JP4736682B2 - Network system and network system control method - Google Patents

Description

The present invention relates to a network system and a network system control method, and can be applied to, for example, Ethernet (registered trademark).

  The network system includes a server and a plurality of terminals. The server has a NIC (Network Interface Card). Only a terminal set to a predetermined network address can access the server via the NIC. The plurality of terminals share one line with each other and are connected to the server via the line. One end of the line is connected to the NIC.

  Such a network system is employed in, for example, a bus type Ethernet (registered trademark).

  The prior art related to the present invention is shown below.

JP 9-36862 A JP-A-2005-130152 JP 2004-320300 A JP-A-9-50417 JP 2004-32452 A JP 2004-356784 A

  For example, when a failure occurs in the line, such as when the line is disconnected, a terminal connected to the other end of the position where the failure has occurred cannot access the server.

  In this case, the terminal that has become inaccessible cannot access the server until the line failure is removed. Therefore, it takes a long time to access the server.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to quickly recover access to a server of a terminal that has become unable to access the server due to a line failure.

Network system according to claim 1 of the invention comprises a server, and times lines, and a plurality of terminals which are respectively connected to different positions on the line, the server may set a network address to a first value A first NIC (Network Interface Card) that permits access to the server from a designated terminal only when it is active, and a terminal from which the network address is set to a second value to the server A second NIC that permits access only when it is active, a server-side determination unit that determines whether the server can access the terminal, the first NIC, and the second NIC A NIC control unit that activates or deactivates each of the NICs, and the line is connected between the first NIC and the second NIC, and the NIC control unit is connected to the first NIC. When the server side determination unit determines that the server cannot access the terminal set to the first value in a situation where one NIC is activated and the second NIC is deactivated. From the above situation, the NIC control unit also activates the second NIC, and each of the plurality of terminals sets the network address to one of the first and second values. And a terminal-side determination unit that determines whether or not the server can be accessed. The terminal-side determination unit includes a terminal that includes the terminal-side determination unit. The NIC control unit activates the first NIC and deactivates the second NIC, and all the setting units of the plurality of terminals set the network address to the network address. First When the server side determination unit determines that the server cannot access at least one of the plurality of terminals in the normal setting, the NIC control unit determines that the second NIC is based on the normal setting. When the terminal side determination unit of the terminal determines that the server is not accessible, the setting unit of the terminal changes the network address from the first value to the second value. Change to

Network system according to claim 2 of the present invention is the network system according to claim 1, wherein in the normal setting, the terminal outputs a first signal to the line, the server-side determination unit, the Whether or not the server can access the terminal is determined based on whether or not the server has received the first signal.

Network system according to claim 3 of the present invention is the network system according to claim 2, wherein the server outputs a second signal to the line, the terminal-side determination unit, the terminal said second Whether the terminal can access the server is determined based on whether or not the signal is received.

The network system according to a fourth aspect of the present invention is the network system according to the third aspect , wherein the server is determined only when the server side determination unit determines that the server is accessible to the terminal. A second signal is output to the line.

Network system according to claim 5 of the invention is a network system according to claim 1, in the normal setting, the server outputs a first signal to the line, the terminal-side determination unit, the terminal Determines whether or not the terminal can access the server depending on whether or not the first signal has been received.

In the network system according to claim 6 of the present invention, the terminal outputs the second signal to the line only when the terminal side determination unit determines that the terminal is accessible to the server. 6. The network system according to item 5 , wherein the server side determination unit determines whether the server can access the terminal based on whether the server has received the second signal.

Network system according to claim 7 of the present invention, the terminal according to claim 1 to a network system according to claim 6, which is connected to the line adjacent to the second NIC When the server side determination unit determines that the server is accessible, the NIC control unit does not activate the second NIC.

In the network system according to an eighth aspect of the present invention, the server further includes a line failure determination unit that determines whether or not the failure has been removed from the line, and both the first and second NICs have When activated, the server sends a third signal from one of the first NIC and the second NIC to the other, and a fourth signal from the second NIC, respectively. The line failure determination unit determines whether or not the line has been removed according to whether or not the server has received the third signal on the other side, and the network address is the first address. The terminal-side determination unit of the terminal set to a value of 2 determines whether the terminal can access the server based on whether the terminal has received the fourth signal, respectively. claim 1 The network system according to any one of Motomeko 7, when the obstacles of the line has been removed line failure determination unit has determined, the NIC control unit only the second NIC non If the terminal-side determination unit of the terminal that is activated and the network address is set to the second value determines that the terminal cannot access the server, the setting of the terminal The unit changes the network address of the terminal from the second value to the first value.

