Which of the following statements about the merits of the HoVPN networking are true?

Which of the following statements about the merits of the HoVPN networking are true?
A . If the UPE are SPE are separated by an IP/IPMLS network, they can be connected through a generic routing encapsulation (GRE) or LSP runnel. A hierarchical MPLS VPN provides good scalability.
B . The SPE and UP exchange routes and advertise labels through MP-BG
C . Each UPE runs only one C BGP peer, reducing system overheads and simplifying configuration.
D . The BGP/MPLS VPN can be deployed layers by layer. When the performance of a super strum provider edge (SPE) is insufficient, a user-end provider edge (UPE) can be added and the SPE moved to a lower layer. When the access capability of a UPE is insufficient, and SPE can be added.
E . Packets are forwarded between a UPE and an SPE after being label. The UPE and SPE are connected through an interface (or a subinterface), helping reduce the usage of limited interface resources.
F . Only local VPN routes need to be maintained on an SPE and remote routes on the SPE are represented by a default route or an aggregate route, reducing the load of the SP

Answer: B, D, A