JP5475706B2 - Monitoring device, communication device, and network monitoring method - Google Patents

Description

  The present invention relates to a data communication technique, and more particularly to a technique for detecting a connection state between communication apparatuses.

  Ethernet OAM (Operations, Administration and Maintenance) technology that enables end-to-end communication path monitoring in layer 2 communications over wide-area Ethernet ("Ethernet" is a registered trademark) in response to growing quality requirements for networks ITU-T Y. 1731. In Ethernet OAM, one section to be maintained using an OAM frame that is a MAC frame for confirming a communication state is defined as ME (Maintenance Entity). Also, a set of MEs is defined as MEG (Maintenance Entity Group), and an end point of MEG that terminates the OAM frame is defined as MEP (MEG End Point).

The following functions are mainly used between the MEPs.
1. ETH-CC: A function for constantly monitoring the path between MEPs by CCM (Continuity Check Message Connectivity Check Message).
2. ETH-LB: Communication check function between designated MEPs by LBM (LoopBack Message Loopback Message) and LBR (LoopBack Reply Loopback Reply).
3. ETH-LTM: A function for confirming the communication path to the specified MEP by LTM (Link Trace Message) and LTR (Link Trace Reply).

JP 2009-278451 A

  In a wide area Ethernet network composed of layer 2 switches (hereinafter also referred to as “L2SW”), communication paths are constantly monitored by transmitting and receiving OAM frames (for example, the above-mentioned CCM) between L2SWs. When a communication path abnormality is detected, the abnormality may be notified to a network maintenance person or the like. By the way, the wide area Ethernet network may have a configuration in which the L2SW is made redundant in order to improve the reliability of the network. The present inventor, when monitoring a communication path by transmitting an OAM frame in a layer 2 network in which L2SW is made redundant, provides an idea of notifying a message in accordance with L2SW redundancy as a message for detecting an abnormality, or a specific example thereof. I thought that no new method has been proposed enough.

  The present invention has been made in view of such problems, and its main purpose is to notify a message in accordance with the redundancy of the communication device as an abnormality detection message when the communication state is monitored by transmission of an OAM frame. Is to provide technology for.

  In order to solve the above problems, a monitoring device according to an aspect of the present invention is a group to which a part of a plurality of communication devices belonging to a predetermined MEG belongs, and a group including a plurality of redundant communication devices. When defined, an acquisition unit for acquiring an OAM frame for confirming a connection state from each communication device belonging to the group, including an ID of the group, and a group according to the acquisition status of the OAM frame If the connection state between the determination unit that determines the connection state with each communication device belonging to and the communication device belonging to the group is abnormal, the abnormality is performed in a manner according to the connection state with the other communication device belonging to the group A notification unit that notifies information indicating

  Another aspect of the present invention is a communication device. This device is a group to which a part of a plurality of communication devices belonging to a predetermined MEG belongs, and when a group including a plurality of redundant communication devices is defined, One OAM frame specifying a group ID is a monitoring device that should determine the connection state with each communication device belonging to the group, and the connection state with a certain communication device belonging to the group is abnormal. In this case, a transmission unit is provided that transmits information indicating the abnormality to the monitoring device to be notified to the outside in a manner corresponding to a connection state with another communication device belonging to the group.

  Yet another embodiment of the present invention is a network monitoring method. This method is a group to which a part of a plurality of communication devices belonging to a predetermined MEG belongs, and when a group including a plurality of redundant communication devices is defined, a connection is established from each communication device belonging to the group. An OAM frame for confirming a state, the step of acquiring an OAM frame including a group ID, and a step of determining a connection state with each communication device belonging to the group according to an acquisition state of the OAM frame; A step of notifying information indicating the abnormality to the outside in a manner corresponding to a connection state with another communication device belonging to the group when the connection state with a certain communication device belonging to the group is abnormal.

  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, when the communication state is monitored by transmitting an OAM frame, a message conforming to the redundancy of the communication device can be notified as an abnormality detection message.

