JP5545720B2 - Communication control device - Google Patents

Description

  The present invention relates to a data communication technique, and more particularly to a communication control technique for relaying communication data.

  In recent years, the communication industry has been switching from a relatively expensive communication system based on SDH (Synchronous Digital Hierarchy) / SONET (Synchronous Optical NETwork) technology to a relatively inexpensive communication system based on Ethernet (registered trademark) technology. . This is also true for large-capacity backbone communication lines that connect communication carriers, so-called backbone lines.

  However, since the quality of the backbone line does not allow the communication quality to be lowered, OAM (Operation Administration and Maintenance) signals may be transmitted / received between devices constituting the Ethernet network. The communication quality may be maintained by detecting a failure based on the state of the OAM signal and dealing with the failure.

JP 2009-033573 A

  In a current communication system, a plurality of virtual lines are set using one physical line, and a main signal storing user data may be transmitted through each of the plurality of virtual lines. Further, in order to further improve the communication quality of the communication system, physical line redundancy and an OAM signal may be used in combination. Specifically, communication reliability is improved by transmitting / receiving an OAM signal on each virtual line and switching a physical line that transmits a main signal of each virtual line according to the state of the OAM signal. There is also.

  In such a method using an OAM signal (hereinafter also referred to as “individual OAM signal”) for monitoring individual virtual circuits, the reliability of the individual virtual circuits can be improved. However, since it is necessary to individually determine the state of each of the plurality of individual OAM signals in order to detect a virtual circuit failure, it takes a long time to detect a virtual circuit failure, resulting in failure recovery. The present inventor considered that a long time was required.

  The present invention has been made in view of these problems, and a main object of the present invention is to provide a technique for realizing efficient failure handling in an apparatus that relays communication data.

  In order to solve the above-described problem, a communication control device according to an aspect of the present invention includes a main signal receiving unit that receives a plurality of main signals transmitted through a plurality of virtual circuits for a main signal storing user data; An OAM (Operation Administration and Maintenance) signal transmitted via a main signal transfer unit that executes transfer processing to the outside for each of the plurality of main signals, and a path that is used for transmission of any of the plurality of main signals. Is detected as a bundle OAM signal for monitoring a plurality of virtual circuits collectively, and abnormality of the bundle OAM signal is detected, it is determined that all of the plurality of virtual circuits are abnormal. An abnormality determination unit.

  The “user data” is communication data to be transmitted through the backbone line, and may be data transmitted / received between end-to-end terminal devices (such as user terminals). The “main signal” may be in various data formats defined in various communication layers. For example, it may be a layer 2 Ethernet frame or a layer 3 IP packet. “External” serving as a transfer destination of the main signal means a main signal processing entity existing outside the main signal transfer unit. For example, it may be various telecommunication devices (hereinafter also referred to as “NE”) such as an exchange, a transmission device, a switch, and a router installed outside the communication control device. Further, it may be another functional block such as a switch fabric or a network card provided in the communication control device. The “OAM signal” may be an Ethernet OAM defined by IEEE802.1ag. The “path used in any transmission of a plurality of main signals” may be a communication path used in at least a part of any main signal transmission. For example, it may be a specific physical line, one or more NEs, or a specific functional block such as a network card inside the NE.

  According to this aspect, when the bundle OAM signal is abnormal, all of the plurality of main signals transmitted through the plurality of virtual circuits are abnormal. Therefore, when one bundle OAM signal becomes abnormal, it can be determined that all of the plurality of virtual circuits are abnormal. That is, it is possible to collectively detect an abnormality in a plurality of virtual lines without individually determining the state of each of the plurality of virtual lines, and to quickly execute failure recovery processing for each virtual line.

  The main signal receiving unit receives a plurality of main signals from each of the working route and the standby route, and the main signal transfer unit is based on the bundle OAM signal transmitted through the working route. When the abnormality determination unit determines that any of the plurality of virtual circuits via the path is abnormal, the plurality of main signals received via the backup path may be transferred to the outside.

  The “working path” may be a physical line defined as the working system, and the “backup path” may be a physical line defined as the protection system. According to this aspect, the reception path of the main signal is made redundant, and when an abnormality of the bundle OAM signal is detected, the main signal is switched to transfer of the main signal received from the backup path. Thereby, the failure recovery process for each virtual circuit can be executed quickly.

  The OAM signal receiving unit further receives a plurality of individual OAM signals associated with the plurality of virtual lines using the OAM signal for individually monitoring the plurality of virtual lines as an individual OAM signal, and the abnormality determination unit The state of each of the plurality of individual OAM signals may be determined on condition that the state of the OAM signal is normal.

  The individual OAM signal may be an OAM signal transmitted through the same path as the main signal transmitted through the virtual circuit to be monitored. According to this aspect, not only the monitoring by the bundle OAM signal but also the monitoring by the individual OAM signal is performed together, so that the reliability of the communication system can be further improved. For example, even when a part of the communication path of a certain virtual circuit is not covered by the communication path of the bundle OAM signal, an abnormality of the virtual circuit can be detected as an abnormality of the individual OAM signal, and a failure recovery process for the virtual circuit can be performed. In addition, the state determination of a plurality of individual OAM signals is based on the condition that the bundle OAM signal is normal. As a result, if the bundle OAM signal is abnormal, the state of each of the plurality of individual OAM signals is not determined, and all of the plurality of virtual circuits are collectively determined to be abnormal. Can be detected quickly.

  The OAM signal receiving unit further receives a plurality of individual OAM signals associated with the plurality of virtual lines using the OAM signal for individually monitoring the plurality of virtual lines as an individual OAM signal, and the abnormality determining unit When an interrupt notifying the abnormality that does not specify the type of the bundle OAM signal and the individual OAM signal is received from the signal receiving unit, the state of the bundle OAM signal is determined before determining the state of each of the plurality of individual OAM signals. Also good.

  The OAM signal reception unit may be implemented by hardware, and the abnormality determination unit may be implemented by software and may perform its function by the CPU. According to this aspect, even when there is a restriction that only relatively simple information can be notified by interruption to the abnormality determination unit, the state determination of the bundle OAM signal is performed with priority over the individual OAM signal. As a result, if the bundle OAM signal is abnormal, the state of each of the plurality of individual OAM signals is not determined, and all of the plurality of virtual circuits are collectively determined to be abnormal. Can be detected quickly.

