JP3573982B2 - ATM communication equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ATM (asynchronous communication mode) communication device having a virtual path (VP) switching function.
[0002]
[Prior art]
In the ATM communication network, a method of setting two communication paths for the same section is adopted for failure countermeasures. That is, a method is adopted in which a backup VP (secondary VP) to be paired is set in advance with respect to the active VP (primary VP). By adopting such a method, even if a failure occurs in the active VP, communication can be continued by immediately switching the communication path to the standby VP.
[0003]
Conventionally, such VP switching is performed by an in-device control unit in an ATM communication device (XC device, exchange, etc.). When recognizing the failure of the active VP, the control unit in the device identifies the standby VP to which the active VP is to be switched, and issues a switch instruction to the interface unit (IF unit) that transmits the ATM cell, thereby switching the VP. Execute.
[0004]
The internal control unit and each IF unit are connected via an internal LAN, a control bus, or the like, and exchange of messages (data) relating to VP failure detection, switching instructions, and other processing is performed through such communication paths. Has been done via
[0005]
[Problems to be solved by the invention]
However, in the case of the related art, since the switching process is executed under the initiative of the control unit in the apparatus, there is a problem that the following case cannot be dealt with.
(1) When the control unit in the device itself fails, or when a failure occurs in a communication path connecting the control unit in the device and each IF unit, VP switching cannot be performed.
(2) Since the switching process is performed under the initiative of the in-device control unit, it takes time for the switching process (failure detection and switching instruction, etc.).
[0006]
The present invention has been made in view of the above problems, and proposes an ATM communication device that can execute a VP switching process reliably and in a short time.
[0007]
[Means for Solving the Problems]
In order to solve such a problem, in the present invention, each of the interface units for terminating communication with a user terminal or another ATM communication device with the other terminal includes the following means.
[0008]
That is, (1) a position information table storing information on whether the ATM communication device to which the own interface unit belongs is a relay station or a switching station, (2) a routing table storing VP routing information, and (3) a own interface unit. When the OAM cell received via the working VP from the upstream requests the switching of the working VP, the own interface unit If the ATM communication device to which the OAM cell belongs is a switching station located on the upstream side with respect to the failure point, the OAM cell received from the downstream side via the backup VP requests the switching of the working VP. And an APS program unit that directly controls VP switching based on information stored in a routing table provided in Obtain so.
[0009]
With such a configuration, each ATM communication device can execute VP switching by the interface unit alone without the intervention of the in-device control unit. As a result, VP switching can be executed autonomously even when the in-apparatus control unit itself fails or when a failure occurs in the communication path between the in-apparatus control unit and the interface unit.
[0010]
Further, unlike the conventional device, the VP switching does not involve the control unit in the device, and the processing is completed in the interface unit (that is, since communication with other units is not required), Switching itself can be speeded up.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
(A) First Embodiment (A-1) Overall Configuration In the following, an ATM communication device according to the present invention is provided at a connection point (UNI: User Network Interface) between a user terminal and a network. A case in which the present invention is applied to an ATM cross connector provided at a connection point (NNI: Network Node Interface).
[0012]
The ATM communication device according to the present embodiment includes three functional units, similarly to the configuration of a general device. That is, it is configured by an in-apparatus control unit 1, an interface (IF) unit 2, and a switch (SW) unit 3. Among them, the IF units 2 are provided in a number corresponding to the number of other ATM communication devices (ATM exchanges and ATM cross connectors) facing this device and the number of subscribers accommodated.
(A-2) Configuration of Each Unit (A-2-1) Configuration of In-Device Control Unit 1 The in-device control unit 1 is a unit for controlling processing in the device, and is configured by the following programs. . That is, it comprises a reception control program 11, an XC control program 12, an alarm processing program 13, a communication control program 14, and other programs.
[0013]
Here, the reception control program 11 is a program that receives a control order from an OpS (Operation System) connected to the ATM communication device and corresponds thereto. The XC control program 12 is a program for checking VP connection information such as a band based on a control order from OpS, and instructing the IF unit 2 to set a line (VP connection). The alarm processing program 13 is a program that specifies a failure location and notifies the OpS based on alarm information notified from the alarm processing program 22 of the interface unit 2 and the alarm processing program 32 of the switch unit 3. The communication control program 14 is a program that controls communication with the interface unit 2 and the switch unit 3.
(A-2-2) Configuration of the Interface Unit 2 The interface unit 2 is a means for accommodating a user line or an intra-office line and performing multiplexing of user cells (ATM cells), failure detection, traffic monitoring, and the like. Specifically, it is composed of the following various programs and an LSI.
