Route monitor control system and method in an ATM switching network

Abstract: A route monitor control system includes a plurality of OAM cell handlers (OCHs); a plurality of virtual path handlers (VPHs); a plurality of virtual channel handlers (VCHs); trunks (3); and a control unit (5). The control unit issues an OAM (operation and maintenance) cell send instruction to a specific one of the plurality of OAM cell handlers, and carries out a loop back control to at least one of the virtual path handler, the virtual channel handler, and the trunk, which are associated with the specific OAM cell handler, as an object unit in response to the OAM cell send instruction. Also, when the specific OAM cell handler sends out an OAM cell from the specific OAM cell handler to the object unit in response to the OAM cell send instruction, the control unit determines a fault position based on returning or non-returning of the OAM cell from the object unit to the specific OAM cell handler.

Description: The present invention relates to a route monitor control system which monitors an ATM (Asynchronous Transfer Mode) switching apparatus, and a route monitor control method. In recent years, a variety of services supported by an ATM switching apparatus are required in rapid spreading of a market of the ATM switching apparatus. Therefore, various types of hardware is installed into the ATM switching apparatus to provide the variety of services and a service function of each type of hardware is extended. On the other hand, in the quality verification of these hardware functions, after a maintenance person recognizes a kind of hardware to be verified, a maintenance command is given to carry out a conductiveness test between a trunk and a node by a monitoring apparatus installed in or out of the system. However, because a managing method is different for every system in such a conventional route monitor control system, there is a problem to need professional knowledge for maintenance operation for every system. In conjunction with the above description, a test system of an ATM switching apparatus is disclosed in Japanese Laid Open Patent application (JP-A-Heisei 9-214498). In this reference, an ATM switching system is composed of the ATM switching apparatus, a maintenance console, and a test apparatus. A package " test control section is provided in the ATM switching apparatus. When the package of a communication route unit is installed, the package test control section detects from a signal outputted the installation of the package from the package, and specifies a kind of the package. In the TU-T Recommendation I.610 of the Telecommunication Standardization Sector of the International Telecommunication Union, Geneva, Ch, 1 November 1995, it is described a loop back capability of both the virtual paths and the virtual channels of an ATM layer wherein test cells are sent from one single source point to one loopback point and back to the one single source point. Confirmation of the loopback is performed at the ATM layer. The European Paten Application EP 0 777 401 A1 discloses control of a loopback test between ATM points wherein an ATM setup message is sent from a user application interface to an ATM switch. Two ATM points are selected as the loopback and source endpoints by a network operator. A test cell is injected at the source endpoint and routed based on the header address. The targeted loopback endpoint monitors the node identified in the setup message. The test cell is captured and examined at the loopback endpoint and then retransmitted to the source point. The United States Patent 5,974,046 discloses a maintenance method for subscriber lines of a broadband network termination apparatus. A loopback OAM cell is sent from an ATM switching system to the broadband network termination apparatus and subsequently a loopback response message is received by the ATM switching system. The present invention is accomplished in view of above problem. An object of the present invention is to provide a route monitor control system in which in a monitoring apparatus for maintenance operation, does not need professional knowledge special to the monitoring apparatus, a route monitor control method and a recording medium. In an aspect of the present invention, a route monitor control system includes a plurality of OAM cell handlers (OCHs); a plurality of virtual path handlers (VPHS); a plurality of virtual channel handlers (VCHs); trunks; and a control unit. The control unit issues an OAM (operation and maintenance) cell send instruction to a specific one of the plurality of OAM cell handlers, carries out a loop back control to at least one of the virtual path handler, the virtual channel handler, and the trunk, which are associated with the specific OAM cell handler, as an object unit in response to the OAM cell send instruction, and when the specific OAM cell handler sends out an OAM cell from the specific OAM cell handler to the object unit in response to the OAM cell send instruction, determines a fault position based on returning or non-returning of the OAM cell from the object unit to the specific OAM cell handler. Here, the control unit may carry out a switching operation of a route from the virtual path handler to the trunk for fault avoidance based on the determining fault position. Also, the plurality of OAM cell handlers, the plurality of virtual path handlers, the plurality of virtual channel handlers, the trunks, and the control unit may be contained in an ATM (asynchronous