Abstract:
A monitoring path changing method is disclosed that changes monitoring paths by sending and receiving monitoring path control information in a system having a monitoring control terminal to control and monitor plural transmission devices with use of the monitoring paths. Each of the monitoring paths corresponds to an area within a transmission channel data frame. The monitoring path control information controls the monitoring paths. The monitoring control terminal is connected to one of the transmission devices. The transmission devices are connected to each other via transmission channels so as to form a network. The method comprises steps of causing one of the transmission devices opposed by another of the transmission devices via one of the transmission channels to return monitoring path control information sent from the opposing transmission device, and causing the opposing transmission device to execute a monitoring path change when the opposing transmission device receives the monitoring path control information sent by itself.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a U.S. continuation application filed under 35 USC 111(a) claiming benefit under 35 USC 120 and 365(c) of PCT application JP2002/012927, filed on Dec. 10, 2002, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a monitoring path changing method and a transmission device using the same, and particularly relates to a monitoring path changing method that changes monitoring paths of a network monitoring system and a transmission device using the same.  
         [0004]     2. Description of the Related Art  
         [0005]     There are some systems that have a configuration shown in  FIG. 1 , in which a monitoring control terminal  10  monitors a network comprising plural transmission devices A through G connected via a transmission channel with the use of a communication path for monitoring control constructed in the network.  
         [0006]     In SONET (Synchronous Optical Network) used mainly in North America and SDH (Synchronous Digital Hierarchy) used in other countries, a monitoring path control frame is usually allocated to a SOH (Section Overhead) or an available area in a payload of a normal transmission channel frame.  
         [0007]     In the case where the network configuration or a line is changed, it is necessary to move the monitoring path control frame from the SOH to the payload, or change the allocated area within the payload without affecting areas used by a user.  
         [0008]     If there is a multiplexing device between the transmission devices, only the payload is multiplexed and the monitoring path control frame allocated to the SOH remains without being multiplexed. Therefore, the monitoring path control frame should be moved to the payload.  
         [0009]     A method illustrated in  FIG. 2  is known as a method for changing a monitoring path, in which the monitoring control terminal  10  broadcasts monitoring path change instructions to all the transmission devices A through G in the network.  FIG. 3  shows another known method, in which operators manually change the monitoring path of the respective devices A through G using front control panels thereof.  
         [0010]     However, if the method of broadcasting monitoring path change instructions to the transmission devices A through G is used in a large network, it is difficult to synchronize the monitoring path changes of all the transmission devices because of transmission delays and differences in the monitoring processing time. If the timing of the monitoring path change differs device to device, the monitoring path change instruction cannot reach a device located at a distal end of the network. This results in differences in the allocation area of the monitoring path control frame, so that the monitoring cannot be performed.  
         [0011]     On the other hand, in the case where operators manually change the monitoring path of the respective transmission devices, there might occur execution time differences of the path changes among the transmission devices as well as a data loss or incorrect data input due to operational mistakes.  
         [0012]     Relating to the above methods, Japanese Laid Open Publication No. 63-211835 discloses a network monitoring path setting/control system. Also, Japanese Laid Open Publication No. 1-128640 discloses a network path switching method in the event of a failure, and Japanese Laid Open Publication No. 5-110545 discloses a device capable of correctly switching path routes in the event of a failure.  
       SUMMARY OF THE INVENTION  
       [0013]     A general object of the present invention is to provide a monitoring path changing method and a transmission device using the same to solve at least one problem described above. A specific object of the present invention is to provide a monitoring path changing method and a transmission device using the same capable of quickly changing monitoring paths without losing important failure and control information.  
         [0014]     To achieve these and other object of the present invention, there is provided a monitoring path changing method for changing monitoring paths by sending and receiving monitoring path control information in a system having a monitoring control terminal to control and monitor plural transmission devices with use of the monitoring paths, each of the monitoring paths corresponding to an area within a transmission channel data frame, the monitoring path control information controlling the monitoring paths, the monitoring control terminal being connected to one of the transmission devices, the transmission devices being connected to each other via transmission channels so as to form a network, the method comprising steps of causing one of the transmission devices opposed by another of the transmission devices via one of the transmission channels to return monitoring path control information sent from the opposing transmission device, and causing the opposing transmission device to execute a monitoring path change when the opposing transmission device receives the monitoring path control information sent by itself.  
         [0015]     This monitoring path changing method makes it possible to synchronize monitoring path changes among the transmission devices and to quickly change monitoring paths without losing important failure and control information. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     The preferred embodiments of the present invention are described in detail below with reference to the following drawings.  