[0014]
That is, an HCV (Header Converter) program 21, a band control program 22, an alarm processing program 23, an OAM (Operation Administration and Maintenance) program 24, a communication control program 25, an APS (Auto Protection Switch) program 26, a routing table 27, a line termination. It comprises a unit 28, an OAM unit 29, a UPC (Usage Parameter Control) / NPC (Network Parameter Control) unit 210, a header conversion unit 211, and a position information table 212.
[0015]
Here, the HCV program 21 is a program for instructing the header conversion unit 211 to convert the header of the ATM cell. The band control program 22 is a program for setting band control information in the UPC / NPC section 210. The alarm processing program 23 is a program that detects failures of various LSIs and notifies the control unit in the device at a period of 100 [msec]. The OAM program 24 is a program that receives an OAM cell from the OAM unit 29 and analyzes and controls the OAM cell. The communication control program 25 is a program that controls communication between the IF unit 2 and the in-device control unit 1. The APS program 26 is a program that performs switching control based on an instruction from the OAM program 24.
[0016]
The routing table 27 is a table that stores routing information of the primary VP and the secondary VP, and the like. FIG. 2 shows a specific configuration example of the routing table 27. In the routing table 27, information such as operation status, route information, and band information is set for each line number.
[0017]
The circuit terminating unit 28 is an LSI for converting an optical signal transmitted via an optical fiber connected to a user terminal or another station into an electric signal. The OAM unit 29 is an LSI for performing insertion, removal, and monitoring (monitoring) of OAM cells in the VP. The UPC / NPC section 210 is an LSI for controlling the cell flow rate of the transmission path. The header conversion unit 211 is an LSI for controlling exchange (XC) of ATM cells by a header conversion process.
[0018]
The position information table 212 is a table in which data indicating whether the corresponding device (IF unit) is a switching terminal or a relay station is set. This data is identification information set by OpS at the time of initial setting of the device by the maintenance person. For example, (1) is set for the switching end, and (0) is set for the relay station.
(A-2-3) Configuration of SW Unit 3 The SW unit 3 refers to the header information of the ATM cell input from the IF unit 2 and performs a process of distributing cells to an output route (IF unit). The SW unit 3 includes a communication control program 31, an alarm processing program 32, and the like.
(A-3) Configuration of OAM Cell FIG. 3 shows a specific configuration example of the OAM cell detected by the OAM unit 29. The OAM cell includes an ATM cell header 41, a type of OAM cell such as failure, performance management, and switching, a type OAM type 42, an OAM function type 43 that shows more details of the OAM type, and a switching that shows the result of performing a switching operation such as APS switching. It comprises a failure factor 44, an error detection code 46 for the information of the payload portion, an opposite-side switching flag 47 indicating whether the opposite-side switching end has been switched, and the like.
(A-4) Content of Switching Processing Operation by Embodiment (A-4-1) Switching of VP In the following description, a case in which VP switching is performed on the network system shown in FIG. 4 will be described. In the figure, it is assumed that all four VPHs arranged on the network are devices according to the present embodiment (that is, devices having the device configuration shown in FIG. 1).
[0019]
Normally, the active VP (primary VP) and the standby VP (secondary VP) are set to different routes in preparation for the occurrence of a network failure or the like. For example, as shown in FIG. 4, different routes are set such as a primary VP (VPI # 1) indicated by a solid line and a secondary VP (VPI # 2) indicated by a broken line.
[0020]
Normally (when the network is normal), the ATM cell transmitted from the subscriber A reaches the subscriber B via the primary VP (route represented by VPH1 → VPH2 → VPH4). Of course, data can be exchanged between the subscriber A and the subscriber B via the secondary VP, but the data is not normally used (band 0) and only the primary VP is used.
[0021]
However, when an abnormality occurs (for example, when a failure occurs in the primary VP), as shown in FIG. 5, the ATM cell output from the subscriber A becomes a secondary VP (VPH1 → VPH3 → VPH4) to the subscriber B.
(A-4-2) Execution procedure of switching operation (outline)
Subsequently, an outline of a specific procedure in which the VP switching is performed will be described with reference to FIG.
[0022]
Here, it is assumed that a failure has occurred in a link portion (primary VP) located between VPH1 and VPH2. In this case, the VPH2 located on the downstream side (right side in the figure) of the link detects a communication alarm (failure detection) on the transmission path. Next, VPH2 transmits an OAM cell (FIG. 3) to VPH4, which is a downstream (right side in the figure) switching terminal, and instructs switching to the secondary VP.
