IPv6 Information

What is IPv6?

Internet Protocol version 6 (IPv6) is the latest IP revision, developed as a successor to IPv4. IPv6 provides a much larger address pool so that many more devices can be connected to the Internet. It also improves addressing and routing of network traffic. Because the free pool of IPv4 addresses has been depleted, customers will want to request IPv6 address space for new networks, and eventually transition their networks from IPv4 to IPv6.

For a more complete understanding of IPv6, the video below provides a walkthrough of many of the finer details of IPv6.

Why Do You Need IPv6?

Now that IPv4 is depleted, there are extra costs associated with staying IPv4-only, which will likely increase over time. On the other hand, it is easy to get IPv6 from ARIN, there are generally no additional costs for ISPs, and fees were recently reduced for end users.

Don’t forget that we also have a reserve IPv4 block that is dedicated for IPv6 transition support, which you can read more about in ARIN’s Number Resource Policy Manual (Section 4.10). You can receive one /24 every six months to support your IPv6 transition effort.

Preparing for IPv6

Before you implement IPv6, it’s a good idea to make sure your equipment, software, and staff are ready. Think about how many network addresses you’ll need, and how you’ll set up your network.

To learn more about how to determine how much IPv6 address space you need, visit Your First IPv6 Request.

Get advice from those who have already adopted IPv6, and ask questions! You can read case studies from organizations that have already adopted IPv6 including ISPs, hosting providers, enterprise businesses, universities, and governments.

For More Information

For more information, see:

• Guide to Internet Number Resources
• Your First IPv6 Request
• IPv6 Case Studies
• IP Address Blocks from which ARIN Issues Resources
• IPv6 Wiki Archive
• IPv6 Consulting and Training Services
• IPv6 Hosting and DNS Providers

How ARIN uses IPv6

• How ARIN Adopted IPv6
• Video Part 1 | Part 2

How is IPv6 Different than IPv4?

IPv6 differs from IPv4 in many ways, including address size, format, notation, and possible combinations.

An IPv6 address consists of 128 bits (as opposed to the 32-bit size of IPv4 addresses) and is expressed in hexadecimal notation. The IPv6 anatomy graphic below represents just one possible configuration of an IPv6 address, although there are many different possibilities.

Determining the Netmask and Gateway of an IPv6 Address

As with IPv4, in IPv6 there is no way to definitively calculate the netmask and gateway using only a given address. Both are established when a person sets up a network, and you would need to contact your network administrator to determine what they are. However, when given an address and a prefix, one can compute the starting and ending addresses of a subnet, just like in IPv4.

To conform to typical conventions about IPv6 addressing of network interfaces, most networks use a /64 prefix. This prefix length accommodates stateless address autoconfiguration (SLAAC). Note that the length of a given IPv6 network prefix cannot be shorter than the registered IPv6 allocation or assignment.

There is no strong convention as to where to number the gateway; although choosing the smallest number in the network is common.