JPH09289509A - System and method for network management - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the network management system wherein the load of a network monitoring process on a center is small and the occurrence of abnormality in each terminal can be detected directly. SOLUTION: A service request part 113 of each terminal 110 sends a message showing normal operation to the center 150 at constant time intervals. Each time a service process part 151 of the center 150 receives a message from each terminal 110, the reception of the message is recorded in a message log storage part 153 by terminals 10. A message check part 155 checks the message log storage part 153 at constant time intervals and informs a service processor 51 of the terminal number of a terminal 110 which does not have received the message among the terminals 110 to which the line is not connected. After the message log storage part 153 is checked, the storage contents of the message log storage part 153 are cleared at each time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital CATV (Community Antenna) including a plurality of terminals and a center.
In television networks, the present invention relates to a network management system that detects the occurrence of an abnormality in the network and performs processing corresponding to the detected abnormality.

[0002]

2. Description of the Related Art A CATV network monitoring system (Japanese Patent Laid-Open No. 6-46422) will be described below as a conventional example. FIG. 27 is a block diagram showing the configuration of a conventional CATV network monitoring device 800.

The CATV network monitoring device 800 is
It is equipped in the center that constitutes the CATV network,
Monitoring polling timer 801, storage device 802, communication control device 803, RF-MODEM 804a, 804
b, 804c, status monitor units 805a, 8
05b, 805c, an interrupt timer 806, and a control processing unit 807.

The monitoring polling timer 801 counts a certain elapsed time. The storage device 802 has a storage area for storing the addresses of the status monitor units 805a, 805b, 805c. In the communication control device 803, the CATV network monitoring device 800 is R
Status monitor units 805a, 805b, 8 via F-MODEMs 804a, 804b, 804c.
It controls communication when polling 05c.

RF-MODEM 804a, 804b, 8
04c converts a digital signal into an analog signal. Status monitor units 805a, 805b, 805c
Displays the status of terminals connected to
The V network monitoring device 800 is notified. The interrupt timer 806 counts a certain elapsed time independently of the monitoring polling timer 801.

The control processing device 807 controls the overall operation of the CATV network monitoring device 800. Further, the following processing is performed. The control processing device 807 performs polling at the timing of the monitoring polling timer 801. When the response of a certain status monitor unit 805 cannot be obtained, the address of the status monitor unit 805 is stored in the storage device 802. Control processor 8
07, at the timing of the interrupt timer 806, the retransmission request is made to the status unit 805 of the address stored in the storage device 802, and the failure determination is performed based on this result.

As described above, in the CATV network monitoring device 800, the center side performs all the processing for monitoring the network. That is, the CATV network monitoring device 800 polls all status monitor units 805, and polls the status monitor units 805 that have not responded again.

[0008]

However, this conventional technique has a problem that the load on the center side for monitoring the network becomes very large. Also, CA
The TV network monitoring device 800, at regular time intervals,
Since the polling is sequentially performed, it takes a considerable time to check all the status monitor units 805.

Further, the CATV network monitoring device 8
00 is a status monitor unit 805 which is a repeater
Since it checks the response of, the abnormality of the terminal under the repeater cannot be directly understood. That is, when a plurality of terminals are connected to each status monitor unit 805, there is a problem in that it is not possible to know which terminal has an abnormality.

A first object of the present invention is to provide a network management system that reduces the load on the center side and directly detects the occurrence of an abnormality. A second object of the present invention is to provide a network management system that performs more appropriate processing for detected abnormalities.

[0011]

A network management system of the present invention is a network management system comprising a plurality of terminals provided in a digital CATV network and a center, and each of the terminals is normally receiving. A message indicating that the message is transmitted to the center at a first time interval, and the center transmits the ID of the terminal to which the line is connected to the center.
The line connection list storage means for storing the line connection list, the message reception means for receiving the message from each terminal, the message reception storage means for storing the reception of the message for each terminal, and the line An investigating means for investigating whether or not the reception of a message from each terminal listed in the connection list is stored in the message receiving / storing means at a second time interval longer than the first time interval, and an investigating means. Clearing means for clearing the contents stored in the message receiving and storing means after the investigation by
As a result of the investigation, an abnormality determination unit that determines that an abnormality has occurred is provided for the terminal for which the reception of the message is not stored in the message reception storage unit.

In the network management system of the present invention, the message transmitting means of each terminal transmits a message indicating that it is being normally received to the center at a first time interval. The line connection list storage means of the center stores the I of the terminal connected to the center.
The line connection list in which D is listed is stored. The message receiving means receives a message from each terminal. The message receiving / storing means stores that the message is received for each terminal. The examining means examines whether or not the reception of the message from each terminal listed in the line connection list is stored in the message reception storing means at the second time interval longer than the first time interval. The clearing means clears the stored contents of the message receiving and storing means after the investigation by the investigating means. As a result of the investigation, the abnormality determining means has an action of determining that the terminal for which the message reception storage means does not store the reception of the message has an abnormality.

According to the network management system of the present invention, since each of the terminals transmits a message indicating that it is being normally received to the center at the first time interval, each of the terminals transmits the message. It is possible to determine that an abnormality has occurred in each of the terminals without inquiring the status of each of the terminals, and it is possible to reduce the load on the center side in network management.

Further, since the occurrence of the abnormality in the terminal is determined by the presence or absence of the message received from each of the terminals, it is possible to directly determine with which terminal the abnormality has occurred. At the same time, it is possible to determine an abnormality in the transmission path between the terminal and the center as an abnormality in the terminal.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A network management system 100 according to a first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing the configuration of a network management system 100 according to the first embodiment of the present invention.

The network management system 100 is composed of a center 150, which is a video-on-demand server or a CATV broadcasting station, and a plurality of terminals 110 connected to the center 150 via a dedicated line. The terminal 110 includes a message storage unit 111, a message transmission timer 112, a service request unit 113, an abnormality detection unit 114, a video / audio information reception unit 115, and a service storage unit 116.

The center 150 includes a service processing unit 15
1, terminal number storage unit 152, message log storage unit 15
3, a message reception timer 154, a message check unit 155, a line information storage unit 156, a video / audio information transmission unit 157, a video / audio information storage unit 158, a video / audio information extraction unit 159, and a usage status storage unit 160. The message storage unit 111 stores a terminal number unique to each terminal 110 and a character string that is the content of the message for transmission.

FIG. 2 is an explanatory diagram showing an example of the stored contents of the message storage unit 111. For example, the message storage unit 111 stores the terminal number “0x8ab60a14”,
Message "Service O" indicating that the message is being received normally
In the present embodiment, the fact that the message from the terminal 110 is received by the center 150 indicates that the terminal 110 is receiving normally. Therefore, the transmission content as a message does not necessarily have to be a fixed-length character string of "service OK", and may actually be any character string. It may be data whose size is not fixed or a flag.

The message transmission timer 112 internally temporarily stores a predetermined set time, for example, about 5 minutes, and when the service request unit 113 resets it to "0", the set time is reached. Count up to.
When the set time is counted, the service request unit 113 is instructed to interrupt the message transmission. The setting time of the message transmission timer 112 does not necessarily need to be about 5 minutes, and may be set appropriately according to the setting time of the message reception timer 154 described later.

The service request unit 113 sends a service request to the center 150 according to an input from an input unit (not shown) or the like. However, the service request unit 113
If the line is not connected to the center 150, first, a request to connect the line to the center 150 is transmitted, and after the line is connected by the approval of the center 150,
A service request shall be sent. The transmission content of the service request includes the terminal number of the terminal 110 and the center 150.
Is a process name of a process which is requested to be executed, and a command which specifically instructs the process. It should be noted that a plurality of the service requests are transmitted in response to the processing requesting the center 150 to execute.

The service request unit 113 resets the message transmission timer 112 to "0" every time a service request is transmitted. The service request unit 113 reads the terminal number and the character string that is the message content from the message storage unit 111 according to the interrupt command from the message transmission timer 112, creates a message for transmission, and centralizes the created message for transmission. 150 to reset the message transmission timer 112 to "0".

Further, the service request unit 113 stops the transmission of the above message in response to the abnormality detection signal from the abnormality detection unit 114. For example, the service request unit 113 interrupts the creation of the message for transmission and the transmission of the message for transmission in response to the interrupt instruction from the message transmission timer 112 while the abnormality detection signal is at the H (high) level, and transmits the message. Only "0" reset of the timer 112 is performed. The abnormality detection signal from the abnormality detection unit 114 is L
During the (low) level, the message transmission timer 112
Message generation and transmission according to the interrupt instruction from the message transmission timer, and "0" of the message transmission timer 112.
Perform a reset.

The abnormality detecting section 114 monitors the occurrence of an abnormality inside the terminal 110, and when detecting the occurrence of the abnormality, outputs an abnormality detection signal to the service requesting section 113. The abnormality inside the terminal 110 is, for example, a demodulation error when the video / audio information receiving unit 115 receives the video / audio information, or an error during transmission of the video / audio information (line abnormality,
A decoding error in a reproducing unit (not shown) caused by noise).

The abnormality detecting unit 114 is always connected to the service requesting unit 113 by, for example, a connection line for outputting the abnormality detecting signal, and normally, the abnormality detecting signal is L.
When the abnormality is detected inside the terminal 110, the abnormality detection signal is activated to the H level and output to the service request unit 113. The method of outputting the abnormality detection signal is not necessarily limited to this. For example, the service request unit 113 includes a register that stores a flag, and the abnormality detection unit 114 includes the service request unit 113.
On the other hand, an abnormality detection flag may be output such that "1" indicates abnormality and "0" indicates normality. In this case, the service request unit 113 updates the stored content of the register each time the abnormality detection flag is input from the abnormality detection unit 114.

