JP2004080397A - Snmp agent provided with lan monitor function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the loss of traps transmitted from an agent to a manager to the minimum when a LAN communication is impossible. <P>SOLUTION: A LAN monitor control unit 11 makes a trap processing part 13 to check the possibility of the communication by a LAN 3 in a prescribed cycle. When the LAN communication is possible, the trap processing part 13 transmits the trap issued at a trap issue section 12 to the manager via the LAN 3. While, when the LAN communication is impossible, the trap issued at the trap issue section 12 is saved in a local buffer 14 until the LAN communication becomes possible again, as soon as the LAN communication becomes possible again, the trap saved in the local buffer 14 is transmitted to the manager via the LAN 3. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an SNMP (Simple Network Manager Protocol) agent having a LAN (Local Area Network) monitoring function, and more particularly to an SNMP agent having a LAN monitoring function of detecting a LAN communication failure and avoiding the disappearance of an SNMP trap.
[0002]
[Prior art]
SNMP is a network protocol mainly using UDP (User Datagram Protocol) and IP (Internet Protocol). This SNMP is a protocol for transmitting and receiving management information between an agent and a manager when a communication device called a manager manages the state of another communication device called an agent in a network management system having a plurality of communication devices. used.
[0003]
In a network management system using SNMP, an agent holds event and failure information of the agent in the form of an object. The manager obtains the state of the agent stored in the agent object by a command. Further, the manager sends a setting request to the agent to the agent as a command, and the agent returns the result to the manager. Further, the agent voluntarily transmits information on an event or a failure that has occurred in the agent to the manager as a trap (Trap) at any time.
[0004]
SNMP uses UDP, which is a lower protocol of SNMP, when transmitting and receiving data. The UDP is a connectionless type protocol in which data is transmitted directly without checking whether a connection on the network has been established (whether network communication is possible).
[0005]
Therefore, SNMP has an advantage that data can be transmitted and received at a relatively high speed, but has low reliability. For example, in a network management system on a LAN using SNMP, LAN communication between an agent and a manager is impossible. Sometimes, when a trap is sent from an agent to a manager on a LAN, all the traps are lost.
[0006]
In order to detect the disappearance of a trap, for example, in Japanese Patent Application Laid-Open No. 2001-67291, two managers are installed and two managers communicate with each other so that one manager receives a trap from an agent. However, there is disclosed a network monitoring method in which, when the other manager cannot receive the trap, the trap is determined to be lost.
[0007]
[Problems to be solved by the invention]
However, in the network monitoring system disclosed in the above-mentioned patent publication, it is necessary to install at least two managers, and there is a problem that the system scale is increased.
[0008]
In addition, since the agent cannot recognize that the trap has disappeared, the agent continues to transmit the trap to the manager without knowing the fact, and there is a problem in that the amount of trap loss increases.
[0009]
There is also a problem that a trap issued by an agent may disappear due to LAN communication being disabled and not reach the manager.
[0010]
Therefore, an object of the present invention is to minimize the disappearance of SNMP traps issued when LAN communication is not possible without increasing the system scale, and to ensure that the SNMP traps issued when LAN communication is not available to the manager. The present invention provides an SNMP agent having a LAN monitoring function, which can be passed to an SNMP agent.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, an SNMP agent having a LAN monitoring function according to the present invention is connected to a communication device serving as a manager via a LAN using SNMP, and manages management information with the manager via the LAN. An SNMP agent having a LAN monitoring function, which is a communication device for transmitting and receiving a message, a trap issuing unit for issuing the management information including information on an event or a failure occurring in the SNMP agent as a trap at any time, and the trap issuing unit A local buffer for temporarily saving traps issued in step 2, a LAN communication check unit for checking whether communication with the manager is possible via the LAN, and the LAN communication check unit is capable of performing communication via the LAN. Detected by the trap issuing means, Trap transmitting means for transmitting the trap to the manager, and when the LAN communication checking means detects that communication by the LAN is impossible, the trap issued by the trap issuing means is stored in the local buffer. The trap evacuation means for temporarily evacuation and the manager, via the trap transmission means, send the trap evacuation to the local buffer when the LAN communication check means detects that the communication via the LAN has been enabled again. Evacuation trap transmitting means for transmitting to
[0012]
In this case, when checking whether or not communication by the LAN is possible, the LAN communication check means transmits a test packet to the manager, and based on a reply status of the test packet from the manager, the LAN communication check means transmits the test packet to the manager. It may be determined whether communication is possible.