[0023]
Upon receiving the switching request (OAM cell), the VPH 4 connects the secondary VP to the terminal A (connection between VPI # 1 and VPI # 2), and uses the secondary VP to switch the upstream side (left side in the figure). A switching request (OAM cell) is transmitted to the terminal VPH1. The VPH1 receiving the switching request (OAM cell) connects the secondary VP to the terminal A (connection between VPI # 1 and VPI # 2).
[0024]
With the above procedure, switching from the primary VP to the secondary VP is completed.
(A-4-3) Execution procedure of switching operation (specific example)
Next, the contents of processing executed in each VPH (VPH1, VPH2, VPH3, and VPH4 in FIG. 6) to perform the above operation will be described.
(1) Processing of VPH2 First, the alarm processing program 23 for VPH2 detects a transmission path alarm (communication alarm) caused by a failure in the VPH1-VPH2 section. Next, the alarm processing program 23 analyzes the alarm and, when judging that the primary VP has failed, transmits an OAM cell (FIG. 3) shown in FIG. 3 to request a VP switch from a switching terminal located downstream. I do.
[0025]
This OAM cell (FIG. 3) is generated and transmitted by the OAM program 24 in the same subscriber-side IF 2 as the alarm processing program 23 that has detected a failure. Note that the OAM type 42 of the OAM cell is “switch management”, the OAM function type 43 is “VP switching request”, the switching failure factor 44 is “normal”, and the opposing switching flag 47 is “opposite switching terminal”. Is set.
(2) Processing of VPH4 Next, processing of VPH4, which is a switching terminal, will be described. FIG. 7 shows a configuration of the IF unit 2 in the VPH4. The OAM cell transmitted from the VPH 2 is taken into the device via the station-side IF unit “A” (“A” is an identifier used for convenience of explanation), and then is switched via the SW unit 3 to the switching end IF unit. (Subscriber-side IF unit).
[0026]
Thereafter, the switching end IF unit leads a series of switching processing and transmission of the OAM cell. Specifically, the OAM unit 29 of the switching end IF unit detects an OAM cell, and analyzes the OAM type 43 by the OAM program 24. Here, if the OAM type 43 is the switching management, it is determined that the OAM cell is the OAM cell of the switching request (FIG. 3). Next, the OAM program 24 uses the position information table 212 to determine whether the IF unit to which the OAM program belongs belongs to the IF unit located at the switching end.
[0027]
Here, upon obtaining the conclusion that the self is the switching end, the OAM program 24 analyzes the OAM function type 43 in the OAM cell (FIG. 3), and executes the VP switching if it is a VP switching request. If it is not the switching end, the OAM cell is transferred to the downstream side as it is.
[0028]
A specific VP switching process is executed by the APS program 26. First, the APS program 26 extracts the VPI number from the ATM cell header in the OAM cell (FIG. 3), and refers to the routing table 27 using the VPI number as an index value. As a result, the switching destination VPI number, band information, and other switching information can be obtained. Based on this information, the APS program 26 sets the HCV program 21 and the band control program 22.
[0029]
The HCV program 21 and the band control program 22 execute a VPI failure state check and a band check based on the switching information (VPI number, band information and other switching information, etc.) input from the APS program 26. If the result is normal, the HCV program 21 and the band control program 22 set data in the UPC / NPC section 210 and the header conversion section 211.
[0030]
After the switching is completed, the opposing switching flag 47 in the OAM cell (FIG. 3) is referred to, and if the switching flag = 0 (opposite switching end has not been switched), the switching route (to the opposing switching end) is set. The OAM cell (FIG. 3) of the VP switching request is transferred using the secondary VP route. Here, the OAM type of the OAM cell is set to "switching management", the OAM function type is set to "normal", and the opposing switching flag is set to "opposite switching end switched".
[0031]
The information of the secondary VP set in the routing table 27 is input from the OpS by the maintenance person, similarly to the information of the primary VP.
(3) Processing of VPH3 Next, processing of VPH3 located on the secondary VP will be described. VPH3 is located between VPH1 and VPH4 and plays the role of a relay station. The switching process is not performed, and the OAM cell (FIG. 3) received from VPH4 is simply passed through to VPH1 as the downstream station. is there.
[0032]
Specifically, like the VPH4, the OAM cell (FIG. 3) is received, the OAM type 42 is analyzed, and if the switching management is performed, the position information table 212 is further analyzed. Here, if the position information of VPH4 is the relay station (0), the input OAM cell (FIG. 3) is passed through as it is. FIG. 8 shows the flow of OAM cells in VPH3.
(4) Processing of VPH1 Next, the processing of VPH1, which is the other switching terminal, will be described. The operation up to the switching is the same as that of the VPH4. However, the VPH1 sends an OAM cell (FIG. 3) at the end of the process, and notifies the switching result to the VPH4.
