Assigning IPv6 address to prefix from available pool starts from 0 instead of 1 #426

New Issue

MrUnknownDE · 2026-04-05T16:31:51+02:00

MrUnknownDE commented

2026-04-05 16:31:51 +02:00

Originally created by @bctiemann on 2/3/2026

NetBox Edition

NetBox Community

NetBox Version

v4.5.1

Python Version

3.12

Steps to Reproduce

Here are the steps to recreate.
Step 1: Create an RIR (if you don’t already have one)
IPAM → RIRs → Add
Name: ARIN
Private: ✔ (if internal)

Step 2: Create an IPv6 aggregate
IPAM → Aggregates → Add
Example:
RIR: ARIN
Prefix: 2001:db8::/32 (documentation range — safe for demos)
Description: Global IPv6 allocation
Step 3: Create container prefixes
IPAM → Prefixes → Add
Example:Prefix: 2001:db8:1000::/40
Status: Container

Step 4: Create an active /64
IPAM → Prefixes → Add
Example:Prefix: 2001:db8:1000:10::/64
Status: Active.

Step 5: Assign an IPv6 address
From the prefix view:
Click “Available IPs”
Select First available THIS IS WHERE THE ERROR OCCURS. When selecting it gives the error "2001:db8:1000:10:: is a network ID, which may not be assigned to an interface." Seems like it's choosing the ID and not first available IP.

(Use the "Many IPs available" button in the above view)

Expected Behavior

The IPAddress 2001:db8:1000:10::1/64 should be created (the first available non-network IP in the pool, matching the behavior of IPv4 addresses (where for example 111.112.113.1 would be allocated in a prefix of 111.112.113.0/24).

Observed Behavior

The IPAddress 2001:db8:1000:10::/64 is created, which is a network address.

*Originally created by @bctiemann on 2/3/2026* ### NetBox Edition NetBox Community ### NetBox Version v4.5.1 ### Python Version 3.12 ### Steps to Reproduce Here are the steps to recreate. Step 1: Create an RIR (if you don’t already have one) IPAM → RIRs → Add Name: ARIN Private: ✔ (if internal) Step 2: Create an IPv6 aggregate IPAM → Aggregates → Add Example: RIR: ARIN Prefix: 2001:db8::/32 (documentation range — safe for demos) Description: Global IPv6 allocation Step 3: Create container prefixes IPAM → Prefixes → Add Example:Prefix: 2001:db8:1000::/40 Status: Container Step 4: Create an active /64 IPAM → Prefixes → Add Example:Prefix: 2001:db8:1000:10::/64 Status: Active. Step 5: Assign an IPv6 address From the prefix view: Click “Available IPs” Select First available THIS IS WHERE THE ERROR OCCURS. When selecting it gives the error "2001:db8:1000:10:: is a network ID, which may not be assigned to an interface." Seems like it's choosing the ID and not first available IP. <img width="823" height="507" alt="Image" src="https://github.com/user-attachments/assets/d23a216d-9095-47b6-8880-ddfeaf3c0dec" /> (Use the "Many IPs available" button in the above view) ### Expected Behavior The IPAddress `2001:db8:1000:10::1/64` should be created (the first available _non-network_ IP in the pool, matching the behavior of IPv4 addresses (where for example `111.112.113.1` would be allocated in a prefix of `111.112.113.0/24`). ### Observed Behavior The IPAddress `2001:db8:1000:10::/64` is created, which is a network address.

MrUnknownDE closed this issue

2026-04-05 16:31:51 +02:00

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main

21455-sql-indexes-audit

21357-register-model-actions

feature

20924-plugin-ui-components

21766-improve-test-coverage-for-sortable-table-columns

21157-export-template-public-models

21025-pre-render-config-contexts

21364-swagger

feature-ip-prefix-link

20911-dropdown-3

fix_module_substitution

21160-filterset

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20044-elevation-stuck-lightmode

7604-filter-modifiers-v3

20660-script-load

19724-graphql

14884-script

19720-macaddress-interface-generic-relation

fix-19669-api-image-download

7604-filter-modifiers

19275-fixes-interface-bulk-edit

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11507-show-aggregate-and-rir-on-api

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Reference: github/netbox#426