[0013]
Further, the LAN communication checking means waits for the reception of the test packet from the manager until a time-out period after transmitting the test packet to the manager, and the time-out period has elapsed. At this point, it may be determined that communication via the LAN is not possible.
[0014]
Further, the LAN communication check means may check whether or not communication via the LAN is possible at regular intervals.
[0015]
The trap evacuation unit creates a trap transmission command line based on the trap issued by the trap issuance unit, and saves the created trap transmission command line as the trap in the local buffer. The transmission means may transmit the trap transmission command line saved in the local buffer as the trap to the manager via the trap transmission means.
[0016]
When the LAN communication checking means detects that the communication by the LAN is impossible, the trap evacuation means detects that the communication by the LAN is enabled again thereafter. By the time, the trap issued by the trap issuing means may be temporarily saved in the local buffer.
[0017]
Further, when the capacity of the local buffer becomes full due to the trap, the trap evacuation unit may write a new trap by overwriting the oldest trap sequentially.
[0018]
Further, the evacuation trap transmitting means may read out the traps saved in the local buffer in order from the oldest one and transmit the traps to the manager via the trap transmitting means.
[0019]
(Action)
In the present invention configured as described above, when the LAN communication check means detects that the LAN communication is not possible, the trap issued thereafter is saved in a local buffer, and the LAN communication check means later determines that the LAN communication is possible. When detected, the traps saved in the local buffer are sent to the manager.
[0020]
Thus, it is possible to prevent the trap issued when the LAN communication is disabled from being sent to the LAN and to be lost, and to reliably transfer the trap issued when the LAN communication is disabled to the manager after the LAN communication is restored.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0022]
(1st Embodiment)
FIG. 1 is a block diagram showing a configuration of a network management system using an SNMP agent (hereinafter, referred to as an agent) having a LAN monitoring function according to a first embodiment of the present invention. Referring to FIG. 1, this network management system has a configuration in which an agent 1 as a communication device and a manager 2 as a communication device are connected by a LAN 3 using SNMP.
[0023]
FIG. 2 is a block diagram showing a configuration of the agent 1 shown in FIG. Referring to FIG. 2, the agent 1 includes a LAN monitoring control unit 11, a trap issuing unit 12, a trap processing unit 13, and a local buffer 14.
[0024]
The LAN monitoring control unit 11 causes the trap processing unit 13 to monitor the LAN 3 at regular intervals, and the trap issuing unit 12 issues management information such as an event or a failure that has occurred in the agent 1 as a trap at any time.
[0025]
The trap processing unit 13 checks whether LAN communication is possible or not at regular intervals under the control of the LAN monitoring control unit 11, and when LAN communication is possible, the trap issued by the trap issuing unit 12 is transmitted via the LAN 3. Send to Manager 2. On the other hand, if the LAN communication is not possible, the trap issued by the trap issuing unit 12 is saved in the local buffer 14, and the trap saved in the local buffer 14 is directed to the manager 2 via the LAN 3 as soon as the LAN communication becomes possible. To send.
[0026]
FIG. 3 is a block diagram showing a detailed configuration of the trap processing unit 13 shown in FIG. 3, the trap processing unit 13 includes a LAN check / evacuation trap transmission unit 131, a LAN communication check unit 132, an evacuation trap transmission unit 133, a trap control unit 134, a trap evacuation unit 135, and a trap transmission unit. A section 136 and a LAN status flag 137 are provided.
[0027]
Under the control of the LAN monitoring control unit 11, the LAN check / evacuation trap transmitting unit 131 calls the LAN communication checking unit 132 at regular intervals, and checks whether LAN communication between the agent 1 and the manager 2 is possible. If LAN communication is possible, the evacuation trap transmission unit 133 is called. If there is a trap saved in the local buffer 14 at that time, the trap saved in the local buffer 14 is sent to the manager via the trap transmission unit 136. 2 is transmitted.
[0028]
If LAN communication is possible when the trap issuing unit 12 issues the trap, the trap control unit 134 transmits the trap to the manager 2 via the trap transmitting unit 136. If LAN communication is not possible when the trap issuing unit 12 issues the trap, the trap saving unit 135 is called to temporarily save the trap issued by the trap issuing unit 12 in the local buffer 14.
