Internet Protocol, Version 6 (IPv6) is the successor to the popular network layer protocol IPv4 and is one of the foundational protocols of the modern Internet. The first published RFC for IPv6, RFC 1883, was released in December 1995. The protocol has had many updates and revisions since it was first introduced. Today, IPv6 is gaining popularity thanks to its many improvements over IPv4.

Why IPv6?

The rapid expansion of the Internet and the increasing number of connected devices have brought about a critical need for more IP addresses. The 32-bit address space of IPv4 can support approximately 4.3 billion unique addresses. While this seemed sufficient at the time IPv4 was created in the early 80s, with the explosive growth of the Internet, it became clear that a more robust solution was necessary.

IPv4 Exhaustion

The reality today is that the IPv4 address space has been completely exhausted. All the Regional Internet Registries (RIRs) have delegated their remaining IPv4 address blocks. There are no new IPv4 address assignments available. Organizations must reclaim unused IPv4 address space or purchase them on the aftermarket. Of course, the best solution is to migrate to IPv6.

IPv6 Address Space

IPv6 uses a 128-bit address space which yields 340 undecillion unique IP addresses. Here’s what that number looks like.


In fact, the default network prefix size with IPv6 is /64, which allows for 18 quintillion hosts. Here’s what that number looks like.


As you can see, IPv6 far exceeds the 4.3 billion addresses provided by IPv4. With such a vast pool of IP addresses, network engineers no longer must consider how many hosts will fit on a network.

Additional Benefits

Although the most significant improvement with IPv6 is its vast address space, that’s just one of only many advantages it has over IPv4. Here are a few essential features of IPv6 to consider.

Simplified Addressing

There’s no need to conserve IP addresses with IPv6. Network engineers are freed from the constraints of small address allocations and can focus on creating sites and networks. The default subnet size in IPv6 is /64 (that’s 18 quintillion addresses!), so worrying about how many hosts can fit on a subnet is a thing of the past.

Globally Unique Addresses

A benefit to the ample address space of IPv6 is that all hosts are globally unique. IPv6 restores end-to-end communication, a vision of the original Internet, and eliminates the need for Network Address Translation (NAT).

No Broadcasts

IPv6 eliminates traditional broadcast addressing and instead uses multicast and anycast addressing for similar purposes. By using multicast and anycast, IPv6 provides more efficient and controlled ways to communicate with specific sets of devices or to reach the nearest instance of a service.

Fixed Header Length

IPv6 features a fixed header length of 40 bytes. Fixed header length was a design choice made to simplify and optimize packet processing in routers and networking devices. The fixed header length enables faster routing decisions and reduced processing overhead.

No Router Fragmentation

IPv6 removes the need for routers to perform packet fragmentation and reassembly. Fragmentation is left to the source and destination devices. This simplifies routers’ tasks and can lead to faster packet forwarding.


IPv6 adoption is essential in today’s rapidly evolving technological landscape. With the exhaustion of available IPv4 addresses and the proliferation of internet-connected devices, IPv6’s vast address space provides the scalability needed to accommodate the growing demands of an interconnected world. By embracing IPv6, organizations can future-proof their networks, support the Internet of Things (IoT), and ensure the continued growth and innovation of the Internet while overcoming the limitations of IPv4 and enabling a seamless transition to the next generation of Internet protocols.


Internet Protocol Version 6 Specification – RFC 8200

IPv6 Capable Rate by Country – APNIC

Per-Country IPv6 Adoption – Google

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