  You may further provide the transfer mode change part which changes the transfer mode of a main signal according to the state of bundle OAM signal, and the state of an individual OAM signal. The main signal transfer unit is newly set between a transfer mode based on an individual OAM signal associated with the virtual line and a transfer mode based on a bundle OAM signal when the main signal is received on a virtual line. The main signal transfer process may be executed according to the transfer mode.

  The “transfer mode” may be whether the main signal is transferred or discarded. The “transfer mode based on the individual OAM signal” and the “transfer mode based on the bundle OAM signal” may be a transfer mode as a result of being changed by the transfer mode changing unit based on each OAM signal. The “newer set transfer mode” may be a transfer mode as a result of a recently implemented change. According to this mode, when the transfer mode of the main signal is changed based on the bundle OAM signal, the newly set transfer mode becomes the transfer mode based on the bundle OAM signal, and the main mode is transferred regardless of the transfer mode based on the individual OAM signal. Signal transfer is possible. In other words, when the transfer mode of the main signal is changed based on the bundle OAM signal, the transfer mode based on the individual OAM signal is not individually changed so as to match the transfer mode after the change, and the change can be made. The main signal transfer process can be executed quickly without waiting for completion.

  For each of the plurality of virtual circuits, an individual line information holding unit that holds the individual time stamp indicating the setting of the transfer mode based on the individual OAM signal and the transfer mode of the main signal, and transfer based on the bundle OAM signal You may further provide the bundle | flux information holding | maintenance part which matches and hold | maintains the bundle | flux time stamp which shows the time of a mode setting, and the transfer mode of a main signal. When at least one of the individual time stamp and the bundle time stamp overflows, the transfer mode changing unit initializes both time stamps and sets the transfer mode of the main signal associated with each time stamp to a newer one. You may unify to the transfer mode.

  The time stamp indicating when the transfer mode is set indicates the context of the transfer mode change based on the individual OAM signal and the bundle OAM signal. For example, it may indicate the number of times of change or may indicate the date and time of change. According to this aspect, even when the individual time stamp or the bundle time stamp overflows, the transfer of the main signal can be appropriately continued by matching the information in the individual line information holding unit and the information in the bundle information holding unit.

  The transfer mode change unit sequentially increases the bundle time stamp when the main signal transfer mode is set based on the bundle OAM signal, and the individual time stamp when the main signal transfer mode is set based on the individual OAM signal. When the bundle time stamp matches the individual time stamp, the main signal transfer unit executes the main signal transfer processing according to the transfer mode associated with the individual time stamp, and changes the transfer mode. When the bundle time stamp overflows, the unit updates the information in the bundle information holding unit and then updates the information in the individual line information holding unit to indicate that an overflow has occurred in the individual time stamp and the bundle time stamp. The carry signal is provided so that the main signal transfer unit can transfer the main signal even when the information in the individual line information holding unit is being updated. If the carry bit value of the bundle time stamp does not match the carry bit value of the individual time stamp, the main signal transfer process may be executed according to the transfer mode associated with the bundle time stamp. .

  According to this aspect, the value of the bundle time stamp is equal to or greater than the value of the individual time stamp, that is, a value indicating the same or newer change time. Therefore, the time stamp value of the bundle time stamp overflows first. When the bundle time stamp overflows, the information in the bundle information holding unit is updated, and then the information in the individual line information holding unit is updated. During the update of the information in the individual line information holding unit, the carry bit value of the bundle time stamp and the carry bit value of the individual time stamp do not match, so the main signal is transferred according to the information in the updated bundle information holding unit. Processing is executed. That is, even if the information in the individual line information holding unit is being updated in the background, the main signal transfer process can be executed.

  The data length of the bundle time stamp and the individual time stamp is a period that is positively correlated with both the interval at which the transfer mode change based on the bundle OAM signal can occur and the data length. The period allowed for updating may be set to be equal to or longer than a predetermined period required for updating information in the individual line information holding unit. According to this aspect, the data length of the time stamp can be set to an appropriate length. Further, the data length of the bundle time stamp and the individual time stamp may be determined so that a period allowed for the update is equal to or longer than a predetermined period required for the update and is as small as possible. According to this aspect, the data length of the time stamp becomes as small as possible, and the update efficiency of the time stamp can be improved.

  Another embodiment of the present invention is also a communication control device. This device includes a first input-side network card that receives communication data transmitted from an upstream external device via a predetermined route, and a communication transmitted via a route other than the predetermined route from the upstream external device. Communication data is acquired from any of the second input side network card that receives the data for use, the first input side network card, and the second input side network card, and is transmitted to the downstream external device. An output-side network card. Each of the first and second input-side network cards includes a main signal receiving unit that receives a plurality of main signals transmitted through a plurality of virtual circuits, and a plurality of main signals A main signal transfer unit that executes a transfer process to the output side network card for each, and an OAM signal transmitted through a path used for transmission of any of the plurality of main signals, and a plurality of virtual circuits collectively And an OAM signal receiving unit that receives as a bundle OAM signal for monitoring, and when an abnormality of the bundle OAM signal is detected, an abnormality determination that determines that any of a plurality of virtual circuits is abnormal And a section. The main signal transfer unit stops transferring the main signal transmitted through the virtual circuit determined to be abnormal to the output side network card.

  Also according to this aspect, similarly to the above, it is possible to detect anomalies of a plurality of virtual lines at once without individually determining the state of each of the plurality of virtual lines, and to quickly execute failure recovery processing for each virtual line.

  Yet another embodiment of the present invention is also a communication control device. This device is one of a plurality of communication control devices constituting a ring network, and a main signal for receiving a plurality of main signals transmitted through a plurality of virtual circuits for a main signal storing user data. A reception unit, a main signal transfer unit that executes transfer processing to the outside for each of the plurality of main signals, and a path that is used in any transmission of the plurality of main signals, and two or more in the ring network A bundle OAM receiving unit that receives an OAM signal indicating a communication state of a transmission section formed by a communication control device as a bundle OAM signal for monitoring a plurality of virtual lines at once and an abnormality in the bundle OAM signal are detected. A failure determination unit that determines that all of the plurality of virtual lines are abnormal.

