Configuring IPv6 Hierarchy in IPAM with Nested Subnets

4/21/2026 6:08 PM

4/21/2026 6:08 PM

Problem / Question

You have been allocated an IPv6 prefix (for example, a /40 from an ISP) and want to:

• Divide it into:

  • /44 blocks for regions

  • /48 blocks for individual sites

  • /64 blocks for local subnets/VLANs at each site

• Use 4‑bit nibbles to keep the hierarchy clean

• Represent this hierarchy correctly in SolarWinds IPAM using:

  • IPv6 Global Prefix

  • IPv6 Sites

  • IPv6 Subnets

IP Address Manager

Solution / Resolution

1. Plan the IPv6 hierarchy (nibble-based design)

Use nibbles (4 bits, 1 hex character) to define each level of your hierarchy. This keeps the structure readable and aligns with common IPv6 planning practices.

Typical layout:

• /40 – Global prefix (block from ISP)

• /44 – Regions (16 regions using the next nibble)

• /48 – Sites within a region

• /64 – Local subnets/VLANs within a site

Example:

• Global prefix: 2602:81d:8000::/40

• Regions: 16 x /44

• Sites per region: up to 16 x /48 (within each /44)

• LANs per site: many /64 networks within each /48

Note: SolarWinds documentation also recommends using nibbles for high‑level grouping (country, region, site, building, floor) when planning IPv6 address spaces.

2. Create the IPv6 Global Prefix in IPAM

1. In the web console, go to
   My Dashboards > IP Addresses > Manage Subnets & IP Addresses.

2. In the left tree, select the folder where you want to place the IPv6 hierarchy (for example, IP Networks or a custom group).

3. Click Add > IPv6 Global Prefix.

4. Enter:

   • Name: e.g. Global IPv6 /40 or Org IPv6 Global Prefix

   • Global prefix: your allocated block, e.g.
     2602:81d:8000::/40

5. Click Save.

This creates the top‑level container for your IPv6 hierarchy in IPAM.

3. Create IPv6 Sites (regional or logical containers)

IPv6 Sites in IPAM act as logical containers under the global prefix (for regions, large campuses, etc.).

1. In the left tree, expand the IPv6 Global Prefix you just created.

2. Select the global prefix.

3. Click Add > IPv6 Site.

4. In the Add IPv6 Site dialog:

   • Name: e.g. Region-01, Region-02, etc.

   • IPv6 Site size:

     • This is not a CIDR field.

     • It is the number of additional bits beyond the global prefix that define each site.

5. Click Save.

Example: /40 global prefix to first /44 region

• Global prefix: 2602:81d:8000::/40

• Desired region block: /44

• IPv6 Site size = 44 − 40 = 4 (bits)

This results in the first region block:

• Region 0 site block: 2602:81d:8000::/44

You can repeat this process for additional regions (see Example hierarchy below).

4. Add IPv6 subnets for sites and local LANs

Once IPv6 Sites are defined, you add IPv6 Subnets under them for /44, /48, and /64 levels.

4.1 Create /44 regional subnets (if you want them explicitly as subnets)

If you prefer to show /44 as explicit subnets (in addition to using IPv6 Sites):

1. In the left tree, select the parent IPv6 Site (for the region).

2. Click Add > IPv6 Subnet.

3. Enter:

   • Name: e.g. Region-01 /44

   • IPv6 subnet: e.g. 2602:81d:8000::/44

   • Description and other fields as needed.

4. Click Save.

In many designs, you treat the /44 as the site block for multiple /48 sites and just track /48 and /64 subnets below. Whether you create explicit /44 subnets in IPAM is optional and depends on how granular you want your tree to be.

4.2 Create /48 site subnets within a region

Example: within Region‑01 (2602:81d:8000::/44):

• Site 0: 2602:81d:8000::/48

• Site 1: 2602:81d:8001::/48

• …

• Site 15: 2602:81d:800f::/48

Steps:

1. Select the appropriate IPv6 Site or regional subnet in the tree.

2. Click Add > IPv6 Subnet.

3. Enter:

   • Name: e.g. Region-01 Site-01 /48

   • IPv6 subnet: e.g. 2602:81d:8000::/48

4. Click Save.

5. Repeat for each site subnet you need.

4.3 Create /64 local subnets (VLANs) within each site

Within a /48 site block (for example, 2602:81d:8000::/48):

