We have a ubuntu-12.04 host running another ubuntu-12.04 virtual machine with kvm virtualization and bridged network interface on eth4. This network allows the virtual machine access to the outside world. I want to add another bridge (br0) to the virtual machine so it can access the local network. But every time I try this, the first bridge "collapses" in some way, as in I cannot access the virtual machine via ssh or even ping it.
The following is the /etc/network/interfaces
file on the host that I am trying to get to work
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
auto eth4
iface eth4 inet manual
auto br4
iface br4 inet static
address 10.52.4.247
netmask 255.255.255.0
gateway 10.52.4.1
dns-nameservers 10.27.3.2 10.25.3.2
broadcast 10.52.4.255
bridge_ports eth4
bridge_stp off
bridge_maxwait 5
metric 0
# Local network
auto eth0
iface eth0 inet manual
auto br0
iface br0 inet static
address 192.168.0.21
netmask 255.255.255.0
broadcast 192.168.0.255
bridge_ports eth0
bridge_stp off
bridge_maxwait 5
metric 0
What am I missing here? Any help greatly appreciated!