[vbox-dev] VLAN-Tagging on virtio_net linux guest / linux host

Aleksey Ilyushin aleksey.ilyushin at oracle.com
Tue May 14 13:29:53 GMT 2013

Hi Stephan,

You are absolutely right, there is no need to configure anything on the host if you use bridging, and all three device types should work. Do I understand it correctly that you tried to configure vlan on the same host you run VMs on and on the same interface guest's eth1 bridged to, and it was able to communicate with a remote host which has vlan configured with the same id (29)? If so can you do packet capture both on the host running the virtual machine and on the remote host you are trying to ping. You can email me both files stripped of sensitive info.

Thank you in advance,

On May 14, 2013, at 4:52 PM, Stephan von Krawczynski wrote:

> Hello Aleksey,
> thank you for jumping in.
> The base problem may be that there is no documentation at all how the host
> should be configured regarding the vlans. My current setup is this (all linux):
> Host has 4 interfaces with standard IPs.
> Guest has three interfaces linked via bridge to 3 of the hosts interfaces.
> Guest should be able to use one of this as normal interface as well as use
> several 802.1Q VLANs on top of it.
> Lets assume guests' interface is named eth1. 
> So we are configuring some IP on it:
> 	ip addr add dev eth1.
> Then we create one vlan to test:
> 	vconfig add eth1 29
> And add IP:
> 	ip addr add dev eth1.29
> Now we try to ping some remote host on this vlan:
> 	ping
> Nothing happens, packets are lost somewhere.
> But standard network works:
> 	ping
> works, remote hosts answers.
> If we do the very same thing on a physical host on the same network place,
> everything is ok.
> We tried to give the guest e1000, pcnet32 or virtio-net device types, all act
> the same. 
> Do we have to configure the vlan on the host side as well? Our expectation was
> that this should not be needed in a bridge setup...
> -- 
> Regards,
> Stephan
> On Tue, 14 May 2013 15:50:59 +0400
> Aleksey Ilyushin <aleksey.ilyushin at oracle.com> wrote:
>> Hello Stephan,
>> Please elaborate on your network setup. What exactly is not working as expected? There was a problem with VLAN tag offloading in e1000, but it was fixed in 4.2. Both virtio-net and PCNet do not touch VLAN tags at all, these are processed by guests. Or is this a problem and you need VLAN tag offloading for virtio-net?
>> Regards,
>> Aleksey
>> On May 14, 2013, at 2:32 PM, Stephan von Krawczynski wrote:
>>> Hello all,
>>> is there a chance to get 802.1Q VLANs working "as expected" on linux guests? I
>>> tried all network adapter types for the guest but none worked. Someone on the
>>> user-list told me that there may be a general problem with the packet length
>>> in forwarding.
>>> Indeed this topic is a lot more important for us than the former discussion
>>> about the network performance and multiqueuing. Is there currently a solution?
>>> Will there be one in the future? A solution based on the virtio_net guest
>>> device would be sufficient for us.
>>> Can we help somehow?
>>> -- 
>>> Regards,
>>> Stephan
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