auto br0

iface br0 inet static

address x.x.x.178

network x.x.x.0

netmask x.x.x.x

broadcast 

gateway x.x.x.x[gateway of eth0 earlier]

bridge_ports eth0

bridge_fd 0

bridge_hello 2

bridge_maxage 12

bridge_stp off

#dns-search google.com

dns-nameservers x.x.x.x x.x.x.x 

with this config 

1] net inside host is working

2]net inside vms created using nat is working but i have to manually ser interface file inside the NATD vm.

3] when i create virtualnetwork in routed mode using shared physical device br0 and assign vm to it 

the net inside vm not working .

4] created virtual network using only routed mode with any physical device instaead og br0 still net inside vm not working. 

I followed documentation on libvirt site .

I want vms indifferent nw should communicate with each other like net1 and vm1 can ping vm2 in net2 .