IPv6 in real life network

IPv4 and IPv6 packet can coexist on the same medium

Normally IPv6-only node can talk with IPv6 node only
Need to click www.yahoo.com...

IPv4/v6 dual stack node
A node that can speak both
Use IPv4 to talk with IPv4 node, IPv6 to IPv6 node
You can even use NAT for IPv4 communication
NAT network for IPv4, global network access for IPv6

Translator (between IPv6 only and IPv4 only nodes)
Appilication layer: web proxy, fwtk, sendmail
TCP layer: socks, fwtk
IP layer: header translation
Similar to NAT
Not end-to-end, single point of failure