transfer mode) switching apparatus. Also, it is desirable that the control unit periodically issues the OAM cell send instruction to the specific OAM cell handler. Also, the control unit may carry out the loop back control to all of the virtual path handler (VPH), the virtual channel handler (VCH), and the trunk, which are associated with the specific OAM cell handler, as the object units in response to the OAM cell send instruction, and when the specific OAM cell handler sends out the OAM cells to the object units in response to the OAM cell send instruction, may determine the fault position based on returning or non-returning of each of the OAM cells from the object unit to the specific OAM cell handler. Also, the control unit may carry out the issuing operation, the loop back control and the determining operation while changing the specific OAM cell handler among the plurality of OAM cell handlers. In another aspect of the present invention, a route monitor control method is attained: by (a) issuing an OAM (operation and maintenance) cell send instruction to a specific one of a plurality of OAM cell handlers (OCHs); by (b) carrying out a loop back control to at least one of a virtual path handler (VPH), a virtual channel handler (VCH), and a trunk, which are associated with the specific OAM cell handler, as an object unit in response to the OAM cell send instruction; by (c) sending out an OAM cell from the specific OAM cell handler to the object unit in response to the OAM cell send instruction; and by (d) determining a fault position based on returning or non-returning of the OAM cell from the object unit to the specific OAM cell handler. Also, the route monitor control method may further include the step of: carrying out a route switching operation for fault avoidance based on the determining fault position. Also, the object unit is contained in an ATM (asynchronous transfer mode) switching apparatus. Also, the virtual path handler (VPH), the virtual channel handler (VCH), and the trunk, and the specific OAM cell handler are contained in an ATM (asynchronous transfer mode) switching apparatus. Also, the (a) issuing step may be attained by periodically issuing the OAM cell send instruction to the specific OAM cell handler. Also, the loop back control is carried out to all of the virtual path handler (VPH), the virtual channel handler (VCH), and the trunk as the object units in response to the OAM cell send instruction, and the OAM cells may be sent out from the specific OAM cell handler to the object units in response to the OAM cell send instruction. Fig. 1 is a block diagram showing the structure of a route monitor control system of the present invention. Hereinafter, a route monitor control system in an ATM switching apparatus of the present invention will be described below with reference to the attached drawings. Fig. 1 is a block diagram showing the structure of the route monitor control system according to an embodiment of the present invention. As shown in Fig. 1, the route monitor control system in the embodiment is composed of a plurality of virtual path handler (VPHs) 1, a plurality of virtual channel handlers (VCHs) 2, a plurality of trunks 3. a plurality of OAM cell handlers (OCHs) 4 and a control unit 5. Also, the virtual path handlers (VPHs) 1. the virtual channel handlers (VCHs) 2, the trunks 3, the OAM cell handlers (OCHs) 4 and the control unit 5 are provided in an ATM switching apparatus. The virtual path handler (VPH) 1 relays a virtual path (VP). The virtual channel handler (VCH) 2 relays a virtual channel (VC). The trunk 3 is a unit for the termination of the VC. The OAM cell handler (OCH) 4 processes a F4 flow and a F5 flow in an ATM layer, and is a monitor which carries out a loop back test to the virtual path handler (VPH) 1, the virtual channel handler (VCH) 2, and the trunk 3, which are associated with the OAM cell handler 4, and sends out OAM cells to them. Thus, the monitor of the sent OAM cells is carried out. The control unit 5 controls the virtual path handlers (VPHs) 1, the virtual channel handlers (VCHs) 2, the trunks 3 and the OAM cell handlers (OCHs) 4. Also, the control unit 5 issues an instruction to a specific one of the OAM cell handlers (OCHs) 4 which is provided at a predetermined position. As a result, the specific OAM cell handler (OCH) 4 operates as a starting point of the OAM cell sending-out, and receives the OAM cell returned to the specific OAM cell handler 4 through a loop route. Thus, a fault route in the ATM switching apparatus can be determined, and the control unit 5 carries out a switching control in the route based on the reception or non-reception of the returned OAM cell. In this way, in the loop back test, an OAM cell is sent out along a predetermined route, and the route is checked based on the reception or non-reception of the sent out OAM cell. Next, an operation of the route monitor control system of the present invention will be described below with reference to Fig. 1. First, the control unit 5 instructs a specific OAM cell handler (OCH) 4 of a plurality of OAM cell handler (OCHs) 4 to send out an OAM cell. Also, the control unit 5 controls the specific OAM cell handler (OCH) 4 to carry out a loop back control to the virtual path handler (VPH) 1, the virtual channel handler (VCH) 2 and the trunk 3, which are associated with the specific OAM cell handler (OCH) 4, as a monitoring object. Next, the specific OAM cell handler (OCH) 4 periodically transmits OAM cells to the virtual path