Warning popup when adding IP to interface that is duplicate

[dionrowney]

NetBox version

v3.6.6

Feature type

Change to existing functionality

Proposed functionality

When adding an IP to an interface via the interface screen, when the confirmation popup says added, a warning popup should also be also shown if the IP added is a duplicate.

Use case

When adding IP addresses to interfaces via the interface screen, users cannot tell they have added a duplicate IP unless they click on and inspect the IP record afterwards. This would further reduce the case of human error when entering IP addresses.

We suggest this method as we experienced this on a isolated switch that was not part any VRF (was in global) which could have prevented the duplicate IP entry via the unique IP setting.

Database changes

none

External dependencies

none

[candlerb]

We suggest this method as we experienced this on a isolated switch that was not part any VRF (was in global) which could have prevented the duplicate IP entry via the unique IP setting.

Note that you can reject such duplicates entirely by setting ENFORCE_GLOBAL_UNIQUE=True - which can also be set in the web UI via Admin > Config Revisions.

TBH, this surprises a lot of people, and maybe it would make more sense to make it default to True these days. There were common cases which required duplicate addresses in the past which are no longer necessary if you use FHRP groups.

[dionrowney]

I was aware of the ENFORCE_GLOBAL_UNIQUE = True

I spoke to our network team and they were not excited about creating fake VRFs for these isolated switches as it didnt represent reality but this does seem to be the only way to allow the same IP range to be used in multiple places and still enforce duplicate addresses prevention.

[bitcollector1]

It does seem like the default should be --> ENFORCE_GLOBAL_UNIQUE = True

[jeremystretch]

When adding an IP to an interface via the interface screen, when the confirmation popup says added, a warning popup should also be also shown if the IP added is a duplicate.

We generally avoid this sort of "warn but permit" workflow: It's inconsistent and doesn't really achieve anything. (We also don't have any existing patterns for effecting a pop-up, so that would be new UI work.)

I spoke to our network team and they were not excited about creating fake VRFs for these isolated switches as it didnt represent reality

They may not exist as explicit VRFs in your network, but it certainly sounds like you have multiple L3 forwarding domains. These are modeled using VRFs in NetBox. (Note that the designation of a route distinguisher is optional; these can just be named tables.)

It does seem like the default should be --> ENFORCE_GLOBAL_UNIQUE = True

I've opened #14536 to track this proposal. Please give it a :+1: response to show your support.

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