using a dynamic routing protocol such as BGP.

For this design, the hub or gateway must be configured with the Gateway option for the underlay transport so it can act as the interconnect point between the legacy and SD-WAN domains. Versa documentation further describes configuring a BGP peering session on the MPLS transport VR of the gateway to exchange routes from the MPLS provider to the SD-WAN network, and notes that Director Workflows can automate this configuration. Spoke-to-Spoke-Direct is not sufficient for legacy interconnect, and SD-WAN traffic steering policies do not advertise routes.