Dual Stacking
Dual stacking is the most common type of migration strategy because, well, it’s the easiest on
you—it allows your devices to communicate using either IPv4 or IPv6. Dual stacking lets you
upgrade your devices and applications on the network one at a time. As more and more hosts and
devices on the network are upgraded, more of your communication will happen over IPv6,
and after you’ve arrived, everything is running on IPv6, and you get to remove all the old
IPv4 protocol stacks you no longer need.
Plus, configuring dual stacking on a Cisco router is amazingly easy—all you have to do is
enable IPv6 forwarding and apply an address to the interfaces already configured with IPv4.
It’ll look something like this:
Corp(config)#ipv6 unicast-routing
Corp(config)#interface fastethernet 0/0
Corp(config-if)#ipv6 address 2001:db8:3c4d:1::/64 eui-64
Corp(config-if)#ip address 192.168.255.1 255.255.255.0
But to be honest, it’s really a good idea to understand the various tunneling techniques
because it’ll probably be a while before we all start running IPv6 as a solo routed protocol.