[Xen-users] Some VLAN ideas for discussion

[Florian Heigl <florian.heigl@xxxxxxxxx>]

Hi all,

a question to the Xen networking geeks.

Currently my hosts are running with LACP bonded VLAN trunks that are
then broken into bridges in the dom0.
This is setup quite similar to the oracle wiki article.

I would like to build something that includes:
    - quite a few VLANs
    - multiple VMs that need access to some of them
    - multiple VMs that need access to almost all of them (routers,
vpn portals... things)

This isn't easily done with Xen so far as if you don't want to
terminate the VLANs in a bridge in dom0 but also want to have virtual
machines doing routing.
Dedicating a physical nic to this cause (or a bond of course) isn't so
great either, if, for example your host only has two interfaces :)

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. 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

-- 
the purpose of libvirt is to provide an abstraction layer hiding all
xen features added since 2006 until they were finally understood and
copied by the kvm devs.

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