Which two features prevent routing loops between the OSPF sites of a customer when the sites aremultihomed or a backdoor link is used between the sites？ （）

A.R1（config-route-at）#
B.R1（config-route-map）#
C.R1（config-it）#
D.R1（config-vrf）#
E.R1（config）#
F.R1（router）#

A.P2MP TE uses an OSPF extension that is different from the OSPF extension that is used in P2P TE
B.Loose path is not supported in P2MP TE
C.Multiple IP multicast groups can map to one P2MP tunnel
D.Affinity is not supported in P2MP TE
E.P2MP TE uses Constrained Shortest Path First （CSPF） to calculate paths

A.It supports ATM signaling.
B.It supports traffic shaping of packets in MPLS to the ATM path.
C.It supports ATM switched virtual circuits
D.It supports fragmentation and reassembly.
E.It supports AAL5 SDU switching