IPv6 Nibble Hierarchy Calculator

About this interactive

With a whole hextet of subnet ID, an IPv6 plan can give each level of an organisation its own nibble. One common layout puts the region in the first hex digit of the fourth hextet, the site in the second, and the department in the last two. Then a subnet ID reads like a label: in 2001:db8:77::/48, the network 2001:db8:77:6104::/64 is region 6, site 1, department 04. Each field is counted in hex, so site 10 is a and department 20 is 14. The nibbles also make blocks. Everything in one region shares the /48 and the region digit, a /52; one site in one region is a /56. One ACL line on that prefix matches every network under it. If the counts do not fit, move a nibble from one field to another: each nibble a field gains multiplies its count by 16, and the field that gives it up divides by 16. Seven of the twenty questions are drawn each run. The addresses use the IPv6 documentation prefix 2001:db8::/32. Anything you miss shows the answer and how to work it out.

What you'll learn

Build and read the subnet ID of a hierarchical IPv6 plan that gives each level (region, site, department) whole nibbles of the fourth hextet
Work out how many regions, sites, departments and /64 networks a nibble layout allows, how many nibbles a level needs, and the prefix that covers one region or site

Aligned to

Cisco CCNA

1.8 Configure and verify IPv6 addressing and prefix

Cisco CCST Networking

2.3 Identify IPv6 addresses and prefix formats

CompTIA Network+

3.4 Given a scenario, implement IPv4 and IPv6 network services

Key terms

Hierarchical Subnetting: A structured approach to dividing an IP address space into levels such as regions and sites to reflect an organization's topology.
Nibble Boundary: A subnetting division point aligned to a 4-bit (one hexadecimal digit) boundary in an IPv6 address, simplifying hierarchical address allocation.
Hexadecimal: A base-16 number system using digits 0–9 and letters A–F; each hex digit maps to exactly 4 bits, making it a compact shorthand for representing binary data.
Prefix: The network portion of an IPv6 address, expressed as a slash notation (e.g., /48), that identifies the boundary between the network and host segments.

Topics

Ipv6 Ipv6 Subnetting Hierarchical Subnetting Nibble Boundary Address Planning Interactive Calculation

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