[0033]
When the switching is successful, the VPH 1 sets the OAM type 42 of the OAM cell (FIG. 3) to “switching management” and the OAM function type 43 to “VP switching response”, and sets the switching failure factor 44 to “normal”. Set to.
[0034]
On the other hand, if the switching has failed, the VPH 1 sets the OAM type 42 to “switching management”, the OAM function type 43 to “VP switching response”, and sets the switching failure factor 44 to a corresponding value. For example, if the VPI is out of order, "1" is set as the standby line out of order. FIG. 9 shows the flow of OAM cells in VPH1.
(5) Processing of VPH4 Finally, the VPH4 receives the execution result (the switching failure factor 44) from the VPH1, and notifies the in-device control unit 1 of the result. Thus, a series of switching processing ends.
(A-5) Effect of the Embodiment As described above, in the ATM communication device according to the embodiment, the notification is made by the routing table 27 and the position information table 212 stored in the IF unit 2 and the OAM cell (FIG. 3). The switching of the VP is performed based on the information to be switched, so that the switching of the VP is realized without any intervening control unit 1 in the apparatus.
[0035]
Thus, even when a failure occurs in the in-device control unit 1 or a failure occurs in a communication path between the in-device control unit 1 and the IF unit 2, the VP can be obtained by using the ATM communication device according to the present embodiment. Can be surely executed.
[0036]
In addition, since a series of switching processes is executed in a single IF unit (since communication with another processing unit (for example, the control unit 1 in the apparatus) in the same housing is not required), the switching process is performed. Higher speed can also be realized.
(A-6) Other Embodiments (1) In FIG. 1, the routing table 27 and the position information table 212 are separately illustrated for convenience of explanation, but in an actual device, different storages on a single storage medium are used. It is also possible to store each in the area.
[0037]
Similarly, various programs can be stored in different storage areas of a single storage medium in an actual device. Note that the functions realized by these programs can be realized by hardware.
(2) The case where the optical fiber is terminated as the line terminating unit 28 has been described, but this is not intended to limit the transmission path to the optical fiber.
[0038]
【The invention's effect】
As described above, according to the present invention, each of the interface units terminating the communication with the user terminal or the other ATM communication device includes the position information table, the routing table, and the APS program unit. VP switching can be executed by the interface unit alone without going through the in-device control unit, so that the in-device control unit itself fails or the communication path between the in-device control unit and the interface unit fails. VP switching can be executed autonomously even when the error occurs.
[0039]
Further, unlike the conventional device, since the control unit in the device does not intervene in the VP switching, the processing can be completed in the interface unit, and the VP switching can be speeded up.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of an ATM communication device.
FIG. 2 is a chart showing a routing table.
FIG. 3 is a diagram illustrating a configuration example of an OAM cell.
FIG. 4 is a diagram illustrating a configuration example of a network system.
FIG. 5 is a diagram illustrating an example of route switching when a failure occurs.
FIG. 6 is a diagram conceptually illustrating a VP switching process.
FIG. 7 is a diagram provided for describing processing of VPH4.
FIG. 8 is a diagram provided for describing a process of VPH3.
FIG. 9 is a diagram provided for describing a process of VPH1.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... In-device control part, 11 ... Reception control program, 12 ... XC control program, 13 ... Alarm processing program, 14 ... Communication control program, 2 ... Interface part, 21 ... HCV program, 22 ... Band control program, 23 ... Alarm Processing program, 24 OAM program, 25 communication control program, 26 APS program, 27 routing table, 28 line termination unit, 29 OAM unit, 30 UPC / NPC unit, 211 header conversion unit, 212 ... Position information table, 3 ... SW unit, 31 ... Communication control program, 32 ... Alarm processing program.

Claims (2)

In each of the interface units that terminates communication with the user terminal or the other opposing ATM communication device,
A position information table storing information on whether the ATM communication device to which the own interface unit belongs is a relay station or a switching station,
A routing table storing VP routing information;
If the ATM communication device to which the own interface unit belongs is a switching station located on the downstream side with respect to the failure point, when the OAM cell received via the working VP from the upstream requests the switching of the working VP, When the ATM communication device to which the own interface unit belongs is a switching station located on the upstream side with respect to the failure point, when the OAM cell received via the backup VP from the downstream requests the switching of the working VP, An ATM communication device comprising: an APS program unit that searches the routing table provided in its own interface unit and directly controls VP switching based on stored information. The ATM communication device according to claim 1, when the ATM communication device to which the own interface unit belongs is a relay station, even when an OAM cell received from the upstream side or the downstream side requests switching of the working VP. An ATM communication device for transferring an OAM cell to a downstream side or an upstream side as it is.

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