[0029]
The LAN status flag 137 is a flag indicating a result of periodic LAN communication monitoring by the LAN communication check unit 132. The LAN status flag 137 is set to OFF (LAN communication disabled) as an initial value by the LAN monitoring control unit 11, and thereafter, in accordance with the periodic monitoring result of the LAN communication enabled / disabled by the LAN communication checking unit 132, the LAN check / check is performed. It is set ON (LAN communication is possible) or OFF by the evacuation trap transmitting unit 131.
[0030]
Hereinafter, the operation of each component in the agent 1 according to the present embodiment will be sequentially described using a flowchart.
[0031]
Referring to FIG. 4, the trap issuing unit 12 issues management information such as an abnormality or an event that has occurred in the agent 1 as a trap at any time (step A1).
[0032]
Subsequently, the trap issuing unit 12 calls the trap control unit 134 in the trap processing unit 13 by transferring the trap issued in step A1, and transmits a trap based on whether LAN communication between the agent 1 and the manager 2 is possible. A process for determining a destination and a process for transmitting a trap are executed (step A2), and the process ends.
[0033]
Referring to FIG. 5, the trap control unit 134 first creates a trap transmission command line based on the trap issued by the trap issuing unit 12 in step A1 of FIG. 4 (step B1).
[0034]
Next, the trap control unit 134 checks whether or not LAN communication between the agent 1 and the manager 2 is possible (whether or not a trap can be transmitted from the agent 1 to the manager 2) by using the LAN status flag 137 (step B2).
[0035]
If the LAN status flag 137 is ON (LAN communication is possible), the trap control unit 134 sends the trap to the manager 2 via the trap transmission unit 136 using the trap transmission command line created in step B1. Send (step B3) and end the process.
[0036]
On the other hand, when the LAN status flag 137 is OFF (LAN communication is disabled), the trap control unit 134 calls the trap evacuation unit 135 (step B4), and stores the trap transmission command line created in step B1 in the local buffer for each command line. After evacuating to 14, the process ends.
[0037]
Referring to FIG. 6, first, the trap evacuation unit 134 searches the local buffer 14 to obtain a write destination of a trap transmission command line in the local buffer 14 (step C1). The command line is written in the location acquired in step C1 (step C2), and the process ends. Note that when the capacity of the local buffer 14 is full due to the trap, the trap save unit 134 writes a new trap by overwriting in order from the oldest trap.
[0038]
7 to 10 show the flow of operations that are periodically executed under the control of the LAN monitoring control unit 11 in the present embodiment.
[0039]
Referring to FIG. 7, after the LAN monitoring control unit 11 sets the LAN status flag 137 to OFF (LAN communication disabled) as an initial value (step D1), the loop 1 calls the LAN check / evacuation trap transmission unit 131 at regular intervals. (Steps D2 to D4) are repeated to monitor the LAN3. The period at which the LAN check / evacuation trap transmitting unit 131 is called is a time period during which LAN communication is disabled and traps issued within this period are not guaranteed (traps are lost). In this embodiment, it is set to 1 [sec] in consideration of keeping traffic on the LAN 3 to a minimum.
[0040]
Referring to FIG. 8, first, the LAN check / evacuation trap transmitting unit 131 calls the LAN communication check unit 132 (step E1) and checks whether LAN communication between the agent 1 and the manager 2 is possible.
[0041]
Referring to FIG. 9, first, the LAN communication check unit 132 transmits a test packet to the manager 2 (step F1), and transmits a test packet until a predetermined time (timeout) elapses after transmitting the test packet. The process of loop 1 (steps F2 to F5) for receiving the test packet returned from the manager 2 is repeated, and the process ends when a timeout occurs.
[0042]
Specifically, the LAN communication check unit 132 checks whether a test packet returned from the manager 2 has been received until the timeout occurs (step F3). (Step F4) is repeated to confirm that is a normal packet (a test packet from the manager 2 and that it can communicate normally with the manager 2). If it can be confirmed in step F4, the process exits from loop 1 (steps F2 to F5) and ends the processing. The timeout period was examined as follows. In the measurement by the experiment, the time from the transmission of the test packet to the reception of the test packet when the LAN communication is normal is on the order of 0.0001 [sec]. From this result, a time-out period of 0.1 [sec] is sufficient. Therefore, in this embodiment, the time-out period is set to 0.1 [sec].