The video / audio information receiving unit 115 is coded from the center 150 in response to a service request, for example, Q
The video / audio information modulated and transmitted by AM or the like is received and demodulated. It is assumed that the reception frequency of the video / audio information is notified from the service processing unit 151 to the video / audio information receiving unit 115 via the service requesting unit 113 as a response to the service start request. The demodulated video / audio information is output to, for example, a reproduction unit (not shown) inside the terminal 110, decoded there to be separated into video information and audio information, and if necessary, D (digital) / A (analog). ) Is converted, and is output as video and audio from a display, a speaker and the like (not shown).

The service storage unit 116 stores a service request list showing transmission contents corresponding to various service requests. FIG. 3 is an explanatory diagram showing an example of a service request list stored in the service storage unit 116.
As shown in FIG. 3, each service request consists of a terminal number and a command corresponding to each processing name. A parameter is attached to each command. The parameters are
The service name, the file name, the reproduction start time, the reproduction end time, the reproduction time, and the like for which the command is executed are included. The service name is, for example, "shopping" or "video o".
n demand ", etc. Note that among the above parameters,
The reproduction start time, the reproduction end time, the reproduction time, etc. are added as necessary. Further, service interruption and service restart will be described in the second embodiment.

The service processing unit 151 transmits / receives information to / from each terminal 110 such as message reception from each terminal 110, service request reception, and response thereto. Further, the service processing unit 151 gives an instruction to the video / audio information transmitting unit 157 to control the transmission of the video / audio information. Specifically, the service processing unit 151 uses the terminal 11
When the service request from 0 is received, the message reception timer 154 is reset to "0" and the terminal number of the terminal 110 which is the transmission source of the service request is registered in the terminal number list in the terminal number storage unit 152. The terminal number list is for the terminals 1 that are connected to the center 150.
11 is a list of terminal numbers indicating 10. That is, the terminal number list shows the terminals 110 that have been assigned a frequency for receiving the service of the center 150.

Further, the service processing unit 151 searches the usage status storage unit 160 for a service log with a recovery mark "1" from the terminal 110 which is the transmission source of the service request. The service log having a restoration mark of “1” indicates that the line is temporarily released because the terminal 110 has an abnormality while receiving the service.

The corresponding service log is the usage status storage unit 1.
If it is within 60, the service processing unit 151 starts transmission from the service recorded in the service log.
If not, a service log is created from the content of the received service request, and the usage status storage unit 16 is associated with the terminal number.
Store to 0. Then, the service corresponding to the processing content of the service request is provided. Also, each time the processing indicated by the service log is completed, the service log for which the processing is completed is erased.

Further, the service processing section 151 is provided for each terminal 1
When the message from 10 is received, in the log table in the message log storage unit 153, the message content item corresponding to the terminal number of the sender of the message indicates that the character string received as the message or the message has been received. Stores flags, etc. Further, the service processing unit 151 receives the message from the message check unit 155, so that the terminal 1 which has not received the message receives the message.
When the terminal number of 10 is input, the terminal number storage unit 152
The terminal number is deleted from the terminal number list in the table, and the video / audio information transmitting unit 157 is interrupted to stop transmission of the video / audio information for the terminal number. Furthermore, a restoration mark is added to the service log of the terminal number input from the message check unit 155.

Note that, here, the service processing unit 151
Has reset the message reception timer 154 to "0" each time it receives a service request from the terminal 110, but since the message check unit 155 resets the message reception timer 154 to "0" for each check,
The service processing unit 151 may reset the message reception timer 154 to “0” only when the center 150 is activated.

The response of the service processing unit 151 to the service request means all services provided to each terminal 110, and the video / audio information designated by the user's input is transmitted via the video / audio information transmitting unit 157. Not only providing the terminal 110 with the service, but also setting processing of an individual environment such as setting a delivery method for each user by bidirectional communication with the service requesting unit 113, and individual information such as charge account information. Including provision etc.

The terminal number storage section 152 has a storage area for storing a terminal number list, and the terminal number list stores services from the center 150, that is, video / audio information from the video / audio information transmitting section 157. The terminal number of the terminal 110 currently being received is registered by the service processing unit 151. FIG. 4 is an explanatory diagram showing an example of a terminal number list, which is the stored content of the terminal number storage unit 152.

As shown in FIG. 4, the terminal number storage unit 152
The terminal number of the terminal 110 currently receiving the service from the center 150 is registered in the terminal number list of. In the terminal number list of FIG. 4, the terminal number is currently “0”.
x8ab60a14 "," 0x8ab60a15 ","
0x8ab60a16 "," 0x8ab60a1 "
The terminal 110 of 7 "," 0x8ab60a18 ", ...
This indicates that the service from the center 150 is being received.

The message log storage unit 153 has a storage area for storing a log table. In the log table, items corresponding to the terminal number of the terminal 110 of the transmission source are displayed in accordance with a message from each terminal 110. , A character string that is the content of the message is stored. FIG. 5 is an explanatory diagram showing an example of a log table which is the storage content of the message log storage unit 153.

In the log table shown in FIG. 5, all terminal numbers that can be registered are "0x8ab60a14" and "0x8ab6".
0a15 "," 0x8ab60a16 "," 0x8ab "
Areas for storing the message contents are provided corresponding to 60a17 "," 0x8ab60a18 ", ... And terminal numbers" 0x8ab60a14 "," 0x8ab ".
60a15 "," 0x8ab60a17 "and" 0x
It indicates that a character string of "service OK" is stored in each item of the message content corresponding to "8ab60a18". Further, the terminal number "0x8ab60a1"
The item of the message content corresponding to 6 "indicates that a character string is not stored, that is, null.

In the log table as well, the "service O" is not always stored in the area for storing the message contents.
The character string “K” does not have to be stored, a different character string may be stored, and a flag or code indicating that a message has been received from the terminal 110 may be stored. Message reception timer 154 Has a preset set time, for example, a time of about 10 minutes, temporarily stored therein, and when the service processing unit 151 resets "0", counts until the set time is reached. When the count reaches the set time, the message reception timer 154 interrupts the message check unit 155 to check the reception of the message.

The set time of the message reception timer 154 is set longer than the set time of the message transmission timer 112. Moreover, it is preferable that the message transmission timer 112 is set to be slightly longer than twice the set time. However, message transmission timer 1
The shorter the setting time of 12 and the setting time of the message reception timer 154 are, the higher the real-time property regarding the detection of the abnormality in the network becomes, but the larger the load of the center 150 becomes. Therefore,
The set times of the both timers may be appropriately determined depending on which of the load on the center 150 and the real-time property of abnormality detection is emphasized.

When the reception check interruption is received from the message reception timer 154, the message check unit 155 stores the character string "service OK" as the message content in the message log storage unit 153 for each terminal number recorded in the terminal number list. Is temporarily stored,
Or check if it is null. If the message content is null, the terminal number is used as the service processing unit 1.
Output to 51, reset all message contents in the message log storage unit 153 to null, and reset the message reception timer 154 to “0”.

The line information storage unit 156 is currently used by the center 1.
For each terminal 110 receiving the service from 50, the line information list showing the allocation of frequencies for transmitting the video / audio information is stored. FIG. 6 shows the line information storage unit 1.
5 is an explanatory diagram showing an example of a line information list stored in 56. FIG.

As shown in FIG. 6, the line information list includes
All frequencies that can be used by the center 150 for transmitting audiovisual information are listed. Of these frequencies,
Which frequency is currently assigned to which terminal 110 is registered. In the line information list shown in FIG. 6, for example, the center 150 has 500 MHz, 506 MHz and 512 M as the frequencies for transmitting the audiovisual information.
Hz, 518MHz, ..., 500MHz to 6MHz
If it is used in increments, the terminal 110 with the terminal number “0x8ab60a14” is currently assigned to the transmission frequency of 500 MHz, and the terminal 110 with “0x8ab60a15” with respect to 506 MHz is 512M.
It is shown that the terminal 110 of “0x8ab60a17” is assigned to Hz. Also, 518
For MHz, the currently assigned terminal 110
Has been shown to be absent.

The video / audio information transmission unit 157 registers each terminal 110 in the line information list in the line information storage unit 156 according to the instruction of the service processing unit 151, and the video / audio information extracted from the video / audio information storage unit 158. The terminal 1
Send to 10. Specifically, the video / audio information transmitting unit 15
7 refers to the line information storage unit 156 according to the terminal number and the transmission instruction input from the service processing unit 151 in response to the service request, and determines whether or not the destination terminal 110 is registered in the line information list. Find out. If not registered, the terminal number is registered in the null item of the line information list. When it is already registered or when registration is completed, the registered transmission frequency is read. Then
The video / audio information extraction unit 159 is instructed to extract the video / audio information specified by the service processing unit 151. When the video / audio information extraction unit 159 extracts the video / audio information according to the instruction, the extracted video / audio information is transferred to the terminal 11
0 is transmitted at the transmission frequency read from the line information list.

The video / audio information transmitting unit 157 is currently transmitting the video / audio information to the terminal 110 having the terminal number input from the service processing unit 151 when the transmission interruption is interrupted from the service processing unit 151. Check if there is. If it is being transmitted, the terminal 110 of the relevant terminal number
And an audio / voice information extraction unit 15
9 and the transmission of the video / audio information is interrupted. further,
The video / audio information transmission unit 157 deletes the terminal number from the line information list in the line information storage unit 156 so that the frequency registered in the terminal 110 can be allocated to another terminal 110, and the terminal 110 Release the line between and.

The video / audio information storage unit 158 stores each terminal 11
The pre-recorded audiovisual information to be distributed to 0 is stored.
The video / audio information extraction unit 159 includes a video / audio information transmission unit 15
According to the instruction of No. 7, the video / audio information to be distributed to each terminal 110 is extracted from the video / audio information storage unit 158.