It is a figure which shows the structure of the communication system of embodiment. It is a figure which shows the structure of the OAM frame in embodiment. It is a block diagram which shows the function structure of center L2SW of FIG. It is a figure which shows the example of data stored in CC status table. It is a flowchart which shows operation | movement of center L2SW of FIG.

  FIG. 1 shows a configuration of a communication system according to an embodiment. In the communication system 100, in a wide area Ethernet network (hereinafter also referred to as “wide area Ethernet network 10”), a center L2SW 12 installed on the network monitoring center side, a working L2SW 20 and a spare L2SW 22 installed on the user base side, and the like. The L2SW 28 and the other L2SW 30 are connected. The center L2SW 12 is also connected to a monitoring network 14 for transmitting and receiving information relating to communication state monitoring, and is connected to an operator terminal 16 of the network monitoring center via the monitoring network 14. As will be described later, the center L2SW 12 notifies the network monitoring operator of the network failure by sending the network failure information to the monitoring network 14.

  The active L2SW 20 and the backup L2SW 22 are connected to a media converter (hereinafter referred to as “MC24”) that performs E / O conversion and O / E conversion, and are connected to the user base terminal 26 via the MC 24. The MC 24 may be mounted as an OLT (Optical Line Terminal) device installed on the carrier side of a PON (Passive Optical Network).

  The working L2SW 20 and the backup L2SW 22 are in a redundant relationship, in other words, in an alternative relationship. That is, when the working L2SW 20 is operating normally, the working L2SW 20 executes a frame transmission process between the user base terminal 26 and the wide area Ethernet network 10. When the working L2SW 20 fails, the spare L2SW 22 takes over the frame transmission process. In the present embodiment, it is detected that the MC 24 is disconnected from the working L2SW 20 (for example, detection of link pulse signal disconnection), and thereafter, the MAC frame is transmitted to and received from the spare L2SW 22. Thereby, the continuity of communication at the time of L2SW failure can be improved. For example, even when the working L2SW 20 fails, the influence on the user base terminal 26 is minimized (for example, the duration of the frame transmission disabled state is several seconds to several tens Second).

  The wide area Ethernet network 10 and the center L2SW 12 are hereinafter also referred to as a “core network” in the meaning of a communication backbone network. On the other hand, the working L2SW 20, the spare L2SW 22, the other L2SW 28, the other L2SW 30, and the MC 24 are also referred to as “access networks” in the sense of networks that provide connection lines to the core network for individual users. Each L2SW in FIG. 1 is set as a MEP belonging to the same MEG. The ID of each MEP is as shown in FIG.

Here, the problem recognized by the present inventor will be described.
In the wide area Ethernet network 10 configured by L2SW, the network reliability is improved by constantly monitoring the normality of the user communication path using the ETH-CC between the L2SW installed in the core network and the access network. . For example, MEP is set in each L2SW, and CCM (hereinafter also referred to as “OAM frame”) is transmitted and received between the MEPs, thereby constantly monitoring the communication path. When the CCM from other MEPs is not received in each MEP, a LOC (Loss of continuity) state is detected, and the network monitoring operator is notified that an abnormality has occurred on the communication path.

  By the way, in the wide area Ethernet network 10, in order to improve the reliability, as shown in FIG. 1, the L2SW is made redundant in the access network (working L2SW 20 and backup L2SW 22). Since the center L2SW 12 manages the reception status of the CCM from the active L2SW 20 and the reception status of the CCM from the backup L2SW 22 separately (as independent ones), the active L2SW 20 and the backup L2SW 22 have been configured as redundant nodes so far. I could not recognize that. As a result, the alert notified from the center L2SW 12 to the network monitoring operator does not take into account that the active L2SW 20 and the spare L2SW 22 have the node redundant configuration, and the network monitoring operator can make a response determination based on the node redundant configuration. It was difficult.