[0043]
Referring to FIG. 8 again, the LAN check / evacuation trap transmitting section 131 turns on the LAN status flag 137 (LAN communication) based on the result of the LAN communication check section 132 checking whether or not LAN communication is possible in step E1 (step E2). OK) or OFF (LAN communication disabled) (steps E3 and E5).
[0044]
When the LAN status flag 137 is set to OFF in step E5, the LAN check / evacuation trap transmitting unit 131 ends the processing.
[0045]
On the other hand, when the LAN status flag 137 is set to ON in step E3, the LAN check / evacuation trap transmitting unit 131 calls the evacuation trap transmitting unit 133 (step E4), and the traps saved in the local buffer 14 at that time. If there is, all the traps saved in the local buffer 14 are transmitted to the manager 2, and the process is terminated.
[0046]
Referring to FIG. 10, the evacuation trap transmitting unit 133 checks whether or not there is a trap that has been evicted in the local buffer 14 and has not been transmitted to the manager 2 (step G1).
[0047]
On the other hand, if there are traps that have been saved in the local buffer 14 and have not been sent to the manager 2, the saved trap transmitting unit 133 sends all traps saved in the local buffer 14 to the manager 2 by one trap transmission command line. Is repeated (steps G2 to G5).
[0048]
Specifically, the evacuation trap transmitting unit 133 transmits the trap transmission command lines of the traps saved in the local buffer 14 to the manager 2 in order from the oldest one (step G3). Then, it is checked whether or not the trap transmitted to the manager 2 is the last (remaining one) trap which has been saved to the local buffer 14 and has not been transmitted to the manager 2 (step G4). The processing exits from loop 1 (steps G2 to G5) and ends.
[0049]
Hereinafter, the operation of the agent 1 according to the present embodiment will be described with a specific example. Here, as shown in FIG. 11, it is assumed that the hub 4 is arranged in the middle of the LAN 3 connecting the agent 1 and the manager 2.
[0050]
FIG. 12 is a sequence chart illustrating a specific operation of the agent 1 according to the present embodiment.
[0051]
In this embodiment, the operation of the agent 1 is started (step H1) and the power of the hub 4 is turned on (step H2) at the same time. Shall be
[0052]
However, in this case, it takes time from when the power of the hub 4 is turned on to when communication via the LAN 3 is possible between the hubs 4 (LAN communication via the hub 4 is not guaranteed for 6 seconds after the power is turned on to the hub 4). The trap issued between the start of the operation of the agent 1 and the time when the LAN communication becomes available is not transmitted even if the agent 1 attempts to transmit the trap to the manager 2.
[0053]
In consideration of such circumstances, in this embodiment, the initial value of the LAN status flag 137 of the agent 1 is set to OFF. Therefore, the time from the start of the operation of the agent 1 (step H1) to the execution of the first LAN communication check (step H4) by the LAN communication check unit 132 to set the LAN status flag 137 is the “estimated LAN communication impossible time”. And the trap # 1 issued at this time is saved in the local buffer 14 (step H3).
[0054]
Note that the time T1 from the start of the LAN communication check to the setting of the LAN status flag 137 is the time T1 after the start of the LAN communication check (transmission of the test packet to the manager 2) and the reception of the test packet. This is a time-out period for waiting for the execution, and is set to 0.1 [sec] in the present embodiment.
[0055]
Thereafter, in the agent 1, the LAN communication check unit 132 executes the LAN communication check at a fixed cycle T2 (1 [sec] in this embodiment) (steps H5, H7, H8), and the trap issuing unit 12 After the LAN communication check in steps H5 and H8, traps # 2 and # 3 are issued (steps H6 and H9), and the traps # 2 and # 3 are saved in the local buffer 14. Note that the trap # 3 is issued after the LAN communication is enabled. At this point, since the LAN status flag 137 is OFF, the trap # 3 is saved in the local buffer 14.
[0056]
Eventually, in the present embodiment, "from the start of the operation of the agent 1, the first LAN communication check after the LAN communication is enabled detects the LAN communication possible (step H10), and the LAN status flag 137 is set to ON. All traps # 1, # 2, and # 3 issued until "by the time" are saved in the local buffer 14.