The usage status storage unit 160 stores the content of the service request for each terminal 110 stored by the service processing unit 151. FIG. 7 is an explanatory diagram showing an example of a service log stored in the usage status storage unit 160.
As shown in FIG. 7, each terminal 1 is stored in the usage status storage unit 160.
The terminal number of the terminal 110, the service log, the recovery mark, and the status are stored for each processing content requested by the terminal 10. This status represents the current status value of the service for which the status exists. For example, in the case of Play, the elapsed time from the start of reproduction is stored as the status. The elapsed time from the start of reproduction is output from the video / audio information transmitting unit 157 to the service processing unit 151, and the service processing unit 151 causes the usage status storage unit 1 to operate.
60 is written.

The service log indicates which service is currently delivered to each terminal 110. The restoration mark indicates the center 150 and the terminal 11 concerned.
Between 0 and 0, it indicates whether or not the line is connected.
In FIG. 7, the restoration mark is indicated by "0" when the line is connected and by "1" when the line is released.

The procedure of the network management process of the network management system 100 will be described below with reference to FIGS. FIG. 8 is a flowchart showing an example of a procedure of service request transmission processing by the service request unit 113 of the terminal 110. In the terminal 110, the service request unit 113 reads the service request list from the service storage unit 116 (step S801), and displays the selection menu showing the process name on the display screen (step S802). Description of the menu display is omitted because it is a technique widely used in existing systems.

When the user selects a desired service name from the menu screen by operating the remote controller, which is an input unit (not shown), (step S803), the service request unit 113.
Reads the transmission content of the service request from the service storage unit 116 using the selected process name (step S80).
4) Create a service request (step S805).
The transmission content of the service request is the terminal number (for example, 0x8
ab60a14), a process name (for example, service start), and a command.

The service request unit 113 sends the read transmission contents of the service request to the service processing unit 151 on the center 150 side (step S806). FIG.
9 is a flowchart showing an example of a procedure of message transmission processing by the service requesting unit 113 of the terminal 110. The service request unit 113 resets the message transmission timer 112 to "0" (step S901), and waits for an interrupt from the message transmission timer 112 (step S902). When the message transmission timer 112 is reset by “0” from the service request unit 113, the message transmission timer 112 continues counting until the set time is reached. When the set time is reached, the service request unit 113 is instructed to interrupt the message transmission.

When a message transmission interrupt from the message transmission timer 112 occurs (step S903), the service request unit 113 receives the message storage unit 111.
Is your own terminal number, eg "0x8ab60a
14 "and the character string of" service OK "which is the content of the message (step S904). The service request unit 113 creates a transmission message from these and sends the message to the service processing unit 151 of the center 150. Send (step S905), step S901
Move on to processing.

FIG. 10 is a flowchart showing an example of the procedure of response processing when the service processing unit 151 of the center 150 receives a service request. Service processing unit 1
51 receives the service request (step S100)
1), the message reception timer 154 is reset to "0" (step S1002), and the service log of the terminal number indicated in the transmission content of the service request is read from the usage status storage unit 160 (step S1003).

If there is the service log in which the recovery mark 1 is set in the utilization status storage section 160 (step S
1004), the service indicated by the service log is executed, and the recovery mark is reset to "0" (step S1005). In step S1004, if there is no service log with the recovery mark 1 set,
The requested service is executed in accordance with the newly received service request, and the service log thereof is used by the usage status storage unit 16
It is stored in 0 (step S1006).

FIG. 11 is a flow chart showing an example of the procedure of network management processing by the service processing section 151 of the center 150. The network management process of the service processing unit 151 is started by an interrupt due to the reception of a message from the service request unit 113 or an interrupt due to the output of the check result from the message check unit 155.

When the above interrupt occurs, the service processing unit 151 determines whether or not the interrupt is due to the reception of a message from the terminal 110 (step S110).
1) If so, the terminal number, for example, “0x8ab60a14” and the message content “service OK” are received from the received message, and the message log storage unit 1
53 (step S1102), and step S11.
The process moves to 06.

In step S1101, otherwise, since the terminal number is input from the message check unit 155, the terminal number is input (step S11).
03), a recovery mark is added to the service log of the terminal number stored in the usage status storage unit 160 (step S1104). Further, the video / audio information transmitting unit 157 is notified of the terminal number, and an interrupt to stop the transmission of the video / audio information to the terminal 110 having the notified terminal number is generated (step S1105).

The service processing unit 151 waits until an interrupt due to a message received from the service request unit 113 or an interrupt due to a check result output from the message check unit 155 occurs (step S11).
06). FIG. 12 is a flowchart showing an example of a procedure of message check processing by the message check unit 155 of the center 150.

The message check processing of the message check unit 155 is started when the reception check interrupt is generated by the message reception timer 154. The message check unit 155 uses the message reception timer 1
The system waits for the reception check interruption by 54 (step S1201). Message reception timer 15
The number 4 is reset to "0" by the service processing unit 151 each time the center 150 is activated and each time a message is received, and each time it is reset to "0", counting is performed until the set time is reached. When the count reaches the set time,
The message reception timer 154 interrupts the message check unit 155 to check the reception of the message.

When the reception check interruption by the message reception timer 154 occurs (step S120)
2), the message check unit 155 temporarily stores the message content “service OK” from the terminal 110 in the message log storage unit 153 for the terminal number recorded in the terminal number list of the terminal number storage unit 152. It is checked whether it has been performed or null (step S1203). If there is a terminal number whose message content is null, the terminal number is output to the service processing unit 151 (step S1204). Message content is nu
If there is no terminal number of ll, the process proceeds to the next step.

Next, the message check unit 155
All message contents of the message log storage unit 153 are n
(step S1205), the message reception timer is reset to "0" (step S1206), and the process proceeds to step S1201. FIG. 13 is a flowchart showing an example of a procedure of line release processing by the video / audio information transmitting unit 157 of the center 150.

The video / audio information transmitting unit 157 receives the interrupt from the service processing unit 151 and specifies the designated terminal 11
When the instruction to stop transmission of the video and audio information for 0 is received (step S1301), the line information list is read from the line information storage unit 156 (step S1302). Further, it is checked whether or not the video / audio information is being transmitted to the terminal 110 having the terminal number (step S130).
3) If not being transmitted, the process ends. If it is being transmitted, an interruption command of the extraction process for the terminal 110 is output to the audiovisual information extraction unit 159 (step S130).
4), transmission of the video / audio information to the terminal 110 is stopped (step S1305). Next, the terminal number of the terminal 110 is deleted from the line information list in the line information storage unit 156 (step S1306), and the process ends.

As described above, according to the present embodiment, each terminal 110 sends a message at regular intervals to report to the center 150 that it is operating normally. In order to detect an abnormality of each terminal 110, it suffices to check the stored contents of the terminal number storage unit 152 and the message log storage unit 153, and there is no need to poll each terminal 110. Therefore, as compared with the conventional CATV network monitoring device 800, the load on the network monitoring processing of the center 150 can be reduced.

Further, the message checking unit 155 determines the abnormality of each terminal 110 based on the presence / absence of the message received from each terminal 110. Therefore, the abnormality occurring in the transmission path between each terminal 110 and the center 150, for example, It is also possible to detect line breaks, power failures, etc. Further, it is also possible to detect an abnormality that cannot be detected by the abnormality detecting unit 114 of each terminal 110, for example, a power failure of each terminal 110 due to a lightning strike or a disconnection of the outlet of the terminal 110.

Further, the center 150 suspends the transmission of the video / audio information to the terminal 110 which has detected the abnormality, and releases the line. Accordingly, the center 150 can allocate the released transmission frequency to the new terminal 110. That is, it is possible to efficiently use the line and provide the service to more terminals 110.
Further, when the new terminal 110 is not connected to the released line, the load on the video / audio information transmitting unit 157 that distributes the video / audio information to the terminal 110 can be reduced accordingly.

In the first embodiment described above, the log table in the message log storage unit 153 is provided with an area for storing message contents corresponding to all terminal numbers that can be registered. However, it is not always necessary to provide an area for storing message contents corresponding to all terminal numbers. For example, the service processing unit 151 uses the terminal 110.
The terminal number of the terminal 110 may be registered in the log table each time a service request from the terminal is received, and the message content may be stored in the item corresponding to the terminal 110 when the message is received. In this case, the center 150 may not be provided with the terminal number storage unit 152.

Further, in FIG. 1, a line for bidirectional communication between the service processing unit 151 and the service requesting unit 113, and a video / audio information transmitting unit 157 sends a video to the video / audio information receiving unit 115. Although a line for transmitting voice information is shown by a different line, FIG. 1 shows each as a logical line, and the same line may be physically used. The same applies to the following embodiments.

Further, when the transmission of the service to the terminal 110 whose line has been released once is resumed, the center 150 starts the transmission from the service used by the terminal 110 immediately before the release of the line. The terminal 11
The user of 0 is convenient because it saves the trouble of re-inputting the transmission content of the service request when the service is restarted. In addition, when considering an abnormality that can be recovered if the user notices, such as disconnection of the outlet of the terminal 110, as described above, for the terminal 110 that does not receive a message,
Instead of immediately releasing the line (deregistering the transmission frequency of the video and audio information), the message check unit 155 is provided with a counter or the like for counting the number of checks, and the message check unit 155 checks the message several times. The line may be released to the terminal 110 that has not received the call.