Control method for a network system according to claim 9 of the present invention is provided with servers, a line, and a plurality of terminals connected to different positions on each of said line, said server, the network address is the first A first NIC (Network Interface Card) that permits access to the server from a terminal set to a value of only when it is active, and a terminal that has the network address set to a second value A second NIC that permits access to the server only when it is active, a server-side determination unit that determines whether the server can access the terminal, the first NIC, A NIC control unit that activates or deactivates each of the second NICs, and the NIC control unit activates the first NIC and deactivates the second NIC. If the server-side determination unit determines that the server cannot access the terminal set to the first value in the situation, the NIC control unit has the second NIC from the situation. activity, and each of said plurality of terminals, set the network address in one of said first and said second value, a setting unit capable of changing the one in the other, the terminal accesses the server A terminal-side determination unit that determines whether or not the terminal-side determination unit determines whether the terminal itself having the terminal-side determination unit can access the server. A control method for a network system connected between a first NIC and a second NIC, wherein the NIC control unit activates the first NIC, deactivates the second NIC, and All devices In the normal setting in which the setting unit sets the network address to the first value, when the server side determination unit determines that the server cannot access at least one of the plurality of terminals, When the second NIC is also activated in the NIC control unit from the normal setting and the terminal side determination unit of the terminal determines that access to the server is impossible, the setting unit of the terminal The network address is changed from the first value to the second value.

A network system control method according to a tenth aspect of the present invention is the network system control method according to the ninth aspect , wherein, in the normal setting, the terminal outputs a first signal to the line, and the server Determines whether the server can access the terminal based on whether the first signal is received or not.

A network system control method according to an eleventh aspect of the present invention is the network system control method according to the tenth aspect , in which the server outputs a second signal to the line, and the terminal transmits the second signal. The terminal side determination unit determines whether the terminal can access the server based on whether or not a signal has been received.

A network system control method according to a twelfth aspect of the present invention is the network system control method according to the eleventh aspect , wherein the server side determination unit determines that the server can access the terminal. Only the server is caused to output the second signal to the line.

A network system control method according to a thirteenth aspect of the present invention is the network system control method according to the ninth aspect , wherein, in the normal setting, the server outputs a first signal to the line. Whether or not the terminal can access the server is determined by the terminal-side determination unit depending on whether or not the first signal has been received.

According to a fourteenth aspect of the present invention, in the network system control method, the second signal is sent to the terminal only when the terminal-side determining unit determines that the terminal can access the server. 14. The method of controlling a network system according to claim 13, wherein the server side determines whether the server can access the terminal based on whether the server has received the second signal. Let the department judge.

A network system control method according to a fifteenth aspect of the present invention is the network system control method according to any one of the ninth to fourteenth aspects, wherein the line is adjacent to the second NIC. When the server side determination unit determines that the server is accessible to the terminal connected to the network, the second NIC is not activated in the NIC control unit.

According to a sixteenth aspect of the present invention, in the network system control method, the server further includes a line failure determination unit that determines whether or not a failure has been removed from the line, and the first NIC and the second NIC. When both are activated, the server receives a third signal from one of the first and second NICs toward the other, and a fourth signal from the second NIC. Each of the lines is output to the line, and the line failure determination unit determines whether the line has been removed from the failure depending on whether the server has received the third signal on the other side. The terminal-side determination unit of the terminal whose address is set to the second value determines whether the terminal can access the server based on whether the terminal has received the fourth signal. Each size Let, in the case where a control method of a network system according to any one of claims 9 to 15, wherein the disorder of the line has been removed line failure determination unit has determined, the NIC control unit Only the second NIC is deactivated, and the terminal-side determination unit of the terminal whose network address is set to the second value determines that the terminal cannot access the server. In this case, the setting unit of the terminal is caused to change the network address of the terminal from the second value to the first value.

According to the network system according to the first aspect of the present invention or the network system control method according to the ninth aspect , at the time of normal setting, a failure occurs in the line, and at least one of the plurality of terminals cannot access the server. However, the NIC control unit also activates the second NIC, and the setting unit of the at least one terminal changes the network address of the terminal from the first value to the second value. Will be able to access the server again.

According to the network system according to the second aspect of the present invention or the network system control method according to the tenth aspect , it is easy to determine whether or not the server can access the terminal.

According to the network system according to claim 3 or claim 5 of the present invention, or the network system control method according to claim 11 or claim 13 , it is easy to determine whether or not the terminal can access the server. is there.

According to the network system according to claim 4 or claim 6 of the present invention, or the network system control method according to claim 12 or claim 14 , the server and the terminal are linked to each other, and the NIC control unit on the server side The second NIC is activated, and on the terminal side, the setting unit changes the network address of the terminal from the first value to the second value. Thus, access recovery is quick.

According to the network system according to claim 7 of the present invention or the network system control method according to claim 15 , if the server can access a terminal connected to the line adjacent to the second NIC, Even if the server cannot access a terminal connected to the line on the first NIC side with respect to the terminal, no trouble has occurred in the line. Therefore, unnecessary settings are avoided by not activating the second NIC in the NIC control unit.

According to the network system according to the eighth aspect of the present invention or the control method for the network system according to the sixteenth aspect , it is easy to determine whether or not the line trouble has been removed. When the line trouble is removed, the network can be returned to the normal setting.

First embodiment.
1 and 2 conceptually show a network system according to the present embodiment. FIG. 1 shows a case where no failure has occurred in the line 100, and FIG. 2 shows a case where a failure has occurred at a position L 21 on the line 100.

  The network system includes a line 100, a server 2, and terminals 11-16. The server 2 has NICs 21 and 22, and the line 100 is connected between the NIC 21 and the NIC 22.