[0057]
Then, after the LAN communication is enabled, the first LAN communication check (step H10) detects that the LAN communication is possible, and when the LAN status flag 137 is turned ON, all the data saved in the local buffer 14 are saved. Traps # 1, # 2, and # 3 are transmitted to the manager 2 (step H11).
[0058]
In the subsequent LAN communication check (step H12), the LAN communication is detected and the LAN status flag 137 is set to ON, so that the trap # 4 is transmitted to the manager 2 without being saved in the local buffer 14 (step H12). H13).
[0059]
(Second embodiment)
An SNMP agent (hereinafter, referred to as an agent) having a LAN monitoring function according to the second embodiment of the present invention has the same basic configuration as the first embodiment shown in FIG. However, the difference from the first embodiment is that all traps issued by the trap issuing unit 12 are saved in the local buffer 14.
[0060]
Specifically, when LAN communication between the agent 1 and the manager 2 is possible, the trap processing unit 13 transmits the trap issued by the trap issuing unit 12 to the local buffer 14 and the manager 2 at the same time.
[0061]
Further, when the trap processing unit 13 first detects that LAN communication is impossible by the LAN communication check (the first detection means that LAN communication is possible in the previous LAN communication check, but the LAN communication is impossible in this check). ), Assuming that traps issued since the last LAN communication check have been lost, one of the traps saved in the local buffer 14 after the last LAN communication check, that is, one cycle from the current check ( 1 [sec]), traps issued before and after are sent to the manager 2 as soon as LAN communication becomes possible again.
[0062]
As a result, in the first embodiment, the trap issued from when the LAN communication is disabled until the first LAN communication check cannot be guaranteed (is lost), but in the present embodiment, the trap is guaranteed. In this embodiment, it is assumed that the LAN communication is disabled after the LAN communication check immediately before the LAN communication is disabled, and the trap issued after this point is the LAN communication recovery time. This is because it is transmitted to the manager 2 later.
[0063]
However, for this reason, the trap issued from the LAN communication check immediately before the LAN communication is disabled to the LAN communication being disabled (the relevant trap is immediately transmitted to the manager 2) is restored to the LAN communication. Later, it is transmitted to the manager 2 again (the same trap is transmitted twice).
[0064]
Referring to FIG. 13, the trap processing unit 13 has a configuration in which a LAN communication disable detection time holding unit 138 is added to the configuration of the first embodiment shown in FIG. Has become.
[0065]
The LAN communication disable detection time holding unit 138 first detects the LAN communication disable by the LAN communication check unit 132 (the first detection means that the LAN communication check was performed by the previous LAN communication check of the LAN communication check unit 132, The check indicates that the time is not possible.)
[0066]
Hereinafter, the operation of each component in the agent 1 according to the present embodiment will be sequentially described using a flowchart.
[0067]
As in the first embodiment (FIG. 4), the trap issuing unit 12 issues management information such as an abnormality or an event occurring in the agent 1 as a trap at any time (step A1 in FIG. 4). Then, by transferring the trap, the trap control unit 134 in the trap processing unit 13 is called, and the process of determining the destination of the trap and the process of transmitting the trap are performed based on whether LAN communication between the agent 1 and the manager 2 is possible. (Step A2 in FIG. 4), and the process ends.
[0068]
Referring to FIG. 14, the trap control unit 134 first creates a trap transmission command line based on the trap issued by the trap issuing unit 12 as in step B1 of FIG. 5 (step I1).
[0069]
Subsequently, unlike the first embodiment (FIG. 5), the trap control unit 134 determines whether LAN communication between the agent 1 and the manager 2 is possible (whether a trap can be transmitted from the agent 1 to the manager 2). The trap saving unit 135 is called (step I2), and the command line for trap transmission created in step I1 is saved in the local buffer 14 for each command line. The operation of the trap evacuation unit 135 in this step I2 is the same as that in FIG.
[0070]
Subsequently, the trap control unit 134 checks the LAN status flag 137 (step I3), similarly to step B2 in FIG. 5, and ends the process if the LAN status flag is OFF (LAN communication is disabled).
[0071]
On the other hand, if the LAN status flag 137 is ON (LAN communication is possible), the trap control unit 134 sends the trap to the manager 2 via the trap transmission unit 136 using the trap transmission command line created in step I1. (Step I4), and the process ends.
