Having come this far in your CCNA studies, you should be well familiar with the concepts of static and dynamic IPv4 addresses. Static IPv4 addresses are permanently assigned to devices like servers and routers that need to have persistent addresses. Other devices like PCs can live with IPv4 addresses assigned dynamically by DHCP (Dynamic Host Configuration Protocol). IPv6 uses the same general scheme, with devices like servers and routers using pre-configured IPv6 addresses, while user devices making use of dynamically learned IPv6 addresses. In this section, we will configure different types of IPv6 addresses used by routers to participate in different protocols.
Enterprise networks have been using IPv4 as the exclusive protocol for quite some time now. In other words, TCP/IP has been the only protocol stack in use in company networks. IPv6 is the new protocol that is supposed to replace IPv4 over time, requiring end-user hosts, servers, routers, and all other networked devices to implement IPv6. You probably can understand that the world cannot migrate all IPv4 devices to IPv6 in a week or month. The migration will rather be a process that will occur gradually, and one that has already started. Most companies will gradually migrate from IPv4 to IPv6 and the process may span years. In the mean time, most enterprise networks will be a mix of IPv4 and IPv6 protocol stacks. Our guess is that the process will be quite slow and you will still have to deal with IPv4 for the rest of your working life.
You will hear a lot about dual-stack strategy for implementing IPv6 in enterprise networks. The strategy offers a gradual migration path from IPv4 to IPv6 letting IPv4 and IPv6 to coexist. The routers are configured with IPv6 addresses on their interfaces, and they router IPv6 packets just like they route IPv4 packets. The hosts can implement IPv6 when ready, running dual stack or running both IPv4 and IPv6.