CentOS virt - Sep 2013 - Upgrade of CentOS and libvirt: need help on configuring network - Solved

> I upgraded from CentOS 5.9 to CentOS 6.4.
>
> I try to reuse my virtual machines and am only partially successful: I
> can run them, I just cannot get the network OK and need some help with
that.
>
>
> What I had in the past was pretty simple: both the host and the VM?s
> used eth0 and each had an IP in the same subnet and could communicate
freely.
> With the new install it seems somewhat more complex and I think I need to
configure a bridge and use that.
> Unfortunately, info I find through google is overwhelming and
> confusing. All examples either configure something else, or the outcome is
not what? expected.
>
>
> So: how to go about setting things up to have say:
>
> My physical machine is on 192.168.0.90
>
> My Virtual machines are on 192.168.0.100 and 101.
>
> These are to be fixed addresses.
>
> The 2 VM?s have to communicate with each other and with the physical
machine.
>
> The VM?s do not necessarily need to communicate with the rest of the world.
>
> The physical machine needs to communicate with the rest of the world.
>
>
> I use:
>
> - CentOS-6.4_64
>
> - Virtual Machine Manager 0.9.0
>
> - xen 4.2.3
>
> - libvirt 0.10.2.7-5
>
> - VM?s show Hypervisor = xen (fullvirt)
>
> - Emulator = qemu-dm
>
> - NIC points to Shared device name virbr0
>
> - on the host, virbr0 has IQ 192.168.122.1
>
>
> I have been fighting this for 2 weeks, now. I tried to follow several
> advises which resulted in either the VM?s not connecting to anything,
> or my host losing its connection to the rest of the world, or both. So
either I still do something not-right, or I follow the wrong gidelines.
>
>
> Can someone give me a push in the right direction, please?
Thanks to all who responded to this: it is working now.
Solution was relatively easy and mainly a matter of understanding the
"ifcfg-eth0 - like" files.

What I did:
1 - yum install bridge-utils
2 - change /etc/sysconfig/network-scripts/ifcfg-eth0 to:
DEVICE="eth0"
BOOTPROTO=none
ONBOOT="yes"
TYPE="Ethernet"
HWADDR=xx:xx:xx:xx:xx:xx
BRIDGE="br0"
USERCTL=no
IPV6INIT=no
NM_CONTROLLED="no"
3 - change change /etc/sysconfig/network-scripts/ifcfg-br0 to:
DEVICE="br0"
BOOTPROTO=none
ONBOOT="yes"
IPADDR=192.168.0.95
NETMASK=255.255.255.0
GATEWAY=192.168.0.1
DNS1="192.168.0.1"
PEERDNS="yes"
TYPE="Bridge"
DELAY=0
STP=off
USERCTL=no
IPV6INIT=no
NM_CONTROLLED=no
4 - /etc/init.d/network restart
5 - choose Host device eth0 (Bridge 'br0') in the VM-manager GUI for the
virtual-machine's NIC
6 - restart the virtual machines

That made it all work.
So what I had wrong initially were settings in the ifcfg-xxx files. There are
different settings that may work and I just tried some of the not-working
combinations.
Cheers,
Koos.
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