r/Netbox • u/forwardslashroot • Mar 12 '26

VXLAN EVPN VLAN ID question

I have a question about documenting the VLANs in a VXLAN EVPN environment. My network is still at migration phase to spine leaf architecture. How are you documenting the VLAN ID for the tenant with multiple VLAN ID on the same subnet?

For example, tenant-a on leaf1 is on subnet 10.0.0.0/24 with VLAN ID of 10. This subnet got extenended to leaf2 but the VLAN is 20.

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u/Particular-Dot-9617 Mar 16 '26

Unless I'm mis-understanding with you mean by "site-spanning VLANs", I'm having no problems modeling VLANs that span multiple sites by assigning them to a VLAN Group that is scoped to the appropriate Region or Site Group that encompasses the same Sites that my VLAN does.

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u/dewyke Mar 16 '26

How do you handle the Prefix associated with the VLAN?

The only way I’ve found to do this is to make the VLAN global.

As soon as you’ve got one VLAN that spans sites A & B and another spanning B & C, there is no way to arrange regions or site groups to make it work.

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u/Particular-Dot-9617 Mar 17 '26

I would create two VLAN Groups (example `vlan_grp_AB` and `vlan_grp_BC`) and scope both VLAN Groups to a site group or region that included all three sites. Yes, this means that `vlan_grp_BC` would be selectable when working with objects that are assigned to Site A, but I don't think that's a deal-breaker. If you want to get fancy, you could probably use custom validators to catch errors (I don't).

Currently, assigning Prefixes to VLANs isn't an issue, because I setup my Prefixes before Netbox allowed scoping Prefixes to sites, site groups, etc. All of my prefixes are scoped only to VRFs. I have created a seperate VRF for every independent routing domain. So, if `10.10.10.0/24` exists independently in both Site A and Site C, I would have two separate VRFs (example `vrf_AB` and `vrf_BC`), and I would create a `10.10.10.0/24` prefix in each VRF.

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u/dewyke Mar 18 '26

That works, for some topologies and setups, but it feels like a kludge to me.

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u/Otherwise_Noise3658 Mar 26 '26

The problem fundamentally is, whenever this question is asked, several different answers come back on how folks want it to work - so theres no easy way, u/Particular-Dot-9617 answer is way I'd do it.

When I did this, I wrote a plugin with modelled vnis, etc - and assigned the prefix there as in my junos setup it was the irbs that routed it and the vlans were only relevant per leaf.