Method for detecting line state of ip network and ip communication device

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a technique for detecting a line state between IP communication devices connected to an IP network such as the Internet or IP-VPN (Internet Protocol-Virtual Path Network).

【0002】

[Conventional technology]

IP communication devices such as Internet terminals often use TCP / IP (Transmission Control Protocol / Internet Protocol) to establish a call with the other device. Therefore, even if congestion occurs in the IP network and the line delay is large due to this, it is possible to establish a link by the retransmission control / flow control function of TCP / IP.

【0003】

[Problems to be Solved by the Invention]

In recent years, a system for performing telephone communication and fax communication using an IP network such as a VoIP (Voice over IP) telephone system has been proposed. By the way, real-time performance is required for telephone communication and fax communication. Therefore, if a line delay occurs due to IP network congestion or the like, voice interruption or fax communication error may occur even if the link establishment is maintained.

【0004】

The present invention has been made in view of the above circumstances, and an object of the present invention is to realize communication requiring real-time performance such as telephone communication and fax communication by using an IP network after the link is established. The purpose is to reduce the possibility of voice interruptions and fax communication errors.

【0005】

[Means for solving problems]

In order to solve the above problems, in the present invention, ICMP (Internet Control Message Protocol) echo request (commonly known as PING) and echo response are periodically exchanged between IP communication devices, and one IP communication device is the other. The time (response time) from sending an echo request to the IP communication device of the above to the arrival of the echo response from the other IP communication device to one IP communication device is measured. Then, according to this measurement result (line status between IP communication devices), control of blocking / unblocking of the corresponding line, alarm notification of the line status to the management terminal, etc., and SNMP (Simple Network Management Protocol) Use TRAP to notify the network monitoring device of the line status.

【0006】

According to the present invention, it is possible to periodically monitor the line state between IP communication devices by the above configuration. Then, if there is a line failure or the line delay is large, the use of the line is regulated or used by blocking the line or notifying an appropriate device to that effect. It is possible to call attention to, or to switch to a backup line. As a result, when communication that requires real-time performance is realized by using an IP network, the possibility that an error or the like occurs after the link is established can be reduced.

【0007】

In the present invention, most of the IP communication devices equipped with TCP / IP support the echo request / echo response of ICMP used for monitoring the line status between IP communication devices. That is, even if the IP communication device of the communication partner is made by another manufacturer or another model, the line status monitoring between the IP communication devices according to the present invention is possible.

【0008】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described.

【0009】

FIG. 1 is a schematic diagram of an IP communication system to which one embodiment of the present invention is applied.

【0010】

In FIG. 1, reference numeral 30 is a PBX (Private Branch Exchange) or voice, fax terminal (hereinafter referred to as PBX / terminal), reference numeral 40 is a router, and reference numeral 10 is a PBX / terminal 30 via a router 40. It is an IP communication device that connects to 60. Reference numeral 20 is a management terminal, and reference numeral 50 is a network monitoring device.

【0011】

The IP communication device 10 establishes a call with a communication partner (IP communication device 10) via the IP network 60, for example, by performing a VoIP call control procedure specified in H.323 of ITUT. Then, communication signals such as voice signals and fax signals are transmitted and received via this call. That is, the communication signal sent from the PBX / terminal 30 is packetized and transmitted to the communication partner via the IP network 60. In addition, a communication signal is extracted from a packet received from a communication partner via the IP network 60 and transmitted to the PBX / terminal 30.

【0012】

Further, the IP communication device 10 polls another IP communication device 10 connected to the IP network 60 by using an echo request of ICMP (Internet Control Message Protocol). Then, by measuring the response time of the echo response from the communication partner (IP communication device 10), the line state (failure and delay state) with the communication partner is monitored. When the line condition with the communication partner is in a state of a large failure or a large delay, the IP communication device 10 executes at least one of the following control processes. That is, the call to the communication partner is restricted, and the line with the communication partner is blocked. An alarm is notified of the line status (failure or delay) to the management terminal 20 connected to the own device or the display unit provided in the own device. Notify the network monitoring device 50 of the line status using TRAP of SNMP (Simple Network Management Protocol).