  According to this aspect, in the communication control device that configures the ring network, as described above, it is possible to collectively detect abnormalities in a plurality of virtual circuits without individually determining the status of each of the plurality of virtual circuits. The failure recovery process can be executed quickly.

  It should be noted that any combination of the above-described constituent elements and a representation of the present invention converted between an apparatus, a method, a system, a program, a recording medium storing the program, and the like are also effective as an aspect of the present invention.

  According to the present invention, efficient failure handling can be realized in an apparatus that relays communication data.

It is a flowchart which shows the outline of the switching control in the communication control apparatus of embodiment. It is a figure which shows the structure of the communication system of embodiment. It is a block diagram which shows the function structure of the communication control apparatus of FIG. It is a figure which shows the structure of the data stored in a transfer information holding part. It is a figure which shows the structure of an individual time stamp and bundle | flux time stamp. It is a flowchart which shows operation | movement of a communication control apparatus. It is a flowchart which shows operation | movement of a communication control apparatus. It is a flowchart which shows S46 of FIG. 7 in detail. It is a flowchart which shows S48 of FIG. 7 in detail. It is a figure which shows the example of a transition of individual line information and bundle information. It is a figure which shows the structure of the communication system of a modification. It is a block diagram which shows the function structure of the 1st communication control apparatus of FIG.

The outline of the embodiment of the present invention will be described before the configuration thereof is described.
In recent years, software has become responsible for switching control of virtual lines against the background of increasing capacity and diversification of communication systems. As an outline of the operation in that case, an abnormality notification interruption is performed from the hardware that detected the abnormality of the OAM signal to the software, and the software searches for which virtual circuit is abnormal. As a result of the search, switching control is performed for the virtual line that is found to be abnormal. In this case, a period from when the abnormality notification is interrupted until the switching control is performed is a period required for switching.

  When a plurality of virtual circuits are to be monitored, conventionally, individual OAM signals for individually monitoring the plurality of virtual circuits are transmitted and received between the communication control devices, and each virtual circuit is based on the state of the individual OAM signal. An abnormality was detected for each line. However, in this method, as the number of virtual lines to be monitored increases, it takes time to detect an abnormality of each virtual line, and as a result, the time required to switch the virtual line where the abnormality has occurred increases.

  Moreover, in a communication control apparatus, it is common to store the transfer mode of the main signal transmitted on each virtual line in an information storage area associated with each of the plurality of virtual lines. In this case, if a plurality of virtual circuits become abnormal, it is necessary to rewrite data in a plurality of information storage areas before restarting the main signal transfer process. Therefore, when many virtual circuits fail at the same time, many data rewrites occur, and it may take a long time to resume the main signal transfer process. In particular, when the communication control device is composed of a general-purpose CPU or RAM (Random Access Memory), a longer time is required.

  Therefore, in the present embodiment, a communication control apparatus that transmits and receives a bundle OAM signal for collectively monitoring a plurality of virtual lines in addition to the conventional individual OAM signal is proposed. This bundle OAM signal is an OAM signal associated with a plurality of virtual circuits, and is used in at least a part of the plurality of main signals transmitted through the plurality of virtual circuits in any main signal transmission. Is transmitted via a communication path. In other words, it is transmitted via a communication path used in transmission of any individual OAM signal. Therefore, if the bundle OAM signal is abnormal, all the individual OAM signals are also abnormal, that is, all the virtual lines are also abnormal.

  FIG. 1 is a flowchart illustrating an outline of switching control in the communication control apparatus according to the embodiment. The communication control device detects an abnormality in the bundle OAM signal or the individual OAM signal (S10). If the bundle OAM signal is abnormal (Y in S12), processing at the time of abnormality, for example, processing for switching to a standby physical line is executed for all virtual lines associated with the bundle OAM signal (S14). . As will be described later, the switching process in the present embodiment is executed as a change in the transfer mode of the main signal received via the virtual line, that is, switching between transferring the main signal to the outside or discarding it.

  When the bundle OAM signal is normal (N in S12), an individual line loop that is repeated by the number of individual virtual lines is executed. Within this loop, the state of a plurality of individual OAM signals is individually determined. If the specific individual OAM signal is abnormal (Y in S16), the abnormal time process is executed for the specific virtual line corresponding to the individual OAM signal (the individual OAM signal is the monitoring target) ( S18). If the specific individual OAM signal is normal (N in S16), S18 is skipped.

  According to the switching control shown in FIG. 1, if the bundle OAM signal is abnormal, it is determined that all virtual lines associated with the bundle OAM signal are abnormal regardless of the state of each of the plurality of individual OAM signals. . Therefore, the virtual line switching process can be executed without performing the state determination of each of the plurality of individual OAM signals. As a result, even when a plurality of virtual circuits fail at once, quick failure recovery can be realized.

  In addition, the communication control apparatus according to the embodiment transfers a transfer mode (hereinafter also referred to as “individual line transfer mode”) as a result of the switching process based on the individual OAM signal and a transfer result as a result of the switching process based on the bundle OAM signal. Modes (hereinafter also referred to as “bundle transfer modes”) are managed separately. Each transfer mode holds a time stamp for indicating the front-rear relationship between the switching process based on the individual OAM signal and the switching process based on the bundle OAM signal. The communication control device refers to the time stamp and executes the main signal transfer process according to the transfer mode that is the result of the newly executed switching process. As a result, when an abnormality of the bundle OAM signal is detected, the bundle transfer mode and its time stamp need only be rewritten, and rewriting of the individual line transfer mode for each of the plurality of virtual lines becomes unnecessary. As a result, the virtual line switching process can be executed quickly.

  FIG. 2 shows a configuration of the communication system according to the embodiment. The communication system 1000 includes the communication control device 100, the upstream device 102, the downstream device 104, the NE-A 106a, the NE-B 106b, the NE-C 106c, and the NE-D 106d. Note that the communication control device 100, the upstream device 102, and the downstream device 104 are convenient names, and these are all NEs. Hereinafter, the communication paths of the upstream apparatuses 102 to NE-A 106 a to NE-B 106 b to the communication control apparatus 100 are referred to as first communication paths 108, and the upstream apparatuses 102 to NE-C 106 c to NE-D 106 d to the communication control apparatus 100. The communication path is referred to as the second communication path 110.