  Terminals 11 to 16 are connected to the line 100 at different positions L11 to L16 on the line 100, respectively. For example, as shown in FIG. 1, they are connected to the line 100 via connectors C1 to C6 provided at positions L11 to L16, respectively. Each of the connectors C1 to C6 has two terminals connected in series to the line 100 and one terminal connecting the terminals 11 to 16 to the line 100.

  FIG. 3 conceptually shows the configuration of the terminal 11. The terminal 11 has a control unit 111.

  The control unit 111 includes a terminal side determination unit 1111 and a setting unit 1112.

  The terminal side determination unit 1111 determines whether or not the terminal 11 can access the server 2.

  The setting unit 1112 can set the network address of the terminal 11 to one of the addresses Ad1 and Ad2, Ad1 (Ad2), and change the one to the other Ad2 (Ad1). The change of the addresses Ad1 and Ad2 by the setting unit 1112 is performed based on the determination of the terminal side determination unit 1111. Details will be described later.

  Similarly to the terminal 11, the terminals 12 to 16 also have control units 121 to 161 including terminal side determination units 1211 to 1611 and setting units 1212 to 1612, respectively.

  FIG. 1 shows a case where all the network addresses of the terminals 11 to 16 are set to the address Ad1. FIG. 2 shows a case where the network addresses of the terminals 11 to 13 are set to the address Ad1, and the network addresses of the terminals 14 to 16 are set to the address Ad2. In FIG. 1 and FIG. 2, the terminal whose network address is set to the address Ad1 is surrounded by a broken line 201, and the terminal whose network address is set to the address Ad2 is surrounded by a broken line 202.

  FIG. 4 conceptually shows the configuration of the server 2. The server 2 further has a control unit 23.

  The control unit 23 includes a server side determination unit 231 and a NIC control unit 232.

  The server side determination unit 231 determines whether the server 2 can access the terminals 11 to 16.

  The NIC control unit 232 activates or deactivates each of the NICs 21 and 22. The NICs 21 and 22 are controlled by the NIC control unit 232 based on the determination of the server side determination unit 231. Details will be described later. In FIGS. 1 and 2, the cases where the NICs 21 and 22 are activated are indicated by hatching.

  The NIC 21 permits access to the server 2 from the terminals 11 to 16 whose network address is set to the address Ad1 only when the NIC 21 is active. The NIC 22 permits access to the server 2 from the terminals 11 to 16 whose network address is set to the address Ad2 only when the NIC 22 is active.

  In FIG. 1, only the NIC 21 is activated and access to the server 2 by the terminals 11 to 16 is permitted by the NIC 21. In FIG. 2, both NICs 21 and 22 are activated, and the access to the server 2 by the terminals 11 to 13 is permitted by the NIC 21, and the access to the server 2 by the terminals 14 to 16 is permitted by the NIC 22.

  As shown in FIG. 1, when the NIC control unit 232 activates the NIC 21, deactivates the NIC 22, and the setting units 1112 to 1612 set all the network addresses of the terminals 11 to 16 to the address Ad1 (in this case) (Hereinafter referred to as “normal setting”), each of the terminals 11 to 16 can access the server 2 via the NIC 21.

  On the other hand, when a failure occurs at the position L21 on the line 100, access to the terminals 14 to 16 is blocked, so that the terminals 14 to 16 cannot access the server 2 with the normal setting.

  Therefore, as shown in FIG. 2, the NIC control unit 232 activates both the NICs 21 and 22, the setting units 111 to 113 set the network addresses of the terminals 11 to 13 to the address Ad1, and the setting units 114 to 116 to the terminals. Network addresses 14 to 16 are set to the address Ad2. Thereby, the terminals 11 to 13 can access the server 2 via the NIC 21, and the terminals 14 to 16 can access the server 2 via the NIC 22.

  Specifically, the server-side determination unit 231 determines that the server 2 cannot access the terminals 14 to 16 through the NIC 21 in the normal setting, and based on this, the NIC control unit 232 determines the NIC 22 from the normal setting. Is also active. On the other hand, the terminal side determination units 1411 to 1611 determine that the terminals 14 to 16 cannot access the server 2 via the NIC 21, and based on this, the setting units 1412 to 1612 determine the network addresses of the terminals 14 to 16. Is changed from the address Ad1 to the address Ad2.

  The above-described control can also be applied when a failure occurs at a position on the line 100 different from the position L21, for example. For example, when a failure occurs in the line 100 between the terminal 15 and the terminal 16, the terminal 16 and the server 2 cannot be accessed under normal settings. However, by applying the control described above to the terminal 16 and the server 2, the terminal 16 and the server 2 can be accessed via the NIC 22.

  Considering that the above control can be applied even when only the terminal 16 becomes inaccessible to the server 2, it can be grasped as follows. In other words, the server-side control among the above-described controls is performed when the server-side determination unit 231 determines that the server 2 cannot access at least one of the terminals 11 to 16. It also activates NIC22.

  According to the network system and the control method described above, a failure occurs in the line 100 during normal setting, and at least one of the terminals 11 to 16 (terminals 14 to 16 in the case of FIG. 2) cannot access the server 2. The NIC control unit 232 also activates the NIC 22, and the setting units 1412 to 1612 of the at least one terminal 14 to 16 change the network address of the terminals 14 to 16 from the address Ad1 to the address Ad2, respectively. Therefore, the terminals 14 to 16 can access the server 2 again.