         [0017]      FIG. 1  is a block diagram showing the configuration of a network;  
         [0018]      FIG. 2  is a diagram illustrating a related-art monitoring path changing method;  
         [0019]      FIG. 3  is a diagram illustrating another related-art monitoring path changing method;  
         [0020]      FIG. 4  is a functional block diagram of an embodiment of a transmission device of the present invention;  
         [0021]      FIG. 5  is a block diagram showing a first embodiment of a network system;  
         [0022]      FIG. 6  is a diagram showing the structure of a transmission channel data frame;  
         [0023]      FIG. 7  is a sequence diagram for a first embodiment of a method of the present invention;  
         [0024]      FIG. 8  is a sequence diagram for a second embodiment of the method of the present invention;  
         [0025]      FIG. 9  is a block diagram showing a second embodiment of the network system;  
         [0026]      FIG. 10  is a sequence diagram for a third embodiment of the method of the present invention; and  
         [0027]      FIG. 11  is a sequence diagram for a fourth embodiment of the method of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0028]     Referring to  FIG. 4 , there is shown a functional block diagram of an embodiment of a transmission device of the present invention. In order to simplify the explanation,  FIG. 4  illustrates two transmission devices A and B interconnected via a transmission channel and having the same functional configuration. In  FIG. 4 , a monitoring path controller  20  controls the transmission/reception of monitoring path control information (i.e., monitoring path control frame), and determines whether to execute a return control based on received monitoring path control information. A monitoring path information database  22  stores the monitoring path control information. A transmission channel IF (interface)  24  is a point connected to the transmission channel.  
         [0029]     A multiplexer  26  executes data multiplexing and the return control. A monitoring path transmission manager  28  manages the transmission of the monitoring path control information according to an instruction from the monitoring path controller  20 . A monitoring path reception manager  30  manages the reception of the monitoring path control information according to an instruction from the monitoring path controller  20 . A data inserting section  32  inserts the monitoring path control information from the monitoring path transmission manager  28  into an area of an outgoing transmission channel data frame specified by the monitoring path controller  20 . A data extracting section  34  extracts the monitoring path control information from the area of the transmission channel data frame, which is received according to an instruction of the monitoring path controller  20 , specified by the monitoring path controller  20  and sends the information to the monitoring path controller  20 .  
         [0030]     In the transmission device A, the monitoring path controller  20  adds a sender address, i.e., the address of the transmission device A, to the monitoring path control information acquired from the monitoring path information database  22  and sends the information to the monitoring path transmission manager  28 . The monitoring path transmission manager  28  sends the monitoring path control information to the data inserting section  32  to insert the information into the transmission channel data frame. The inserted monitoring path control information is transmitted to the transmission device B via the multiplexer  26  and the transmission channel IF  24 .  
         [0031]     In the transmission device B, the data extracting section  34  extracts the monitoring path control information from the received transmission channel data frame. The monitoring path control information is relayed by the monitoring path reception manager  30  to be sent to the monitoring path controller  20 . The monitoring path controller  20  adds a sender address, i.e., the address of the transmission device B, to the received monitoring path control information and sends back the information.  
         [0032]     During normal operations, the transmission/reception of the monitoring path information is executed on a regular basis. For executing the monitoring path change with the initiative of the transmission device A, the monitoring path controller  20  of the transmission device A changes a monitoring path of thereof to trigger the monitoring path change while having the multiplexer  26  execute a return control.  
         [0033]     With the return control, the monitoring path control information transmitted from the transmission device B is sent back to the transmission device B by the multiplexer  26  of the transmission device A. When the monitoring path controller  20  of the transmission device B refers to the sender address of the monitoring path control information and recognizes that the sender address is its own address (the address of the device B), the monitoring path controller  20  of the transmission device B changes a monitoring path thereof. The monitoring path change is thus completed between the transmission devices A and B.  
         [0034]     Referring to  FIG. 5 , there is shown a block diagram of a first embodiment of a network system.  FIG. 5  illustrates two transmission devices A an B interconnected via a transmission channel as in  FIG. 4 . In  FIG. 5 , the transmission device A has a controller  40  (corresponding to the monitoring path controller  20 ) and a transmission channel IF  41  (corresponding to the transmission channel IF  24 ). The transmission device B also has a controller  40  and a transmission channel IF  41 . The transmission channel IFs  41  of the transmission devices A and B are connected to each other by a transmission channel  50 . The controller  40  of the transmission device A is connected to a monitoring terminal  52 , which executes settings of the monitoring path change.  
         [0035]      FIG. 6  is a diagram showing the structure of a transmission channel data frame. The transmission channel data frame comprises a SOH and a payload. An area of a monitoring path control frame is allocated to the payload. A monitoring path control frame comprises a control type, an originating device address, a destination device address, and changed destination area address. The control type stores control contents of a definition, an instruction, and a response.  