In the example shown in FIG. 7 as the storage contents of the usage status storage unit 160, the center 150 uses the contents of the service request received from each terminal 110 as the terminal 110.
Although it was saved as a sequence of service logs for each, it is not always necessary to save in this way. For example, each terminal 1
The distribution status of each terminal 110 at each time, such as the content of the service distributed to the server 10 and the elapsed time from the start of the distribution of the service, may be stored as an object.

(Second Embodiment) In the following, FIGS.
A network management system 1400 according to a second embodiment of the present invention will be described with reference to FIG. FIG.
FIG. 6 is a block diagram showing a configuration of a network management system 1400 that is a second exemplary embodiment of the present invention. Note that, in FIG. 14, the same components as those of the network management system 100 according to the first embodiment have already been described, and therefore, the same reference numerals are given and the description thereof will be omitted.

The network management system 1400, as in the first embodiment, comprises a center 1450 and a plurality of terminals 1410 connected to the center 1450 via a dedicated line. The terminal 1410 includes a video / audio information receiving unit 115, a service storage unit 116, a service requesting unit 1411, an input unit 1412, a service check timer 1413, a service checking unit 1414, a video / audio switching unit 1416, and a video / audio message extracting unit 141.
7, video / audio message storage unit 1418, reproduction unit 141
9, a display unit 1420, an abnormality detection unit 1421, an internal information storage unit 1422, a receiving service storage unit 1423, an internal information transmission timer 1424, and a voice output unit 1425.

The center 1450 has a line information storage unit 15
6, video / audio information transmitting unit 157, video / audio information extracting unit 1
59, usage status storage unit 160, service processing unit 145
1, a terminal information storage unit 1452, a totaling unit 1453, and a video / audio information storage unit 1454. Service request section 1
411 is an internal information transmission timer 1424 and a service check timer 1413 when the terminal 1410 is powered on.
And are reset to "0".

Further, the service request is transmitted to the center 1450 in the same manner as the service request unit 113 of the first embodiment. The service request unit 1411 instructs the video / audio switching unit 1416 to switch the video / audio information so that the output of the video / audio message extraction unit 1417 is input to the reproduction unit 1419 each time the service request is transmitted.
As a result, each time a service request is transmitted, notification information indicating that the service processing unit 1451 is currently waiting for a response is extracted from the video / audio message storage unit 1418 and displayed on the display unit 1420. Is output from the audio output unit 1425.

Each time the service request is transmitted, the service requesting unit 1411 creates a service log from the transmission contents and stores it in the receiving service storage unit 1423. The service log is almost the same as the service log stored in the usage status storage unit 160 of the first embodiment, except that the elapsed time from the reception start time of the service is always recorded as the parameter. different. Service request unit 1411
Whenever the processing indicated in the service log ends,
The service log is deleted from the receiving service storage unit 1423.

Further, the service request unit 1411 indicates that the abnormality detection signal from the abnormality detection unit 1421 is from "L" to "H".
When it is switched to, or the service check unit 14
When a timeout error is notified by 14,
A service interruption request is transmitted to the center 1450. Next, the service requesting unit 1411 causes the video / audio switching unit 1
An interrupt is generated in 416, and the video / audio switching unit 141
6 is instructed to switch the input destination of 6 from the video / audio information receiving unit 115 to the video / audio message extracting unit 1417. Further, the video / audio message extraction unit 1417 is instructed to extract the video / audio message from the video / audio message storage unit 1418.

The service request unit 1411 is the abnormality detection unit 1
By monitoring 421, what kind of error has occurred is checked, and the generated error is recorded in the internal information storage unit 1422. The service requesting unit 1411 stores that a time-out error has occurred, and if there is an operation input from the input unit 1412 after the time-out error, it determines that the time-out error has been resolved. After determining that the timeout error has been resolved, if the abnormality detection signal is "L", or if the abnormality detection signal is "H", wait for switching to "L", and then store in the receiving service storage unit 1423. Send the service request that requested to send the service indicated in the service log of. Further, the video / audio message extraction unit 1417 is instructed to suspend the extraction of the video / audio information from the video / audio message storage unit 1418.

The service request unit 1411 receives the internal information stored in the internal information storage unit 1422 in response to the interrupt from the internal information transmission timer 1424.
It is transmitted to the service processing unit 1451 on the 50 side. Input unit 1
412 is realized by a remote controller, a control pad, a mouse, a keyboard, etc.
A signal associated with each process such as menu selection and execution is input to the terminal 1410.

The service check timer 1413 is
Every time it is reset to "0", the set time (about 30 minutes) is counted, and if the time is out, the service check unit 1
Perform timer interrupt at 414. When the service check timer 1413 interrupts, the service check unit 1414 first determines whether or not there is an input from the input unit 1412 between the previous interrupt and the current interrupt (specifically, the input unit 1412 does Check whether an input event has occurred). When there is an input, the service check timer 1413 is reset to "0". If there is no input, the service request unit 1411
Checks whether the service request is currently being transmitted, is being processed for transmission, and / or neither. If the service request is being transmitted or is being transmitted, the service check timer 1413 is reset to "0". If neither is the case, the terminal side video / audio information receiving unit 115 checks whether or not video / audio information is currently being received. If it is not being received, the service check unit 1414 notifies the service request unit 1411 of a timeout error, and the service check timer 1
413 is reset to "0".

When the abnormality detecting section 1421 detects an abnormality, the video / audio switching section 1416 causes an interrupt from the service requesting section 1411 to cause the input terminal of the reproducing section 1419, which is the output destination, to change the input terminal of the reproducing section 1419. Switch to the terminal on the side connected to the audio separation unit. Further, the data input destination is switched from the video / audio information receiving unit 115 to the video / audio message extracting unit 1417.

The video / audio information switching unit 1416 is
The output of the video / audio information from the video / audio information receiving unit 115 is monitored, and when the video / audio information is output from the video / audio information receiving unit 115, the input terminal of the reproducing unit 1419 is connected to the reproducing unit 1.
Switching to the terminal on the side connected to the decoder inside 419. Next, the data input destination is switched from the video / audio message extracting unit 1417 to the video / audio information receiving unit 115.

The video / audio message extraction unit 1417 extracts the video / audio information of the specified content from the video / audio message storage unit 1418 in accordance with the instruction from the service request unit 1411. The video / audio message storage unit 1418 is
Notification information for notifying the user of the processing status of the terminal 1410 in response to the user's operation and the state of waiting for a response from the center 1450, and the audio / video information for notification that is not compression-coded in preparation for an error in the decoder in the playback unit 1419. , And other video and audio information are stored in association with the contents of each video and audio information. It should be noted that the video / audio message storage unit 1418 may store only the notification video / audio information that has not been compression-encoded.

The reproducing section 1419 has a decoder (not shown), a video / audio separating section, a video D / A converting section and an audio D (not shown).
A / A converter is provided. The video / audio information that has been compression-encoded and multiplexed according to a standard such as MPEG2 and transmitted is decoded by a decoder and separated into video information and audio information by a video / audio separation unit. The separated video information is converted into an analog signal by the video D / A converter,
It is supplied to the display unit 1420. The separated audio information is
The audio D / A conversion unit converts the analog signal and supplies the analog signal to the audio output unit 1425. Also, the reproducing unit 1419
Has two input terminals (not shown) realized by a selector or the like, one input terminal is connected to the decoder, and the other input terminal is directly connected to the video / audio separation unit without passing through the decoder. . Abnormality detection unit 1421
When an error in the decoder is detected by the video / audio switching unit 1416, the other input terminal is selected, and the video / audio message extracted by the video / audio message extraction unit 1417 is input to the video / audio separation unit. It The video D / A conversion unit is the display unit 1420.
May not be provided if the X corresponds to a digital signal.

The display unit 1420 displays the video information supplied from the reproduction unit 1419 on a screen such as a CRT. The abnormality detecting unit 1421 detects an error such as a demodulation error of video / audio information caused by a hardware error or a software error in the video / audio information receiving unit 115, or a decoding error caused by a hardware error or a software error in the reproducing unit 1419. Performs a check and holds the check result for each check item. As a result of the check, when any of the above errors is detected, the abnormality detection signal is inverted from “L” to “H” and the service request unit 1411 is notified of the occurrence of the abnormality. Further, the component in which the abnormality is detected, for example, the demodulation circuit of the video / audio information receiving unit 115 or the decoder of the reproducing unit 1419 is initialized, and when the initialization is completed, the abnormality detection signal is changed from “H” to “L”. , And notify the service request unit 1411 of error recovery.

The internal information storage unit 1422 stores the internal information created by the service request unit 1411. FIG. 15 is an explanatory diagram showing an example of internal information stored in the internal information storage unit 1422. This internal information is detailed information on the terminal 1410 side necessary for maintenance and the like in the network management system 1400, and more specifically, the number of service request transmission errors detected by the abnormality detection unit 1421 and transfer data. It is the number of reception errors of the video / audio information. The internal information includes MPE.
For a component (for example, a decoding unit (not shown) of the reproduction unit 1419) implemented by software, such as a G driver, version information of the software is recorded. The internal information is written by the service request unit 1411.

The receiving service storage unit 1423 currently stores
A service log indicating the service delivered from the center 1450 is stored. The service log is updated by the service request unit 1411. The internal information transmission timer 1424 counts the internally set time (about 10 minutes) each time it is reset to “0”. When the internal information transmission timer 1424 times out, it interrupts the service request unit 1411.