【0013】

Further, the IP communication device 10 releases the line condition between the communication partner and the communication partner if the line is blocked when the line condition with the communication partner recovers from a failure or a state with a large delay. In addition, the line status (recovery) is notified as an alarm to the management terminal 20 connected to the own device or the display unit of the own device, and the line status is notified to the network monitoring device 50 using SNMP TRAP. ..

【0014】

In addition, when the line with all other IP communication devices 10 connected to the IP network 60 is blocked, the IP communication device 10 is connected to its own device by, for example, making the signal line to the PBX / terminal 30 busy. Block the connection with the PBX / terminal 30. Here, when the PBX / terminal (A) 30 connected to the plurality of IP communication devices A and B (10) detects that the connection with the IP communication device (A) 10 is blocked, for example, the PBX / terminal (A) 30 is IP for communication. It is also possible to switch to use the backup line (detour route) via the communication device (B) 10.

【0015】

FIG. 2 is a diagram showing a route of an ICMP echo request packet / echo response packet in the IP communication system of the present embodiment. Here, the route of the ICMP echo request packet / echo response packet performed by the IP communication device (A) 10 to monitor the line status with the IP communication device (C) 10 is shown.

【0016】

As shown in the figure, the IP communication device (A) 10 periodically creates an ICMP echo request packet destined for the IP communication device C (10) and sends it to the IP network 60 side. This echo request packet reaches the IP communication device (C) 10 via the router (A) 40, the IP network 60, and the router (C) 40. In response to this, the IP communication device (C) 10 creates an echo response packet for this echo request packet and sends it to the IP network 60 side. This echo response packet reaches the IP communication device (A) 10 via the router (C) 40, the IP network 60, and the router (A) 40. The time from when the IP communication device (A) 10 transmits the echo request packet to the IP communication device (C) 10 until the echo response packet for the echo request packet is sent from the IP communication device C (10). Measure (response time). Then, according to this result, the IP communication device (A) 10 performs KEEP-ALIVE (communication confirmation) and line delay detection with the IP communication device (C) 10.

【0017】

FIG. 3 is a diagram showing the KEEP-ALIVE of the echo request packet / echo response packet shown in FIG. 2 and the response time for detecting the line delay. As shown in the figure, the response time T (ms) is the transmission time T1 (ms) of the echo request packet from the IP communication device (A) 10 to the IP communication device (C) 10 and the IP communication device of the echo response packet ( It is the time obtained by adding the transmission time T2 (ms) from C) 10 to the IP communication device (A) 10. Therefore, the response time T (ms) also includes the delay time in the router 40 and the like. Therefore, as described above, the IP communication device (A) 10 transmits the echo request packet to the IP communication device (C) 10, and then the echo response packet for the echo request packet is sent from the IP communication device (C) 10. The response time is detected by measuring the time until it is sent.

【0018】

FIG. 4 is a diagram showing the relationship between the polling interval and the line state (presence or absence of failure) in the IP communication system of the present embodiment. Here, in FIG. 1, the polling interval of the ICMP echo request packet performed by the IP communication device (A) 10 to monitor the line status (presence or absence of failure) with the IP communication device (C) 10 is shown. There is.

【0019】

As shown in the figure, when the response time of the echo request packet / echo response packet exchanged with the IP communication device C (10) is within the first predetermined timeout time of the IP communication device (A) 10 ( T711), the polling interval shall be the first polling interval. If the echo response packet does not arrive even after the first predetermined timeout time (T711), polling is performed at a second polling interval shorter than the first polling interval. Then, if the echo response packet does not come even after the second predetermined timeout time (T712) shorter than the first predetermined timeout time (T711), the line with the IP communication device (C) 10 is connected. Judge that an obstacle such as a disconnection has occurred. After that, polling is continued at the second polling interval, and when the response is within the second predetermined timeout time for a predetermined number of times in a row, it is determined that the failure occurring in the line has been resolved, and polling is performed. Return the interval to the first polling interval.

