# Pastebin aiPqweew
    def update_floatingip_gateway(self, fip, lswitch):
        subnets = lswitch.get_subnets()
        for subnet in subnets:
            if subnet.get_cidr() == fip.external_cidr:
                # external gateway ip changed
                if subnet.get_gateway_ip() != fip.external_gateway_ip:
                    old_fip = copy.deepcopy(fip)
                    fip.set_external_gateway_ip(subnet.get_gateway_ip())
                    return (fip, old_fip)
        return None