'Setup or teardown the network structures on hosts related to
instance.'

def setup_networks_on_host(self, context, instance, host=None, teardown=False):

    host = (host or instance.host)
    args = {'instance_id': instance.id, 'host': host, 'teardown': teardown, 'instance': instance}
    self.network_rpcapi.setup_networks_on_host(context, **args)
