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

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 ;)



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