【0020】

FIG. 5 is a diagram showing the relationship between the polling interval and the line state (presence or absence of delay) in the IP communication system of the present embodiment. Here, in FIG. 1, the polling interval of the ICMP echo request packet performed by the IP communication device (A) 10 to monitor the line status (presence or absence of delay) with the IP communication device (C) 10 is shown. There is.

【0021】

As shown in the figure, the IP communication device (A) 10 polls the IP communication device (C) 10 at the first polling interval. Then, when the response time of the echo request packet / echo response packet exceeds the predetermined reference time (however, shorter than the timeout time) for a predetermined number of consecutive times (T713), the connection with the IP communication device (C) 10 is performed. Judge that there is a large delay in the line. Then, when the response is within the reference time for a predetermined number of times in succession, it is determined that the large delay occurring in the line has been eliminated.

【0022】

The polling interval, timeout time, reference time, number of continuous detections when determining that the line status is failure / delay, and continuous detection when determining that the line status has recovered from the failure / delay are described above. The number of times can be changed by the set value of the IP communication device 10.

【0023】

FIG. 6 is a schematic view of the IP communication device 10.

【0024】

Here, the LAN interface (IF) unit 101 controls frame transmission / reception with the router 40 connected via the LAN.

【0025】

The IP processing unit 102 controls the transmission and reception of IP packets with the LAN interface unit 102, the ICMP control unit 103, the call control unit 108, the SNMP agent 107, and the RTP (Real-time Transfer Protocol) control 109.

【0026】

The ICMP control unit 103 performs an ICMP echo request packet generation / transmission process and an ICMP echo response packet reception / analysis process for the ICMP control unit 103. In addition, the reception / analysis process of the ICMP echo request packet and the generation / transmission process of the ICMP echo response packet for the receive / analysis process are performed.

【0027】

The monitoring control unit 104 measures the response time for each communication partner based on the processing result by the ICMP control unit 103. Then, the line state with each communication partner is determined according to the measurement result, and the call control unit 108, the SNMP agent 107, and the alarm notification unit 106 are controlled. Specifically, the call control unit 108 is instructed to set the line blockage / release. In addition, the alarm notification unit 106 and the SNMP agent 107 are instructed to notify the line status.

【0028】

The PBX / terminal interface (IF) unit 105 controls the transmission and reception of call signals and control signals with the PBX / terminal 30. For example, when a 4-wire SS / SR / OD interface is adopted for connection with the PBX / terminal 30, the PBX / terminal interface unit 105 notifies the call control unit 108 of the status of the SS signal line and calls. The state of the SR signal line is controlled according to the instruction of the control unit 108. In addition, the call signal sent from the RTP control unit 109 is sent to the telephone line, and the call signal received from the telephone line is passed to the RTP control unit 109.

【0029】

The alarm notification unit 106 notifies the management terminal 20 of the line status and the like in accordance with the instruction from the monitoring control unit 104. Alternatively, the line status or the like is displayed on a display unit (not shown) or the like provided in the own device.

【0030】

The SNMP agent 107 transmits TRAP to the SNMP manager (network monitoring device 50 in FIG. 1) in accordance with the instruction from the monitoring control unit 104. As a result, the line status and the like are notified.

【0031】

The call control unit 108 establishes a call with a communication partner (IP communication device 10) via the IP network 60, for example, by performing a VoIP call control procedure specified in H.323 of ITUT. Further, the call control unit 108 controls the PBX / terminal interface unit 105 in accordance with the instruction from the monitoring control unit 104 to set the blockage / release of the line with the designated communication partner. Specifically, a busy tone is returned to the PBX / terminal 30 in response to a call from the PBX / terminal 30 to the communication partner set to be blocked. If the blockage is set for all communication partners, all the lines to and from the PBX / terminal 30 are set to the busy state.