  However, when the access network has a non-redundant configuration, user communication is interrupted due to a failure of one L2SW (a so-called single point of failure exists), whereas when the access network has a redundant configuration, one L2SW fails. However, user communication is continued. Accordingly, the actions to be taken by the network operator are often different depending on each case. Therefore, the center L2SW 12 recognizes whether or not the working L2SW 20 and the spare L2SW 22 are in a node redundant configuration, and the alert notified to the network monitoring operator also takes into account whether the working L2SW 20 and the spare L2SW 22 are in a node redundant configuration. It is desirable that

  Therefore, in the communication system 100 according to the present embodiment, a group of MEPs that belong to a plurality of L2SWs belonging to the same MEG (in other words, communication devices in which MEPs are set) and to which a plurality of redundant L2SWs belong is included. Define. This group is a subgroup in the MEG, and is hereinafter referred to as a “MEP group”. In FIG. 1, the MEP group to which the working L2SW 20 and the backup L2SW 22 belong is applicable.

  In addition, a priority, that is, a priority between redundant L2SWs is assigned in advance to each MEP in the same MEP group. In the present embodiment, “0” indicating a relatively high priority is assigned to the working L2SW 20, and “1” indicating a relatively low priority is assigned to the backup L2SW 22. In the CCM from the working L2SW 20 to the center L2SW 12 and the CCM from the backup L2SW 22 to the center L2SW 12, the MEP group ID and the priority in the MEP group are designated.

  As a result, the center L2SW 12 that receives the CCM from each L2SW in the MEG identifies whether the failed L2SW has a redundant configuration and the priority in the redundant configuration, and issues an alert according to the redundant configuration of the communication network. The operator can be notified. Then, it is possible to support the implementation of the response according to the redundant configuration of the communication network by the operator.

  FIG. 2 shows a configuration of the OAM frame in the embodiment. This figure shows the structure of the MEG-ID field included in the OAM frame, and shows the byte string vertically and the bit string of each byte horizontally (upper bit on the left). In general, in the MEG-ID field, 0 is set for all bit values after the 17th byte. Therefore, in the present embodiment, an ID assigned to the MEP group in advance is set in a part (12 bits) of 17 bytes and 18 bytes. Then, the priority of each MEP in the MEP group is set in the lower 4 bits of the 18th byte. Although not shown in FIG. 2, in the present embodiment, the value “1” is set in the “OpCode” field to refer to the OAM frame as the CCM.

  For example, it is assumed that MEP-ID “40” and MEG-ID “ABC” are specified in the OAM frame (CCM) periodically transmitted from the other L2SW 28 not belonging to the MEP group of FIG. 1 to the center L2SW 12. In this case, in the OAM frame (CCM) from the working L2SW 20 to the center L2SW 12 periodically, in addition to the MEP-ID “20” and the MEG-ID “ABC”, the MEP group ID “500” and the MEP priority “0”. Is specified. In addition, in the OAM frame transmitted by the spare L2SW 22, in addition to the MEP-ID “20” and the MEG-ID “ABC”, the MEP group ID “500” and the MEP priority “1” are designated.

  FIG. 3 is a block diagram showing a functional configuration of the center L2SW 12 of FIG. The center L2SW 12 includes a CC status table 40, an e-support 42, an OAM acquisition unit 44, a connection state determination unit 46, an alert setting unit 48, an alert notification unit 50, and a monitoring network port 52.

  Each block shown in the block diagram of this specification can be realized by hardware such as a computer CPU, memory, HDD, and other elements, electronic circuits, and mechanical devices, and can be realized by a computer program or the like in terms of software. However, in the block diagram, functional blocks realized by their cooperation are depicted. 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.

  In FIG. 3, as a general function of the L2SW, a MAC processing unit that executes a MAC frame setting process, an ingress processing unit that executes a flow rate control / bandwidth control of input data, and a flow rate control / bandwidth control of output data are executed. Description of an egress processing unit to be performed and a switch processing unit for switch processing (route determination processing) is omitted. Also, description of a functional block for transmitting an OAM frame to each L2SW on the access network side is omitted, and only a block related to an OAM frame receiving function is drawn.