  Below, control of the control part 23 of the server 2 and control of the control parts 111-116 of the terminals 11-16 are demonstrated in detail.

Second embodiment.
FIG. 5 is a flowchart showing a control method according to the present embodiment. In FIG. 5, the flow of control in the terminal 14 and the flow of control in the server 2 are indicated by solid arrows, and the relationship between the terminal 14 and the server 2 is indicated by broken arrows. The same applies to FIGS. 8 and 11 described in the second and third embodiments, respectively.

  6 and 7 show the relationship between time for transmission and reception of the signals S1 and S2. 6 and FIG. 7, the case where the signals S1 and S2 transmitted from the terminal 14 and the server 2 can be received by the server 2 and the terminal 14 is indicated by solid arrows, and the case where the signals S1 and S2 cannot be received by the server 2 and the terminal 14 Shown with dashed arrows. The same applies to FIGS. 9, 10, 12, and 13 described in the second and third embodiments, respectively. FIG. 6 shows a case where the line 100 has no failure, and FIG. 7 shows a case where the line 100 has a failure.

  In any of the following embodiments including the present embodiment, not only the case where a failure occurs in the line 100 and the signal S1 output from the terminals 11 to 16 to the line 100 reaches the server 2, but also the arrival The terminal 11 to 16 outputs the signal S1 to the line 100 toward the server 2 including the case where the terminal 11 to 16 does not transmit the signal S1 to the server 2. Similarly, when the server 2 outputs the signal S2 to the line 100 toward the terminal 14, the server 2 “transmits” the signal S2 to the terminal 14.

  In the normal setting, the terminal 14 transmits the signal S1 to the server 2 every predetermined time Δt1 (step 201). Specifically, the signal S1 is transmitted to the server 2 at time t11, and the signal S1 is transmitted to the server 2 every time a predetermined time Δt1 elapses from time t11 (time t31, t51,...) (FIG. 6). , FIG. 7). The signal S1 is transmitted by, for example, the transmission unit 112 (FIG. 3).

  In parallel with the transmission of the signal S1 from the terminal 14, the server 2 transmits the signal S2 from the NIC 21 to the terminal 14 every predetermined time Δt2 (step 301). Specifically, the signal S2 is transmitted to the terminal 14 at time t21, and the signal S2 is transmitted to the terminal 14 every time a predetermined time Δt2 has elapsed from time t21 (time t41, t61,...) (FIG. 6). , FIG. 7). The signal S2 is transmitted by, for example, the transmission unit 24 (FIG. 4).

  Whether the terminal 14 can access the server 2 via the NIC 21 based on whether or not the terminal S14 has received the signal S2 within a predetermined time Δt11 from a certain time (hereinafter, “Yes”). Or not (hereinafter referred to as “No”) (step 202). The signal S2 is received by, for example, the reception unit 113, and the reception unit 113 notifies the terminal side determination unit 1411 whether or not the signal S2 has been received (FIG. 3).

  According to such control, the terminal side determination unit 1411 can easily determine whether or not the terminal 14 can access the server 2.

  6 and 7, times t11, t31, and t51 are employed as the certain time. However, a time different from the times t11, t31, and t51 may be adopted.

  When the terminal side determination unit 1411 determines “Yes” in step 202, the terminal side determination unit 1411 executes step 202 again.

  FIG. 6 shows a case where the terminal 14 receives the signal S2 at times t211, t411, and t611. Since the times t211, t411, and t611 are within the predetermined time Δt11 from the times t11, t31, and t51 (that is, until the times t212, t412, and t612), the terminal side determination unit 1411 determines “Yes” in step 202. to decide.

  When the terminal side determination unit 1411 determines “No” in step 202, the setting unit 1412 changes the network address of the terminal 14 from the address Ad1 to the address Ad2 (step 203).

  FIG. 7 shows a case where a failure occurs in the line 100 at a certain time td between the time t31 and the time 311 (FIG. 2). In this case, the terminal 14 cannot receive the signal S2 within a predetermined time Δt11 from the time 31 (that is, until the time t412). Therefore, the terminal side determination unit 14 determines “No” in step 202, and based on this, the setting unit 1412 changes the network address of the terminal 14 from the address Ad1 to the address Ad2 (step 203).

  Whether the server 2 can access the terminal 14 via the NIC 21 based on whether or not the server-side determination unit 231 has received the signal S1 within a predetermined time Δt21 from a certain time (hereinafter referred to as “Yes”). , Whether or not (hereinafter referred to as “No”) is determined (step 302). The signal S1 is received by the receiving unit 25, for example, and the receiving unit 25 notifies the server-side determining unit 231 whether or not the signal S1 has been received (FIG. 4).

  According to such control, the server side determination unit 231 can easily determine whether or not the server 2 can access the terminal 14.

  6 and 7, times t21 and t41 are adopted as the certain time. However, a time different from the times t21 and t41 may be adopted.

  If the server-side determination unit 231 determines “Yes” in step 302, the server-side determination unit 231 executes step 302 again.