【0032】

The RTP control unit 109 packetizes the voice signal received from the telephone line of the PBX / terminal interface unit 105 according to the RTP and sends it to the IP processing unit 102. Further, according to RTP, an audio signal is extracted from the IP packet received from the IP processing unit 102 and transmitted to the PBX / terminal interface unit 105.

【0033】

Next, the operation of the monitoring control unit 104 of the IP communication device 10 will be described in more detail. In the present embodiment, the operation of the monitoring control unit 104 is an individual line control process individually performed for each of the other IP communication devices 10 connected to the IP network 60, and the IP communication device 10 for the PBX / terminal 30. Can be divided into all-line control processing to notify that is in an unusable state.

【0034】

First, the individual line control process will be described.

【0035】

FIG. 7 is a flow chart for explaining the individual line control process in the monitoring control unit 104 of the IP communication device 10. This flow is performed for each of the other IP communication devices 10 connected to the IP network 60. It is assumed that the destinations and the like of each IP communication device 10 to be a communication partner are registered in advance.

【0036】

First, the monitoring control unit 104 instructs the ICMP control unit 103 to make an echo request to the IP communication device 10 to be monitored. In response to this, the ICMP control unit 103 creates an ICMP echo request packet destined for the IP communication device 10 to be monitored. This request packet is sent to the IP network 60 via the IP processing unit 102 and the LAN interface unit 101 (S7001).

【0037】

Next, in the monitoring control unit 104, the echo response packet from the IP communication device 10 to be monitored for the echo request packet is sent to the ICMP control unit 103 via the LAN interface unit 101 and the IP processing unit 102 within a predetermined timeout period. Wait for it to arrive (S7002, S7003).

【0038】

Then, if it arrives within the predetermined timeout time (Yes in S7003), whether or not the response time from sending the echo request packet to receiving the echo response packet for the echo request packet is within the predetermined reference time. Investigate (S7004). If it is within the reference time and the current line status with the monitored IP communication device 10 is normal (No for both S7005 and S7006), wait for the first polling interval to elapse (No). S7007), return to S7001, and continue the echo request to the IP communication device 10 to be monitored.

【0039】

Further, the monitoring control unit 104 echoes when the echo response packet from the monitored IP communication device 10 for the echo request packet sent by the S7001 does not reach the ICMP control unit 103 within the timeout time (No in the S7002). Check how many times the response packet does not arrive within the timeout time in a row (number of consecutive TO detections) (S7008).

【0040】

Then, if the number of continuous TO detections is within the predetermined reference number S1, wait for the second polling time shorter than the first polling interval to elapse (S7009), return to S7001, and perform IP communication to be monitored. Continue monitoring for device 10.

【0041】

On the other hand, when the number of continuous TO detections exceeds the reference number S1, the monitoring control unit 104 determines that a failure has occurred in the line with the IP communication device 10 to be monitored, and monitors the call control unit 108. Instruct to restrict calls to the target IP communication device 10. As a result, the call control unit 108 responds to the call to the monitored IP communication device 10 issued by the PBX / terminal 30, for example, by returning a busy tone to the PBX / terminal 30 and performing busy processing to perform the monitoring target. Block the line with the IP communication device 10 (S7010). Further, the monitoring control unit 104 tells the alarm notification unit 106 and the SNMP agent 107 that the line with the monitored IP communication device 10 is in a failed state and / or the line with the monitored IP communication device 10. Instructs notification that is blocked. As a result, the alarm notification unit 106 indicates that the line with the IP communication device 10 to be monitored is in a faulty state in the management device 20 or the display unit (not shown), and / or the IP communication device 10 to be monitored. Notify that the line with is blocked. In addition, the SNMP agent 107 has a TRAP that causes the line between its own device and the IP communication device 10 to be monitored to fail, and / or the line between its own device and the IP communication device 10 to be monitored is blocked. Notify that (S7011). Then, the monitoring control unit 104 waits for the second polling time to elapse (S7009), returns to S7001, and continues monitoring the IP communication device 10 to be monitored.