  The CC status table 40 is a storage area in which a reception status of an OAM frame (hereinafter, “CCM”) from each L2SW in the MEG is held. FIG. 4 shows an example of data stored in the CC status table 40. The data in the MEP-ID field and MEG-ID field of the CC status table 40 is preset as an attribute of the monitoring target L2SW. The MEP group ID and MEP priority are extracted from the received OAM frame (CCM) by the connection state determination unit 46 described later and reflected in the CC status table 40. As described above, the MEP group ID and the MEP priority are dynamically extracted from the OAM frame, so that the MEP is assigned to the MEP, for example, when switching between the active system and the standby system occurs between the redundant L2SWs. Even when the MEP priority changes, the connectivity confirmation with each MEP can be continued. As a modification, the data of the MEP group ID and MEP priority field may also be set in advance as attributes of the monitoring target L2SW.

  In the present embodiment, as shown in FIG. 4, the MEP group ID and MEP priority are also retained for the working L2SW 20 (MEP-ID = 20) and the spare L2SW 22 (MEP-ID = 30) belonging to the MEP group. . The CCM reception status field of the CC status table 40 is sequentially updated according to the reception status of the OAM frame from each L2SW.

  Returning to FIG. 3, the e-support 42 is a communication port that transmits and receives MAC frames to and from the wide area Ethernet network 10. The monitoring network port 52 is a communication port that transmits and receives MAC frames to and from the monitoring network 14. The OAM acquisition unit 44 specifies an OAM frame according to the ether type and OpCode in the MAC frame received by the e-support 42, and acquires the OAM frame. For example, when the ether type is a predetermined value indicating an OAM frame and the OpCode is a value indicating CCM (= 1), it is determined that the OAM frame is a reception status confirmation target.

  The connection state determination unit 46 manages the reception status of the OAM frame for each L2SW of the MEG, in other words, for each entry (record) in the CC status table of FIG. Specifically, the reception time of the OAM frame is held for each L2SW of the MEG. When a new OAM frame from a certain L2SW is received within a predetermined time (for example, within 3 seconds) from the reception time of the previous OAM frame, the record of the L2SW in the CC status table 40, that is, the OAM frame indicates The CCM reception status field of the record in which the MEP-ID to MEP priority is set is updated to “receiving”. In other words, “receiving” is maintained as the CCM reception status of the L2SW. On the other hand, when a new OAM frame from a certain L2SW is not received within a predetermined time (for example, within 3 seconds) from the reception time of the previous OAM frame, the LOC is detected by a predetermined timer timeout or the like. Then, the CCM reception status of the L2SW in the CC status table 40 is updated to “LOC state”.

  A record indicating the combination of MEP-ID and MEG-ID specified in the OAM frame exists in the CC status table 40, while a record indicating a combination of MEP-ID to MEP priority exists in the CC status table 40. It may not be. Typically, this is when the first OAM frame is received from a MEP belonging to a certain MEP group. In this case, the connection state determination unit 46 newly sets a record indicating the combination of MEP-ID to MEP priority specified in the OAM frame in the CC status table 40.

  The alert setting unit 48 monitors each entry of the CC status table 40, and sets an alert message indicating that when the CCM reception status in at least one entry is “LOC”. Here, when the MEP group ID is set to the entry in the LOC state, a message corresponding to the CCM reception status in the entry of the same MEP group is set. Details of the message will be described later. The alert notification unit 50 makes a TRAP notification of the alert message set in the alert setting unit 48 to the external SNMP server via the monitoring network port 52 to the monitoring network 14. The alert message notified by TRAP to the SNMP server is referred to by the operator terminal 16 and a predetermined response such as contact with the end user is performed by the operator. Of course, the alert notification unit 50 may directly send an alert message to the operator terminal 16.

The operation of the above configuration will be described below.
First, each L2SW of the access network in FIG. 1 transmits a new OAM frame to the center L2SW 12 when detecting that a predetermined time (for example, 1 second) has elapsed since the transmission of the previous OAM frame. In the case of the L2SW belonging to the MEP group (the working L2SW 20 and the spare L2SW 22 in FIG. 1), the MEP group ID and the MEP priority determined in advance are held, and an OAM frame including the MEP group ID and the MEP priority is transmitted. .