The audio output unit 1425 outputs the audio information D / A converted by the reproduction unit 1419 as audio. The service processing unit 1451 is similar to the service processing unit 151 in the first embodiment in that the service request unit 1451.
The response process according to the service request from 11 is performed. For example, when a service interruption request is received from each terminal 1410, a recovery mark is set in the service log corresponding to the terminal 1410 in the usage status storage unit 160, and the terminal 1
Release of the line with 410 is performed by the video / audio information transmission unit 157.
To instruct. Further, when the service restart request is received, the terminal 1 which has once released the line by the service interruption request.
The video / audio information transmitting unit 157 is instructed to newly secure the line to 410, and the transmission of the service is started from the service in which the restoration mark is set. Next, the recovery mark of the service log in the usage status storage unit 160 corresponding to the terminal 1410 is reset to “0”. other than this,
Every time internal information is transmitted from each terminal 1410, the terminal information stored in the terminal information storage unit 1452 is updated. In addition, in response to an input operation from an input unit (not shown) on the center 1450 side, the totaling unit 1453 is instructed to total internal information, and the totalized result is output to a display unit (not shown) or a printing unit on the center 1450 side.

The terminal information storage unit 1452 stores each terminal 141
The internal information transmitted from 0 is stored for each terminal 1410. FIG. 16 is an explanatory diagram showing an example of the stored contents of the terminal information storage unit 1452. As shown in FIG. 16, the terminal information is internal information transmitted from each terminal 1410 and stored for each terminal number of each terminal 1410.

The totaling unit 1453 is the service processing unit 145.
According to the instruction No. 1, each item of the terminal information stored in the terminal information storage unit 1452 is totalized, and the totalized result is output to the service processing unit 1451. Video and audio information storage unit 145
Reference numeral 4 denotes the video / audio information storage unit 1 in the first embodiment.
Similar to 58, video / audio information to be distributed to each terminal 1410 is stored, but the video / audio information includes maintenance information to be distributed to a specific terminal 1410 selected by the center 150 side. include. The maintenance information is video / audio information including notification of software version upgrade of the corresponding terminal 1410.

FIG. 17 is a flow chart showing an example of the procedure of the timeout error detection processing of the service check unit 1414. The service check unit 1414 monitors for the occurrence of an input event by the input unit 1412 (step S1701), and the service check timer 1
When the interrupt due to the timeout of 413 occurs (step S1702), it is checked whether or not there is an input from the input unit 1412 between the previous interrupt and the current interrupt (step S1703).

If there is, the process proceeds to step S1707, and if there is not, the service request unit 1411 checks whether or not the service request transmission process is currently in progress (step S).
1704). In step S1704, if transmission processing is in progress, the process proceeds to step S1707, and if transmission processing is not in progress, it is further checked whether the video / audio information receiving unit 115 is currently receiving video / audio information ( Step S1705). If receiving, step S170
7 and the service request unit 1 if not receiving
Notify 411 of the timeout error (step S1)
706).

The service check unit 1414 resets the service check timer 1413 to "0" (step S1707) and returns to the process of step S1701. FIG. 18 is a flowchart showing an example of the procedure of the video / audio information switching processing by the video / audio switching unit 1416. When the interrupt from the service request unit 1411 occurs, the video / audio switching unit 1416 checks whether or not the video / audio information receiving unit 115 outputs the video / audio information (step S1801). The extraction unit 1417 checks whether or not the audio / video information is currently being extracted from the audio / video message storage unit 1418 (step S1802). If not being extracted, the output of the video / audio message extracting unit 1417 is output from the reproducing unit 1419 instead of the output of the video / audio information receiving unit 115.
So as to be input to the video / audio message extraction unit 1417 (step S1803), and instructs the video / audio message extraction unit 1417 to extract the video / audio information (step S180).
4).

If the extraction is being performed in step S1802, the process returns to step S1801. Step S1
In 801, if there is an output from the video / audio information receiving unit 115, the reproducing unit 1419 is configured such that the output from the video / audio information receiving unit 115 is input to the reproducing unit 1419 instead of the output of the video / audio message extracting unit 1417. The connection on the input side of is switched (step S1805).

Next, the video / audio message extraction unit 141
7 checks whether video / audio information is being extracted from the video / audio message storage unit 1418 (step S180).
6) If it is being extracted, the video / audio message storage unit 14
18 is instructed to suspend the extraction (step S1807), and the process ends. In step S1806, if extraction is not in progress, the process ends.

FIG. 19 is a flow chart showing an example of the procedure of the internal information transmission processing of the service request unit 1411. The service request unit 1411 resets the internal information transmission timer 1424 to "0" when the terminal 1410 is powered on (step S1901). When an interrupt from the internal information transmission timer 1424 occurs (step S19)
02), the internal information is read from the internal information storage unit 1422 (step S1903), and the read internal information is transmitted to the service processing unit 1451 (step S190).
4). Then, the process returns to step S1901.

FIG. 20 is an explanatory diagram showing an example of the display contents of the display unit 1420 when the video / audio information is delivered from the center 1450. When each terminal 1410 receives some kind of distribution from the center 1450, the processing is always started from the transmission of the service request. Therefore,
For example, after the terminal 1410 is powered on, the input unit 1
412 is not operated, the display unit 14
An initial menu (not shown) listing service names (for example, distribution of video / audio information, online shopping, display of billing information, etc.) that can receive distribution of the center 1450 is displayed at 20.

FIG. 20A is an explanatory diagram showing an example of the input menu screen when the distribution of the video / audio information is selected from the initial menu at the time of creating the service request. FIG.
(B) is an explanatory view showing an example of a menu screen for inputting detailed items at the time of creating a service request. For example, FIG.
When "Start service" shown in (a) is selected,
The process of creating a service request for requesting the distribution of the video / audio information is started, and an input menu screen for selecting more detailed items as shown in FIG. 20B is displayed. Further, when "end of service" is selected, an initial menu is displayed.

In this case, since the distribution of the video / audio information has already been selected in the initial menu, the detailed items to be further selected are the titles of movies for which distribution is requested, as shown in FIG. 20 (b). Become a name. The title name of the movie selected on the input menu screen is set as the file name of the parameter of the reproduction request, and is transmitted as a service request when the reproduction button of the input unit 1412 such as a remote controller is pressed, for example.

FIG. 20C is an explanatory diagram showing a screen in which the notification is being displayed immediately after the service request is transmitted. FIG.
As shown in (c), immediately after the service request is transmitted, the notification video / audio information extracted from the video / audio message storage unit 1418 is displayed. FIG. 20D is an explanatory diagram showing a screen on which the video / audio information received from the center 1450 is normally displayed.

When the video / audio information receiving unit 115 receives the video / audio information from the video / audio information transmitting unit 157, the video / audio switching unit 1416 inputs the input terminal of the reproducing unit 1419 and the input data to the reproducing unit 1419. Is switched, and the video / audio information distributed by the center 1450 as shown in FIG. 20D is displayed. FIG. 21 shows that while reproducing the audiovisual information distributed by the center 1450,
It is explanatory drawing which shows an example of the display content of the display part 1420 when abnormality generate | occur | produces.

FIG. 21A is an explanatory diagram showing a display image when a decoding error occurs in the reproducing section 1419. When a decoding error of the reproducing unit 1419 or a demodulation error of the video / audio information receiving unit 115 occurs, the display unit 142.
The image displayed at 0 is distorted. When such an error is detected by the abnormality detecting unit 1421, the service requesting unit 1411 transmits a service request for requesting service termination.

FIG. 21B is an explanatory diagram showing a screen displaying the video / audio information extracted from the video / audio message storage unit 1418 after the line with the center 1450 is disconnected. After the service request for ending the service is transmitted, the line with the center 1450 is disconnected, but the video / audio information for notification extracted from the video / audio message storage unit 1418 is input to the reproduction unit 1419, and the display unit 1
An image as shown in FIG. 21B is displayed at 420.

FIG. 21C is an explanatory diagram showing a display image by restarting the service after decoding error recovery. For example, when initialization of the decoder of the reproducing unit 1419 is completed,
The service request unit 1411 transmits a service restart request for video / audio information when a decoding error occurs. Center 1
When the video / audio information receiving unit 115 receives the video / audio information of the pause reproduction by the distribution 450, the video / audio information is displayed on the display unit 1420.

As described above, according to this embodiment, each terminal 1410 detects the occurrence of a recoverable abnormality inside the terminal 1410, and when an abnormality is detected inside each terminal 1410, the terminal 1410 side Since the service interruption request is transmitted from the center 1450, the center 1450 does not need to poll each terminal 1410 to detect an abnormality,
The load on the center 1450 side in the network management process can be greatly reduced.

Further, since the service request unit 1411 transmits a service interruption request when an abnormality is detected, the center 1
On the side of 450, the line for the terminal 1410 in which the abnormality has occurred can be released and assigned to another terminal 1410. In addition, a line to the terminal 1410 in which the distributed service is not used, such as the user leaving the seat during the input operation, can be assigned to another terminal 1410. Therefore, according to the present embodiment, the center 1450
The line with the terminal 1410 can be effectively used, and when the released line is not assigned to another terminal 1410, the distribution load of the center 1450 can be reduced accordingly.

Further, since the service request unit 1411 automatically transmits the request for restarting the service received at the time of detecting the abnormality after the timeout error is resolved or after the detected abnormality is recovered, The user
It is not necessary to perform an input operation after restoration, and the video and audio information from the point of interruption can be received after reconnection. Therefore, for the user, there is relatively little feeling that the received content is interrupted due to an abnormality or a timeout error,
It is possible to continue receiving the service (viewing the audiovisual information) with a natural feeling.

Each terminal 1410 periodically transmits the internal information indicating the details of the error that has occurred inside the terminal 1410 to the center 1450, and the center 1450 stores the received internal information in the terminal information storage unit 1452. Therefore, the center 1450 can retrieve and aggregate the information necessary for network maintenance at any time, such as when the load for distribution is small.