         [0036]     A first embodiment of a method of the present invention using the network shown in  FIG. 5  is described with reference to a sequence diagram of  FIG. 7 . Circled numbers in  FIG. 7  indicate step numbers. The monitoring path change in this embodiment is to switch a monitoring path area address from 1 to 5.  
         [0037]     In step S 1 , contents of the monitoring path control frame are set with use of a front control panel of the monitoring terminal  52  or the transmission device A. In this example, the control type is set to “definition”, and the monitoring path area address is set to “5”.  
         [0038]     In steps S 2  and S 3 , the monitoring path control frame having the change definition information is transmitted/received regularly during the operation.  
         [0039]     Specifically, in step S 2 , the transmission device A transmits a monitoring path control frame having “definition” for the control type, “A” for the originating device address, “B” for the destination device address, and “5” for the changed destination area address.  
         [0040]     In step S 3 , the transmission device B transmits a monitoring path control frame having “definition” for the control type, “B” for the originating device address, “A” for the destination device address, and “5” for the changed destination area address.  
         [0041]     In step S 4 , the execution of the monitoring path change is ordered with use of the front control panel of the monitoring terminal  52  or the transmission device A. In step S 5 , the transmission device A is set to execute the return control upon reception of the monitoring path control frame.  
         [0042]     In step S 6 , as in step S 3 , the transmission device B transmits the monitoring path control frame having the change definition information. The transmission device A executes the return control set in step S 5  over the received monitoring path control frame having the change definition information (step S 7 ), and sends back the frame to the transmission device B (step S 8 ). This operation corresponds to a monitoring path change instruction to the transmission device B.  
         [0043]     In step S 9 , the transmission device A executes the monitoring path change to switch the monitoring path area address from 1 to 5, and stops the return control.  
         [0044]     In step S 10 , the transmission device B recognizes the reception of the monitoring path change instruction since the originating device address in the monitoring path control frame is B, or, its own address. In step S 11 , the transmission device B executes the monitoring path change to switch the monitoring path area address from 1 to 5. In step S 12 , the transmission device B sets “response” to the control type to inform the completion of the monitoring path change. With the above sequence, the monitoring path change is completed.  
         [0045]     A second embodiment of the method of the present invention using the network shown in  FIG. 5  is described with reference to a sequence diagram of  FIG. 8 . Circled numbers in  FIG. 8  indicate step numbers. The monitoring path change in this embodiment is to switch a monitoring path area address from 1 to 5.  
         [0046]     In step S 1 , contents of the monitoring path control frame are set with use of the front control panel of the monitoring terminal  52  or the transmission device A. In this example, the control type is set to “definition”, and the monitoring path area address is set to “5”.  
         [0047]     In steps S 2  and S 3 , the monitoring path control frame having the change definition information is transmitted/received regularly during the operation.  
         [0048]     Specifically, in step S 2 , the transmission device A transmits a monitoring path control frame having “definition” for the control type, “A” for the originating device address, “B” for the destination device address, and “5” for the changed destination area address.  
         [0049]     In step S 3 , the transmission device B transmits a monitoring path control frame having “definition” for the control type, “B” for the originating device address, “A” for the destination device address, and “5” for the changed destination area address.  
         [0050]     In step S 4 , the execution of the monitoring path change is ordered with use of the front control panel of the monitoring terminal  52  or the transmission device A. In step S 5 , the transmission device A sets “instruction” to the control type so as to instruct the transmission device B to change the monitoring path.  
         [0051]     In step S 6 , the transmission device B sets “response” to the control type to report the receipt of the instruction of the monitoring path change.  
         [0052]     In step S 7 , the transmission device B executes the monitoring path change to switch the monitoring path area address from 1 to 5.  
         [0053]     On receiving the monitoring path control frame having the “response” for the control type from the transmission device B, the transmission device A executes the monitoring path change to switch the monitoring path area address from 1 to 5 (step S 8 ). With the above sequence, the monitoring path change is completed.  
         [0054]      FIG. 9  shows a block diagram of a second embodiment of the network system, wherein elements identical to those in  FIG. 5  bear the same reference numerals. In  FIG. 9 , a transmission device A has a controller  40  (corresponding to the monitoring path controller  20 ) and a transmission channel IF  41  (corresponding to the transmission channel IF  24 ). A transmission device B has a controller  40  and transmission channel IFs  41 ,  42 ,  43  and  44 . The transmission channel IFs  41  of the transmission devices A and B are connected to each other by a transmission channel  50 . The controller  40  of the transmission device A is connected to a monitoring terminal  52 , which executes settings of the monitoring path change.  
