When you configure a 6to4 tunnel, you specify only the local IPv6 address, which has the local IPv4 address embedded in it. You do not have to specify the tunnel destination - that is done by recovering the IPv4 destination from bits 17 to 48 of the IPv6 destination. In that way 6to4 is multipoint covering the whole IPv4 address range.
So how does IPv6 multicasting work through the tunnel? Does the router map the IPv6 multicast destination onto an IPv4 multicast destination somehow? But if that is so, when the packet is decapsulated at the other end, how can the remote router recover the IPv6 multicast destination, given that there are many more IPv6 multicast addresses than IPv4.
Can anyone point me to a book or document that discusses this aspect of 6to4?
Kevin Dorrell
Luxembourg