[LiSA-Users] Regarding LiSA trunk mode

[Radu Rendec]

On Tue, 2013-06-04 at 15:57 -0400, chicany wrote:
> 
> I've managed to replicate Ammar's topology and reproduce the problem.
> I can confirm that the problem is actually caused by hardware VLAN
> untagging. But the problem is that I have no idea how to change the
> NIC type for GNS3 VirtualBox guests. All NIC settings in VirtualBox
> are overwritten by GNS3 at the time when it starts the virtual
> machines. I couldn't find any NIC type setting in the GNS3 interface.
> 
> 
> Drag  Vbox guest from the left panel  and drop it on GNS3 desktop.
> Left click on Vbox guest and select Configure. Now you select  NIC
> type for particular VBox guest. 


Thanks for the hints! I managed to start the test topology (screenshot
attached) with "pcnet2" instead of "automatic". Now it works as
expected. I attached config.text for the lisa nodes (it's the same on
both nodes). I guess this is the "official" workaround for getting lisa
trunk interfaces to work in VirtualBox. Perhaps you can do me a favour
and add this note to your page that describes lisa configuration in
GNS3 :)

Change of MAC for VLAN interfaces isn't necessary in this particular
scenario, since I'm not using any layer 3 functionality on top of lisa
(the VLAN interfaces don't even exist for the 2 VLANs that I
configured). It is required though when VLAN interfaces are used and
they are assigned IP addresses.

> I successfully tested trunking between two LiSA instances emulated by
> QEMU on GNS3. I used i82557b eth card type. Change of MAC for VLAN
> interface was required in order to get it working.
> 

I took a look to the kernel tree. The i82557 is supported by the "e100"
driver. Quoting from e100.c - the big comment at the beginning of the
file, section V:


        VLAN offloading of tagging, stripping and filtering is not
        supported, but driver will accommodate the extra 4-byte VLAN tag
        for processing by upper layers.

So hardware VLAN untagging (or "stripping" as they call it) is not
supported at all, and the driver will pass the original frame (including
the 802.1q tag) to the upper layers. This is why it worked for you in
QEMU.

Thanks again for all the hard work of integrating lisa into GNS3 and
creating the VM images!

Cheers,

Radu

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!
hostname localhost.localdomain
!
!
!
vlan 5
!
vlan 10
!
interface Ethernet 1
 switchport trunk allowed vlan 5
 switchport mode trunk
!
!
interface Ethernet 2
 switchport access vlan 5
!