         [0055]     The transmission channel IF  42  of the transmission device B is connected to a transmission channel IF  41  of a transmission device C via a transmission channel  53 . The transmission channel IF  43  of the transmission device B is connected to a transmission channel IF  41  of a transmission device D via a transmission channel  54 . The transmission channel IF  44  of the transmission device B is connected to a transmission channel IF  41  of a transmission device E via a transmission channel  55 .  
         [0056]     In this network, the monitoring terminal  52  instructs the transmission device A to change a monitoring path. Then, the transmission device A instructs the transmission device B to change a monitoring path. The transmission device B instructs the transmission devices C, D and E to change monitoring paths. As such, all the transmission devices sequentially change the monitoring paths.  
         [0057]     A third embodiment of the method of the present invention using the network shown in  FIG. 9  is described with reference to a sequence diagram of  FIG. 10 . Circled numbers in  FIG. 10  indicate step numbers.  
         [0058]     In step S 11 , steps S 1  through S 12  in  FIG. 7  are executed to complete the monitoring path change between the transmission devices A and B.  
         [0059]     In step S 12 , the controller  40  of the transmission device B, triggered by the completion of the monitoring path change, searches for the transmission channels  53 ,  54  and  55  for which the change is not yet executed. The controller  40  of the transmission device B recognizes that the changes between the transmission devices B and C, B and D, and B and E are not yet executed, and starts the monitoring path change.  
         [0060]     In step S 13 , the monitoring path changes between the transmission devices B and C, B and D, and B and E are executed. That is, the transmission device B is set to execute the return control upon reception of a monitoring path control frame. Each of the transmission devices C, D and E transmits a monitoring path control frames having change definition information. The transmission device B executes the return control over the received monitoring path control frame having the change definition information, and sends back the corresponding frame to the transmission devices C, D and E. This operation corresponds to a monitoring path change instruction to the transmission devices C, D and E. The transmission device B executes the monitoring path change to switch the monitoring path area address, and stops the return control.  
         [0061]     Each of the transmission devices C, D and E recognizes the reception of the monitoring path change instruction since the originating device address in the corresponding monitoring path control frame is own address, and executes monitoring path change to change the monitoring path area address. Then, each of the transmission devices C, D and E sets “response” to the control type to report the completion of the monitoring path change. These steps correspond to steps S 5  through S 12  of  FIG. 7 . The monitoring path change is sequentially executed among plural transmission devices as described above, and thus the monitoring path change in all the devices in the network is completed.  
         [0062]     A fourth embodiment of the method of the present invention using the network shown in  FIG. 9  is described with reference to a sequence diagram of  FIG. 11 . Circled numbers in  FIG. 11  indicate step numbers.  
         [0063]     In step S 11 , steps S 1  through S 8  in  FIG. 8  are executed to complete the monitoring path change between the transmission devices A and B.  
         [0064]     In step S 12 , the controller  40  of the transmission device B, triggered by the completion of the monitoring path change, searches for the transmission channels  53 ,  54  and  55  for which the change is not yet executed. The controller  40  of the transmission device B recognizes that the changes between the transmission devices B and C, B and D, and B and E are not yet executed, and starts the monitoring path change.  
         [0065]     In step S 13 , the monitoring path changes between the transmission devices B and C, B and D, and B and E are executed. That is, the transmission device B sets “instruction” to the control type to instruct each of transmission devices C, D and E to change the monitoring path. Each of the transmission devices C, D and E sets “response” to the control type to report the receipt of the instruction of the monitoring path change.  
         [0066]     Then, the transmission devices C, D and E respectively execute the monitoring path change to switch the monitoring path area address. On receiving the corresponding monitoring path control frames having the “response” for the control type from the transmission devices C, D and E, the transmission device B executes the monitoring path change to change the monitoring path area address. The monitoring path change is sequentially executed among plural transmission devices as described above, and thus the monitoring path change in all the devices in the network is completed.  
         [0067]     According to this method, in the case where a network configuration or a line is changed, it is only needed to give an instruction for changing the monitoring path allocation area to one transmission device instead of to all the transmission devices. Other transmission devices then automatically sequentially execute the change. Therefore, compared to a method of broadcasting change instructions to all the devices or a method of individually changing the path in each device, the change is performed quickly and securely.  
         [0068]     It should be understood that the monitoring path transmission manager  28  corresponds to a monitoring path transmission managing part in the following claims; the monitoring path reception manager  30  corresponds to a monitoring path transmission managing part; and the monitoring path controller  20  corresponds to a monitoring path control part.