Note that the maintenance information does not necessarily have to be only the video / audio information for notification of maintenance. For example, the center 1450 is provided with difference data for software version upgrade or a maintenance information storage unit for storing a difference program, and the difference data read from the maintenance information storage unit is targeted by the service processing unit 1451. Terminal 14
Alternatively, it may be directly transmitted to the ten service requesting units 1411.

In addition, in the present embodiment, the terminal 141
0 When an internal abnormality is detected, the service request unit 1
Although 411 transmits the service interruption request, the service interruption request is not necessarily required. For example, terminal 1
When an abnormality inside 410 is detected, a service request requesting a pause of the audiovisual information at that time may be transmitted. However, in this case, the video / audio switching unit 1416 does not detect the output from the video / audio information receiving unit 115 and switches the input of the reproducing unit 1419, but always reproduces in accordance with the instruction of the service requesting unit 1411. The input of the unit 1419 is switched. With this configuration, even when an abnormality occurs, the pause at the time of abnormality detection is always received by the video / audio information receiving unit 115. Therefore, the terminal 1410 promptly reproduces the received video / audio information after the abnormality is recovered. be able to.

The service processing unit 1451 is provided in the center 1450, but it does not necessarily have to be provided in the center 1450. For example, a relay station that relays a plurality of terminals may be provided between the center 1450 and each terminal 1410 in the network management system 1400, and the relay station may be provided. Furthermore, the usage status storage unit 160 does not store the sequence of service logs, but rather stores each terminal 14 at each time.
The distribution status to 10 may be saved as an object.

Further, in the present embodiment, the set time of the service check timer 1413 is set to 30 minutes, but the congestion degree of the transmission line, the center 1450 or each terminal 141 is set.
It may be appropriately determined according to the load of 0. The same applies to the set time of the internal information transmission timer 1424. (Embodiment 3) In the following, referring to FIGS.
A network management system 2300 according to the third embodiment of this invention will be described.

FIG. 22 is a block diagram showing the configuration of the network management system 2300 according to the third embodiment of the present invention. Note that, in FIG. 22, the same components as those of the network management system 1400 of the second embodiment have already been described, and therefore, the same reference numerals are given and the description thereof is omitted. The network management system 2300 is similar to the first embodiment in that the center 235
0 and a plurality of terminals 2310 connected to the center 2350 via a dedicated line.

The terminal 2310 has a video / audio information receiving unit 11
5, service storage unit 116, video and audio switching unit 141
6, video / audio message extraction unit 1417, video / audio message storage unit 1418, reproduction unit 1419, display unit 142
0, a voice output unit 1425, a service request unit 2311, and an end processing unit 2312. Center 2350
Line information storage unit 156, video / audio information transmission unit 157, video / audio information extraction unit 159, video / audio information storage unit 145.
4, a service processing unit 2351, an abnormality detection unit 2352, and a message storage unit 2353.

The service request unit 2311 stores the terminal number “0x0” of the center 2350, the message from the center 2350 and the processing content corresponding to the message in the internal memory (not shown).
When the end message from 350 is received, the audiovisual message extracted by the audiovisual message extracting unit 1417 is set as the input of the audiovisual switching unit 1416, and the audiovisual message is extracted from the audiovisual message storage unit 1418. So that the video / audio message extraction unit 1417 is instructed. Then, the end processing unit 23
The received end message is output to 12.

The end processing unit 2312 is the service request unit 2
When the end message is input from 311, the audio / video information receiving unit 115, the audio / video switching unit 1416, the audio / video message extracting unit 1417, the reproducing unit 1419, the display unit 1420, the audio output unit 1425, the service requesting unit 231.
1. End processing of the end processing unit 2312 is performed. The service processing unit 2351 performs distribution processing according to the service request from the service requesting unit 2311.

The abnormality detector 2352 is the service processor 2
The occurrence of an error is detected by monitoring 351, the video / audio information transmitting unit 157, and the video / audio information extracting unit 159. When an error is detected in each part that is being monitored, it is checked what kind of error the error is, and if the detected error is a fatal error that requires time to recover, a message is stored. Part 2353
The message is read from and the end message is transmitted to the terminal number registered in the line information list in the line information storage unit 156.

The message storage unit 2353 is used by the center 2
A terminal number indicating that the message is 350 and predetermined data indicating the content of the message are stored. FIG. 23 is an explanatory diagram showing an example of the end message stored in the message storage unit 2353. The terminal number “0x0” represents the terminal number of the center 2350. Further, the character string "end", which is the content of the message, indicates that the distribution of the service of the center 2350 is ended because an abnormality has occurred in the center 2350. Note that, although the message content is represented by a character string in FIG. 23, the message content does not necessarily have to be a character string and may be a specific code or other data.

FIG. 24 is a flow chart showing an example of the processing procedure after the error detection of the abnormality detecting section 2352 on the center 2350 side. The abnormality detection unit 2352 detects the occurrence of an error by monitoring the service processing unit 2351, the video / audio information transmission unit 157, and the video / audio information extraction unit 159, and when detecting the occurrence of the error, the center 235 is detected.
0, what kind of error has occurred, the message is read from the message storage unit 2353 according to the content of the error (step S2401), and the line information storage unit 1
An end message is transmitted to the terminal numbers registered in the line information list in 56 (step S240).
2).

FIG. 25 is a flow chart showing an example of the processing procedure of the service request unit 2311 on the terminal 2310 side. The service requesting unit 2311 receives the end message from the center 2350 (step S250).
1), the video / audio message extracted by the video / audio message extracting unit 1417 is the video / audio switching unit 141.
6 is set (step S250)
2) The video / audio message extraction unit 1417 is caused to execute the extraction of the video / audio message (step S250).
3). The reproduction unit 1419 outputs the input video / audio message to the display unit 1420 and the audio output unit 1425 to reproduce the video / audio message (step S250).
3). Next, the service request unit 2311 uses the end processing unit 2
An end message is output to 312 (step S250).
4).

When the end message is input, the end processing unit 2312 causes the video / audio information receiving unit 115, the video / audio switching unit 1416, and the video / audio message extracting unit 141.
7, playback unit 1419, display unit 1420, audio output unit 14
25, the service request unit 2311, and the end processing unit 2312 are executed. FIG. 26 is an explanatory diagram showing an example of display contents of the display unit 1420 when an abnormality occurs in the center 2350 during reproduction of the video / audio information distributed by the center 2350.

FIG. 26A shows the video / audio information transmitting section 15
FIG. 7 is an explanatory diagram showing a display image when a modulation error occurs in No. 7. When a modulation error occurs in the video / audio information transmitting unit 157, the video / audio information received by the video / audio information receiving unit 115 cannot be demodulated, and a decoding error occurs in the reproducing unit 1419. As a result, the display screen of the display unit 1420 is disturbed. Abnormality detection unit 2352
Detects a modulation error of the video / audio information transmitting unit 157,
An end message is transmitted to the service request unit 2311.

FIG. 26B is an explanatory diagram showing an end message image on the display unit 1420 after receiving the end message. Upon receiving the end message, the service request unit 2311 outputs the end message to the end processing unit 2312. The service requesting unit 2311 inputs the video / audio switching unit 1416 to the video / audio message extracting unit 141.
7, the video / audio message extraction unit 1417 is caused to extract the end message image, and the reproduction unit 1419 displays it on the display unit 1420. End processing unit 231
2 is a service requesting unit 2311 and a video / audio information receiving unit 1
15, a video / audio switching unit 1416, a video / audio message extracting unit 1417, a reproducing unit 1419, and an end processing unit 23.
The end process of 12 is performed.

As described above, according to the present embodiment, the abnormality detecting unit 2352 causes the fatal specific hardware error (for example, modulation error) inside the center 2350 to occur,
When software errors (for example, service start error) are detected, and when these errors are detected, the connected terminals 2310 to which the line (transmission frequency) of the video / audio information is allocated are connected. Send a termination message. In response to this, each terminal 2310 that has received the end message displays that the center 2350 temporarily ends the distribution of the service due to the occurrence of an abnormality in the center 2350, and then performs the terminal 2310 end processing. As a result, it is possible to prevent each connected terminal 2310 from malfunctioning for a long time due to an abnormality that has occurred in the center 2350, and to notify the user of each terminal 2310 of the reason for performing the termination process.

In the present embodiment, the center 235
Although the example in which the termination message is transmitted from 0 and the termination processing is executed by the terminal 2310 has been shown, it is also possible to transmit another predetermined message from the center 2350 and the terminal 2310 may perform the processing corresponding to the message. Is.
Also, in the message storage unit 2353, the center 2350
Although the terminal number of "0x0" is set, other numbers may be used.
It suffices to be able to recognize the terminal number of the center 2350. Further, the service request unit 2311 outputs the received end message to the end processing unit 2312, but it is not necessary to output the end message itself to the end processing unit 2312, and other data indicating that the end message has been received or , Flag, or simply the end processing unit 2
It may be a control signal or the like for causing the 312 to start the termination process.

[0122]

In the network management system of the present invention, the message transmitting means of each terminal transmits a message indicating that it is being normally received to the center at the first time interval. The line connection list storage means of the center stores a line connection list in which IDs of terminals connected to the center are listed.
The message receiving means receives a message from each terminal. The message receiving / storing means stores that the message is received for each terminal. The examining means examines whether or not the reception of the message from each terminal listed in the line connection list is stored in the message receiving / storing means at the second time interval longer than the first time interval. The clearing means clears the stored contents of the message receiving and storing means after the investigation by the investigating means. As a result of the investigation, the abnormality determining means has an action of determining that the terminal for which the message reception storage means does not store the reception of the message has an abnormality.

Therefore, according to the network management system of the present invention, since each of the terminals sends a message indicating that it is being normally received to the center at the first time interval, the center side From this, it is possible to determine that an abnormality has occurred in each of the terminals without receiving a message from each of the terminals, depending on the presence or absence of a message, and reduce the load on the center side in network management. There is an effect that can be.

