In the case of Openstack the vlan driver permits to isolate each project's layer 2. This way each project's L3 can overlaps without any problem. You can create many L3 segments within only one VLAN ID.

I do not use vcenter but for old ESXi it was "possible to create" many vswitches whom contains same vlan ID, but this is very different and vmware misuses term of switch.

From: Ignazio Cassano <ignaziocassano@gmail.com>
Sent: Saturday, February 8, 2020 3:55 PM
To: openstack-discuss
Subject: [Queens][neutron] multiple networks with same vlan id

Hello, I trying to create multiple networks with the same vlan id and different address but it is impossibile because neutron returns vlan id is already present.

I tried with success on vcenter and it works.

On openstack I can create more subnets with different adresses under the same vlan id, but instances receive static routes from dhcp for all subnets.

Any workaround ?

I am also trying with segments but they do not seem to fit my case.

Regards

Ignazio