  Each device of this embodiment constitutes a layer 2 communication network, and transmits and receives a tagged Ethernet frame defined by IEEE 802.1Q as a main signal and an OAM signal. A VLAN (Virtual Local Area Network) -ID is set in the tag field. In this embodiment, each of the VLANs with VLAN-IDs “100” to “199” is set as a virtual line. Specifically, the main signal and the individual OAM signal in which 100 types of VLAN-IDs are set are transmitted in 100 VLANs. The VLAN with VLAN-ID “200” is set as a virtual line through which a bundle OAM signal is transmitted.

  The communication control device 100 transfers the main signal transmitted from the upstream device 102 to the downstream device 104. Specifically, the upstream device 102 transmits the main signal, the individual OAM signal, and the bundle OAM signal to both the first communication path 108 and the second communication path 110. The communication control apparatus 100 receives the main signal, the individual OAM signal, and the bundle OAM signal from both the first communication path 108 and the second communication path 110. Then, the main signal received from either the first communication path 108 or the second communication path 110 is transmitted to the downstream apparatus 104.

  FIG. 3 is a block diagram showing a functional configuration of the communication control apparatus 100 of FIG. The communication control device 100 includes a first input card 10, a second input card 12, a SW unit 14, an output card 16, an abnormality determination unit 18, a count holding unit 19, and a transfer mode change. Part 20.

  Each block shown in the block diagram of the present specification can be realized in terms of hardware by elements and mechanical devices such as a CPU and a memory of a computer, and in terms of software, it can be realized by a computer program or the like. Then, the functional block realized by those cooperation is drawn. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by a combination of hardware and software.

  However, in the communication control apparatus 100 of the present embodiment, the abnormality determining unit 18 and the transfer mode changing unit 20 are implemented by software and are executed by the CPU. The other functional blocks are implemented by hardware such as various electronic circuits. Various information holding units are implemented by a RAM.

  The output side card 16 is a network card also called an EG (EGress Block), and transmits the main signal received from the SW unit 14 to the downstream side device 104. The SW unit 14 is a switch fabric, and transfers the main signal sent from the first input side card 10 and the second input side card 12 to the output side card 16. Since there is an upper limit on the amount of processing data per unit time in the SW unit 14, a main signal cannot be received from both the first input side card 10 and the second input side card 12. Accordingly, either the first input card 10 or the second input card 12 sends a main signal to the SW unit 14. This switching control is executed by a transfer mode changing unit 20 described later.

  Each of the first input side card 10 and the second input side card 12 is a network card also called an IG (InGress Block), and accepts communication data transmitted from the upstream device 102. Each of the first input side card 10 and the second input side card 12 includes a transfer information holding unit 22, a main signal receiving unit 24, a main signal transferring unit 26, and an OAM signal receiving unit 28.

  The transfer information holding unit 22 is a storage area that holds information indicating the transfer mode of the main signal. FIG. 4 shows a configuration of data stored in the transfer information holding unit 22. FIG. 4A shows a pointer table for storing a line information pointer for accessing an individual line transfer mode and a bundle information pointer for accessing a bundle transfer mode in association with each virtual circuit. . In the figure, the virtual line a, the virtual line b, and the virtual line c are associated with the bundle OAM signal A as virtual lines to be monitored.

  FIG. 4B shows, for each virtual circuit, an individual line transfer mode indicating transfer or discard, and a time stamp (hereinafter also referred to as “individual time stamp”) indicating when the individual line transfer mode is set. It is a table that holds associated individual line information. This individual line information is accessed via the line information pointer in the pointer table.

  In FIG. 4C, for each bundle OAM signal, a bundle transfer mode indicating transfer or discard and a time stamp (hereinafter also referred to as a “bundle time stamp”) indicating when the bundle transfer mode is set correspond. It is a table that holds attached bundle information. This bundle transfer information is accessed via the bundle information pointer in the pointer table.

  FIG. 5 shows the configuration of individual time stamps and bundle time stamps. In both time stamps, a value indicating the number of times of transfer mode switching is set in the second and subsequent n bits. The first bit is a carry bit for indicating an overflow of the number of switching times. The value of the carry bit is changed from 0 to 1 or 1 to 0 when the number of switching times overflows.

  The main signal receiving unit 24 receives the main signal transmitted from the upstream device 102. Specifically, the main signal receiver 24 of the first input card 10 receives the main signal transmitted through the first communication path 108, and the main signal receiver 24 of the second input card 12 The main signal transmitted through the second communication path 110 is received.

  When the main signal is received by the main signal receiving unit 24, the main signal transfer unit 26 switches the main signal according to either the individual line transfer mode or the bundle transfer mode held in the transfer information holding unit 22. The data is transferred to the unit 14 or discarded without being transferred. In principle, the main signal transfer process is executed in accordance with the transfer mode that has been updated more recently among the individual line transfer mode and the bundle transfer mode. The specific transfer logic will be described later.

  The OAM signal receiving unit 28 receives the OAM signal transmitted from the upstream device 102. Specifically, the main signal receiving unit 24 of the first input card 10 receives the bundle OAM signal and the individual OAM signal transmitted through the first communication path 108, and receives the main signal of the second input card 12. The receiving unit 24 receives the bundle OAM signal and the individual OAM signal transmitted through the second communication path 110. Of course, the main signal receiving unit 24 and the OAM signal receiving unit 28 may be physically configured as the same receiving unit.

  When the OAM signal receiving unit 28 receives each of the bundle OAM signal and the plurality of individual OAM signals, the reception time of each OAM signal is sequentially recorded in a storage area (not shown) (hereinafter also referred to as “OAM reception history table”). To do. Further, the OAM signal receiving unit 28 determines whether or not to receive the next OAM signal within a predetermined period after receiving the previous OAM signal for each of the bundle OAM signal and the plurality of individual OAM signals. Timer monitoring. If the next OAM signal is not received within a predetermined period, the abnormality determination unit 18 (specifically, the CPU that executes the function of the abnormality determination unit 18) is notified of the occurrence of an abnormality in the OAM signal. Perform a predetermined hardware interrupt. In this interrupt, it is not notified whether the OAM signal in which an abnormality has occurred is a bundle OAM signal or an individual OAM signal, and which virtual line corresponds to an individual OAM signal.