Further, since the occurrence of an abnormality in the terminal is determined based on the presence or absence of the message received from each terminal, it is possible to directly determine with which terminal the abnormality has occurred. At the same time, it is possible to determine an abnormality in the transmission path between the terminal and the center as an abnormality in the terminal. Further, in the other network management system of the present invention, the terminal ID deleting means of the center further deletes the ID of the terminal determined to have an abnormality from the line connection list. The line releasing means has an action of releasing the line connection with the terminal whose ID is deleted from the line connection list.

Therefore, according to the other network management system of the present invention, the connection of the line with the terminal judged to have an abnormality is released, so that the released line is connected with another terminal. Can be assigned to, and the line can be effectively used. Further, when the released line is not assigned to the connection with another terminal, the load on the center can be reduced accordingly.

In yet another network management system of the present invention, the service ID of the center is further added.
The storage unit stores the ID of the service provided at the time of the abnormality determination with respect to the terminal determined to have an abnormality, together with the ID of the terminal. The service starting means has an action of starting the service from the service of the ID stored in the service ID storage means after resuming the connection with the terminal whose connection of the line is once released.

Therefore, according to the above still another network management system of the present invention, the service, which has been provided at the time of abnormality determination, is resumed to the terminal whose connection has been released once, after the connection is resumed. The user of each terminal is
This is convenient because it is not necessary to input an operation for transmitting a service request after resuming the connection. In still another network management system of the present invention, the error detecting means of each terminal detects the occurrence of a predetermined error (for example, a decoding error) inside the terminal. The message transmission stop means has the function of stopping the transmission of the message when the occurrence of the error is detected.

Therefore, according to still another network management system of the present invention, in addition to the above effects, each terminal voluntarily sends a message when a predetermined error inside the terminal is detected. Since it stops, it does not mean that there is an abnormality that makes it impossible to send messages, but even if an error occurs that the service from the center can not be played normally, report the occurrence of the abnormality to the center There is an effect that it is possible. This effect is particularly effective when the system that performs bidirectional communication between the center and the terminal and the system that performs one-way communication from the center to the terminal are physically different components.

As a result, the center side can take measures such as releasing the line to the terminal in which the error has occurred. In still another network management system of the present invention, the error detecting means has an action of detecting a specific software error inside the terminal. As a result, the transmission of the message is stopped when a specific software error inside the terminal is detected.

Therefore, according to the above still another network management system of the present invention, a software error such as a decoding error or out-of-synchronization of the receiving unit occurs inside the terminal and the message can be transmitted, but the service from the center is provided. Even if a situation occurs where the message cannot be received normally, by voluntarily stopping the message transmission,
The terminal side can report the occurrence of an abnormality to the center.

In still another network management system of the present invention, the error timer of the error detecting means measures a fixed time. The error timer resetting means resets the error timer every time the operator operates the terminal. When the error timer times out, the reception state determination means determines whether the terminal is receiving the service from the center, is in the reception waiting state after transmitting the service request, or is neither of them. The error detection notifying means has an action of notifying the message transmission stopping means of the detection of the error when the reception state determining means determines that there is none. As a result, if there is no instruction input from the operator for a certain period of time in the terminal, and the service is not being received from the center and is not in the waiting state for receiving the service request, the message transmission is stopped.

Therefore, according to the still another network management system of the present invention, the terminal side determines the state where the service from the center is not used by the user, and reports it to the center by stopping the transmission of the message. be able to. As a result, the center side can release the line with the terminal for which the service is not used and allocate it to the connection with another terminal, and can effectively use the line. Further, when the released line is not assigned to the connection with another terminal, there is an effect that the load for service transmission can be reduced.

In yet another network management system of the present invention, the recovery detecting means of each terminal detects recovery from the detected error. When the restoration is detected, the transmission resuming means has a function of transmitting a service request for requesting connection of the line with the center and resuming transmission of the message. Therefore, according to the above still another network management system of the present invention, when the abnormality in the terminal is detected, the line with the center is released, and the abnormality can be automatically recovered in the terminal. Has an effect that each terminal can automatically restore the line connection with the center after the recovery from the error.

In still another network management system of the present invention, the video / audio information storage means of each terminal stores predetermined video / audio information. The reception determination means determines, each time a service request is transmitted, whether or not the terminal has received a service from the center. The reproduction means reproduces the video / audio information stored in the video / audio information storage means and judges that the service from the center has been received when the reception determination means does not determine that the service from the center has been received. Then, the content of the received service is reproduced.

Therefore, according to the above still another network management system of the present invention, by storing in the video / audio information storage means a notice indicating that the center is waiting for a response, the center responds to the service request. Even if the response delay occurs, the user on the terminal side can be notified of such a state. Further, the video / audio information stored in the video / audio information storage means does not necessarily have to be such a notification.

As a result, in addition to the above-described effects of the present invention, it is possible to reduce the waiting consciousness of the terminal side user even when the response delay of the center occurs. In still another network management system of the present invention, the error detecting means of each terminal detects occurrence of a predetermined error inside the terminal.
The release requesting means has an effect of transmitting a release request for releasing the line connection to the center when the occurrence of the error is detected while connecting the line with the center.

Therefore, according to the above network management system of the present invention, when a predetermined error occurs in each terminal, a release request from the terminal causes
The line between the center and the terminal can be released. This allows the center side to allocate the released line to the connection with another terminal. Further, when the released line is not assigned to another terminal, the load on the center side for service distribution can be reduced accordingly.

In still another network management system of the present invention, the video / audio information storage means of each terminal further stores predetermined video / audio information. The reproducing means has the function of reproducing the video / audio information stored in the video / audio information storage means when the occurrence of the error is detected while connecting the line with the center.

Therefore, according to still another network management system of the present invention, each terminal requests the release of the line when the occurrence of the error is detected while connecting the line with the center. At the same time, the video / audio information stored in the video / audio information storage means is reproduced. As described above, by storing in the video / audio information storage means a notice indicating that error recovery processing is in progress, it is possible to notify the user of the terminal of the processing status in the terminal. Thus, it is possible to reduce the user's waiting consciousness.

In still another network management system of the present invention, the service ID storage means of each terminal further includes the I of the service being received when the error is detected.
Remember D. When the detected error is resolved, the connection requesting means transmits a request for line connection with the center. The service request means, when the line with the center is connected, the ID stored in the service ID storage means.
This has the effect of transmitting a service request for requesting the service.

Therefore, according to still another network management system of the present invention, in addition to the effects of the present invention, each of the terminals detects an error in the center when the detected error is eliminated. It is possible to automatically request the transmission of the service which is being received at the time. This is convenient because the user on the terminal side does not need to perform the input operation for transmitting the service request again after the error is resolved.

In still another network management system of the present invention, the internal information transmitting means of each terminal transmits internal information including software version information and a history of errors detected in each terminal to the center. The internal information storage means of the center has an action of storing the internal information transmitted from each terminal for each terminal.

Therefore, according to the above still another network management system of the present invention, in addition to the effects of the present invention, the user on the center side selects the time when the load on the center is small and stores it in the internal information storage means. It is possible to read stored internal information and collect information for network maintenance based on the read internal information of each terminal.

In still another network management system of the present invention, the maintenance information providing means of the center may send maintenance information to each corresponding terminal based on the internal information stored in the internal information storage means. Has the action of providing. Therefore, according to the still another network management system of the present invention, in addition to the effects of the present invention, by processing the error history of the internal information stored in the internal information storage means in the center. The effect that the maintenance information necessary for maintenance of the terminal can be provided to the corresponding terminal.

In still another network management system of the present invention, the center side error detecting means detects the occurrence of a predetermined error inside the center. When the occurrence of the error is detected, the center side message transmitting means transmits a center side message indicating that an abnormality has occurred in the center to each of the terminals. The message processing means of each terminal has an action of performing predetermined terminal-side processing for occurrence of an abnormality in the center when the center-side message is received. As a result, when a specific hardware error (eg modulation error) or software error (eg service start error) inside the center is detected, the center sends a message to each terminal. , Each of the terminals executes a predetermined process for the occurrence of an abnormality in the center by the message.

Therefore, according to the still another network management system of the present invention, when the error occurs inside the center, a message is sent from the center to each terminal so that the error on the center side is predetermined. It is possible to automatically perform more appropriate processing in each terminal. The predetermined processing for the error occurrence on the center side is, for example, terminating each terminal. As a result, it is possible to prevent a long-term malfunction on the terminal side due to an error inside the center. Also, when performing maintenance inside the center, it is possible to easily terminate the center by terminating each connected terminal by sending a message, and therefore maintenance work of the center can be easily performed. Produce an effect.

In still another network management system of the present invention, the video / audio message storage means of each terminal stores a video / audio message in which the content corresponding to the center side message is represented as video / audio information. The video / audio message reproducing means has an action of reproducing the video / audio message corresponding to the center side message stored in the video / audio message storage means when the center side message is received.

Therefore, according to the above still another network management system of the present invention, the user of each terminal can view the video / audio message reproduced (displayed on the screen being received) by the video / audio message reproducing means. Thus, according to the message on the center side (that is, regardless of the user's intention), it is possible to confirm the cause and reason of the processing automatically performed on the terminal side.

Since the network management method of the present invention can achieve the same effects as those obtained by the network management system of the present invention, the description thereof will be omitted.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a network management system 100 according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of stored contents of a message storage unit 111.

FIG. 3 is an explanatory diagram showing an example of a service request list, which is the storage content of a service storage unit 116.

FIG. 4 is an explanatory diagram showing an example of a terminal number list, which is the stored content of a terminal number storage unit 152.