  FIG. 6 shows a case where the server 2 receives the signal S1 at times t311 and t511. Since the times t311 and t511 are within the predetermined time Δt21 from the times t21 and t41 (that is, until the times t312 and t512), the server side determination unit 231 determines “Yes” in step 302.

  When the server side determination unit 231 determines “No” in step 302, the NIC control unit 232 also activates the NIC 22 (step 303).

  Referring to FIG. 7, since the failure of the line 100 occurs at time td, the server 2 transmits from the terminal 14 to time t31 within the predetermined time Δt21 from time t21 (that is, until time 312). The received signal S1 cannot be received. Therefore, the server side determination unit 231 determines “No” in step 303, and based on this, the NIC control unit 232 activates the NIC 22 (step 303).

  According to the network system and the control method thereof according to the present embodiment, as in the first embodiment, the terminal 14 that has become inaccessible due to a failure in the line 100 at the time of normal setting is returned to the server 2 again. Will be accessible.

  If a failure occurs at the position L21 on the line 100 during normal setting, the terminals 15 and 16 also cannot access the server 2. However, similarly to the terminal 14, the setting units 1512 and 1612 can access the server 2 again via the NIC 22 by changing the network address of the terminals 15 and 16 from the address Ad1 to the address Ad2. become.

  In FIG. 7, the terminal 14 transmits the signal S1 every predetermined time Δt1 and the server 2 transmits the signal S2 every predetermined time Δt2 even after the time td when the line 100 has failed. However, after the terminal 14 executes step 203, the server 2 may stop transmitting the signals S1 and S2 after executing step 303, respectively.

  Returning to FIG. 5, after the NIC control unit 232 activates the NIC 22 (step 303), the server 2 transmits a packet from the NIC 21 to the NIC 22 (step 304). Only when the NIC 22 is activated, the server 2 transmits a signal S3 from the NIC 22 to the terminals 14 to 16 whose network address is set to the address Ad2 (step 307). Then, the process proceeds to step 305. For example, the control unit 23 detects that the NIC control unit 232 has activated the NIC 22, and causes the packet transmission unit 26 to transmit a packet and the transmission unit 28 to transmit a signal S3 (FIG. 4).

  The server 2 further includes a line failure determination unit 233 in the control unit 23 (FIG. 4). The line failure determination unit 233 determines whether or not the failure of the line 100 has been removed depending on whether or not the server 2 has received a packet at the NIC 22 (hereinafter referred to as “Yes”). Are respectively determined (step 305). Judging. For example, the packet reception unit 27 receives the packet (FIG. 4).

  If the line failure determination unit 233 determines “No” in step 305, the line failure determination unit 233 executes step 304 again. At this time, since the fault remains in the line 100, the server 2 and the terminals 14 to 16 are maintained with the changed settings.

  If the line failure determination unit 233 determines “Yes” in step 305, the NIC control unit 232 deactivates the NIC 22 (step 306).

  The terminal side determination units 1411 to 1611 of the terminals 14 to 16 whose network address is set to the address Ad2 determines whether the terminals 14 to 16 have received the signal S3, and the terminals 14 to 16 transmit to the server 2 via the NIC 22. Whether access is possible (hereinafter referred to as “Yes”) or not (hereinafter referred to as “No”) is determined (step 204).

  When the terminal side determination units 1411 to 1611 determine “Yes”, the terminal side determination units 1411 to 1611 execute step 204 again.

  When the terminal side determination units 1411 to 1611 determine “No”, the setting units 1412 to 1612 change the network addresses of the terminals 14 to 16 from the address Ad2 to the address Ad1 (step 205).

  Specifically, when the NIC 22 is deactivated, the server 2 does not transmit the signal S3 from the NIC 22. Then, the terminals 14 to 16 cannot receive the signal S3. Therefore, the terminal side determination units 1411 to 1611 determine “No” in step 205.

  According to such control, it is possible to easily determine whether or not the failure of the line 100 has been removed by the line failure determination unit. When the trouble of the line 100 is removed, the network system can be returned to the normal setting.

Third embodiment.
In the present embodiment, the network system described in the second embodiment is described. The network system transmits the signal S2 to the terminal 14 only when the server 2 receives the signal S1 from the terminal 14. To do.

  FIG. 8 is a flowchart showing a control method according to the present embodiment. 9 and 10 show the relationship between time for transmission and reception of the signals S1 and S2. 9 shows a case where the line 100 has no failure, and FIG. 10 shows a case where the line 100 has a failure.

  The terminal 14 transmits the signal S1 to the server 2 every predetermined time Δt1 in the same manner as in the second embodiment (step 201 shown in FIG. 5) (step 211).

  Whether or not the server-side determination unit 231 can receive the signal S1 within a predetermined time Δt22 from a certain time, so that the server 2 can access the terminal 14 via the NIC 21 (hereinafter referred to as “Yes”). (Hereinafter referred to as “No”) respectively (step 311). 9 and 10, time t22 (also time t42 in FIG. 9) is adopted as the certain time. However, a time different from the times t22 and t42 may be adopted.

  If the server-side determination unit 231 determines “Yes” in step 311, the server 2 transmits the signal S 2 from the NIC 21 to the terminal 14 (step 312), and the server-side determination unit 231 executes step 311 again. The The transmission of the signal S2 is performed by the transmission unit 24 based on, for example, a command from the server side determination unit 231 (FIG. 4).

