IPv6 Subnetting Explained

Subnetting is a fundamental concept in networking, and while IPv4 subnetting may have been a challenge for many, IPv6 subnetting brings a breath of fresh air. With IPv6, subnetting becomes easier and more straightforward. No longer do you need to perform complex calculations to determine subnet start/end addresses, usable addresses, or the null route. IPv6 subnetting simply requires adding or chopping off digits and adjusting the prefix length by a multiple of four. In this blog post, we will delve into the simplicity and differences of IPv6 subnetting, exploring how you can effortlessly divide or combine subnets without the hassle of intricate calculations or concerns about broadcast addresses. Get ready to embrace the ease of IPv6 subnetting and unlock its full potential.

Understanding the intricacies of IP addressing is crucial in today's digital landscape. While IPv4 used a subnet mask in dotted quad notation, it was eventually replaced by CIDR masking. However, with the advent of IPv6, there is a notable shift in terminology. IPv6 does not employ a subnet mask but refers to it as a "Prefix Length," commonly known as the "Prefix." This blog delves into the differences between IPv4 subnet masks and IPv6 Prefix Lengths, highlighting their similarities in functionality. Whether you are a network administrator or simply interested in the subject, this article will provide valuable insights into the world of IP addressing.

IPv6 subnets can seem complex and overwhelming, but there is a simple trick that can make them much easier for humans to understand and differentiate. By using prefix lengths in multiples of four, designing and organizing subnets becomes a breeze. Whether you need a larger or smaller subnet, all it takes is adjusting the prefix by a multiple of four. To further assist you in this process, we have compiled a comprehensive IPv6 Subnet Table that lists all the possible IPv6 addresses, along with the number of IP addresses contained within each subnet. In this blog post, we will explore how using prefix lengths in multiples of four can greatly simplify the management of IPv6 subnets and enhance your overall understanding of this technology.

If auto configuration is desired, the smallest subnet that can be used locally is a standard size IPv6 subnet defined by the IETF, specifically, a /64.

In establishing service on the WAN, it is customary for an ISP to assign a subnet of /64 or smaller. On the other hand, for LAN use, an additional network is routed. The extent of the allocation is contingent on the ISP, however, it is not unusual for end users to be allotted a minimum of /64 and potentially even up to a /48.

Hurricane Electric, the operator of tunnelbroker.net, offers the provision of a /48 alongside a routed /64 subnet and a /64 interconnect.

In the case of larger assignments exceeding /64, it is common practice to allocate the initial /64 for local area network (LAN) implementation and divide the remaining pool of addresses according to specific needs, such as for establishing VPN tunnels, creating a DMZ, or setting up a guest network.