handler (VPH) 1, the virtual channel handler (VCH) 2 and the trunk 3, in response to the instruction to monitor that the OAM cells are sent back to the specific OAM cell handler (OCH) 4 through loops. The specific OAM cell handler (OCH) 4 notifies the monitoring result to the control unit 5. Lastly, the control unit 5 specifies or determines a fault portion based on the monitoring result notified from the specific OAM cell handler (OCH) 4 and carries out a fault avoidance control such as the switching of a route in the ATM switching apparatus. In the route monitor control system of the described present invention, an OAM cell handler (OCH) 4 is specified as a starting point sending out OAM cell. However, the control unit 5 operates in such a manner that a plurality of OAM cell handler (OCHs) 4 may operate as the starting points sending out OAM cells at a time or sequentially. That is, by setting a plurality of starting points for monitoring the routes of the ATM switching apparatus, the load to monitor the ATM switching apparatus can be distributed. Also, the OAM cell handler (OCH) 4 may be not an independent unit and may be incorporated into the virtual path handler (VPH) 1, the virtual channel handler (VCH) 2, or the trunk 3. Moreover, the trunk 3 may be TE (Terminal Equipment) as the unit which carries out the relay of VC. As described above, according to the route monitor control system of the present invention, the OAM cell in the ATM is looped-back in the ATM switching apparatus as a monitoring object. Therefore, the existing ATM technique can be used for the monitor control in the ATM switching apparatus. Therefore, without needing the knowledge special to the monitor control of the ATM switching apparatus, it is possible to simply carry out a maintenance operation of the monitor control.

Claims: A route monitor control system comprising: a plurality of OAM cell handlers (OCHs); a plurality of virtual path handlers (VPHs); a plurality of virtual channel handlers (VCHs); trunks (3); and a control unit (5) which is adapted to: issue an OAM cell, operation and maintenance cell, send instruction to a specific one of said plurality of OAM cell handlers, carry out a loop back control to the plurality of said virtual path handlers (VPHs), the plurality of said virtual channel handlers (VCHs), and a trunk (3), which are associated with said specific OAM cell handler, in response to said OAM cell send instruction, and when said specific OAM cell handler sends out OAM cells in response to said OAM cell send instruction, determine a fault position based on returning or non-returning of each of the OAM cells to said specific OAM cell handler. The route monitor control system according to claim 1, wherein said control unit (5) is adapted to carry out a switching operation of a route from at least one of said virtual path handlers (VPHs) to said trunk (3) for fault avoidance based on the determined fault position. The route monitor control system according to claim 1 or 2, wherein said plurality of OAM cell handlers, said plurality of virtual path handlers, said plurality of virtual channel handlers, said trunks, and said control unit (5) are contained in an ATM, asynchronous transfer mode, switching apparatus. The route monitor control system according to any of claims 1 to 3, wherein said control unit is adapted to periodically issue said OAM cell send instruction to said specific OAM cell handler. The route monitor control system according to any of claims 1 to 4, wherein said control unit (5) is adapted to carry out the issuing operation, the loop back control and the determining operation while changing said specific OAM cell handler among said plurality of OAM cell handlers. A route monitor control method comprising the steps of: (a) issuing an OAM cell, operation and maintenance cell, send instruction to a specific one of a plurality of OAM cell handlers (OCHs); (b) carrying out a loop back control to a plurality of virtual path handlers (VPHs), a plurality of virtual channel handlers (VCHs), and a trunk 3), which are associated with said specific OAM cell handler, as object units in response to said OAM cell send instruction, (c) sending out OAM cells from said specific OAM cell handler to said object units in response to said OAM cell send instruction; and (d) determining a fault position based on returning or non-returning of the OAM cells from said object units to said specific OAM cell handler. The route monitor control method according to claim 6, further comprising the step of carrying out a route switching operation for fault avoidance based on the determined fault position. The route monitor control method according to claims 6 or 7, wherein said object units are contained in an ATM, asynchronous transfer mode, switching apparatus. The route monitor control method according to claim 6 or 7, wherein said virtual path handlers (VPHs), said virtual channel handlers (VCHs), and said trunk (3), and said specific OAM cell handler are contained in an ATM, asynchronous transfer mode, switching apparatus. The route monitor control method according to any of claims 6 to 9, wherein said (a) issuing step comprises the step of: periodically issuing said OAM cell send instruction to said specific OAM cell handler.

Inventors: TAKASAKI YOSHINORI, TAKASAKI, YOSHINORI, Takasaki, Yoshinori, c/o NEC Corporation
Applicants: JUNIPER NETWORKS INC, JUNIPER NETWORKS, INC.
Application year: 2001
Main classification: H04L12
IPC codes: H04Q11, H04L29, H04M3, H04L12