  FIG. 9 shows a case where the server 2 receives the signal S1 at times t311 and t511. Since the times t311 and t511 are within the predetermined time Δt22 from the times t22 and t42 (that is, until the times t322 and t522), the server side determination unit 231 determines “Yes” in step 311.

  Then, at time t42 and t62 after time 311 and t511, the server 2 transmits a signal S2 to the terminal 14 (step 312).

  When the server side determination unit 231 determines “No” in step 311, the NIC control unit 232 also activates the NIC 22 (step 313).

  FIG. 8 shows a case where a failure occurs in the line 100 at a certain time td between the time t31 and the time t311 (FIG. 2). In this case, the server 2 cannot receive the signal S1 within the predetermined time Δt22 from the time t22 (that is, until the time t322). Therefore, the server side determination unit 231 determines “No” in step 311, and based on this, the NIC control unit 232 activates the NIC 22 (step 313).

  Whether the terminal 14 can access the server 2 via the NIC 21 based on whether or not the terminal-side determination unit 1411 has received the signal S2 within a predetermined time Δt12 from a certain time (hereinafter referred to as “Yes”). , Whether or not (hereinafter referred to as “No”) is determined (step 212). 9 and 10, times t11, t31, and t51 are employed as the certain time. However, a time different from the times t11, t31, and t51 may be adopted.

  If the terminal side determination unit 1411 determines “Yes” in step 212, the terminal side determination unit 1411 executes step 212 again.

  FIG. 9 shows a case where the terminal 14 receives the signal S2 at times t221, t421, and t621. Since the times t221, t421, and t621 are within a predetermined time Δt12 from the times t11, t31, and t51 (that is, until the times t222, t422, and t622), the terminal side determination unit 1411 determines “Yes” in step 212. to decide.

  If the terminal side determination unit 1411 determines “No” in step 212, the setting unit 1412 changes the network address of the terminal 14 from the address Ad1 to the address Ad2 (step 213).

  Referring to FIG. 8, since the failure of the line 100 occurs at time td, the server 2 cannot receive the signal S1 within the predetermined time Δt22 from the time t22, so that the server 2 receives the signal S2. Do not send. Then, the terminal 14 cannot receive the signal S2 within a predetermined time Δt12 from the time t31 (that is, until the time t422). Accordingly, the terminal side determination unit 1411 determines “No” in step 212, and based on this, the setting unit 1412 changes the network address of the terminal 14 from the address Ad1 to the address Ad2 (step 213).

  According to the control method of the network system according to the present embodiment, the server 2 and the terminal 14 are linked to each other, the NIC control unit 232 activates the NIC 22 on the server 2 side, and the setting unit 1412 receives the network address on the terminal 14 side. Is changed from the address Ad1 to the address Ad2. Thus, access recovery is quick.

  If a failure occurs at the position L21 on the line 100 during normal setting, the terminals 15 and 16 also cannot access the server 2. However, similarly to the terminal 14, the setting units 1512 and 1612 can access the server 2 again via the NIC 22 by changing the network address of the terminals 15 and 16 from the address Ad1 to the address Ad2. become.

  In FIG. 8, the terminal 14 transmits the signal S1 every predetermined time Δt1 even after the time td when the line 100 has failed. However, the terminal 14 may stop transmitting the signal S1 after step 213 is executed.

  As described in the second embodiment, it is desirable that the server 2 execute steps 304 to 307 after execution of step 313 and the terminals 14 to 16 execute steps 204 and 205 after execution of step 213, respectively. .

Fourth embodiment.
In the present embodiment, the network system described in the second embodiment is described. The network system transmits the signal S1 to the server 2 only when the terminal 14 receives the signal S2 from the server 2. To do.

  FIG. 11 is a flowchart showing a control method according to the present embodiment. 12 and 13 show the relationship with time for transmission and reception of the signals S1 and S2. FIG. 12 shows a case where the line 100 has no failure, and FIG. 13 shows a case where the line 100 has a failure.

  The server 2 transmits the signal S2 to the terminal 14 every predetermined time Δt2 in the same manner as in the second embodiment (step 301 shown in FIG. 5) (step 321).

  The terminal-side determination unit 1411 determines whether the terminal 14 can access the server 2 via the NIC 21 depending on whether or not the signal S2 has been received within a predetermined time Δt13 from a certain time (hereinafter referred to as “Yes”). , Whether or not (hereinafter referred to as “No”) is determined (step 221). 12 and 13, times t13 and t33 (also time t53 in FIG. 12) are adopted as the certain times. However, a time different from the times t13, t33, and t53 may be adopted.

  If the terminal side determination unit 1411 determines “Yes” in step 321, the terminal 14 transmits the signal S 1 to the server 2 (step 222), and step 221 is executed again by the terminal 14. The transmission of the signal S1 is performed by the transmission unit 112 based on, for example, a command from the terminal side determination unit 1411 (FIG. 3).

  FIG. 12 shows a case where the terminal 14 receives the signal S2 at times t211, t411, and t611. Since the times t211, t411, and t611 are within the predetermined time Δt13 from the times t13, t33, and t53 (that is, until the times t232, t432, and t632), the terminal side determination unit 1411 determines “Yes” in step 221. To do.

