I am using OpenStack - Grizzly.
I have 100 vLANs in my OpenStack setup. I have created 100 Tenant/Projects and when I created VM instances each in all 100 Tenants, the vLANs were automatically assigned to Tenants.
That means when I create an instance in a tenant , a vLAN is automatically assigned to that tenant.
So, my all 100 vLANs are mapped to 100 Tenants.
but, when I delete the VM instance and the respective Tenant, its vLAN didn't get released automatically.
and now if I try to create any new tenant and try to create an instance in that tenant, instance cannot be create and got stuck at 'scheduling' state.
When I check the nova-compute log files, I found the error "RemoteError: Remote error: NoMoreNetworks An unknown exception occurred."
So, when I checked the nova network-list using 'nova-manage network list' , I got the list of all the Fixed-Networks (vLANs) with their associated Tenants.
I found that my deleted tenant's Tenant-ID is still associated with its vLAN.
So, what happens is when we delete any tenant, its associated vLAN didn't get released automatically, and vLAN contains the entry of invalid and non-existing tenant.
Hence, those vLANs are neither occupied nor available for other tenants. So, we need to disassociate those vLANs manually using CLI.
OpenStack must provide a way to disassociate the vLANs with tenants automatically when their tenants are deleted.
Ideally need to check if this still happens, I think grizzly is now unsupported.