[fedora-virt] Routed networking in libvirt

[Anders Rayner-Karlsson]

* Kenni Lund <kenni at kelu.dk> [20100520 17:42]:
> 2010/5/20 Kenni Lund <kenni at kelu.dk>:
> > 2010/5/20 Dennis J. <dennisml at conversis.de>:
> >> On 05/20/2010 12:05 PM, Kenni Lund wrote:
> >>> Hello
> >>>
> >>> I just bought a new hosted server in a data center, which I'm going to
> >>> run a few virtual machines on with libvirt/KVM.
> >>>
> >>> The server have 4 public IP addresses, but due to the data center,
> >>> bridges are not an option.
> >>
> >> Why exactly is that? I don't see what one has to do with the other?
> >
> > I'm actually not exactly sure, but I think it is because a bridge
> > needs to have a valid MAC-address? And the datacenter doesn't allow
> > (eg. they block) data from unknown sources/MAC addresses. That said, I
> > haven't tested it, but their documentation mentions the use of a
> > routed network in virtual environments, as bridges will not work.
> 
> Or perhaps it's even more simple; The host and the additional
> addresses are not on the same subnet, eg. a bridge working at the
> datalink layer is unaware of the procedures performed on the upper
> level protocols, like IP addressing, while a router takes care of
> this.

Or you could use 1:1 NAT and use all three extra addresses for your
VM's. Might take some fiddling with the iptables setup on the
phys-host, but should be doable.

-- 
Anders Rayner-Karlsson <anders at trudheim.co.uk>
All-Round Linux Tinkerer, RHCE and PITA DeLuxe