Multiplex communications – Diagnostic testing – Path check
Reexamination Certificate
1998-02-12
2001-07-24
Hsu, Alpus H. (Department: 2662)
Multiplex communications
Diagnostic testing
Path check
C370S399000, C370S535000
Reexamination Certificate
active
06266325
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method of controlling path audit in a switch. More particularly, the invention relates to a path audit control method of detecting and, and adjusting for, an abnormality in the setting of a path in an ATM switch.
ATM (Asynchronous Transfer Mode) technology has been agreed upon by the ITU-T for the next generation of switching systems and various facilities are carrying out comprehensive research in an effort to realize broadband ISDNs (Integrated Service Digital Networks).
An ATM switch includes (1) a line interface unit for interfacing lines and for executing UPC control, billing control, NDC (Network Data Collection) control and OAM control, etc.; (2) a switch (an ATM switch) for switching cell paths, (3) a multiplexer/demultiplexer for multiplexing cells that have arrived from a plurality of lines, inputting the cells to a switch, demultiplexing cells that have arrived from the switch and outputting the cells to a prescribed line interface unit, and (4) a central controller for controlling the overall switch. The above-mentioned UPC (Usage Parameter Control) includes performing monitoring to determine whether actual cell inflow rate has exceeded a reported cell inflow rate (transmission rate), passing all arriving cells if the reported value has not been exceeded and, if the reported value has been exceeded, discarding cells that are in violation in such a manner that the cell inflow rate will not exceed the reported value.
In such an ATM switch, the central controller (CC) establishes whether control originally to be executed by the line interface unit is possible or impossible [this is referred to as a “CTP (Connection Terminating Point) setting”] and establishes whether UPC control is possible or impossible (this is referred to as a “UPC setting”). More specifically, the central controller performs a CTP setting and a UPC setting for the line interface unit in regard to paths conforming to channel identifiers (VPI/VCI or internal channel identifiers). If both the CTP and UPC settings are performed with regard to a prescribed channel identifier, full control of the line interface unit becomes possible with regard to cells having this channel identifier. In other words, transmission of cells by UPC control, collection of billing data and traffic data and OAM control, etc., become possible. In a case where the CTP setting and not the UPC setting is performed in regard to a prescribed channel identifier transmission of cells having this channel identifier is not possible but operations other than those related to UPC are possible. In a case where neither the CTP setting nor the UPC setting has been performed with regard to a prescribed channel identifier, none of these control operations can be carried out.
Further, the central controller CC sets routing information (tag information) in a multiplexer/demultiplexer in correspondence with channel identifiers. The multiplexer/demultiplexer places the routing information in a table and, whenever a cell arrives, obtains the routing information, which conforms to the particular channel identifier, from the table, attaches the routing information to the cell and then sends the cell to the ATM switch. The ATM switch routes the cell to a prescribed path based upon this routing information.
In the prior art, path matching processing is not executed (1) between the central controller (CC) and multiplexer/demultiplexer (common unit) and (2) between the central controller (CC) and the line interface unit (discrete unit). Consequently, if paths are left unestablished or if paths are left floating for some reason while the central controller CC is executing path setting/release processing in regard to a common unit or discrete unit, the path setting information being managed by the central controller CC and the path setting information being managed by the common/discrete units will not agree. It should be noted that “floating” of a path refers to a situation in which a path that should have been deleted by the central controller CC is left on the side of a common or discrete unit.
Since path matching processing is not executed in the prior art, however, the above-mentioned mismatch cannot be detected and dealt with in a prompt manner. As a result, communication may become impossible. Since a path that should have been eliminated by the central controller CC will be left on the side of a common or discrete unit, a problem such as excessive billing may arise.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to make possible the prompt and easy detection of unset paths and floating paths.
Another object of the present invention is to execute matching processing in such a manner that path setting information being managed by a central controller and path setting information being managed by common/discrete units will match.
A further object of the present invention is to detect promptly disagree between path setting information being managed by a central controller and path setting information being managed by common/discrete units, execute matching processing in such a manner that these two items of information will match and prevent communication failure and abnormal operation such as excessive billing.
According to the present invention, the foregoing objects are attained by providing a method of controlling path audit of a switch in which a central controller establishes, in correspondence with channel identifiers, cell routing paths in a unit within the switch, and cells are routed to prescribed lines in accordance with the routing paths, comprising the steps of (1) causing information, which indicates whether each channel identifier is being used to establish a path, to be held in bitmap form in a unit (e.g., a multiplexer/demultiplexer) within the switch, (2) sending information, which indicates whether each channel identifier has been used to establish a path, from the central controller to the unit in bitmap form, and (3) causing the unit to compare the bitmap information which it itself is holding with the bitmap information that has been sent from the central controller, thereby to determine whether a path has been normally established in said unit as specified by the central controller. In a case where the bitmap information held and the bitmap information that has been sent do not agree, matching processing is executed by cooperation between the central controller and the unit in such a manner that the compared bitmap information will be made to agree.
Further, according to the present invention, the foregoing objects are attained by providing a method of controlling path audit of a switch in which a central controller establishes, in correspondence with channel identifiers, cell routing paths for a unit within the switch, and cells that have entered from lines are routed to prescribed lines in accordance with the routing paths, comprising the steps of (1) causing information to be held in bitmap form, and for each channel identifier, in a line interface unit, the information indicating, in regard to a path specified by the channel indicator, whether control to be executed originally is possible (CTP setting) and whether UPC control is possible (UPC setting), (2) performing a CTP setting and a UPC setting for each channel identifier and sending bitmap information indicating a CTP setting state and bitmap information indicating a UPC setting state of each channel identifier, and (3) causing the line interface unit to compare bitmap information which it itself is holding with bitmap information that has been sent, thereby to determine whether a CTP setting and a UPC setting have be made as specified by the central controller. In a case where the bitmap information held and the bitmap information that has been sent do not agree, matching processing is executed in such a manner that the compared bitmap information will be made to agree.
Other features and advantages of the present invention will be apparent from the following description tak
Ishioka Eiji
Morita Sumie
Odaka Hiromi
Oishi Toshiaki
Sekine Shigeru
Fujitsu Limited
Helfgott & Karas P.C.
Ho Duc
Hsu Alpus H.
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