Open Stack

Hi all:

in reference to the following specification about the creation of VLAN 
trunking network for NFV

https://review.openstack.org/#/c/136554/3/specs/kilo/nfv-vlan-trunks.rst

I would like to better understand how the tagged traffic will be 
realized. In order to explain myself, I report the following use case:

A VNF is deployed in one VM, which has a trunk port carrying traffic for 
two VLANs over a single link able to transport more than one VLAN 
through a single integration-bridge (br-int) port. So, How does br-int 
manage the VLAN-ID? In other words, what are the action performed by the 
br-int when a VM forwards traffic to another host?
Does it put an additional tag or replace the existing one keeping the 
match with a table or something like that?

Thank you very much.

Daniele