What is required to allow for FCoE multihop prior to the ratification of FC-BB-6?

What is required to allow for FCoE multihop prior to the ratification of FC-BB-6?

A.
VN to VF encapsulation

B.
FIP snooping

C.
FCoE proxy

D.
Fibre Channel bridging at FC-2

E.
VE to VE tunneling