【0042】

Further, the monitoring control unit 104 indicates that the echo response packet from the monitored IP communication device 10 for the echo request packet sent by the S7001 arrives within the timeout time, but the response time exceeds the reference time ( S7004 No), check how many times the response time exceeds the reference time in a row (number of consecutive reference over detections) (S7012).

【0043】

Then, if the number of continuous reference over detections is within the predetermined reference number S2, it waits for the first polling interval to elapse (S7007), returns to S7001, and continues the echo request to the monitored IP communication device 10.

【0044】

On the other hand, when the number of continuous reference over detections exceeds the reference number S2, the monitoring control unit 104 determines that a large delay has occurred in the line with the monitored IP communication device 10, and determines that the call control unit 108 has a large delay. , Instruct to restrict calls to the monitored IP communication device 10. As a result, the call control unit 108 responds to the call to the monitored IP communication device 10 issued by the PBX / terminal 30, for example, by returning a busy tone to the PBX / terminal 30 and performing busy processing to perform the monitoring target. Block the line with the IP communication device 10 (S7013). Further, the monitoring control unit 104 tells the alarm notification unit 106 and the SNMP agent 107 that the line with the monitored IP communication device 10 is in a delayed state and / or the line with the monitored IP communication device 10. Instructs notification that is blocked. As a result, the alarm notification unit 106 indicates that the line with the IP communication device 10 to be monitored is in a delayed state in the management device 20 or the display unit (not shown), and / or the IP communication device 10 to be monitored. Notify that the line with is blocked. In addition, the SNMP agent 107 has a delay in the line between its own device and the IP communication device 10 to be monitored by TRAP, and / or the line between its own device and the IP communication device 10 to be monitored is blocked. Notify that (S7014). Then, the monitoring control unit 104 waits for the first polling time to elapse (S7007), returns to S7001, and continues monitoring the IP communication device 10 to be monitored.

【0045】

Further, the monitoring control unit 104 determines that the echo response packet from the monitored IP communication device 10 for the echo request packet sent by the S7001 arrives within the timeout time and the response time is within the reference time. If it is determined that the current line status with the monitored IP communication device 10 is a failure status (Yes in S7005), the echo response packet has arrived within the timeout period and its Check how many times the response time is within the reference time in a row (number of consecutive clear detections) (S7015).

【0046】

Then, if the number of continuous clear detections is within the predetermined reference number S3, it waits for the second polling interval to elapse (S7009), returns to S7001, and continues the echo request to the monitored IP communication device 10.

【0047】

On the other hand, when the number of continuous clear detections exceeds the reference number S3, the monitoring control unit 104 determines that the failure occurring in the line with the monitored IP communication device 10 has been resolved, and the call control unit 108 determines. Instruct the IP communication device 10 to be monitored to lift the restriction on making calls. As a result, the call control unit 108 performs normal processing in accordance with the call control procedure for the call to the monitored IP communication device 10 issued from the PBX / terminal 30, and thereby performs normal processing with the monitored IP communication device 10. Unblock the line (S7016). In addition, the monitoring control unit 104 tells the alarm notification unit 106 and the SNMP agent 107 that the line failure with the monitored IP communication device 10 has been resolved and / or that the line with the monitored IP communication device 10 has been resolved. Instruct to notify that the blockage has been released. As a result, the alarm notification unit 106 resolves the line failure with the monitored IP communication device 10 in the management device 20 and the display unit (not shown), and / or with the monitored IP communication device 10. Notifies that the line is unblocked. In addition, the SNMP agent 107 resolved the line failure between its own device and the monitored IP communication device 10 by TRAP, and / or released the line between its own device and the monitored IP communication device 10. Notify that it has been done (S7017). Then, the monitoring control unit 104 waits for the first polling time to elapse (S7007), returns to S7001, and continues monitoring the IP communication device 10 to be monitored.

