Which of the following methods of tunneling Internet Protocol version 6 (IPv6) traffic through an IPv4 network
increases protocol overhead because of IPv6 headers?

A.
Protocol translation

B.
IPv6 over dedicated WAN links

C.
Dual-Stack Backbones

D.
IPv6 over IPv4 tunnels

Explanation:
IPv6 over IPv4 tunnels is a method of tunneling IPv6 traffic through an IPv4 network that eliminates the need to
create separate circuits to connect to the IPv6 networks. This model increases protocol overhead because of
IPv6 headers.
The following deployment models are available for IPv4 to IPv6 migration:
IPv6 over IPv4 tunnels: IPv6 traffic is encapsulated into IPv4 packets. Then these packets are transferred
over IPv4 WAN. This model eliminates the need to create separate circuits to connect to the IPv6 networks.
This model increases protocol overhead because of the IPv6 headers and requires both ends to be capable
of both protocols.
Protocol translation: A method allowing an IPv6 host to communicate with an IPv4 host. This is
accomplished with the help of Network Address Translation – Protocol Translation (NAT-PT) used to
configure translation between IPv6 and IPv4 hosts. NAT-PT allows communication between IPv6 hosts and
applications, and native IPv4 hosts and applications.
IPv6 over dedicated WAN links: A new deployment of IPv6 is created. In this model, IPv6 hierarchy,
addressing, and protocols are used by all nodes. However, this model involves cost for creating IPv6 WAN
circuits. This solution is not designed for LAN translation but rather translation over WAN links.
Dual-Stack Backbones: A hybrid model in which backbone routers have dual-stack functionality, which
enables them to route both IPv4 and IPv6 packets. It is suitable for an enterprise that uses both IPv4 and
IPv6 applications. Running IPv6 and IPv4 together in a network is known as dual-stack routing.
Objective:
Network Fundamentals
Sub-Objective:
Identify the appropriate IPv6 addressing scheme to satisfy addressing requirements in a LAN/WAN
environment

Cisco > Technology Support > IP > IPv6 > Configure > Configuration Examples and TechNotes > Tunneling
IPv6 through an IPv4 Network > Document ID: 25156