def getNgpfGatewayIpMacAddress(self, gatewayIp):
        """
        Description
            Get the NGPF gateway IP Mac Address. The IPv4
            session status must be UP.

        Parameter
            gatewayIp: <str>: The gateway IP address.

        Return:
            - 0: No Gateway IP address found.
            - removePacket[Unresolved]
            - The Gateway IP's Mac Address.
        """
        queryData = {'from': '/',
                    'nodes': [{'node': 'topology',    'properties': [], 'where': []},
                              {'node': 'deviceGroup', 'properties': [], 'where': []},
                              {'node': 'ethernet',  'properties': [], 'where': []},
                              {'node': 'ipv4',  'properties': ['gatewayIp'], 'where': []}
                    ]}
        queryResponse = self.ixnObj.query(data=queryData, silentMode=False)
        for topology in queryResponse.json()['result'][0]['topology']:
            for deviceGroup in topology['deviceGroup']:
                try:
                    # Getting in here means IPv4 session status is UP.
                    ipv4Href = deviceGroup['ethernet'][0]['ipv4'][0]['href']
                    ipv4SessionStatus = self.getSessionStatus(ipv4Href)
                    gatewayIpMultivalue = deviceGroup['ethernet'][0]['ipv4'][0]['gatewayIp']
                    self.ixnObj.logInfo('\t%s' % ipv4Href)
                    self.ixnObj.logInfo('\tIPv4 sessionStatus: %s' % ipv4SessionStatus)
                    self.ixnObj.logInfo('\tGatewayIpMultivalue: %s' % gatewayIpMultivalue)
                    response = self.ixnObj.getMultivalueValues(gatewayIpMultivalue)
                    valueList = response
                    
                    self.ixnObj.logInfo('gateway IP: %s' % valueList)
                    if gatewayIp in valueList:
                        gatewayIpIndex = valueList.index(gatewayIp)
                        self.ixnObj.logInfo('Found gateway: %s ; Index:%s' % (gatewayIp, gatewayIpIndex))

                        queryData = {'from': deviceGroup['ethernet'][0]['href'],
                                    'nodes': [{'node': 'ipv4',  'properties': ['gatewayIp', 'resolvedGatewayMac'], 'where': []}
                                    ]}
                        queryResponse = self.ixnObj.query(data=queryData, silentMode=False)
                        response = self.ixnObj.get(self.ixnObj.httpHeader+ipv4Href+'?includes=resolvedGatewayMac')
                        gatewayMacAddress = response.json()['resolvedGatewayMac']
                        self.ixnObj.logInfo('gatewayIpMacAddress: %s' % gatewayMacAddress)
                        if 'Unresolved' in gatewayMacAddress:
                            raise IxNetRestApiException('Gateway Mac Address is unresolved.')
                        return gatewayMacAddress[0]
                        
                except:
                    pass
        return 0