[openstack-dev] [Neutron] VLAN trunking network for NFV

Ian Wells ijw.ubuntu at cack.org.uk
Tue Mar 24 18:17:56 UTC 2015

That spec ensures that you can tell what the plugin is doing.  You can ask
for a VLAN transparent network, but the cloud may tell you it can't make

The OVS driver in Openstack drops VLAN tagged packets, I'm afraid, and the
spec you're referring to doesn't change that.  The spec does ensure that if
you try and create a VLAN trunk on a cloud that uses the OVS driver, you'll
be told you can't.  in the future, the OVS driver can be fixed, but that's
how things stand at present.  Fixing the OVS driver really involves getting
in at the OVS flow level - can be done, but we started with the basics.

If you want to use a VLAN trunk using the current code, I recommend VXLAN
or GRE along with the Linuxbridge driver, both of which support VLAN
transparent networking.  If they're configured and you ask for a VLAN trunk
you'll be told you got one.

On 24 March 2015 at 09:43, Daniele Casini <daniele.casini at dektech.com.au>

> 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
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