  When the abnormality determination unit 18 detects an interrupt indicating that an abnormality has occurred in the OAM signal, the abnormality determination unit 18 refers to an OAM reception history table (not shown) to search for an unreceived OAM signal within a predetermined period, and the OAM signal in which an abnormality has occurred. Specify the type of. Specifically, after determining the state of the bundle OAM signal, the state of each of the plurality of individual OAM signals is determined only when the bundle OAM signal is normal. The abnormality determination unit 18 notifies the transfer mode change unit 20 that an abnormality has occurred in the bundle OAM signal or one or more specific individual OAM signals.

  The count holding unit 19 is a storage area for holding a counter value serving as a setting reference for time stamp values set as individual time stamps and bundle time stamps. The format of this counter value is the same as the format of the time stamp value shown in FIG.

  When the abnormality of the individual OAM signal is notified, the transfer mode changing unit 20 detects the abnormality of the transfer information holding unit 22 for the virtual line (hereinafter also referred to as “abnormal virtual line”) associated with the individual OAM signal. Updates individual line information related to virtual lines. Specifically, the counter value of the count holding unit 19 is set to the individual time stamp. At the same time, the bundle OAM signal bundle transfer mode for monitoring the abnormal virtual circuit is set to the individual transfer mode as the transfer mode switched from transfer to discard or from discard to transfer.

  In addition, when the abnormality of the bundle OAM signal is notified, the transfer mode changing unit 20 updates the bundle information of the transfer information holding unit 22 associated with the bundle OAM signal. Specifically, a new count value obtained by incrementing the count value held in the count holding unit 19 is set in the bundle time stamp. At the same time, the new count value is recorded in the count holding unit 19. Further, the bundle transfer mode is switched from transfer to discard, or from discard to transfer.

  When the bundle time stamp overflows, that is, when the carry bit value changes from 0 to 1 or from 1 to 0, the transfer mode change unit 20 updates the bundle information. At this time, the changed carry bit and the switching count value initialized to 0 are set in the bundle time stamp. Thereafter, the updated bundle information is sequentially reflected on each of the plurality of pieces of individual line information. Specifically, the individual time stamp is updated to match the updated bundle time stamp, and the individual transfer mode is updated to match the updated bundle transfer mode.

  When the bundle information is updated, the transfer mode change unit 20 notifies the main signal transfer unit 26 to that effect, and the main signal transfer unit 26 that has received the notification notifies the main signal transfer process even if the individual line information is being updated. Resume (transfer or discard). The transfer mode change unit 20 updates the individual line information in parallel with the main signal transfer process by the main signal transfer unit 26. In other words, the individual line information update process associated with the overflow of the bundle time stamp is executed as a background process of the main signal transfer process.

  By the way, in order to update the bundle time stamp and the individual time stamp at high speed, it is desirable that the bit length (that is, n bits in FIG. 5) of the switching number field is as small as possible. On the other hand, when the bundle time stamp overflows, the individual line information is updated in parallel with the transfer process of the main signal. Therefore, a certain length is required for the bit length of the switching number field. This is because if the bundle time stamp overflows again while the update process of the individual line information is not completed, the carry bit of the bundle time stamp and the carry bit of the individual time stamp match, and their context is unknown. Because it ends up.

Here, assuming that the bit length of the switching number field is n bits, and update of bundle information due to abnormality of the bundle OAM signal can occur with A (milliseconds) as a minimum unit,
Allowable time for update processing of individual line information (“allowable time”) = the shortest time when a bundle time stamp overflows next allowable time = A × 2 ⁿ
It becomes. In addition, the time required for the update process of the individual line information (“required time”) is a given value measured in advance, and it is only necessary to satisfy the relationship of required time ≦ allowable time.
Required time ≤ A x 2 ⁿ
It is necessary to satisfy. Furthermore, since it is desirable that the value of n is as small as possible, the smallest n that satisfies the above relationship is the most desirable bit length of the switching number field.

  The transfer mode changing unit 20 sets the transfer mode of the main signal in the first input side card 10 and the transfer mode of the main signal in the second input side card 12 to complement each other. For example, in the initial state, the first communication path 108 is defined as the active communication path, the second communication path 110 is defined as the standby communication path, the transfer mode in the first input card 10 is “transfer”, the second Assume that the transfer mode in the input side card 12 is defined as “discard”. In this case, when an abnormality of the bundle OAM signal in the first input card 10 is detected, the transfer mode in the first input card 10 is switched to “discard” and the transfer mode in the second input card 12 is switched. To “Transfer”. The same applies when an abnormality of the individual OAM signal is detected. As a result, the reliability of the main signal transmission can be improved, and it is possible to prevent duplicate main signals from being sent from the first input side card 10 and the second input side card 12.

The operation of the above configuration will be described below.
FIG. 6 is a flowchart showing the operation of the communication control apparatus 100. This figure shows the operation related to the switching control of the main signal transfer mode. When the OAM signal reception unit 28 receives the OAM signal transmitted from the upstream device 102 and detects an abnormality of the OAM signal according to the reception status, the OAM signal reception unit 28 executes an interrupt process for the abnormality determination unit 18 (S20). The abnormality determination unit 18 identifies an OAM signal in which an abnormality has occurred. Specifically, after determining the state of the bundle OAM signal, when the bundle OAM signal is normal, the state of the plurality of individual OAM signals is individually determined (S22).

  When the bundle OAM signal is normal and the individual OAM signal is abnormal (N in S24), the transfer mode changing unit 20 stores the transfer information holding unit 22 in each of the first input side card 10 and the second input side card 12. The retained individual line information is updated (S26). When the bundle OAM signal is abnormal (Y in S24), the transfer mode changing unit 20 updates the bundle information held in the transfer information holding unit 22 of each of the first input side card 10 and the second input side card 12. (S28). When the carry bit value of the bundle time stamp changes due to the update of the bundle information (Y in S30), the transfer mode changing unit 20 transfers the transfer information holding units of the first input side card 10 and the second input side card 12, respectively. The individual line information held in 22 is matched with the bundle information (S32). If there is no change in the carry bit value of the bundle time stamp (N in S30), S32 is skipped.