FIG. 5 is a flowchart showing the operation of the center L2SW 12 of FIG. First, the first failure information to the third failure information shown in FIG.
The first failure information is information indicating that a LOC (abnormal connection state) has occurred with the L2SW and that there is no L2SW receiving CCM in the same MEP group. It can also be said that the information indicates that a failure has occurred at a single point of failure.
The second failure information is information indicating that a LOC has occurred with a high priority L2SW among the plurality of L2SWs of the MEP group. For example, this is information indicating a failure occurrence in the active L2SW that is currently executing the frame transfer process. It can also be said that the information indicates that switching from the active system to the standby system has occurred in the MEP group.
The third failure information is information indicating that a LOC has occurred with a low priority L2SW among a plurality of L2SWs of the MEP group. For example, this is information indicating the occurrence of a failure in the standby L2SW that is not currently executing frame transfer processing and is in a standby state.

  When the MAC frame transmitted through the wide area Ethernet network 10 is received by the center L2SW 12 (Y in S10) and the MAC frame is a CCM OAM frame (Y in S12), the OAM acquisition unit 44 acquires the OAM frame. (S14). The connection state determination unit 46 refers to the MEP-ID set in the OAM frame acquired by the OAM acquisition unit 44, and displays the CCM reception status associated with the MEP-ID in the CC status table 40 as “receiving”. (S16). The connection state determination unit 46 detects the L2SW that does not accept the OAM frame for a certain time or more as the LOC state, and updates the CCM reception state of the CC state table 40 to the “LOC state”. If the MAC frame received at the center L2SW 12 is a non-OAM frame (N in S12), normal frame transfer processing (switch processing) is executed for the MAC frame (S18). If no MAC frame is received (N in S10), S12 to S18 are skipped.

  When the LOC is detected in the connection status determination unit 46, for example, when the alert setting unit 48 detects an entry in which the LOC status is recorded in the reception status of the CC status table 40 (Y in S20), the alert setting unit 48 performs First to third failure information is set. That is, if one or more L2SWs belonging to the same MEP group as the L2SW that detected the LOC are in the LOC state for any OAM frame (N in S22), the first failure information is set (S24). The first failure information is also set when there is no L2SW belonging to the same MEP group as the L2SW that detected the LOC, or when the L2SW that detected the LOC does not belong to the MEP group in the first place.

  An OAM frame is being received from any L2SW belonging to the same MEP group (Y in S22), and the L2SW (MEP) in the LOC state is higher than the L2SW (MEP) that is continuously receiving the OAM frame. In the case of priority (N in S26), second failure information is set (S28). If the L2SW (MEP) that is continuously receiving the OAM frame has a higher priority than the L2SW (MEP) in the LOC state (Y in S26), the third failure information is set (S30). The alert notification unit 50 notifies the external SNMP server of the failure information set by the alert setting unit 48 (S32). If the LOC is not detected in the connection state determination unit 46, in other words, if the reception statuses in the CC status table 40 are all “receiving” (N in S20), S22 to S32 are skipped.

  According to the communication system 100 of the present embodiment, in the center L2SW 12 that receives the CCM from each L2SW in the MEG, the communication is performed by identifying whether or not the failed L2SW has a redundant configuration and the priority in the redundant configuration. Alerts according to the redundant configuration of the network can be notified to the operator. Then, it is possible to support the implementation of the response according to the redundant configuration of the communication network by the operator.

  For example, by notifying the first failure information, it is possible to assist the operator in recognizing that the transmission process of the user frame is stopped and performing the highest priority failure response. In this case, for example, the operator may contact an end user affected by the failure.

  Also, by notifying the second failure information, the operator can recognize that a failure has occurred in the active L2SW, but the user frame transmission process is continuing by switching to the standby L2SW. it can. In this case, since the user frame transmission process continues, it is not necessary to immediately restore the active L2SW. However, when SLA (Service Level Agreement) is set for the switching time from the active system to the standby system (user frame transmission stop time), the switching time (user frame transmission stop time) is set to the L2SW log, etc. Need to be measured and reported to end users.