【0048】

Further, the monitoring control unit 104 determines that the echo response packet from the monitored IP communication device 10 for the echo request packet sent by the S7001 arrives within the timeout time and the response time is within the reference time. If it is determined that the current line status with the monitored IP communication device 10 is in the delayed status (Yes in S7006), the echo response packet has arrived within the timeout period, and the echo response packet has arrived within the timeout period. Check how many times the response time is within the reference time in succession (number of consecutive clear detections) (S7018).

【0049】

Then, if the number of continuous clear detections is within the predetermined reference number S4, the process returns to S7001 after waiting for the first polling interval to elapse (S7007), and the echo request to the monitored IP communication device 10 is continued.

【0050】

On the other hand, when the number of continuous clear detections exceeds the reference number S4, the monitoring control unit 104 determines that the delay occurring in the line with the monitored IP communication device 10 has been eliminated, and the call control unit 108 determines that the delay has been eliminated. Instruct the IP communication device 10 to be monitored to lift the restriction on making calls. As a result, the call control unit 108 performs normal processing in accordance with the call control procedure for the call to the monitored IP communication device 10 issued from the PBX / terminal 30, and thereby performs normal processing with the monitored IP communication device 10. Unblock the line (S7016). In addition, the monitoring control unit 104 tells the alarm notification unit 106 and the SNMP agent 107 that the line delay with the monitored IP communication device 10 has been resolved and / or that the line with the monitored IP communication device 10 is connected. Instruct to notify that the blockage has been released. As a result, the alarm notification unit 106 eliminates the line delay with the monitored IP communication device 10 in the management device 20 and the display unit (not shown), and / or with the monitored IP communication device 10. Notifies that the line is unblocked. In addition, the SNMP agent 107 has resolved the line delay between its own device and the monitored IP communication device 10 by TRAP, and / or released the line between its own device and the monitored IP communication device 10. Notify that it has been done (S7017). Then, the monitoring control unit 104 waits for the first polling time to elapse (S7007), returns to S7001, and continues monitoring the IP communication device 10 to be monitored.

【0051】

Next, the whole line control process will be described.

【0052】

FIG. 8 is a flow chart for explaining the all-line control process in the monitoring control unit 104 of the IP communication device 10.

【0053】

First, when the lines with each of all the IP communication devices 10 (the IP communication devices 10 of the communication partner) connected via the IP network 60 are set to be blocked (Yes in S8001), the monitoring control unit 104 has all the lines. If the batch blockage is not set (No in S8002), the call control unit 108 is instructed to set the batch blockage for all lines. As a result, the call control unit 108 controls the PBX / terminal interface unit 105, sets the signal line with the PBX / terminal 30 to a busy state, and does not accept any calls from the PBX / terminal 30. (S8003). In addition, the monitoring control unit 104 instructs the alarm notification unit 106 and the SNMP agent 107 to notify that all lines are collectively blocked. As a result, the alarm notification unit 106 notifies the management device 20, a display unit (not shown), and the like that all lines are collectively blocked. In addition, the SNMP agent 107 notifies that all the lines of its own device are collectively blocked by TRAP (S8004).

【0054】

Further, when the line with at least one IP communication device 10 connected via the IP network 60 is not set to be blocked (No in S8001), the monitoring control unit 104 is set to block all lines at once. (Yes in S8005), instruct the call control unit 108 to release the batch blockage of all lines. As a result, the call control unit 108 controls the PBX / terminal interface unit 105 to eliminate the busy state of the signal line with the PBX / terminal 30 so that the call from the PBX / terminal 30 can be accepted. (S8006). In addition, the monitoring control unit 104 instructs the alarm notification unit 106 and the SNMP agent 107 to notify that the batch blockage of all lines has been released. As a result, the alarm notification unit 106 notifies the management device 20, a display unit (not shown), and the like that the batch blockage of all lines has been released. In addition, the SNMP agent 107 notifies that the batch blockage of all lines of its own device has been released by TRAP (S8007).

