Since 1998, IPv6 has struggled to address the shortage of available IPv4 IP addresses, yet despite its efficiency and security advantages, IPv6 adoption has been slow.

For the most part, no one has repeatedly sounded the alarm about the dire state of running out of Internet addresses, because the migration from the World of Internet Protocol Version 4 (IPv4) to IPv6 has begun, slowly but surely, and the software is in place to prevent the address exhaustion many predict.

But before we see where IPv6 is and where it’s headed, let’s go back to the early days of Internet addressing.

What is IPv6 and why is it important?

IPv6 is the latest version of the Internet Protocol, The Internet Protocol (IP), which identifies devices across the Internet to determine their location. Each device using the Internet must be identified by its own IP address so that it can communicate over the Internet. In that respect, it’s like you need to know your street address and zip code in order to mail a letter.

The previous version of IPv4, which used a 32-bit addressing scheme to support 4.3 billion devices, was supposed to be sufficient. However, the growth of the Internet, personal computers, smartphones and now internet-of-things devices proves that the world needs more addresses.

Fortunately, the Internet Engineering Task Force (IETF) recognized this 20 years ago. In 1998, it created IPv6, using 128-bit addressing to support something like 34 trillion trillion trillion (or two to the power of 128, if you prefer). An IPv4 address can be expressed as four groups of one – to three-digit digits. An IPv6 address uses eight groups of four-digit hexadecimal digits, separated by colons.

What are the benefits of IPv6?

In its work, the IETF has added enhancements to IPv6 over IPv4. The IPv6 protocol can process packets more efficiently, improving performance and increasing security. It enables Internet service providers (ISPs) to reduce the size of their routing tables by making them more hierarchical.

Network Address translation (NAT) and IPv6

The adoption of IPv6 has been delayed in part by Network Address translation (NAT), which translates private IP addresses into public ones. In this way, machines in an enterprise with a private IP address can send and receive packets to machines with a public IP address located outside the private network.

Without NAT, large companies with thousands or tens of thousands of computers gobbled up a lot of public IPv4 addresses if they wanted to communicate with the outside world. But those IPv4 addresses are limited and so depleted that allocation has to be limited.

NAT helps alleviate this problem. With NAT, thousands of private address computers can be presented on the public Internet via NAT devices such as firewalls or routers.

The way NAT works is that when an enterprise computer with a private IP address sends a packet to a public IP address outside the enterprise network, the packet first goes to the NAT device. NAT records the source and destination addresses of packets in the translation table. NAT changes the source address of the packet to the public address of the NAT device and sends the packet together to the external destination. When the packet replies, NAT translates the destination address into the private IP address of the computer that initiated the communication. In this way, a public IP address can represent multiple computers with private addresses.

Who is deploying IPv6?

Carrier networks and Internet service providers were among the first to deploy IPv6 on their networks, with mobile networks leading the way. T-mobile USA, for example, has more than 90 percent of its traffic over IPv6, followed by Verizon Wireless at 82.25 percent. That compares with 63% for Comcast and 65% for AT&T, according to industry group World Ipv6 Launch.

Major sites come in second — less than 30% of Alexa’s top 1,000 sites are currently accessible via IPv6, according to World IPv6 Launch.

Enterprises are lagging behind in deployment, with less than a quarter advertising their IPv6 prefixes, according to the Internet Society’s “State of IPv6 Deployment 2017” report. Complexity, cost, and time required to complete the migration were all cited as reasons. In addition, some projects have been delayed due to software compatibility issues. For example, a January 2017 report said that a bug in Windows 10 “undermined Microsoft’s efforts to roll out a pure IPv6 network at its Seattle headquarters.”

When will there be more deployments?

The Internet Society says prices for IPv4 addresses will peak in 2018 and then fall after IPv6 deployment passes the 50 percent mark. Currently, according to Google, IPv6 adoption is 20 to 22 percent worldwide, but about 32 percent in the United States.

As the price of IPv4 addresses begins to fall, the Internet Society recommends that businesses sell their existing IPv4 addresses to help finance their IPv6 deployment. MIT has already done just that, according to a note posted on GitHub. The university concluded that it had 8 million IPv4 addresses that were “surplus” and could be sold without affecting current or future demand because it also held 20 nonillion IPv6 addresses that were not at the billion level. (Non-100m addresses are exponential 1 followed by 30 zeros).

In addition, as deployment increases, more companies will start charging for the use of IPv4 addresses and offering IPv6 services for free. Mythic Beasts, a UK ISP, says that “IPv6 connectivity is standard” while “IPv4 connectivity is an optional extra”.

When is IPv4 “turned off”?

Between 2011 and 2018, most of the world “ran out” of new IPv4 addresses — but we won’t run out of IPv4 addresses entirely, as IPv4 addresses will be sold and reused (as mentioned), and the remaining addresses will be used for the IPv6 transition.

There is no official IPv4 shutdown date, so people don’t have to worry that their Internet access will suddenly disappear one day. As more networks transition, more content sites support IPv6, and more end users upgrade their devices for IPv6 functionality, the world will slowly move away from IPv4.

Why is there no IPv5?

There was an IPv5, also known as the Internet Stream Protocol, or ST for short. It is designed for connection-oriented communication across IP networks with the intention of supporting voice and video.

It was successful in this task and was used experimentally. One drawback is its 32-bit address scheme – the same one used for IPv4 – which has affected its popularity. As a result, it suffers from the same problem as IPv4 – the number of AVAILABLE IP addresses is limited. This led to the development and eventual adoption of IPv6. Although IPv5 has never been publicly adopted, it has dropped the IPv5 name.

Via: www.networkworld.com/article/325…

By Keith Shaw and Josh Fruhlinger

This article is originally compiled by LCTT and released in Linux China