Re: [Xen-users] Some VLAN ideas for discussion

["Michael A. Collins" <mike.a.collins@xxxxxxxxxxx>]

On 10.01.2012 18:12, Florian Heigl wrote:
> Hi all,
>
> a question to the Xen networking geeks.
> ...
> Some ideas I'm looking at:
>     - NICs that support multiple PCI functions (Intel 1000PT,
> similar), give virtual functions to each of the routers.
>     - Buy Solarflare NICs and use their netback driver (might work. I
> don't know it; wish more people would be using them so they end up
> soldered onto mainboards)
>     - OpenVSwitch, I'm not sure if it is able to pass like 100 VLANs
> into a domU? I don't have experience with it yet, sadly. It being a
> softswitch it might be able to run LACP over two nics on it's own,
> outside of the kernel.
I've been using OpenVSwitch for my bridges in Xen for quite a while, 
almost a year.  I run them at the house, but with no bells or whistles.  
I do run them at work and use them for my LACP trunks to my real 
switches, so I know that will work.  You can also setup your vifs to be 
trunk ports and then add the sub interfaces using ip link inside the VM, 
I do that also.  From reading over their technical documentation and 
running performance tests in my environment, I doubt that you'd have 
much difficulty running 100s of VLANs through them.  I have been able to 
saturate a 10Gbe adapter using it with iSCSI traffic inside 20 VMs, so 
it can handle the through-put.  There are some issues, mainly none of 
the Xen hotplug scripts and udev rules work well with it, so I've had to 
rewrite them and add udev rules to get vifs added and removed from an 
OVS bridge, once you get past that it's smooth sailing.  With all the 
features that OVS supports, GRE, SPAN/RSPAN, and openflow/NOX, you can 
really do some interesting things with it.  QinQ is not supported yet, 
but probably will be in the future.  Hope this helps.

> How about MSTP and native QinQ? *grin* Yes,
> there's a few interesting points there.
>
> Attaching a number of virtual nics that each carry a single VLAN is
> not acceptable (management overhead that would make the Solarflares
> look *cheap* and doesn't scale anyway)
>
> On the other hand, I've had the feeling I'm missing something.
> For one, how about QinQ, how about L2TPv3 -
> the standard linux bridge could not mess up^W^W strip away VLAN tags
>          - that it can't see due to encapsulation in a proper tunnel
> that just passes the bridge as IP and is extracted in dom0 and domUs
>          - that have a specified outer VLAN type (note that some
> postings about linux qinq use the same ethertype, that is not qinq,
> that's just vlan injection ;))
>
>
> My testbed is currently looking like this, if anyone considers 
> reproducing:
> a vm named "start"
>   a xen host
>     a journey through the internet
>   a xen host
> a vm named "goal"
>
> The next step is to add two alpine linux router VMs (for failover
> options) in each host and then I want to somehow build the
> interconnection - ideally not by passing a bridge(or softswitch) in
> the xen host all too often.
>
> Any comments?
> (besides "you have too much time" - I don't ;)
>
>
> Greetings,
> Florian
Mike

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