IPv6 Address Plan Best Practices

[Samuel Mwamsaku]

The 3 phases of IPv6 address planning are:

1. Estimate the required space needed

2. Procure the required space

3. Implement

[Stephen Olude]

Unlike IPv4, where we care about the number of hosts on the network, IPv6 doesn’t care about the number of hosts; rather, it cares about the number of subnets.

[DICKSON KASANO]

That is a great way to frame the paradigm shift between the two protocols. You’ve hit on the core philosophical difference in how address space is managed.

In IPv4, we are constantly fighting address scarcity. We use Variable Length Subnet Masking (VLSM) to “right-size” a subnet, often trying to find the smallest mask—like a $/30$ for a point-to-point link—to avoid wasting any of the 4.2 billion available addresses.

In IPv6, the “scarcity mindset” is replaced by a “hierarchy mindset.” Here is why the focus shifts entirely to the subnet:

[Zeinab Mohammed]

In IPV6 we don’t care about the no of hosts, only subnets
Isn’t that a limiting factor while doing planning

[Roger Bruce Guelor Talla]

<strong data-start="”41″" data-end="”361″">No, this is not a limiting factor when planning an IPv6 network. On the contrary, it is a simplification. In IPv6, each subnet is assigned a default /64 prefix, which provides 2⁶⁴ possible addresses — about 18 quintillion addresses. This means there are far more addresses than needed for all the hosts in a network.

<strong data-start="”363″" data-end="”575″" data-is-last-node="””">Therefore, instead of focusing on the number of hosts as in IPv4, IPv6 planning focuses on the logical structure of the network and the allocation of subnets, since the address space is practically unlimited.

[Roger Bruce Guelor Talla]

Please help me. I’ve been stuck at this level since this morning and I can’t move forward. However, I’ve finished the lesson, but it’s not showing 100%. What should I do to advance to the next lesson? @tamon

[Uwimana Jean Lambert]

me too i am stacked with this issue

[Uwimana Jean Lambert]

[Uwimana Jean Lambert]

[DICKSON KASANO]

same here

[Oscar MIFOUENI]

I’m facing the same issue

[Juan Klopper]

I am trying to catch up, but it seems that I am also unable to progress due to the same issue.

[Eduardo Brito da Cunha]

I had the same problem, Try clicking the back button at the end of this same chapter; it will go back and forward as a new topic.

It worked for me.

[Madalitso Cheyo]

A well-structured IPv6 address plan is critical for scalability, manageability, and efficient routing. Unlike IPv4, IPv6 provides an enormous address space, so the focus shifts from conservation to organization and clarity.

Start with your allocated prefix. Most organizations receive a /48 prefix from their ISP or Regional Internet Registry (RIR). This gives 16 bits for subnetting, allowing up to 65,536 subnets, each with a /64 prefix containing 18 quintillion host addresses.

Use a consistent subnet size. Always use /64 for end-user subnets regardless of how many hosts are needed. This ensures compatibility with SLAAC, EUI-64, and Neighbor Discovery Protocol. Avoid the IPv4 habit of sizing subnets to the number of hosts.

Plan a logical hierarchy. Divide your address space into structured tiers; for example, allocating specific ranges for data centers, branch offices, management networks, and DMZs. A clear hierarchy simplifies routing, troubleshooting, and future growth.

Reserve space for growth. Allocate address blocks generously and leave gaps between assignments. Since address space is abundant, there is no reason to assign blocks back-to-back, which would complicate future expansion.

Document everything. Maintain an IP Address Management (IPAM) system that records every assigned prefix, its purpose, location, and owner. Good documentation is the foundation of a manageable network.

Avoid embedding IPv4 addresses. While it may seem convenient to map IPv4 subnets into IPv6 (e.g., using the last octets of an IPv4 address as the subnet ID), this practice limits scalability and creates confusion as the network grows.

[Martin Chunga]

Why is it that I cannot go to the next phase after finishing this module. Anyone to help?

[Jonas Ababio]

What are some of the popular tools for IP Address Management?