[Openstack-operators] Openvswitch flat and provider in the same bond

Dan Sneddon dsneddon at redhat.com
Wed Apr 19 21:14:37 UTC 2017

If all of the VLANs are tagged, then I am having a hard time imagining
why you want to use only one of them as a flat network.

The only difference between a VLAN network and a flat network in Neutron
is that OVS handles tagging/untagging on VLAN networks and flat networks
are untagged.

It is possible to create a VLAN interface, and then add that VLAN
interface to a new OVS bridge. Since the VLAN interface will already
have stripped the VLAN tags by the time they get to the OVS bridge, you
would create a flat network in that case. However, I don't believe that
you can do this while simultaneously adding the other VLANs as VLAN
networks to a different OVS bridge. You might actually have to create
three separate bridges to add the three VLANs to and create three flat
networks instead.

In any case, the traffic will be untagged when it reaches the VM. So
from the VM perspective, all those choices have the same end result.

Dan Sneddon         |  Senior Principal Software Engineer
dsneddon at redhat.com |  redhat.com/openstack
dsneddon:irc        |  @dxs:twitter

On 04/19/2017 12:06 PM, Ignazio Cassano wrote:
> Hi Dan, on the physical  switch the 567 is not the native vlan but is
> tagged like 555 and 556.
> I know I could set 567 as a native vlan to receive it untagged.
> But if I would like more than one flat network ?
> I am not skilled in networking but I think only one native vlan can be
> set in switch.
> Any further solution or suggestion ?
> Regards
> Ignazio
> Il 19/Apr/2017 20:19, "Dan Sneddon" <dsneddon at redhat.com
> <mailto:dsneddon at redhat.com>> ha scritto:
>     On 04/19/2017 09:02 AM, Ignazio Cassano wrote:
>     > Dear All,  in my openstack Newton installation compute e controllers
>     > node have e separate management network nic and a lacp bond0 where
>     > provider vlan (555,556) and flat vlan (567) are trunked.
>     > Since I cannot specify the vlan id (567) when I create a flat
>     network, I
>     > need to know how I can create the bridge for flat network in
>     openvswitch.
>     > For providers network I created a bridge br-ex and added bond0 to that
>     > bridge and configured openvswitch agent and ml2 for mapping br-ex.
>     > I don't know what can I do for flat network : must I create another
>     > bridge ? What interface I must add to the bridge for flat (567)
>     network ?
>     > I configured the same scenario with linuxbridge mechanism driver 
>     and it
>     > seems more easy to do.
>     > Sorry for my bad english.
>     > Regards
>     > Ignazio
>     I assume that the VLAN 567 is the native (untagged) VLAN on the port in
>     question? If that's so, you can do the following:
>     Create two provider networks of "provider:network_type vlan", plus one
>     provider network with "provider:network_type flat", with all three using
>     the same physical network.
>     neutron net-create --provider:physical_network datacentre \
>     --provider:network_type vlan --provider:segmentation_id 555 \
>     --shared <net-name1>
>     neutron net-create --provider:physical_network datacentre \
>     --provider:network_type vlan --provider:segmentation_id 556 \
>     --shared <net-name2>
>     neutron net-create --provider:physical_network datacentre \
>     --provider:network_type flat --shared <net-name3>
>     Of course, remove shared if you don't want tenants directly attaching to
>     any of the above networks, and add "--router:external" if any of these
>     are to be used for SNAT/floating IP.
>     --
>     Dan Sneddon         |  Senior Principal Software Engineer
>     dsneddon at redhat.com <mailto:dsneddon at redhat.com> | 
>     redhat.com/openstack <http://redhat.com/openstack>
>     dsneddon:irc        |  @dxs:twitter

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