【0055】

Finally, the difference in the blockage settings described with reference to FIGS. 7 and 8 will be described. FIG. 9 is a diagram for explaining the difference between the total line blockage (blockage according to FIG. 8) and the individual line blockage (blockage according to FIG. 7). As shown in the figure, when all lines are blocked, the signal line with the PBX / terminal 30 is made busy so that no calls from the PBX / terminal 30 are accepted (in this case, from the IP network 60). We do not accept any incoming calls). On the other hand, in the case of individual line blockage, calls to a specific IP communication device 10 are only restricted, and calls to other IP communication devices 10 and incoming calls from the IP network 60 can be processed as usual.

【0056】

The embodiment of the present invention has been described above.

【0057】

According to this embodiment, the line status between the IP communication devices 10 can be monitored. Then, when the line delay is large or a line failure occurs, the corresponding line is blocked. In addition, the management terminal 20 and the network monitoring device 50 are notified to that effect. As a result, it is possible to regulate the use of the corresponding line, call attention to the use, or switch to the backup line. As a result, when communication that requires real-time performance is realized by using an IP network, the possibility that an error or the like occurs after the link is established can be reduced.

【0058】

The present invention is not limited to the above embodiment, and many modifications can be made within the scope of the gist thereof.

【0059】

For example, in the above embodiment, not all IP communication devices 10 connected to the IP network 60 need to have the configuration shown in FIG. It is sufficient that any one of the pair of IP communication devices 10 that perform IP communication has the configuration shown in FIG. The other may be a normal IP communication device equipped with TCP / IP. Since most of the IP communication devices equipped with TCP / IP support the echo request / echo response of ICMP, the present invention even if the IP communication device 10 of the communication partner is made by another manufacturer or another model. It is possible to monitor the line status by.

【0060】

Further, in the above embodiment, the IP communication device 10 may be constructed as a dedicated device using an ASIC (Application Specific Integrated Circuit) or a DSP (Digital Signal Processor), or may be constructed on a general-purpose computer system. It may be built as software. Here, a program for constructing the IP communication device 10 by software on a general-purpose computer system may be stored in a recording medium such as a CD-ROM and provided to the computer system. Alternatively, it may be provided to the computer system via the network.

【0061】

[Effect of the invention]

As described above, according to the present invention, when communication requiring lutime is realized by using an IP network, it is possible to reduce the possibility that voice interruption or fax communication error occurs after the link is established.

[Simple explanation of drawings]

[Figure 1]

It is the schematic of the IP communication system to which one Embodiment of this invention is applied.

[Figure 2]

It is a figure which shows the route of the echo request packet / echo response packet of ICMP in the IP communication system of this embodiment.

[Fig. 3]

It is a figure which shows the KEEP-ALIVE of the echo request packet / echo response packet shown in FIG. 2 and the response time for line delay detection.

[Fig. 4]

It is a figure which shows the relationship between the polling interval and the line state (presence or absence of failure) in the IP communication system of this embodiment.

[Fig. 5]

It is a figure which shows the relationship between the polling interval and the line state (presence or absence of delay) in the IP communication system of this embodiment.

[Fig. 6]

It is the schematic of the IP communication apparatus 10 shown in FIG.

[Fig. 7]

It is a flow diagram for demonstrating the individual line control processing in the monitoring control unit 104 of the IP communication apparatus 10.

[Fig. 8]

It is a flow diagram for demonstrating the whole line control processing in the monitoring control unit 104 of the IP communication apparatus 10.

[Fig. 9]

It is a figure for demonstrating the difference between the blockage of all lines (blockage according to FIG. 8) and blockage of individual lines (blockage according to FIG. 7).

[Explanation of symbols]

10 ... IP communication device 20 ... Management terminal 30 ... PBX / voice terminal 40 ... router 50 ... network monitoring device 60 ... IP network 101 ... LAN interface section 102 ... IP processing unit 103 ... ICMP control unit 104 ... Monitoring and control unit 105 ... PBX / terminal interface 106 ... Alarm notification section 107 ... SNMP agent section 108 ... Call control unit 109 ... RTP control unit