  FIG. 7 is a flowchart showing the operation of the communication control apparatus 100. The figure shows the operation related to the main signal transfer process, and is common to the first input side card 10 and the second input side card 12. The main signal receiving unit 24 receives the main signal transmitted from the upstream device 102 (S40). The main signal transfer unit 26 refers to the bundle time stamp and the individual time stamp held in the transfer information holding unit 22 (S42), and when the carry bit of the bundle time stamp is 1 (Y in S44), will be described later. First transfer mode determination processing is executed (S46). When the carry bit of the bundle time stamp is 0 (N in S44), a second transfer mode determination process described later is executed (S48). The main signal transfer unit 26 executes main signal transfer processing (sending to the SW unit 14 or discarding) in accordance with the transfer mode employed in the first transfer mode determination process or the second transfer mode determination process. (S50).

  FIG. 8 is a flowchart showing in detail S46 of FIG. If the carry bit of the individual time stamp is 1 (Y in S60), and the number of times of switching the bundle time stamp and the number of times of switching of the individual time stamp are the same (N in S62), the main signal transfer unit 26 performs the individual line transfer. A mode is selected (S64). If the number of times of switching the bundle time stamp is larger than the number of times of switching the individual time stamp (Y in S62), or the carry bit of the individual time stamp is 0 (N in S60), the main signal transfer unit 26 changes the bundle transfer mode. Select (S66). This is because N in S60 indicates that the carry bit values are different, that is, that the individual line information is being updated due to the overflow of the bundle time stamp.

  FIG. 9 is a flowchart showing in detail S48 of FIG. If the carry bit of the individual time stamp is 0 (N in S70) and the number of times of switching the bundle time stamp is the same as the number of times of switching of the individual time stamp (N in S72), the main signal transfer unit 26 transfers the individual line. A mode is selected (S74). If the number of times of switching the bundle time stamp is larger than the number of times of switching the individual time stamp (Y in S72), or if the carry bit of the individual time stamp is 1 (Y in S70), the main signal transfer unit 26 changes the bundle transfer mode. Select (S76). This is because Y in S70 also indicates that the individual line information is being updated due to the overflow of the bundle time stamp.

  FIG. 10 shows a transition example of individual line information and bundle information. The figure shows individual line information and bundle information corresponding to one virtual line held in the first input side card 10. The transfer mode indicated by a circle in the figure indicates the transfer mode selected in the main signal transfer unit 26 of the first input side card 10. In the state 30, since the individual time stamp = the bundle time stamp, the individual line transfer mode is selected. In state 32, the bundle transfer mode is selected because the individual time stamp is smaller than the bundle time stamp. In the state 34, since the individual time stamp = the bundle time stamp, the individual line transfer mode is selected again. In the state 34, since the abnormality of the individual OAM signal is detected in the second input side card 12, the first input side card 10 is switched to “transfer”.

  Subsequently, in the state 36 and the state 42, since the individual time stamp <the bundle time stamp, the bundle transfer mode is selected. In the state 38 and the state 44, since the carry bit values are different, the bundle transfer mode is selected. In the states 40 and 46, since the individual time stamp = the bundle time stamp, the individual line transfer mode is selected. The individual line information and bundle information held in the second input card 12 are set to have the same time stamp value, but the transfer mode is set to the opposite value.

  According to the communication control apparatus 100 of the present embodiment, anomalies of a plurality of virtual circuits are collectively detected based on the state of the bundle OAM signal. As a result, failure recovery processing for each virtual line can be quickly executed without individually determining the state of each of the plurality of virtual lines. Further, the bundle transfer mode and the individual transfer mode are managed separately, and the transfer mode set more newly is selected in the main signal transfer. As a result, even when a plurality of virtual circuits become abnormal all at once, a new transfer mode can be applied quickly without changing the individual transfer mode. Also, the consistency between the bundle transfer mode and the individual transfer mode can be maintained even when the time stamp overflows to determine the front-rear relationship between the bundle transfer mode and the individual transfer mode. In addition, since the rewriting process of the individual transfer mode for maintaining the consistency is executed in the background of the main signal transfer process, the delay of the main signal transfer process can be avoided.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

  As a modification, the technical idea of the present invention can be applied to a ring network in which the physical topology of the communication network is configured in a ring state. FIG. 11 shows a configuration of a communication system according to a modification. In the communication system 2000, the first communication control device 200a, the second communication control device 200b, the third communication control device 200c, the fourth communication control device 200d, and the fifth communication control device 200e are connected via the ring network 202. Connected.

  Here, each of the first communication control device 200a, the third communication control device 200c, and the fourth communication control device 200d is connected to the NE (NE-A 206a, NE-B 206b, NE-C 206c) via the communication network 204. Connected with. In the communication system 2000, a virtual line between NE-A 206a and NE-B 206b and a virtual line between NE-A 206a and NE-C 206c are formed. In the initial state, main signals transmitted through these virtual lines are transmitted from the first communication control device 200a to the second communication control device 200b to the third communication control device 200c to the fourth communication control device 200d. It is assumed that it is transmitted via a route.

  Further, in the communication system 2000, a bundle OAM signal for collectively managing virtual lines including the second communication control device 200b to the third communication control device 200c in the transmission path is defined. This bundle OAM signal is for notifying each communication control device of the communication state between the second communication control device 200b and the third communication control device 200c. Therefore, the virtual circuit between NE-A 206a and NE-B 206b and the virtual circuit between NE-A 206a and NE-C 206c are monitored by the bundle OAM signal. Similar to the embodiment, in the communication system 2000, in addition to the bundled OAM signal, an individual OAM signal for monitoring each individual virtual line is also transmitted.

  FIG. 12 is a block diagram showing a functional configuration of the first communication control apparatus 200a of FIG. The first communication control device 200a includes a main signal receiving unit 24, an OAM signal receiving unit 28, an abnormality determination unit 18, a count holding unit 19, a transfer mode changing unit 20, and a transfer processing unit 50. In addition, the same code | symbol is attached | subjected about the functional block similar to the functional block shown in FIG. 3, and the overlapping description is abbreviate | omitted below.

