Which routing protocol requires minimal reconfiguration when establishing a MPLS Layer 3 VPN over DMVPN encrypted using GETVPN?

OSPF operates as an IGP and is not natively designed to carry VPN routing information between PE routers in an MPLS L3 VPN, requiring significant redistribution and configuration changes.

RIP lacks scalability and is not used as a control-plane protocol in MPLS L3 VPN architectures, making it unsuitable and requiring substantial reconfiguration.

IS-IS is an IGP used within the provider core for reachability but does not carry VPN customer routes between PE routers, so it would need extensive reconfiguration or redistribution for L3 VPN support.

BGP (specifically MP-BGP with VPNv4/VPNv6 address families) is already the standard control-plane protocol used between PE routers in an MPLS L3 VPN architecture to distribute VPN routes. Because GETVPN and DMVPN operate at the data and transport plane and do not change the BGP peering or VRF route-distribution model, BGP requires minimal reconfiguration compared to IGPs that would need additional overlay or redistribution work.