[0072]
FIG. 15 to FIG. 17 show the flow of operations that are periodically executed under the control of the LAN monitoring control unit 11 in the present embodiment.
[0073]
Referring to FIG. 15, as in the first embodiment (step D1 in FIG. 7), the LAN monitoring control unit 11 sets the LAN status flag 137 to OFF (LAN communication is disabled), as in the first embodiment (step D1 in FIG. 7). Step J1) In addition to the first embodiment, the current time is assigned to the LAN communication disable detection time holding unit 138 (step J2).
[0074]
Subsequently, the LAN monitoring control unit 11 repeats the processing of the loop 1 (steps J3 to J5) that calls the LAN check / evacuation trap transmitting unit 131 at regular intervals, and monitors the LAN3. The cycle at which the LAN check / evacuation trap transmitting unit 131 is called is 1 [sec] as in the first embodiment.
[0075]
Referring to FIG. 16, first, the LAN check / evacuation trap transmitting unit 131 calls the LAN communication check unit 132 (step K1) and checks whether LAN communication between the agent 1 and the manager 2 is possible. The operation of the LAN communication check unit 132 in step K1 is the same as that in FIG.
[0076]
Subsequently, the LAN check / evacuation trap transmitting unit 131 sets the LAN status flag 137 to ON (LAN communication enabled) or OFF based on the result of the LAN communication checking unit 132 checking LAN communication availability at step K1 (step K2). (LAN communication disabled) is set (steps K3 and K5).
[0077]
When the LAN status flag 137 is set to OFF in step K5, the LAN check / evacuation trap transmitting section 131 substitutes the current time in the LAN communication impossible detection time holding section 138, and ends the processing (step K6). However, if a normal time has already been assigned, the current time is not assigned because the LAN communication is continuously disabled (the LAN communication was not detected by the previous or previous LAN communication check).
[0078]
On the other hand, when the LAN status flag 137 is set to ON in step K3, the LAN check / evacuation trap transmitting unit 131 calls the evacuation trap transmitting unit 133 (step K4), as in step E4 in FIG. During this time, the trap which is supposed to be transmitted to the manager 2 and which has been evacuated to the local buffer 14 is transmitted to the manager 2, and the process is terminated.
[0079]
Referring to FIG. 17, unlike the first embodiment (FIG. 10), the evacuation trap transmitting unit 133 first checks whether the time held in the LAN communication disable detection time holding unit 138 is normal. (Step L1). If the LAN communication disable detection time holding unit 138 holds a normal time, the evacuation trap transmitting unit 133 is called first after the LAN communication is disabled and the LAN communication is enabled (substitute the time. The timing is limited to when the LAN status flag 137 is OFF (step J2 in FIG. 15 and step K6 in FIG. 16). In this case, the evacuation trap transmitting unit 133 performs a loop 1 (steps L2 to L5) for transmitting all the traps corresponding to the traps saved in the local buffer 14 to the manager 2 one command transmission command line at a time. Repeat the process.
[0080]
More specifically, the evacuation trap transmitting unit 133 sets 1 [from the time held in the LAN communication disable detection time holding unit 138 (the time when the LAN communication disable was first detected in the previous or previous LAN communication check). [sec], it is assumed that traps that have been issued and stored in the local buffer 14 up to the present are traps that have not been transmitted to the manager 2. The command lines are transmitted to the manager 2 one by one from the oldest one (step L3). Then, it is checked whether or not the trap transmitted to the manager 2 is the latest trap (the trap last saved in the local buffer 14) (step L4). L2 to L5).
[0081]
Finally, the evacuation trap transmitting unit 133 resets the time held in the LAN communication disable detection time holding unit 138 (step L6), and ends the process.
[0082]
Hereinafter, the operation of the agent 1 according to the present embodiment will be described with a specific example. Here, it is assumed that the agent 1 and the manager 2 are connected by a LAN 3 as shown in FIG.
[0083]
FIG. 18 is a sequence chart illustrating a specific operation of the agent 1 according to the present embodiment.