  The main signal receiving unit 24 receives the main signal transmitted from the NE-A 106a. The OAM signal receiving unit 28 receives bundle OAM signals and individual OAM signals transmitted from various communication control devices and NEs. The transfer mode changing unit 20 controls the bundle information / individual line held in the first direction transfer information holding unit 22a and the second direction transfer information holding unit 22b, which will be described later, according to the state of the bundle OAM signal and the state of the individual OAM signal. Update information.

  The transfer processing unit 50 includes a first direction transfer information holding unit 22a, a second direction transfer information holding unit 22b, a first direction main signal transfer unit 26a, and a second direction main signal transfer unit 26b. The first direction transfer information holding unit 22a and the second direction transfer information holding unit 22b correspond to the transfer information holding unit 22 of the embodiment. The first direction main signal transfer unit 26a and the second direction main signal transfer unit 26b correspond to the main signal transfer unit 26 of the embodiment.

  The first direction transfer information holding unit 22a holds the transfer mode of the main signal in the first direction (here, the second communication control apparatus 200b side) of the ring network 202. The second direction transfer information holding unit 22b holds the transfer mode of the main signal in the second direction of the ring network 202 (here, the fifth communication control device 200e side). Further, the first direction main signal transfer unit 26a executes the main signal transfer process (transfer or discard) in the first direction of the ring network 202 according to the transfer mode held in the first direction transfer information holding unit 22a. To do. The second direction main signal transfer unit 26b executes a main signal transfer process in the second direction of the ring network 202 according to the transfer mode held in the second direction transfer information holding unit 22b.

  As a specific operation, when a bundle OAM signal indicating a failure between the second communication control device 200b to the third communication control device 200c is received in the OAM signal reception unit 28 in the initial state, the abnormality determination unit 18 The failure is identified and notified to the transfer mode changing unit 20. The transfer mode changing unit 20 switches the bundle transfer mode held in the first direction transfer information holding unit 22a to “discard” and changes the bundle transfer mode held in the second direction transfer information holding unit 22b to “transfer”. Switch. As a result, even when a plurality of virtual circuits fail at the same time due to a failure in a specific transmission section in the ring network 202, switching processing of each virtual circuit, that is, switching of the transmission direction of the main signal can be performed quickly.

  The communication control device 100 according to the embodiment switches the main signal received from the upstream device 102 according to either the first input card 10 or the second input card 12 according to the state of the OAM signal. Sent to the unit 14. On the other hand, the first communication control apparatus 200a according to the modified example uses the ring network to transmit the main signal received from the NE-A 206a according to either the first direction or the second direction according to the state of the OAM signal. 202. Therefore, it will be understood by those skilled in the art that the present modification can achieve the same effects as those of the embodiment.

  It should also be understood by those skilled in the art that the functions to be fulfilled by the constituent elements recited in the claims are realized by the individual constituent elements shown in the embodiments and the modified examples or by their linkage.

  18 abnormality determination unit, 19 count holding unit, 20 transfer mode changing unit, 22 transfer information holding unit, 24 main signal receiving unit, 26 main signal transferring unit, 28 OAM signal receiving unit, 100 communication control unit, 202 ring network, 1000 2000 Communication system.

Claims (11)

