Transition from IPv4 to IPv6

Transition from IPv4 to IPv6

There are several ways to integrate an IPv6 structure into an existing IPv4 network. The transition from IPv4 to IPv6 does not have to be done all at once. The three most common transition methods are:

• Dual stack
• Tunneling
• Proxying and translation

In the Dual Stack transition method, both IPv4 and IPv6 configurations are implemented on a network device. Both protocol stacks run on the same device. This method enables IPv4 and IPv6 to coexist.

Tunneling is a technique that is becoming more prominent as the adoption of IPv6 grows. Tunneling is the encapsulation of one protocol packet within another protocol. For example, an IPv6 packet can be encapsulated within an IPv4 protocol.

Cisco IOS Releases 12.3(2)T and later, include Network Address Translation-Protocol Translation (NAT-PT) between IPv6 and IPv4. This translation allows direct communication between hosts that use different versions of the IP protocol.

In relation to Tunneling techniques see question 5 in the www.9tut.com series of questions on IPv6http://www.9tut.com/ccna-ipv6

5. Which three of the following are IPv6 transition mechanisms? (Choose three)

A – 6to4 tunneling
B – GRE tunneling
C – ISATAP tunneling
D – Teredo tunneling
E – VPN tunneling
F – PPP tunneling

Answer: A C D

Below is a summary of IPv6 transition technologies:

6 to 4 tunneling: This mechanism allows IPv6 sites to communicate with each other over the IPv4 network without explicit tunnel setup. The main advantage of this technology is that it requires no end-node reconfiguration and minimal router configuration but it is not intended as a permanent solution.

ISATAP tunneling (Intra-Site Automatic Tunnel Addressing Protocol): is a mechanism for transmitting IPv6 packets over IPv4 network. The word “automatic” means that once an ISATAP server/router has been set up, only the clients must be configured to connect to it.

Teredo tunneling: This mechanism tunnels IPv6 datagrams within IPv4 UDP datagrams, allowing private IPv4 address and IPv4 NAT traversal to be used.

In fact, GRE tunneling is also a IPv6 transition mechanism but is not mentioned in CCNA so we shouldn’t choose it (there are 4 types of IPv6 transition mechanisms mentioned in CCNA; they are: manual, 6-to-4, Teredo and ISATAP).

[MY NOTE: For the CCNA exam, be sure that you can recognize the NAMES of the 3 main tunneling types i.e. 6 to 4, ISATAP and Teredo ]

See also a question on Chris Bryant's website

http://www.thebryantadvantage.com/CCNACertificationPracticeExamIPVersion6.htm

Question 6:

Where will you find IPv6 addresses beginning with 2002 and carrying a /48 prefix?

A. 6to4 tunnel edge routers

B. loopback interfaces

C. 6to4 tunnel access routers

D. Any link-layer master router

E. Any site-local DR

Answer: A.
 6to4 tunnel edge routers - the IPv6 routers that are communicating with each other through the IPv4 cloud - carry an IPv6 address beginning with 2002, followed by their IPv4 address expressed in hex. They carry a /48 prefix.  

The following is a question from the Cisco CCNA Discovery course:

What are two ways that some networks can use IPv6 addreses and still communicate over the Internet with their other networks that use IPv4 (choose two)?

The answers are:
Enable tunneling to allow IPv6 packets to be encapsulated and travel over IPv4 networks AND
Upgrade the IOS image on the IPv6 edge routers to an image that can translate IPv6 packets to IPv4 packets.

For main post on "IPv6 and IPve - Differences between them (for CCNA Exam" see

http://ccnaexam4dummies.blogspot.ie/2012/08/ipv6-and-ipv4-differences-between-them.html

TO BE CONTINUED