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