def getIpv4ObjByPortName(self, portName=None):
        """
        Description
            Get the IPv4 object by the port name.

        Parameter
            portName: <str>: Optional: The name of the port.  Default=None.
        """
        # Step 1 of 3: Get the Vport by the portName.
        queryData = {'from': '/',
                    'nodes': [{'node': 'vport', 'properties': ['name'], 'where': [{'property': 'name', 'regex': portName}]}]}

        queryResponse = self.ixnObj.query(data=queryData, silentMode=False)
        if queryResponse.json()['result'][0]['vport'] == []:
            raise IxNetRestApiException('\nNo such vport name: %s\n' % portName)

        # /api/v1/sessions/1/ixnetwork/vport/2
        vport = queryResponse.json()['result'][0]['vport'][0]['href']
        self.ixnObj.logInfo(vport)

        # Step 2 of 3: Query the API tree for the IPv4 object
        queryData = {'from': '/',
                    'nodes': [{'node': 'topology',    'properties': ['vports'], 'where': []},
                              {'node': 'deviceGroup', 'properties': [], 'where': []},
                              {'node': 'ethernet',  'properties': [], 'where': []},
                              {'node': 'ipv4',  'properties': [], 'where': []},
                              ]}

        queryResponse = self.ixnObj.query(data=queryData, silentMode=False)

        # Step 3 of 3: Loop through each Topology looking for the vport.
        #              If found, get its IPv4 object
        for topology in queryResponse.json()['result'][0]['topology']:
            if vport in topology['vports']:
                # Get the IPv4 object: /api/v1/sessions/1/ixnetwork/topology/2/deviceGroup/1/ethernet/1/ipv4/1
                ipv4Obj = topology['deviceGroup'][0]['ethernet'][0]['ipv4'][0]['href']
                return ipv4Obj