IPv4 and IPv6

You might have heard of World IPv6 Day, held on June 8, 2011. Major organizations, such as Google, Facebook, Yahoo!, and universities like Indiana University have participated. Like many others, you might have wondered how and why this was important to the average internet user. This post will explain the issue: IP (Internet Protocol) address exhaustion. The IP address here refers to IPv4 (IP version 4), which was introduced in 1980 and is the current Internet Protocol. Because the number of available IPv4 addresses is diminishing, IPv6 (IP version 6) will eventually become the standard protocol in the near future.

The IP address exhaustion is derived from the IPv4 addressing structure. An IPv4 address is made up of four 8-bit (totaling 32 bits) sections, and is expressed as four numbers between 0 and 255 separated by a period like this: 129.79.38.88. This “Dot Decimal Notation (DDN)” is a human readable form, but actually computers communicate in binary form, 0s and 1s, so the address above in decimal form will be like this in binary:

Decimal	129.	79.	38.	88
Binary	10000001.	01001111.	00100110.	01011000

• In the binary form, zeros are added between the bytes for a visual purpose.

This addressing structure gives a total IPv4 address space of 2³², or 4,294,967,296. Although the pools of IPv4 look big, IPv4 address exhaustion has been expected because of the dramatic growth of the Internet. On February 3, 2011, the Internet Assigned Numbers Authority (lANA), which is responsible for global IP addressing, allocated the last five address blocks to the five Regional Internet Registry organizations which are responsible for IP addressing within a particular region. The Asia Pacific Network Information Centre (APNIC) was the first to exhaust its regional pool on April, 15, 2011.

IPv6, known as IPng (IP next generation), is the next IP address designed to replace IPv4 and is expressed as 8 groups of two byte hexadecimal values separated by colons. A typical IPv6 address looks like this: 1111:2222:3333:4444:5555:6666:7777:8888. This colon-hexadecimal structure increases the IP address space from 2³² of IPv4 to 2¹²⁸, approximately 340 undecillion or 3.4 x 10³⁸ IP numbers, therefore, provides a much greater number of addressable nodes than IPv4.

These days, most computers have either an IPv4 address or both an IPv4 and IPv6 address as shown in the screenshot above. Until IPv6 completely replaces with IPv4, both IPv4 and IPv6 will exist side-by-side for the near future. The primary limitation to deploying an all IPv6 network is that, not all devices support IPv6 and many special purposes devices, such as network printers, still only support IPv4. In addition, many applications do not support IPv6 addresses yet and will not function correctly on an IPv6 only network.

For more about IU specific IPv6 environment, check at the Knowledge Base and IU Webmaster websites.