What two features are benefits of using GRE tunnelswith IPsec over using IPsec tunnel
alone for building site-to-site VPNs? (Choose two.)

A.
allows dynamic routing securely over the tunnel

B.
IKE keepalives are unidirectional and sent every ten seconds

C.
reduces IPsec headers overhead since tunnel mode isused

D.
supports non-IP traffic over the tunnel

E.
uses Virtual Tunnel Interface (VTI) to simplify theIPsec VPN configuration