VM systems and IPv6?

Bjørn Mork bjorn at mork.no
Thu Mar 18 14:13:01 CET 2010

Jogi Hofmüller <jogi at mur.at> writes:
> On Wed, Mar 17, 2010 at 10:49:40PM -0700, Phil Pennock wrote:
>> Folks,
>> How common is it these days to have people using Windows under VMs?
>> How common is it for VM virtual bridges to somehow be breaking IPv6?
> We have a Debian based kvm environment here and so far no issues with
> native IPv6.  But I can only say that for Debian/Linux guests since we
> don't have any other OSes.

I've been running Olive's (no they don't exist :-), Debian (both Linux
and kFreeBSD based), Juniper SRC (yes, I know that's an appliance - but
it's also a Centos-based OS) and assorted Windows versions, all of which
have been doing IPv6 just fine on KVM using VDE as a bridge.  Under
Debian as host system, not that I see how that matters.

What probably does matter is:
 - which virtualisation tech (kvm, vmware, xen, other)?
 - how do you brigde between them (VDE, Linux bridged tun/tap,
    openvswitch, other)
 - guest OS

As I said, I have good experience using VDE, including bridging tap
connected VDE ports with real ethernet ports.  But I haven't explored
the more fancy IPv6 related switch features like MLD snooping etc. I
assume that is not supported.

For the future, Open vSwitch (http://openvswitch.org/) is probably the
way to go

But anyway, I cannot see any reason to expect virtual switches to be
more broken than hardware.  Go look at low end consumer hardware, like
the switches which are thrown into every CPE, wireless router or
whatever, and you'll find a new dimension of brokenness...  *That's*
what breaks most clients, not virtual switches.


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