In a VPLS design solution, which situation indicates that BGP must be used instead of LDP in the control plane?

MAC address learning is a data plane function performed identically regardless of whether BGP or LDP is used as the VPLS control plane protocol.

While BGP VPLS supports certain interworking scenarios, VPLS interworking is not the primary technical driver that mandates choosing BGP over LDP.

In LDP-based VPLS (RFC 4762), every pseudowire between PE routers must be manually configured, resulting in O(n squared) configuration entries as the number of PEs grows. BGP-based VPLS (RFC 4761) uses BGP to automatically discover remote PEs participating in the same VPLS instance and signals pseudowire parameters without manual intervention, making it the correct choice when configuration overhead is a concern in large deployments.

BGP route reflectors reduce BGP session mesh overhead but VPLS still logically requires a full mesh of pseudowires between all PE routers in the VPLS domain regardless of the BGP topology.