[0084]
In this embodiment, the LAN communication check is performed by the LAN communication check unit 132 while the LAN communication is possible (step M1), and the operation after the LAN communication is detected and the LAN status flag 137 is turned ON. explain. Note that the time T1 from the start of the LAN communication check to the setting of the LAN status flag 137 is a time-out time for transmitting the test packet to the manager 2 and waiting for receiving the test packet. And 0.1 [sec] as in the first embodiment. Further, the cycle T2 at which the LAN communication check is performed by the LAN communication check unit 132 is also set to 1 [sec] as in the first embodiment.
[0085]
The trap # 1 issued during the LAN communication is transmitted to the local buffer 14 and the manager 2 by the trap control unit 134 of the agent 1 (steps M2 and M3).
[0086]
After that, it is assumed that the LAN communication between the agent 1 and the manager 2 is disabled for some reason before the LAN communication check is first performed by the LAN communication check unit 132 (step M6).
[0087]
In this case, trap # 2 issued before the first LAN communication check (step M6) is performed after the LAN communication is disabled, even if agent 1 attempts to transmit to both local buffer 14 and manager 2 (step M6). M4, M5), the transmission to the manager 2 fails, and only the transmission to the local buffer 14 succeeds.
[0088]
If the LAN communication check is executed while the LAN communication is disabled (step M6), the LAN communication disable is detected and the LAN status flag 137 is turned off. The traps # 3 and # 4 issued during the period are transmitted from the agent 1 only to the local buffer 14 (steps M7 and M8). Trap # 4 is a trap issued after the LAN communication is actually restored, but is issued before the first LAN communication check is executed after the LAN communication is restored (step M9). Therefore, the data is transmitted only to the local buffer 14 (step M8).
[0089]
When the LAN communication is first checked after the LAN communication is restored to detect that the LAN communication is possible (step M9), the maximum of the traps saved in the local buffer 14 which is considered to have been issued during the LAN communication disabled state is detected. A limited trap is transmitted from the local buffer 14 to the manager 2 (step M10).
[0090]
The maximum trap that is considered to have been issued during the LAN communication failure is one cycle from the first time T11 when the LAN communication failure is detected in the current LAN communication check (the LAN communication check cycle T2: the first embodiment). This is a trap that is issued from time T10 1 [sec] before, to time T12 when LAN communication recovery is detected, and stored in the local buffer 14. In this embodiment, trap # 1, trap # 2, trap # 3, and trap # 4.
[0091]
Thereafter, the trap # 5 issued while the LAN communication is enabled is transmitted from the agent 1 to the local buffer 14 and the manager 2 (steps M11 and M12).
[0092]
【The invention's effect】
As described above, in the present invention, it is monitored whether or not LAN communication with the manager is possible, and when it is detected that LAN communication is not possible, a trap issued until the LAN communication becomes possible is detected. The trap is saved to a local buffer in the agent, and when the LAN communication is detected, the trap saved in the local buffer is transmitted to the manager.
[0093]
Thus, when LAN communication is not possible, the agent can continue to transmit traps to the manager without knowing that, and it is possible to prevent traps from being lost, thereby minimizing the amount of traps lost. This has the effect that it can be performed. In addition, since the trap issued when LAN communication is disabled is transmitted to the manager as soon as LAN communication is enabled, there is an effect that "a trap is issued but does not reach the manager due to LAN communication being disabled" does not occur.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration example of a network management system using an SNMP agent having a LAN monitoring function according to the present invention.
FIG. 2 is a block diagram showing a configuration of an SNMP agent having a LAN monitoring function according to the first embodiment of the present invention.
FIG. 3 is a block diagram showing a detailed configuration of a trap processing unit in an SNMP agent having a LAN monitoring function according to the first embodiment of the present invention.
FIG. 4 is a flowchart illustrating an operation of an SNMP agent having a LAN monitoring function according to the first embodiment of the present invention.
FIG. 5 is a flowchart illustrating an operation of an SNMP agent having a LAN monitoring function according to the first embodiment of the present invention.
FIG. 6 is a flowchart illustrating an operation of an SNMP agent having a LAN monitoring function according to the first embodiment of the present invention.
FIG. 7 is a flowchart illustrating an operation of an SNMP agent having a LAN monitoring function according to the first embodiment of the present invention.
FIG. 8 is a flowchart illustrating an operation of an SNMP agent having a LAN monitoring function according to the first embodiment of the present invention.
FIG. 9 is a flowchart illustrating an operation of an SNMP agent having a LAN monitoring function according to the first embodiment of the present invention.
