TwoislandsofIPv6networksthatarerunningISIS(IPv6IGP)mustbeconnectedusingatunneloveranIPv4network.Whichtunnelingmethodcanbeusedtoachievethisgoal?() A.GREtunnelsB.automatic6to4tunnelsC.ISATAPtunnelsD.manualtunnels（RFC2893）
TwoislandsofIPv6networksthatarerunningISIS(IPv6IGP)mustbeconnectedusingatunneloveranIPv4network.Whichtunnelingmethodcanbeusedtoachievethisgoal?()
A.GREtunnels
B.automatic6to4tunnels
C.ISATAPtunnels
D.manualtunnels（RFC2893）