def assignPorts(connection, sessionUrl, portListPerCommunity):
    '''
        This method is used to assign ports from a connected chassis to the required NetTraffics.

        Args:
        - connection is the connection object that manages the HTTP data transfers between the client and the REST API
        - sessionUrl is the address of the session that should run the test
        - portListPerCommunity is the dictionary mapping NetTraffics to ports (format -> { community name : [ port list ] })
    '''
    communityListUrl = "%s/ixload/test/activeTest/communityList" % sessionUrl

    communityList = connection.httpGet(url=communityListUrl)
    communityNameList = [community.name for community in communityList]

    for communityName in portListPerCommunity:
        if communityName not in communityNameList:
            errorMsg = "Error while executing assignPorts operation. Invalid NetTraffic name: %s. This NetTraffic is not defined in the loaded rxf." % communityName
            raise Exception(errorMsg)

    for community in communityList:
        if portListPerCommunity.get(community.name):
            portListForCommunity = portListPerCommunity.get(community.name)
            portListUrl = "%s/%s/network/portList" % (communityListUrl, community.objectID)
            for portTuple in portListForCommunity:
                chassisId, cardId, portId = portTuple
                paramDict = {"chassisId": chassisId, "cardId": cardId, "portId": portId}

                performGenericPost(connection, portListUrl, paramDict)
        else:
            errorMsg = "Error while executing assignPorts operation. For community: %s you dont't have ports assigned." % community.name
            raise Exception(errorMsg)