[ovs-discuss] [ovs-dev] [PATCH v2] [PATCH] QinQ: support more vlan headers.

[Eric Garver]

On Tue, Sep 11, 2018 at 01:10:09AM +0000, Lilijun (Jerry, Cloud Networking) wrote:
> Thanks for your reply.
> 
> In my use case, it's OVS userspace datapath with dpdk.
> 
>  My detail case was a bit complicated as follows:
> 1. Start the OVS userspace datapath with dpdk in my host server. 
> 2. A VM was running and the VNIC's  vhostuser port on the userspace datapath is configured as QinQ  mode, qinq-ethtype 802.1q.
> 3. Another kernel OVS is running in that VM to switch packets of some containers. Then the container's VNIC port on the kernel datapath is also configured as QinQ  Mode, qinq-ethtype=802.1q .
> 4. So when the container sends a packet with VLAN tag,  the OVS running in the host will receive a packet with 2 VLANS from the VM.
> 5. Here the QinQ is not worked when we need 3 VLANs. 
> 
> Yes, VXLAN or PBB can work but we need change our basic  network topology and push/pop for every packets.  That maybe the last choice if QinQ can't support triple VLAN.

There is still a push/pop for the third VLAN tag.

I'm not sure it makes sense to support the extra VLANs in upstream OVS.
This is non-standard and there are alternatives such as VXLAN. If it
wasn't splitting the MPLS labels across cache lines then it would be a
harmless change.

> 
> -----Original Message-----
> From: Ben Pfaff [mailto:blp at ovn.org] 
> Sent: Tuesday, September 11, 2018 3:33 AM
> To: Eric Garver <eric at garver.life>; Lilijun (Jerry, Cloud Networking) <jerry.lilijun at huawei.com>; dev at openvswitch.org; ovs-discuss at openvswitch.org
> Subject: Re: [ovs-discuss] [PATCH v2] [ovs-dev] [PATCH] QinQ: support more vlan headers.
> 
> On Mon, Sep 10, 2018 at 03:15:21PM -0400, Eric Garver wrote:
> > On Mon, Sep 10, 2018 at 03:03:19AM +0000, Lilijun (Jerry, Cloud Networking) wrote:
> > > Hi Eric,
> > > 
> > > Yes, I agree with that effect. 
> > > But how about this issue of QinQ that we can only support at most 2 VLANs ?  Do you have any ideas?
> > 
> > I was not NACKing the idea. Just wanted everyone to understand the 
> > implications of increasing the VLAN field size.
> > 
> > I tried playing with the fields, but didn't come with a reasonable way 
> > to rearrange them to make room for the extra VLANs.
> > 
> > I'm curious what you're use case is for triple VLAN. I wonder if VXLAN 
> > or PBB (802.1ah) is a better solution.
> 
> I'd also like to know what datapath we're talking about.  The Linux kernel datapath only supports 2 VLANs in any case.
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