I'm using ubuntu 12.04LTS

I setup a bridged network:

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet dhcp

auto br0
iface br0 inet dhcp
    bridge_ports eth0
    bridge_stp off
    bridge_fd 0
    bridge_maxwait 0

Seems to work.

Then I created a virtual machine using Ubuntu's vmbuilder tool like so:

vmbuilder kvm ubuntu \
            --suite 'precise' \
            --flavour 'virtual' \
            --arch 'amd64' \
            --dest 'myvm' \
            --hostname 'myvm' \
            --mem '2048' \
            --rootsize '4096' \
            --swapsize '1024' \
            --mirror 'http://archive.ubuntu.com/ubuntu' \
            --name 'MyName' \
            --user 'myuser' \
            --pass 'password' \
            --bridge 'br0' \
            --addpkg acpid \
            --addpkg vim \
            --addpkg openssh-server \
            --addpkg avahi-daemon \
            --libvirt 'qemu:///system' \
            --ip '192.168.0.100'

It generates fine and starts up seemingly without a problem as well when I run

virsh start myvm

I am then able to resolve it's IP with MDNS and try

ping myvm.local

So presumably the VM is running? But for some reason I can't communicate with it, I can't SSH in, I don't even get a response to my ping.

Any ideas? I'd be happy to provide further information.

Thanks.