• /64 LANs are indexed by the fourth hextet:

Examples:

• 2602:81d:8000:0000::/64 – e.g. Core/Infra VLAN

• 2602:81d:8000:0001::/64 – e.g. User VLAN 1

• 2602:81d:8000:0002::/64 – e.g. Server VLAN

• 2602:81d:8000:0003::/64 – e.g. Wi‑Fi VLAN

Steps:

1. In the left tree, select the /48 site subnet (e.g. 2602:81d:8000::/48).

2. Click Add > IPv6 Subnet.

3. Enter:

   • Name: e.g. Site-01 VLAN-Users /64

   • IPv6 subnet: e.g. 2602:81d:8000:0001::/64

4. Click Save.

5. Repeat for other VLANs as needed.

5. Example: Full /40 → /44 → /48 → /64 breakdown

This is an example pattern you can follow; substitute your own names and final assignments.

5.1 Sixteen /44 regional blocks from 2602:81d:8000::/40

Each /44 increases the 3rd hextet by 0x0010:

Region	/44 prefix
0	2602:81d:8000::/44
1	2602:81d:8010::/44
2	2602:81d:8020::/44
3	2602:81d:8030::/44
4	2602:81d:8040::/44
5	2602:81d:8050::/44
6	2602:81d:8060::/44
7	2602:81d:8070::/44
8	2602:81d:8080::/44
9	2602:81d:8090::/44
10	2602:81d:80a0::/44
11	2602:81d:80b0::/44
12	2602:81d:80c0::/44
13	2602:81d:80d0::/44
14	2602:81d:80e0::/44
15	2602:81d:80f0::/44

5.2 First /44’s /48 site blocks (inside 2602:81d:8000::/44)

Within 2602:81d:8000::/44, the last nibble of the 3rd hextet indexes /48 sites:

Site	/48 prefix
0	2602:81d:8000::/48
1	2602:81d:8001::/48
2	2602:81d:8002::/48
3	2602:81d:8003::/48
4	2602:81d:8004::/48
5	2602:81d:8005::/48
6	2602:81d:8006::/48
7	2602:81d:8007::/48
8	2602:81d:8008::/48
9	2602:81d:8009::/48
10	2602:81d:800a::/48
11	2602:81d:800b::/48
12	2602:81d:800c::/48
13	2602:81d:800d::/48
14	2602:81d:800e::/48
15	2602:81d:800f::/48

5.3 Example /64s in the first /48 site

For site 2602:81d:8000::/48:

• 2602:81d:8000:0000::/64 – infra

• 2602:81d:8000:0001::/64 – users

• 2602:81d:8000:0002::/64 – servers

• 2602:81d:8000:0003::/64 – Wi‑Fi

• … and so on.

6. Optional: Build the hierarchy via spreadsheet import

If you already maintain your IPv6 plan in Excel/CSV, you can have IPAM auto‑create the hierarchy:

1. Prepare a spreadsheet with at least:

   • Type column (e.g. IPv6 Global Prefix, IPv6 Site, IPv6 Subnet)

   • Address/CIDR (e.g. 2602:81d:8000::/40, 2602:81d:8000::/44, etc.)

   • Optional: Display Name, Description, and any custom property columns.

2. In IPAM, go to Manage Subnets & IP Addresses.

3. Click Import > Import spreadsheet.

4. Select Group/Supernets/Subnets and map your columns.

5. When prompted how to handle hierarchy, choose:

   IPAM will automatically create subnet hierarchy in selected location based on import file (hierarchy preserved)

This will create the same nested IPv6 hierarchy in IPAM as defined by your spreadsheet.

Scope of Support (Design vs. Configuration)

SolarWinds Technical Support can:

• Explain how IPv6 Global Prefix, IPv6 Sites, and IPv6 Subnets work in IPAM

• Provide examples of nibble-based hierarchies (/40 → /44 → /48 → /64)

• Help you configure and troubleshoot IPAM to represent a hierarchy that your team has designed

SolarWinds Technical Support cannot:

• Act as the authoritative designer of a customer’s IPv6 address plan

• Make final decisions about which prefixes to assign to which business units, security domains, or long‑term capacity allocations

You should work with their own network architecture team or consultant to finalize the IPv6 design, then use this article as a reference to implement that design in IPAM.