FIG. 5 is an explanatory diagram showing an example of a log table that is the storage content of a message log storage unit 153.

6 is an explanatory diagram showing an example of a line information list stored in a line information storage unit 156. FIG.

FIG. 7 is an explanatory diagram showing an example of a service log stored in the usage status storage unit 160.

FIG. 8 is a flowchart showing an example of a procedure of service request transmission processing by the service request unit 113 of the terminal 110.

9 is a flowchart showing an example of a procedure of message transmission processing by the service request unit 113 of the terminal 110. FIG.

FIG. 10 is a flowchart showing an example of a procedure of response processing when the service processing unit 151 of the center 150 receives a service request.

FIG. 11 is a flowchart showing an example of a procedure of network management processing by the service processing unit 151 of the center 150.

FIG. 12 is a message check unit 15 of the center 150.
6 is a flowchart showing an example of a procedure of message check processing according to No. 5.

FIG. 13 is a video / audio information transmitting unit 157 of the center 150.
6 is a flowchart showing an example of a procedure of a line release process by the.

FIG. 14 is a block diagram showing a configuration of a network management system 1400 according to a second embodiment of this invention.

FIG. 15 is an explanatory diagram showing an example of internal information stored in an internal information storage unit 1422.

16 is an explanatory diagram showing an example of stored contents of a terminal information storage unit 1452. FIG.

FIG. 17 is a flowchart illustrating an example of a procedure of a timeout error detection process of the service check unit 1414.

FIG. 18 is a flowchart illustrating an example of a procedure of video / audio information switching processing by the video / audio switching unit 1416.

FIG. 19 is a flowchart showing an example of the procedure of an internal information transmission process of the service requesting unit 1411.

FIG. 20 is an explanatory diagram showing an example of display contents of a display unit 1420 when receiving audiovisual information from the center 1450.

FIG. 21 is an explanatory diagram showing an example of display contents of a display unit 1420 when an abnormality occurs during reproduction of video / audio information distributed by the center 1450.

FIG. 22 is a block diagram showing a configuration of a network management system 2300 according to the third embodiment of this invention.

FIG. 23 is an explanatory diagram showing an example of an end message which is the storage content of a message storage unit 2353.

FIG. 24 is a flowchart showing an example of a processing procedure after error detection by the abnormality detection unit 2352 on the center 2350 side.

FIG. 25 is a flowchart showing an example of the processing procedure of the service requesting unit 2311 on the terminal 2310 side.

[Fig. 26] Fig. 26 is an explanatory diagram illustrating an example of display contents of the display unit 1420 when an abnormality occurs in the center 2350 during reproduction of the video / audio information distributed by the center 2350.

FIG. 27 is a conventional CATV network monitoring device 800.
FIG. 3 is a block diagram showing the configuration of FIG.

[Explanation of symbols]

 100 network management system 111 message storage unit 112 message transmission timer 113 service request unit 114 abnormality detection unit 115 video / audio information reception unit 116 service storage unit 150 center 151 service processing unit 152 terminal number storage unit 153 message log storage unit 154 message reception timer 155 Message check unit 156 Line information storage unit 157 Video / audio information transmission unit 158 Video / audio information storage unit 159 Video / audio information extraction unit 160 Usage status storage unit

Claims (19)

[Claims] 1. A network management system comprising a plurality of terminals provided in a digital CATV network and a center, wherein each of the terminals sends a message indicating that it is receiving normally at a first time interval. A message sending means for sending to the center is provided, and the center stores a line connection list storing means for storing a line connection list in which IDs of terminals connected to the center are listed, and A message receiving means for receiving a message, a message receiving / storing means for storing the reception of the message for each terminal, and a reception of a message from each terminal listed in the line connection list are stored in the message receiving / storing means. Investigating means for investigating whether or not the second time interval is longer than the first time interval , After the investigation by the investigation means, clear means for clearing the contents stored in the message reception storage means, and as a result of the investigation, an abnormality is judged to have occurred in the terminal for which no message reception is stored in the message reception storage means A network management system comprising: a determining unit. 2. The network management system according to claim 1, wherein the center further deletes an ID of the terminal determined to have an abnormality from a line connection list, and a line connection list. And a line releasing means for releasing the connection of the line with the terminal whose ID has been deleted from the network management system. 3. The network management system according to claim 2, wherein the center, together with the ID of the terminal, provides the ID of the service provided at the time of the abnormality determination to the terminal determined to have an abnormality. A service ID storing means for storing the information; and a service starting means for starting the service from the service having the ID stored in the service ID storing means after the connection with the terminal once the connection of the line is released is resumed. Network management system. 4. The network management system according to any one of claims 1 to 3, wherein each of the terminals further includes error detection means for detecting occurrence of a predetermined error inside the terminal, and occurrence of the error. And a message transmission stop means for stopping the transmission of the message when is detected. 5. The network management system according to claim 4, wherein the error detection unit detects a specific software error inside the terminal. 6. The network management system according to claim 4 or 5, wherein the error detecting means further resets the error timer for measuring a fixed time and each time the operator operates the terminal. Error timer reset means and when the error timer times out, it is judged whether the terminal is receiving the service from the center, is in the waiting state after sending the service request, or neither of them. A network management system comprising: a means and an error detection notifying means for notifying the message transmission stopping means of the detection of the error when the reception status determining means determines that there is none. 7. The network management system according to claim 4, wherein each of the terminals further includes recovery detection means for detecting recovery from the detected error and recovery is detected. And a transmission resuming means for transmitting a service request for requesting connection of a line with the center and resuming message transmission. 8. The network management system according to claim 1, wherein each terminal has a video / audio information storage unit storing predetermined video / audio information, and a service request transmission unit. Each time, the reception determination means determines whether or not the terminal has received the service from the center, and when the reception determination means does not determine that the service from the center has been received, it is stored in the audiovisual information storage means. A network management system comprising: a reproducing unit that reproduces the video and audio information that is present, and reproduces the content of the received service when it is determined that the service from the center has been received. 9. A network management system comprising a plurality of terminals provided in a digital CATV network and a center, wherein each of the terminals includes an error detecting means for detecting occurrence of a predetermined error inside the terminal, and the center. And a release request means for transmitting a release request for releasing the line connection to the center when the occurrence of the error is detected while connecting the line with the network management system. 10. The network management system according to claim 9, wherein each of the terminals further includes a video / audio information storage unit that stores predetermined video / audio information, and when the occurrence of the error is detected. And a reproducing means for reproducing the video / audio information stored in the video / audio information storage means. 11. The network management system according to claim 9 or 10, wherein each of the terminals further includes a service ID storage unit that stores the ID of the service that was being received when the error was detected, and the detected error. When the line is connected, the connection request means for transmitting a request for line connection with the center is connected, and when the line with the center is connected, the service having the ID stored in the service ID storage means is requested. A network management system comprising: a service request means for transmitting a service request. 12. The network management system according to claim 1, wherein each terminal transmits internal information including version information of software and a history of errors detected in each terminal to a center. The network management system according to claim 1, wherein the center includes an internal information storage unit that stores internal information transmitted from each of the terminals for each terminal. 13. The network management system according to claim 12, wherein the center further provides maintenance information to corresponding terminals based on the internal information stored in the internal information storage means. A network management system comprising a providing unit. 14. The network management system according to claim 1, wherein the center is a center-side error detection unit that detects occurrence of a predetermined error inside the center, and When detected, a center side message transmitting means for transmitting a center side message indicating that an abnormality has occurred in the center to each of the terminals, each of the terminals, when the center side message is received, A network management system comprising message processing means for performing a predetermined process on the terminal side when an abnormality occurs in the center. 15. The network management system according to claim 14, wherein each of the terminals further stores a video / audio message in which content corresponding to the message on the center side is expressed as video / audio information. And a video / audio message reproducing means for reproducing the video / audio message corresponding to the center side message stored in the video / audio message storing means when the center side message is received. Network management system. 16. In a digital CATV network including a center having a line connection list storage unit for storing a line connection list and a message reception storage unit, and a plurality of terminals, an abnormality in the network is detected and detected. And a list-up step of listing, in the line connection list, the IDs of terminals to which a line is connected to the center at the center, In the terminal, a message transmitting step of transmitting a message indicating that it is being normally received to the center at a first time interval, message receiving means for receiving a message from each of the terminals, and a message in the center. That I received
A message reception recording step of recording in the message reception storage means for each terminal, and whether or not reception of a message from each terminal listed in the line connection list in the center is stored in the message reception storage means, A check step of checking at a second time interval longer than the first time interval, a clear step of clearing the stored contents of the message reception storage means after the check by the check means at the center, and a check result at the center An abnormality determination step of determining that an abnormality has occurred in a terminal for which reception of a message is not stored in the message reception storage means. 17. The network management method according to claim 16, further comprising: a terminal I that deletes, from the line connection list, the ID of the terminal determined to have an abnormality in the center.
A network management method comprising: a D deleting step; and a line releasing step of releasing a line connection with the terminal whose ID is deleted from the line connection list in the center. 18. A network management method for detecting an occurrence of an abnormality in a network in a digital CATV network including a center and a plurality of terminals, and performing a process corresponding to the detected abnormality. An error detection step of detecting the occurrence of a predetermined error inside the terminal, and in each of the terminals, when the occurrence of the error is detected while connecting the line with the center, the line connection to the center is performed. And a release request step of transmitting a release request. 19. The network management method according to claim 18, wherein each of the terminals is provided with a video / audio information storage unit that stores predetermined video / audio information, and further, in each of the terminals, the center is provided. A network management method comprising a reproducing step of reproducing the video / audio information stored in the video / audio information storage means when the occurrence of the error is detected during connection of the line with the.