FIG. 10 is a flowchart illustrating an operation of an SNMP agent having a LAN monitoring function according to the first embodiment of the present invention.
FIG. 11 is a block diagram showing a specific example of a network management system using an SNMP agent having a LAN monitoring function according to the present invention.
FIG. 12 is a sequence chart illustrating a specific operation of the SNMP agent having a LAN monitoring function according to the first embodiment of the present invention.
FIG. 13 is a block diagram illustrating a detailed configuration of a trap processing unit in an SNMP agent having a LAN monitoring function according to a second embodiment of the present invention.
FIG. 14 is a flowchart illustrating an operation of an SNMP agent having a LAN monitoring function according to the second embodiment of the present invention.
FIG. 15 is a flowchart illustrating an operation of an SNMP agent having a LAN monitoring function according to the second embodiment of the present invention.
FIG. 16 is a flowchart illustrating an operation of an SNMP agent having a LAN monitoring function according to the second embodiment of the present invention.
FIG. 17 is a flowchart illustrating an operation of an SNMP agent having a LAN monitoring function according to the second embodiment of the present invention.
FIG. 18 is a sequence chart illustrating a specific operation of an SNMP agent having a LAN monitoring function according to the second embodiment of the present invention.
[Explanation of symbols]
1 agent
2 Manager
3 LAN
4 Hub
11 LAN monitoring control unit
12 Trap issuing unit
13 Trap processing unit
14 Local buffer
131 LAN check / evacuation trap transmitter
132 LAN communication check unit
133 evacuation trap transmission unit
134 Trap control unit
135 trap evacuation unit
136 Trap transmitter
137 LAN status flag
138 LAN communication disabled detection time holding unit

Claims (8)

An SNMP agent having a LAN monitoring function, which is a communication device connected to a communication device serving as a manager via a LAN using SNMP and transmitting / receiving management information to / from the manager via the LAN,
A trap issuing unit that issues the management information including information on an event or a failure that has occurred in the SNMP agent as an optional trap;
A local buffer which is a place to temporarily save the trap issued by the trap issuing means,
LAN communication checking means for checking whether communication with the manager is possible through the LAN,
Trap transmitting means for transmitting a trap issued by the trap issuing means to the manager when the LAN communication checking means detects that communication by the LAN is possible;
Trap saving means for temporarily saving the trap issued by the trap issuing means to the local buffer when the LAN communication checking means detects that communication by the LAN is impossible;
Evacuation trap transmission for transmitting the trap saved in the local buffer to the manager via the trap transmission means when the LAN communication check means detects that the communication by the LAN is enabled again. And an SNMP agent. The LAN communication check means transmits a test packet to the manager when checking whether or not communication with the LAN is possible, and determines whether or not communication with the LAN is possible based on a reply status of the test packet from the manager. The SNMP agent according to claim 1, wherein the SNMP agent determines: The LAN communication checking means, after transmitting the test packet to the manager, waits for reception of the test packet from the manager until a time-out period, and when the time-out period has elapsed, The SNMP agent according to claim 2, wherein the SNMP agent determines that communication via the LAN is impossible. 4. The SNMP agent according to claim 1, wherein the LAN communication check unit checks whether communication via the LAN is possible at a fixed cycle. 5. The trap saving unit creates a command line for trap transmission based on the trap issued by the trap issuing unit, and saves the created command line for trap transmission to the local buffer as the trap.
5. The trap save transmission unit according to claim 1, wherein the trap transmission command line saved in the local buffer is transmitted as the trap to the manager via the trap transmission unit. 6. The SNMP agent according to the item. When the LAN communication checking unit detects that the communication by the LAN is not possible, the trap evacuation unit is configured to continue until the LAN communication checking unit detects that the communication by the LAN is enabled again. 6. The SNMP agent according to claim 1, wherein a trap issued by said trap issuing unit is temporarily saved in said local buffer. 7. The SNMP agent according to claim 6, wherein when the capacity of the local buffer becomes full due to the trap, the trap evacuation unit writes a new trap by overwriting the oldest trap sequentially. 8. The SNMP according to claim 6, wherein the evacuation trap transmitting unit reads out traps saved in the local buffer in order from the oldest one and transmits the traps to the manager via the trap transmission unit. 9. Agent.

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