Which two restrictions must the Enterprise Campus network designer consider when evaluatingWAN connectivity options？ （）

A、 OSPF over multicast EMS or VPLS network may not have consistent broadcast or multicastperformance

B、 IP multicast is not supported over Lover 3 MPLS VPN； instead a Layer 2 MPLS WN must beutilized with service provider support

C、 QoS requirements with MPLS-VPN must be implemented by the service provider

D、 Hierarchical VPLS designs are the least scalable

E、 IGMP snooping is not on option with VPLS or EMS； instead administrative scoping or allowingsufficient bandwidth for unnecessary multicast traffic at the edge links is required