def configLoopbackPort(self, portList='all', enabled=True):
        """
        Description
           Configure port to loopback.

        Parameters
           portList: <'all'|list of ports>: 
                     <list>: Format: [[ixChassisIp, str(cardNumber1), str(portNumber1])]...]
                     Or if portList ='all', will modify all assigned ports to the specified mediaType.

           enabled: <bool>: True=Enable port to loopback mode.
        """
        response = self.ixnObj.get(self.ixnObj.sessionUrl+'/vport')
        if portList == 'all':
            portList = self.getPhysicalPortsFromCreatedVports()

        vportList = self.getVportFromPortList(portList)
        for vport in vportList:
            response = self.ixnObj.get(self.ixnObj.httpHeader+vport+'/l1Config', silentMode=False)
            currentPortType = response.json()['currentType']
            self.ixnObj.patch(self.ixnObj.httpHeader+vport+'/l1Config/'+currentPortType, data={'loopback': enabled})