Verify the configuration in the command prompt with ipconfigall. Your results

92 | Lesson 4

11. Verify connectivity to another IPv6 host. For example, this can be done by typing the

following command in the command prompt: ping –6 2001:ab1:442e:1323::2 You should get replies. If not, check the configuration of both computers.

12. Configure a global unicast address in the command prompt. For this exercise, we will

use the Net Shell command, which is netsh. Netsh is a tool that administrators can use to configure and monitor Windows computers from the command prompt. This is a complex command with lots of variables. It is commonly used to configure TCPIP and other networking functions. Add the following example: netsh interface ipv6 add address interface=lan address=2001:ab1:442e:1323::7 You should get a simple OK as a result. If there are other computers you would like to configure with the netsh command, make sure they all get separate host IDs.

13. Check that the new address has been added with ipconfigall.

14. Verify connectivity to other computers with ping.

15. Delete the address you just added with the netsh command. Use the following syntax:

netsh interface ipv6 delete address interface=lan address=2001: ab1:442e:1323::7 If you have any issues deleting the address, try using a nontruncated number. The equivalent for this address would be: 2001:0ab1:442e:1323:0000:0000:0000:0007 16. Reset the GUI IPv6 Properties dialog box by selecting Obtain an IPv6 address auto- matically. If you wish, run an ipconfig to find out your auto-assigned address and another computer’s address. Try pinging those addresses as well. Lots more information about configuring IPv6 can be found at the Microsoft TechNet. Figure 4-17 IPv6 GUI configuration Figure 4-18 Ipconfigall results of added IPv6 address Understanding Internet Protocol | 93 DEFINING THE DUAL IP STACK A dual IP stack exists when there are two Internet Protocol software implementations in an operating system, one for IPv4 and another for IPv6. Dual stack IP hosts can run IPv4 and IPv6 independently, or they can use a hybrid implementation, which is the most commonly used method for modern operating systems. Dual stack TCPIP implementations enable programmers to write networking code that works transparently on IPv4 or IPv6. The software can use hybrid sockets designed to accept both IPv4 and IPv6 packets. When used in IPv4 communications, hybrid stacks use IPv6 methodologies but represent IPv4 addresses in a special IPv6 address format known as the IPv4-mapped address. IPv4-mapped addresses have the first 80 bits set to 0 note the double colon, the next 16 set to 1 shown as ffff , and the last 32 bits populated by the IPv4 address. These addresses look like IPv6 addresses, other than the last 32 bits, which are written in the customary dot- decimal notation. Here is an example: ::ffff:10.254.254.1 This is an IPv4-mapped IPv6 address for the IPv4 address 10.254.254.1. DEFINING IPv4 TO IPv6 TUNNELING IPv6 packets can be encapsulated inside IPv4 datagrams. This is known as IPv6 tunneling, or IP 6 to 4. In Microsoft operating systems, this is generally done with the Teredo adapter, which is a virtual adapter or “pseudo-interface,” not a physical network adapter. This allows connectivity for IPv6 hosts that are behind an IPv4 device or IPv6 unaware device. It ensures backward compatibility. An example of one of these addresses would be: Fe80::5efe:10.0.0.22 Notice that this is a link-local address and that the IPv4 address 10.0.0.2 is actually part of the whole IPv6 address. IPv6 tunneling requires little router configuration and no client computer configuration whatsoever, so it is fairly easy to implement, enabling IPv6 clients to interact with IPv6 servers on the Internet, even though the router is not IPv6 aware. S K I L L S U M M A R Y I N THIS LESSON , YOU LEARNED : • How to categorize IPv4 addresses using classifications such as Class A, B, and C. • What the default gateway and DNS server are and how to configure them within a network adapter’s TCPIP properties dialog box. • How to define advanced TCPIP concepts, such as NAT and subnetting, and how to create a subnetted network. • How to define CIDR. • The basics of IPv6 and how to configure IPv6 in the command line. • How to define IPv6 dual stack and tunneling technologies.