def __init__(self, name, host='127.0.0.1', port=27017):
        self.name = name
        self.host = host
        self.port = port
def encode(self):
        return {
            'af': ip_address(self.gaddr).vapi_af,
            'grp_address': {
                ip_address(self.gaddr).vapi_af_name: self.gaddr
            },
            'src_address': {
                ip_address(self.saddr).vapi_af_name: self.saddr
            },
            'grp_address_length': self.glen,
        }