'Check all input params'

def check_params(self):

    if (not self.is_vrf_exist()):
        self.module.fail_json(msg='Error:    The    VPN    instance    is    not    existed.')
    if (self.state == 'absent'):
        if (self.vrf != self.intf_info['vrfName']):
            self.module.fail_json(msg='Error:    The    VPN    instance    is    not    bound    to    the    interface.')
    if (self.intf_info['isL2SwitchPort'] == 'true'):
        self.module.fail_json(msg='Error:    L2Switch    Port    can    not    binding    a    VPN    instance.')
    if self.vpn_interface:
        intf_type = get_interface_type(self.vpn_interface)
        if (not intf_type):
            self.module.fail_json(msg=('Error:    interface    name    of    %s    is    error.' % self.vpn_interface))
    if (self.vrf == '_public_'):
        self.module.fail_json(msg='Error:    The    vrf    name    _public_    is    reserved.')
    if ((len(self.vrf) < 1) or (len(self.vrf) > 31)):
        self.module.fail_json(msg='Error:    The    vrf    name    length    must    be    between    1    and    31.')