  Then, at times t33 and t53 after times t211 and t411, the terminal 14 transmits a signal S1 to the server 2 (step 222).

  If the terminal side determination unit 1411 determines “No” in step 221, the setting unit 1412 changes the network address of the terminal 14 from the address Ad1 to the address Ad2 (step 223).

  FIG. 13 shows a case where a failure occurs in the line 100 at a certain time td between the time t21 and the time t211 (FIG. 2). In this case, the terminal 14 cannot receive the signal S2 within the predetermined time Δt13 from the time t13 (that is, until the time 232). Accordingly, the terminal side determination unit 1411 determines “No” in step 221, and based on this, the setting unit 1412 changes the network address of the terminal 14 from the address Ad 1 to the address Ad 2 (step 223).

  Whether the server 2 can access the terminal 14 via the NIC 21 based on whether or not the server-side determination unit 231 has received the signal S1 within a predetermined Δt23 from a certain time (hereinafter referred to as “Yes”). Whether or not (hereinafter referred to as “No”) is determined (step 322). 12 and 13, times t21 and t41 are adopted as the certain time. However, a time different from the times t21 and t41 may be adopted.

  If the server-side determination unit 231 determines “Yes” in step 322, the server-side determination unit 231 executes step 322 again.

  FIG. 12 shows a case where the server 2 receives the signal S1 at times t331 and t531. Since the times t331 and t531 are within the predetermined time Δt23 from the times t21 and t41 (that is, until the times t332 and t532), the server side determination unit 231 determines “Yes” in step 322.

  If the server side determination unit 231 determines “No” in step 322, the NIC control unit 232 also activates the NIC 22 (step 323).

  Referring to FIG. 13, since the failure of the line 100 occurs at time td, the terminal 14 cannot receive the signal S2 within the predetermined time Δt13 from the time 13, and therefore does not transmit the signal S1. . Then, the server 2 cannot receive the signal S1 within a predetermined time Δt23 from the time t21 (that is, until the time t332). Therefore, the server-side determination unit 231 determines “No” in step 322, and based on this, the NIC control unit 232 activates the NIC 22 (step 323).

  According to the control method of the network system according to the present embodiment, the server 2 and the terminal 14 are linked to each other, the NIC control unit 232 activates the NIC 22 on the server 2 side, and the setting unit 1412 receives the network address on the terminal 14 side. Is changed from the address Ad1 to the address Ad2. Thus, access recovery is quick.

  If a failure occurs at the position L21 on the line 100 during normal setting, the terminals 15 and 16 also cannot access the server 2. However, similarly to the terminal 14, the setting units 1512 and 1612 also change the network address of the terminals 15 and 16 from the address Ad1 to the address Ad2, so that the server 2 can be accessed again via the NIC 22. Become.

  In FIG. 13, the server 2 transmits the signal S2 every predetermined time Δt2 after the time td when the failure occurs in the line 100, and the server 2 transmits the signal S2 every predetermined time Δt2. However, the server 2 may stop transmitting the signal S2 after step 323 is executed.

  As described in the second embodiment, it is desirable that the server 2 execute steps 304 to 307 after execution of step 323, and the terminals 14 to 16 execute steps 204 and 205 after execution of step 223, respectively. .

  In any of the above-described embodiments, when the server 2 can receive the signal S1 transmitted from the terminal 16 in the normal setting, it receives at least one of the signals S1 from the other terminals 11-15. Even if it is not possible, it is desirable that the NIC control unit 232 does not activate the NIC 22. This is because the terminal 16 is connected to the line 100 on the opposite side of the NIC 21 with respect to any of the other terminals 11 to 15, and therefore, when the server 2 can receive the signal S 1 from the terminal 16, the line 100 This is because there is a high possibility that no failure has occurred. It is understood that the terminal 16 is connected to the line 100 adjacent to the NIC 22.

  The case where the server 2 can receive the signal S1 from the terminal 16 and the server 2 cannot receive the signal S1 from the other terminals 11 to 15, for example, the case where the terminals 11 to 15 are not activated or a failure Etc. can be assumed.

  According to such control, unnecessary settings are not performed when a failure has not occurred in the line 100.

It is a figure which shows notionally the network system demonstrated by 1st Embodiment. 6 is a diagram illustrating a case where a failure occurs at a position L21 on the line 100. FIG. 2 is a block diagram conceptually showing the structure of a terminal 11. FIG. 2 is a block diagram conceptually showing the structure of a server 2. FIG. It is a figure which shows the flow of the control method of the network system demonstrated by 2nd Embodiment. It is a figure which shows the relationship with time about transmission / reception of signal S1, S2. It is a figure which shows the relationship with time about transmission / reception of signal S1, S2. It is a figure which shows the flow of the control method of the network system demonstrated by 3rd Embodiment. It is a figure which shows the relationship with time about transmission / reception of signal S1, S2. It is a figure which shows the relationship with time about transmission / reception of signal S1, S2. It is a figure which shows the flow of the control method of the network system demonstrated by 4th Embodiment. It is a figure which shows the relationship with time about transmission / reception of signal S1, S2. It is a figure which shows the relationship with time about transmission / reception of signal S1, S2.

