[libvirt-users] Using libvirt networking properly.

[Andrew Spiers]

Hi, I'm interested in a setup in which one guest  receives all its
networking services (routed IPv4, dhcp, tftp, dns) from another, which
is connected via a routing through the hypervisor. I think this is a
lot like Guest C and Guest B in the diagram at
http://libvirt.org/archnetwork.html.

I have experimented with setting the network between Guest B and the
hypervisor as a routed network, and the network between Guest B and
Guest C as an isolated network. The problems I am having is that I am
not sure how to set up a persistent static route to Guest C via Guest
B, (I created a file with the route called route-virbr3 in
/etc/sysconfig/network-scripts on the hypervisor, but it doesn't seem
to do anything), and the changes I need to make to allow traffic with
Guest C's source IP to come from Guest B's interface with the
hypervisor seems to get overwritten or superceded by additional rules
that are created when I start my machine.)

I can see something about a qemu-ifup script mentioned at
http://www.linux-kvm.org/page/Networking. Should I create something
like that and put some sort of `ip route add` command in it? When
should that script be called?

Is there a way to specify the necessary  firewall and routing rules in
the xml network configuration?

I am working with  a Fedora 16 hypervisor and Guest B is a Centos 6
machine. I'd like to use all sorts of different distributions where
Guest C is.

Regards,

Andrew.