单项选择题
Based on the paragraph above,it is shown that in order to deploy IPv6 protocol on the Internet,separatednet work has to be built.The network devices which need to communicate with both networks are required to have upgraded software or () in the movement of IPv4 to IPv6 transition,network infrastructures are relatively slow in this event.
A.IPv6 software
B.translator facilities
C.operating systems
D.IPv4 software