def sendMldJoinNgpf(self, mldObj, ipv6AddressList):
        """
        Description
            For IPv6 only.
            This API will take the MLD object and loop through all the configured ports
            looking for the specified ipv6Address to send a join.

        Parameter
            ipv6AddressList: 'all' or a list of IPv6 addresses that must be EXACTLY how it is configured on the GUI.
        """
        # Loop all port objects to get user specified IPv6 address to send the join.
        portObjectList = mldObj+'/mldMcastIPv6GroupList/port'
        response = self.ixnObj.get(portObjectList)

        for eachPortIdDetails in response.json():
            currentPortId = eachPortIdDetails['id']
            # For each ID, get the 'startMcastAddr' multivalue
            startMcastAddrMultivalue = eachPortIdDetails['startMcastAddr']

            # Go to the multivalue and get the 'values'
            response = self.ixnObj.get(self.ixnObj.httpHeader+startMcastAddrMultivalue)
            listOfConfiguredGroupIpAddresses = response.json()['values']
            if ipv6AddressList == 'all':
                listOfGroupAddresses = listOfConfiguredGroupIpAddresses
            else:
                listOfGroupAddresses = ipv6AddressList

            for eachSpecifiedIpv6Addr in listOfGroupAddresses:
                if eachSpecifiedIpv6Addr in listOfConfiguredGroupIpAddresses:
                    # if 'values' match ipv4Address, do a join on:
                    #      http://192.168.70.127.:11009/api/v1/sessions/1/ixnetwork/topology/1/deviceGroup/1/ethernet/1/ipv6/2/mldHost/1/mldMcastIPv6GroupList/port/1/operations/mldjoingroup
                    #    arg1: port/1 object
                    url = mldObj+'/mldMcastIPv6GroupList/port/%s/operations/mldjoingroup' % currentPortId
                    portIdObj = mldObj+'/mldMcastIPv6GroupList/port/%s' % currentPortId
                    # portIdObj = http:/{apiServerIp:port}/api/v1/sessions/1/ixnetwork/topology/1/deviceGroup/1/ethernet/1/ipv6/2/mldHost/1/mldMcastIPv6GroupList/port/1
                    response = self.ixnObj.post(url, data={'arg1': [portIdObj]})
                    self.ixnObj.waitForComplete(response, url+response.json()['id'])