  Also, by notifying the third failure information, the operator can recognize that a failure has occurred in the standby L2SW, but the working L2SW is in a normal state. In this case, since the transmission process of the user frame continues, it is not necessary to quickly restore the standby L2SW. Moreover, since transmission of user frames has not been stopped, notification to the end user is unnecessary if there is no problem with the contract with the end user.

  In the conventional network monitoring device (device corresponding to the center L2SW 12 in the embodiment), the same alert is sent to the operator regardless of whether the L2SW is in a redundant configuration or a non-redundant configuration in the access network. Had been implemented. For example, even if the standby L2SW has just failed and transmission of the user frame is actually continued, the same action is taken as when a single failure point L2SW fails and transmission of the user frame stops. This may cause unnecessary confusion. In the present embodiment, since the alert is notified to the operator according to whether or not the L2SW has a redundant configuration and the priority in the redundant group, it is possible to support the operator to perform an appropriate response.

  Network monitoring using Ethernet OAM technology in wide area Ethernet is expected to expand further in the future, and the number of users who select an access network redundant configuration to avoid long-time communication failures is also expected to increase. The In such a situation, the L2SW configuration of the access network can be recognized on the device side, and the TRAP notification corresponding to the situation can be performed to assist the operator in grasping the situation and speeding up the response.

  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.

  Any combination of the above-described embodiments and modifications is also useful as an embodiment of the present invention. The new embodiment generated by the combination has the effects of the combined embodiment and the modified examples.

  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.

  10 Wide area Ether network, 12 Center L2SW, 14 Monitoring network, 16 Operator terminal, 20 Current L2SW, 22 Spare L2SW, 24 MC, 26 User base terminal, 40 CC status table, 42 E support, 44 OAM acquisition unit, 46 Connection status Determination unit, 48 alert setting unit, 50 alert notification unit, 52 monitoring network port, 100 communication system.

Claims (5)

When a group including a part of a plurality of communication devices belonging to a predetermined MEG (Maintenance Entity Group) and including a plurality of redundant communication devices is defined,
An acquisition unit that acquires an OAM (Operations, Administration and Maintenance) frame for confirming a connection state from each communication device belonging to the group, the OAM frame including an ID of the group;
A determination unit that determines a connection state with each communication device belonging to the group according to an acquisition state of the OAM frame;
When the connection state with a certain communication device belonging to the group is abnormal, a notification unit for notifying information indicating the abnormality to the outside in a mode according to the connection state with another communication device belonging to the group;
A monitoring device comprising:   The monitoring apparatus according to claim 1, wherein the OAM frame including the group ID acquired by the acquisition unit is a CCM (Continuity Check Message) frame. The OAM frame acquired by the acquisition unit further includes information indicating the priority in the group of each communication device belonging to the group,
The notification unit reports the abnormality in a manner according to the magnitude relationship between the priority of the communication device in which the connection state with the present device is abnormal and the priority of the communication device in which the connection state with the present device is normal. The monitoring apparatus according to claim 1, wherein the information to be indicated is notified to the outside. When a group to which a part of a plurality of communication devices belonging to a predetermined MEG belongs and a group including a plurality of redundant communication devices is defined, one of the plurality of redundant communication devices is defined. There,
When the OAM frame specifying the group ID is a monitoring device that should determine the connection state with each communication device belonging to the group, and the connection state with a communication device belonging to the group is abnormal, A communication apparatus comprising: a transmission unit configured to transmit information indicating the abnormality to a monitoring apparatus to be notified to the outside in a manner according to a connection state with another communication apparatus belonging to a group. When a group including a part of a plurality of communication devices belonging to a predetermined MEG and a group including a plurality of redundant communication devices is defined,
Obtaining an OAM frame for confirming a connection state from each communication device belonging to the group, the OAM frame including the ID of the group;
Determining a connection state with each communication device belonging to the group according to the acquisition status of the OAM frame;
When the connection state with a certain communication device belonging to the group is abnormal, the step of notifying outside the information indicating the abnormality in a manner according to the connection state with another communication device belonging to the group;
A network monitoring method comprising:

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