For a main signal for storing user data, a main signal receiving unit for receiving a plurality of main signals transmitted through a plurality of virtual circuits;
A main signal transfer unit that executes transfer processing to the outside for each of the plurality of main signals;
An OAM that receives an OAM (Operation Administration and Maintenance) signal transmitted through a path used for transmission of any of the plurality of main signals as a bundle OAM signal for collectively monitoring the plurality of virtual circuits. A signal receiver;
An abnormality determination unit that determines that any of the plurality of virtual lines is abnormal when detecting an abnormality of the bundle OAM signal;
Equipped with a,
The OAM signal receiving unit further receives a plurality of individual OAM signals associated with the plurality of virtual lines, using the OAM signals for individually monitoring the plurality of virtual lines as individual OAM signals,
The abnormality determining unit, the bundle condition that the state of the OAM signal is normal, the communication control apparatus characterized that you determine the plurality of individual OAM signals respectively state. For a main signal for storing user data, a main signal receiving unit for receiving a plurality of main signals transmitted through a plurality of virtual circuits;
A main signal transfer unit that executes transfer processing to the outside for each of the plurality of main signals;
An OAM that receives an OAM (Operation Administration and Maintenance) signal transmitted through a path used for transmission of any of the plurality of main signals as a bundle OAM signal for collectively monitoring the plurality of virtual circuits. A signal receiver;
An abnormality determination unit that determines that any of the plurality of virtual lines is abnormal when detecting an abnormality of the bundle OAM signal;
Equipped with a,
The OAM signal receiving unit further receives a plurality of individual OAM signals associated with the plurality of virtual lines, using the OAM signals for individually monitoring the plurality of virtual lines as individual OAM signals,
When the abnormality determination unit receives an interrupt for notifying the bundle OAM signal and the type of the individual OAM signal from the OAM signal receiving unit, before determining the state of each of the plurality of individual OAM signals. a communication control apparatus which is characterized that you determine the state of the bundle OAM signal. The main signal receiving unit receives the plurality of main signals from each of an active route and a standby route,
The main signal transfer unit, when the abnormality determination unit determines that any of a plurality of virtual circuits through the working path is abnormal based on the bundle OAM signal transmitted through the working path, the communication control device according to claim 1 or 2, characterized in that for transferring the plurality of main signals received via the route of the backup system to the outside. A transfer mode changing unit that changes the transfer mode of the main signal according to the state of the bundle OAM signal and the state of the individual OAM signal;
When the main signal is received in a certain virtual circuit, the main signal transfer unit is a newer one of the transfer mode based on the individual OAM signal associated with the virtual circuit and the transfer mode based on the bundle OAM signal. the communication control apparatus according to any one of according to set transfer mode from claim 1, characterized in that to execute the transfer processing of the main signal 3. For each of the plurality of virtual lines, an individual line information holding unit that holds an individual time stamp indicating a setting of a transfer mode based on an individual OAM signal and a transfer mode of a main signal in association with each other,
A bundle information holding unit that holds the bundle time stamp indicating the setting of the transfer mode based on the bundle OAM signal and the transfer mode of the main signal in association with each other;
When at least one of the individual time stamp and the bundle time stamp overflows, the transfer mode changing unit initializes both time stamps, and sets the transfer mode of the main signal associated with each of the time stamps to a newer one. 5. The communication control device according to claim 4 , wherein the communication control device is unified to a set transfer mode. The transfer mode changing unit sequentially increases the bundle time stamp when the main signal transfer mode is set based on the bundle OAM signal, and when the main signal transfer mode is set based on the individual OAM signal. Match the individual time stamp with the bundle time stamp;
The main signal transfer unit, when the bundle time stamp and the individual time stamp match, performs a main signal transfer process according to a transfer mode associated with the individual time stamp,
When the bundle time stamp overflows, the transfer mode changing unit updates the information of the bundle information holding unit, and then updates the information of the individual line information holding unit,
The individual time stamp and the bundle time stamp are provided with a carry bit for indicating that an overflow has occurred,
The main signal transfer unit executes a main signal transfer process even when the information in the individual line information holding unit is being updated, and the carry bit value of the bundle time stamp and the carry bit value of the individual time stamp are obtained. 6. The communication control apparatus according to claim 5 , wherein, in the case of mismatch, a main signal transfer process is executed according to a transfer mode associated with the bundle time stamp. The data length of the bundle time stamp and the individual time stamp is a period that is positively correlated with both the interval at which a transfer mode change based on the bundle OAM signal can occur and the data length, and the individual line information holding unit 7. The communication control apparatus according to claim 6 , wherein a period allowed for updating the information is set to be equal to or longer than a predetermined period required for updating information in the individual line information holding unit. A first input-side network card that receives communication data transmitted by a predetermined path from an upstream external device;
A second input-side network card that receives the communication data transmitted from the upstream external device via a path different from the predetermined path;
An output-side network card that acquires the data for communication from either the first input-side network card or the second input-side network card and sends the data to a downstream external device;
Each of the first and second input side network cards is
For a main signal for storing user data, a main signal receiving unit for receiving a plurality of main signals transmitted through a plurality of virtual circuits;
A main signal transfer unit that executes transfer processing to the output-side network card for each of the plurality of main signals;
An OAM signal receiving unit that receives an OAM signal transmitted through a path used in any transmission of the plurality of main signals as a bundle OAM signal for collectively monitoring the plurality of virtual lines; Including
An abnormality determination unit that determines that any of the plurality of virtual circuits is abnormal when detecting an abnormality of the bundle OAM signal;
The OAM signal receiving unit further receives a plurality of individual OAM signals associated with the plurality of virtual lines, using the OAM signals for individually monitoring the plurality of virtual lines as individual OAM signals,
The abnormality determination unit determines the state of each of the plurality of individual OAM signals on condition that the state of the bundle OAM signal is normal,
The communication control device, wherein the main signal transfer unit stops transferring the main signal transmitted through the virtual line determined to be abnormal to the output side network card. A first input-side network card that receives communication data transmitted by a predetermined path from an upstream external device;
A second input-side network card that receives the communication data transmitted from the upstream external device via a path different from the predetermined path;
An output-side network card that acquires the data for communication from either the first input-side network card or the second input-side network card and sends the data to a downstream external device;
Each of the first and second input side network cards is
For a main signal for storing user data, a main signal receiving unit for receiving a plurality of main signals transmitted through a plurality of virtual circuits;
A main signal transfer unit that executes transfer processing to the output-side network card for each of the plurality of main signals;
An OAM signal receiving unit that receives an OAM signal transmitted through a path used in any transmission of the plurality of main signals as a bundle OAM signal for collectively monitoring the plurality of virtual lines; Including
An abnormality determination unit that determines that any of the plurality of virtual circuits is abnormal when detecting an abnormality of the bundle OAM signal;
The OAM signal receiving unit further receives a plurality of individual OAM signals associated with the plurality of virtual lines, using the OAM signals for individually monitoring the plurality of virtual lines as individual OAM signals,
When the abnormality determination unit receives an interrupt for notifying the bundle OAM signal and the type of the individual OAM signal from the OAM signal receiving unit, before determining the state of each of the plurality of individual OAM signals. And determining the state of the bundle OAM signal,
The communication control device, wherein the main signal transfer unit stops transferring the main signal transmitted through the virtual line determined to be abnormal to the output side network card. One of a plurality of communication control devices constituting a ring network,
For a main signal for storing user data, a main signal receiving unit for receiving a plurality of main signals transmitted through a plurality of virtual circuits;
A main signal transfer unit that executes transfer processing to the outside for each of the plurality of main signals;
An OAM signal indicating a communication state of a transmission section formed by two or more communication control devices in the ring network, which is used in any transmission of the plurality of main signals, and the plurality of virtual lines together. An OAM signal receiver that receives as a bundle OAM signal for monitoring
An abnormality determination unit that determines that any of the plurality of virtual lines is abnormal when detecting an abnormality of the bundle OAM signal;
Equipped with a,
The OAM signal receiving unit further receives a plurality of individual OAM signals associated with the plurality of virtual lines, using the OAM signals for individually monitoring the plurality of virtual lines as individual OAM signals,
The abnormality determining unit, the bundle condition that the state of the OAM signal is normal, the communication control apparatus characterized that you determine the plurality of individual OAM signals respectively state. One of a plurality of communication control devices constituting a ring network,
For a main signal for storing user data, a main signal receiving unit for receiving a plurality of main signals transmitted through a plurality of virtual circuits;
A main signal transfer unit that executes transfer processing to the outside for each of the plurality of main signals;
An OAM signal indicating a communication state of a transmission section formed by two or more communication control devices in the ring network, which is used in any transmission of the plurality of main signals, and the plurality of virtual lines together. An OAM signal receiver that receives as a bundle OAM signal for monitoring
An abnormality determination unit that determines that any of the plurality of virtual lines is abnormal when detecting an abnormality of the bundle OAM signal;
Equipped with a,
The OAM signal receiving unit further receives a plurality of individual OAM signals associated with the plurality of virtual lines, using the OAM signals for individually monitoring the plurality of virtual lines as individual OAM signals,
When the abnormality determination unit receives an interrupt for notifying the bundle OAM signal and the type of the individual OAM signal from the OAM signal receiving unit, before determining the state of each of the plurality of individual OAM signals. a communication control apparatus which is characterized that you determine the state of the bundle OAM signal.

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