This bug was initially created as a copy of Bug #1643769

I am copying this bug because: 

Affirm network would like to have the fix backported or a hotfix provided for rhosp 13

Description of problem:
In the context of a live datacenter, sometimes the network teams re-organize their VLANs by changing VLAN IDs .  This is pretty straightforward in the context of network configuration and physical servers but when using ML2 VLAN provider networks, those IDs cannot be updated .  The only possible solution here would be to delete those networks and recreate them with a different VLAN ID which might be a problem when you have 1000 VMs and 2000 ports.

Version-Release number of selected component (if applicable):


How reproducible:
Always

Steps to Reproduce:
1. Create a VLAN ML2 provider network
2. Try updating the segmentation_id
3.

Actual results:
Fails

Expected results:
Succeeds

Additional info: