JP3575449B2 - Cell selection discarding method in ATM communication network and ATM communication network - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cell selection and discarding method in an ATM communication network, and more particularly, to a method in which an invalid cell input from an upstream passing through a failed connection is used as a cell of a node device during a time period from the occurrence of a line failure to the time of taking measures against the failure. The present invention relates to a cell selection and discarding method in an ATM communication network which prevents the packet from staying in a buffer.
[0002]
[Prior art]
As a method of detecting / notifying a failure in a broadband communication network using an ATM (Asynchronous Transfer Mode), an AIS (Alarm Indication Signal) / RDI (Remote Defect Indication) system is widely known. In the AIS / RDI system, when a failure such as a line failure occurs in a network, a node facing an interface (UNI: User Network Interface) or an interface between networks (NNI: Network Node Interface) between networks and user equipment. The device (hereinafter, referred to as a terminal node device) detects and returns the AIS / RDI signal indicating the occurrence of the failure, and notifies the monitoring control device connected to the terminal node device of the occurrence of the failure. The monitoring control device that has received the failure notification performs a failure countermeasure, such as identification of a failure location, isolation, and setting of a bypass route, based on the failure information detected by the terminal node device.
[0003]
FIG. 4 is a diagram for explaining the generation of an AIS cell when a transmission path failure occurs, a procedure for notifying failure information by returning an RDI cell, a procedure for setting a detour path, and a procedure for separating a failure location.
[0004]
According to FIG. 4, two terminal node devices 1-a and 1-e to which a terminal or another communication network is connected are connected to three intermediate node devices 1-b to 1-b relayed and arranged between the terminal node devices. d and communication via main signal transmission lines 2-a to 2-d connecting these node devices. In addition, a supervisory control device is connected to the terminal node devices 1-a and 1-e via a control communication channel (not shown).
[0005]
In the following description, a signal flow from a terminal node device (e.g., 1-a) that is a signal transmission source to a terminal node device (e.g., 1-e) that is a signal transmission destination is referred to as a "downward direction", and The signal flow is defined as “upstream”, and in each direction, the side closer to the source of the signal is defined as “upstream”, and the side closer to the destination of the signal is defined as “downstream”.
[0006]
Now, a notification procedure when a transmission path failure occurs at the failure point 4 will be described. First, upon detecting a transmission path failure, the node device 1-d located downstream of the failure point 4 transmits an AIS cell downstream.
[0007]
When the node device 1-e, which is the terminal node device, terminates and detects the AIS cell, it notifies the monitoring control device of the failure information notified by the AIS cell, and at the same time, transmits the RDI cell toward the upstream in the reverse direction. .
[0008]
Upon detecting the RDI cell, the node device 1-a, which is the terminal node device located at the most upstream position in the section, notifies the monitoring and control device (not shown) of the failure information notified by the RDI cell.
[0009]
When the supervisory control device recognizes that a transmission line failure has occurred in the downstream direction based on the failure information by the AIS cell and the RDI cell from each terminal node device, for example, it sets the connection 3-b of the bypass route. Then, the connection 3-a in which the transmission path failure has occurred is deleted.
[0010]
As described above, when a failure occurs in the connection transmission line between the intermediate node devices relayed and arranged between the two terminal node devices, the failure occurs in the most downstream where the AIS cell generated in the intermediate node device on the receiving side is detected. The terminal node device located notifies the supervisory control device, and furthermore, from the point in time that the most upstream terminal node device that has detected the RDI cell looped back by this terminal node notifies the supervisory control device, the failure node location Failure measures such as identification, separation, and setting of a detour route are performed.
[0011]
Therefore, from the occurrence of the transmission path failure to the time when the monitoring control device sets the bypass route and deletes the failed connection 3-a, the node devices 1-a to 1-c upstream of the failure point 4 Has a problem that invalid cells of the failed connection 3-a passing through the failed point 4 continue to be input.
[0012]
The node devices 1-b to 1-c include not only the connection 3-a in which a transmission path failure via the failure point 4 has occurred but also the connection 3-c in which no failure has occurred on the transmission path. Are transmitted, the cell of the connection 3-a which has become invalid due to the transmission line failure occupies the cell buffer of the node device 1-b to 1-c, or the cell in the upstream direction of the main signal transmission line 2-b. Since the output link band is occupied, there is a problem that the network resources available for the normal connection 3-c decrease and the effective use of the network resources is impaired.
[0013]
[Problems to be solved by the invention]
In the above-described conventional ATM communication network, when a transmission line failure occurs, invalid cells stay in the cell buffer of the node device until the monitoring control device sets a bypass route and deletes the failed connection. There are drawbacks such as a decrease in the use efficiency of the cell buffer and invalid cells flowing out downstream.
[0014]
An object of the present invention is to eliminate such a conventional drawback by detecting a failed connection at the time of receiving an RDI cell for notifying a transmission path failure, and selectively discarding cells passing through the failed connection. It is an object of the present invention to provide a cell selection and discarding method in an ATM communication network that enables effective use of a buffer.
[0015]
[Means for Solving the Problems]
The cell selection and discarding method in the ATM communication network according to the present invention comprises: a terminal node device connected to a terminal or another communication network on a pair of upstream and downstream connections having opposite transmission directions; A cell selection and discard method in an ATM communication network in which an intermediate node device for relaying a connection is provided and a means for setting an alternative connection when a connection failure is detected, wherein a downstream connection failure occurs between the intermediate node devices In this case, when the intermediate node device located upstream of the fault that has occurred detects the faulty connection information of the connection to which the input cell belongs from the header of the main signal cell input from downstream, when the intermediate node device detects the faulty connection information of the cell input from upstream, Is selectively discarded for cells passing through the failed connection.
[0016]
Further, the failure connection information is transmitted in response to an ADI (Alarm Indication Signal) cell transmitted by an intermediate node device located downstream of the generated failure, from an RDI (Remote Defect Indication) transmitted back from the most downstream end node device. It is characterized by being a cell.
[0017]
Also, the intermediate node device located upstream of the generated failure has a failure connection table, determines whether the received failure connection information exists in the failure connection table, and is registered. The method is characterized in that the CAM address is selectively discarded, and when the CAM address is not registered, a free CAM address in the failed connection table is acquired, and the failed connection information is registered in the acquired address.
[0018]
Further, the ATM communication network of the present invention relays between a terminal node device to which a terminal or another communication network is connected, and a terminal node device connected to a pair of upstream and downstream connections having opposite transmission directions. In an ATM communication network in which an intermediate node device is arranged and a means for setting an alternative connection when a connection failure is detected, when a downstream connection failure occurs between the intermediate node devices, an upstream of the generated failure occurs. Means for selecting and discarding a cell passing through the faulty connection among cells input from the upstream when the faulty connection information is detected from the header of the main signal cell input from the downstream. It is characterized by:
[0019]
Further, the failure connection information is an RDI cell that is returned from an end node device at the downstream end with respect to an AIS cell transmitted by an intermediate node device located downstream of the generated failure.
[0020]
Further, the means for selectively discarding includes a failure connection table, determines whether or not the received failure connection information is present in the failure connection table. If not, a free CAM address in the failed connection table is acquired, and the failed connection information is registered in the acquired address.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0022]
First, a procedure for generating an AIS cell when a transmission path failure occurs and notifying failure information by returning an RDI cell will be described. FIG. 1 is a diagram for explaining the procedure of generating an AIS cell when a transmission path failure occurs and reporting failure information by returning an RDI cell.
[0023]
Referring to FIG. 1, node devices 1-a and 1-e, which are two terminal node devices to which a terminal or another communication network is connected, are connected to three node devices 1- 1 relayed between the terminal node devices. Communication is performed via b to 1-d and main signal transmission lines 2-a to 2-d connecting these node devices.
[0024]
Now, when a transmission line failure occurs at the failure point 4, the node device 1-d located downstream of the failure point 4 detects the transmission line failure, generates an AIS cell, and transmits the AIS cell downstream. I do. When detecting the AIS cell, the node device 1-e, which is the terminal node device, notifies the monitoring and control device (not shown) of the failure information notified by the AIS cell, and at the same time, generates an RDI cell and transmits it upstream. Upon detecting the RDI cell, the node device 1-a, which is the terminal node device located at the most upstream, notifies the monitoring control device of the failure information notified by the RDI cell. The supervisory control device recognizes that a transmission line failure has occurred in the downstream direction based on the failure information from each terminal node device, and sets up a detour path connection and establishes a connection in which the transmission line failure has occurred. Perform a failure avoidance measure such as deleting 3-a.
[0025]
Next, the operation of the node device arranged in the middle will be described. FIG. 2 is a block diagram showing a configuration of the node device in the ATM communication network of the present embodiment shown in FIG. In FIG. 2, for simplicity, the main signal transmission line 2 and the SW transmission line 11 are each shown by one line, but in an actual device, the main signal transmission line 2 and the SW transmission line 11 It consists of a pair of lines (input line and output line).
[0026]
According to FIG. 2, the node device includes an IF unit 10, a SW unit 12, and a control unit 14.
[0027]
First, the IF units 10 (10-a to 10-n) receive a cell for user information (user cell) which is a main signal input from an input line of each main signal transmission line 2 by a built-in line interface circuit. Then, the data is output to the SW unit 12 via the input line of the SW transmission line 11 (11-a to 11-n).
[0028]
The SW unit 12 distributes the input cell to an output line of one of the SW transmission lines 11 specified by the routing information included in the cell header, and returns the output cell to the IF unit 10.
[0029]
The IF unit 10 outputs the cell that has been input back to one of the output lines of the main signal transmission line 2 via the line interface circuit.
[0030]
The control unit 14 is connected to each of the IF unit 10 and the SW unit 12 by a control signal 13 for performing operation setting, alarm collection, and the like, and performs control system communication with an external monitoring and control device (not shown). The setting and management information is transmitted and received via the path 5.
[0031]
Subsequently, the operation of the IF unit will be described. FIG. 3 is a block diagram illustrating a configuration example of the IF unit illustrated in FIG.
[0032]
According to FIG. 3, the IF unit 10 includes a physical layer processing unit 101, an ATM layer processing unit 102, a control interface 103, and a cell selection discard processing unit 104.
[0033]
First, the physical layer processing unit 101 receives a cell input from the input line of the main signal transmission line 2, performs a physical layer termination process, and outputs the cell to the cell selection discard processing unit 104.
[0034]
When the cell input from the physical layer processing unit 101 is a user cell, the cell selection discard processing unit 104 obtains connection information of the connection to which the input cell belongs from the header information of the cell, and is provided in the cell selection discard processing unit 104. In addition, it is determined whether or not the information is registered in the information of the faulty connection table 21 shown in FIG. 5, and if registered, the information is selectively discarded and the process of passing is performed.
[0035]
The ATM layer processing unit 102 converts the header information of the cell input from the cell selection discard processing unit 104 based on the header conversion information received from the control unit 14 via the control interface unit 103. Further, the header-converted cell is subjected to ATM layer processing such as AIS and RDI processing, and then output to the SW unit 12 via the input line of the SW transmission line 11. At this time, routing information required by the SW unit 12 is added as internal header information. In the SW unit 12, after the routing, the output is output to the IF unit 10 again from the output line of the SW transmission line 11.
[0036]
The ATM layer processing unit 102 performs ATM layer processing such as removal of an internal header on the cell input from the output line of the SW transmission line 11, and then outputs the cell to the cell selection discard processing unit 104.
[0037]
When an input cell from the ATM layer processing unit 102 is an RDI cell, the cell selection discard processing unit 104 provides connection information of a VPI (Virtual Path Identifier) and a VCI (Virtual Channel Identifier) of the RDI cell. Is extracted, transmitted to the ATM layer processing unit 102 via the control line 105, and the input cell is output to the physical layer processing unit 101. Further, the cell selection discarding unit 104 updates the failed connection table 21 shown in FIG. 5 using the failed connection information received from the ATM layer processing unit 102 via the control line 105.
[0038]
The physical layer processing unit 101 converts the cell received from the cell selection and discard processing unit 104 into a transmission signal, and outputs the transmission signal to the output line of the main signal transmission path 2.
[0039]
The control interface unit 103 converts the operation information input from the control unit 13 via the control signal 13 and control information such as line information settings and alarms into the physical layer processing unit 101, the cell selection discard processing unit 104, and the ATM layer processing. In addition to outputting to each functional block of the unit 102, control information and monitoring information from each functional block are output to the control unit 14 via the control signal 13.
[0040]
Therefore, when the input cell is a user cell, the ATM node device obtains connection information of the connection to which the input cell belongs from the header information of the cell, and obtains information of the failure connection table 21 provided in the cell selection discard processing unit 104. It is determined whether or not it is registered in the, if it is registered, by selectively discarding, to prevent invalid cells from staying in the cell buffer of its own node device, It is possible to prevent the cells of the failed connection from flowing out.
[0041]
Next, an operation of cell selection discarding in the ATM node device will be described.
[0042]
The following description is a case where the present invention is applied to the node device 1-b which is a relay point. The connections 1-a to 1-e set in each node device 1 are set bidirectionally, and a connection that forms a pair with a certain connection is called an opposite connection. Further, assuming that a certain connection is CNx and the opposite connection is CNy, the IF unit 10 to which CNx inputs and the IF unit 10 to which CNy outputs are the same, and the IF unit 10 to which CNx outputs and the CNy to output CNy. The input IF unit 10 is assumed to be the same. In the following description, the VPI / VCI of the connection to which the RDI cell belongs is referred to as VPIa / VCIa. The VPI / VCI of the connection opposite to the connection to which the RDI cell belongs is defined as VPIb / VCIb.
[0043]
First, the physical layer processing unit 101 of the IF unit 10 receives a main signal from the input line of the main signal transmission line 2, performs a physical layer termination process, and outputs the signal to the cell selection discard processing unit 104.
[0044]
When the cell input from the physical layer processing unit 101 is a user cell, the cell selection discard processing unit 104 obtains connection information VPI / VCI of the connection to which the input cell belongs from the header information of the cell, and obtains the obtained connection information VPI / Using the VCI as a search key, it is determined whether the connection to which the input cell belongs is registered in the failed connection table 21. This failure connection table 21 is provided in the cell selection discard processing unit 104 and has a CAM structure as shown in FIG. 5, so that the CAM can be easily searched using the connection information VPI / VCI as a search key.
[0045]
If the connection to which the input cell belongs is registered in the failure connection table 21, the cell selection discard processing unit 104 discards the cell and outputs an empty cell to the ATM layer processing unit 102, and If the connection is not registered in the failure connection table 21, the input cell is output to the ATM layer processing unit 102.
[0046]
The ATM layer processing unit 102 converts the header information of the cell based on the header conversion information set by the control unit 14, performs AIS and RDI processing, and then switches the SW unit via the input line of the SW transmission line 11. 12 is output. In addition, the ATM layer processing unit 102 adds routing information required by the SW unit 12 as internal header information.
[0047]
The SW unit 12 distributes the output line to the SW transmission line 11 based on the routing information included in the cell header, and returns the output line to the IF unit 10 to which the SW transmission line 11 is connected.
[0048]
The ATM layer processing unit 102 receives the cell from the output line of the SW transmission line 11, performs an ATM layer process such as removal of an internal header and replacement with an output VPI / VCI, and outputs the cell to the cell selection discard processing unit 104. .
[0049]
The cell selection discard processing unit 104 determines whether the cell input from the ATM layer processing unit 102 is an RDI cell. If the input cell is an RDI cell, it extracts the connection information VPIa / VCIa of the RDI cell and outputs it to the ATM layer processing unit 102 via the control line 105.
[0050]
The ATM layer processing unit 102 uses the connection information VPIa / VCia of the connection to which the RDI cell received from the cell selection discarding unit 104 as a search key to search the opposite connection table 31 shown in FIG. A search is performed to obtain connection information VPIb / VCIb of the opposite connection, and to output this to the cell selection / discard processing unit via the control line 105. The opposite connection table 31 is a table required for performing AIS and RDI processing in the ATM layer processing unit 102.
[0051]
The cell selection discard processing unit 104 searches the fault connection table 21 shown in FIG. 5 using the fault connection information VPIb / VCIb input from the ATM layer processing unit 102 via the control line 105 as a search key. When the corresponding faulty connection is registered in the faulty connection table 21, the updating process is not performed on the faulty connection table 21. If the corresponding faulty connection is not registered in the faulty connection table 21, the free CAM address of the faulty connection table 21 is obtained from the free address management table 22 shown in FIG. 5, and the faulty connection information VPIb / VCIb is added to the obtained address. Register
[0052]
The physical layer processing unit 102 converts the cell output from the cell selection discard processing unit 104 into a transmission signal, and outputs the transmission signal to the output line of the main signal transmission line 2.
[0053]
On the other hand, the monitoring control device that has received the failure information from each terminal node device sets the detour connection 3-b as shown in FIG. a is deleted.
[0054]
Due to the deletion of the failed connection 3-a, the ATM layer processing unit 102 uses the deletion information of the connection 3-a input from the control unit 14 to the IF unit 10 to delete the connection 3- a and the information of the opposite connection are deleted.
[0055]
Further, the cell selection discarding unit 104 deletes the information of the failed connection 3-a from the provided failed connection table 21. The deletion of the information of the failed connection 3-a is performed by writing ALL “0” to the data (VPIb / VCIb) of the CAM address in which the information of the failed connection is recorded in the failed connection table 21. The deleted CAM address is notified to the free address management unit 22, and can be reused as a free CAM address that can be used when the next CAM data is registered.
[0056]
【The invention's effect】
As described above, according to the cell selection and discarding method in the ATM communication network, the intermediate node device located upstream of the generated transmission line failure detects the faulty connection information from the header of the main signal cell input from downstream. Occasionally, by selecting and discarding cells that pass through a failed connection among cells input from the upstream, it is possible to prevent invalid cells from accumulating in the cell buffer of the node device during the time from the occurrence of a failure to the implementation of the troubleshooting. In addition, there is an effect that the use efficiency is improved.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a procedure for notifying failure information by generation of an AIS cell when a transmission path failure occurs and return of an RDI cell.
FIG. 2 is a block diagram showing a configuration of a node device in the ATM communication network of the present embodiment shown in FIG.
FIG. 3 is a block diagram illustrating a configuration example of an IF unit illustrated in FIG. 2;
FIG. 4 is a diagram for explaining generation of an AIS cell when a transmission path failure occurs, a procedure for notifying failure information by returning an RDI cell, setting a detour path, and separating a failure location.
FIG. 5 is a diagram showing a configuration of a failure connection table.
FIG. 6 is a diagram showing a configuration of an opposite connection table.
[Explanation of symbols]
1 node device 2 main signal transmission path 3 connection 5 control system communication path 10 IF section 11 SW transmission path 12 SW section 13 control signal 14 control section 21 failure connection table 22 free address management section 31 facing connection table 101 physical layer processing section 102 ATM layer processing unit 103 control interface unit 104 cell selection discard processing unit

Claims (6)

A terminal node device to which a terminal or another communication network is connected and an intermediate node device that relays between the terminal node devices are arranged on a pair of upstream and downstream connections in opposite transmission directions, and a connection failure occurs. A method for selecting and discarding cells in an ATM communication network comprising means for setting an alternative connection upon detection of a failure, wherein when a downstream connection failure occurs between intermediate node devices, an intermediate location located upstream of the failure occurred. When the node device detects the faulty connection information of the connection to which the input cell belongs from the header of the main signal cell input from the downstream, the node device selectively discards the cells passing through the faulty connection among the cells input from the upstream. A cell selection and discarding method in an ATM communication network. The failure connection information is an RDI (Remote Defect Indication) cell returned from the most downstream end node device to an AIS (Alarm Indication Signal) cell transmitted by an intermediate node device located downstream of the generated failure. 2. The method for discarding cell selection in an ATM communication network according to claim 1, wherein: The intermediate node device located upstream of the generated failure has a failure connection table, determines whether or not the received failure connection information exists in the failure connection table. 3. The ATM communication network according to claim 1, wherein a selective CAM is discarded, and if not registered, an available CAM address in said faulty connection table is obtained, and said faulty connection information is registered in the obtained address. Cell discarding method in A terminal node device to which a terminal or another communication network is connected and an intermediate node device that relays between the terminal node devices are arranged on a pair of upstream and downstream connections in opposite transmission directions, and a connection failure occurs. In a case where a downstream connection failure occurs between intermediate node devices in an ATM communication network having a means for setting an alternative connection upon detection of An ATM communication network comprising means for selecting and discarding a cell passing through a faulty connection among cells input from an upstream when faulty connection information is detected from a header of an input main signal cell. 5. The fault connection information according to claim 4, wherein the ADI cell transmitted by the intermediate node device located downstream of the generated fault is an RDI cell returned from the most downstream terminal node device. ATM communication network. The means for selectively discarding includes a faulty connection table, determines whether or not the received faulty connection information is present in the faulty connection table, and if registered, selectively discards and registers the faulty connection information. 6. The ATM communication network according to claim 4, wherein when there is no such information, an available CAM address in the failed connection table is acquired, and the failed connection information is registered in the acquired address.

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