IPv6 in real life network

IPv6-capable node needs to be able to talk with IPv4-only node
Need to click www.yahoo.com...

IPv4/v6 dual stack
Ethernet protocol type is different - they can coexist
IPv4/v6 dual stack node can speak with IPv4-only node
You can even use NAT for IPv4 communication
NAT network for IPv4, global network access for IPv6

Translator (for IPv6 only nodes)
Appilication layer: web proxy, fwtk, sendmail
TCP layer: socks, fwtk
IP layer: header translation

Has same problem with NAT (not end-to-end, single point of failure)