Explanation of symbols

2 Server 11-16 Terminal 21, 22 NIC
100 line 231 server side determination unit 232 NIC control unit 233 line failure determination unit 1111 to 1611 terminal side determination unit 1112 to 1612 setting unit Ad1, Ad2 network address (first and second values)
S1-S3 signal

Claims (16)

Server,
And times lines,
A plurality of terminals each connected to a different location on the line;
With
The server
A first NIC (Network Interface Card) that permits access to the server from a terminal whose network address is set to a first value only when it is activated;
A second NIC that permits access to the server from a terminal whose network address is set to a second value only when it is active;
A server-side determination unit that determines whether the server can access the terminal;
A NIC control unit that activates or deactivates each of the first NIC and the second NIC;
Have
The line is connected between the first NIC and the second NIC;
In the situation where the NIC control unit activates the first NIC and deactivates the second NIC, if the server cannot access the terminal set to the first value, the server side If the determination unit determines, the NIC control unit also activates the second NIC from the situation,
Each of the plurality of terminals is
A setting unit configured to set the network address to one of the first and second values, and to change the one to the other;
A terminal-side determination unit that determines whether the server is accessible;
Have
The terminal side determination unit determines whether the terminal itself having the terminal side determination unit can access the server;
In the normal setting in which the NIC control unit activates the first NIC and deactivates the second NIC, and all the setting units of the plurality of terminals set the network address to the first value. ,
When the server-side determination unit determines that the server is inaccessible to at least one of the plurality of terminals, the NIC control unit also activates the second NIC from the normal setting,
When the terminal-side determination unit of the terminal determines that the server cannot be accessed, the setting unit of the terminal changes the network address from the first value to the second value. .   In the normal setting, the terminal outputs a first signal to the line,
  The network system according to claim 1, wherein the server side determination unit determines whether the server can access the terminal based on whether the server has received the first signal.   The server outputs a second signal to the line;
  The network system according to claim 2, wherein the terminal side determination unit determines whether or not the terminal can access the server based on whether or not the terminal has received the second signal.   The network system according to claim 3, wherein the server outputs the second signal to the line only when the server-side determination unit determines that the server is accessible to the terminal.   In the normal setting, the server outputs a first signal to the line,
  The network system according to claim 1, wherein the terminal-side determination unit determines whether the terminal can access the server based on whether the terminal has received the first signal.   The network system according to claim 5, wherein the terminal outputs a second signal to the line only when the terminal side determination unit determines that the terminal can access the server.
  The server-side determination unit determines whether the server can access the terminal based on whether the server has received the second signal.   When the server side determination unit determines that the server can access the terminal connected to the line adjacent to the second NIC, the NIC control unit activates the second NIC. The network system according to any one of claims 1 to 6, wherein:   The server
  Line failure determination unit for determining whether or not the failure has been removed from the line
Further comprising
  When both the first and second NICs are active, the server sends a third signal from one of the first and second NICs to the other, A fourth signal from each of the two NICs to the line,
  The line failure determination unit determines whether the failure has been removed from the line depending on whether the server has received the third signal on the other side;
  The terminal side determination unit of the terminal in which the network address is set to the second value determines whether the terminal can access the server based on whether the terminal has received the fourth signal. Judge each
  When the line failure determination unit determines that the line failure has been removed, the NIC control unit deactivates only the second NIC,
  When the terminal-side determination unit of the terminal whose network address is set to the second value determines that the terminal cannot access the server, the setting unit of the terminal The network system according to any one of claims 1 to 7, wherein the network address of the terminal is changed from the second value to the first value.   Server,
  Line,
  A plurality of terminals respectively connected to different positions on the line;
With
  The server
    A first NIC (Network Interface Card) that permits access to the server from a terminal whose network address is set to a first value only when it is activated;
    A second NIC that permits access to the server from a terminal whose network address is set to a second value only when it is active;
    A server-side determination unit that determines whether the server can access the terminal;
    A NIC control unit that activates or deactivates each of the first NIC and the second NIC;
Have
  In the situation where the NIC control unit activates the first NIC and deactivates the second NIC, if the server cannot access the terminal set to the first value, the server side If the determination unit determines, the NIC control unit also activates the second NIC from the situation,
  Each of the plurality of terminals is
  A setting unit configured to set the network address to one of the first and second values, and to change the one to the other;
  A terminal-side determination unit that determines whether or not the server is accessible;
Have
  The terminal side determination unit determines whether the terminal itself having the terminal side determination unit can access the server;
  The line is a control method of a network system connected between the first and second NICs,
  In the normal setting in which the NIC control unit activates the first NIC and deactivates the second NIC, and all the setting units of the plurality of terminals set the network address to the first value. ,
  When the server-side determination unit determines that the server is inaccessible to at least one of the plurality of terminals, the NIC control unit is also activated from the normal setting by the second NIC,
  A network that causes the setting unit of the terminal to change the network address from the first value to the second value when the terminal-side determination unit of the terminal determines that the server is inaccessible How to control the system.   In the normal setting, the terminal outputs a first signal to the line,
  10. The network system control method according to claim 9, wherein the server-side determination unit determines whether the server can access the terminal based on whether the server has received the first signal. 11. .   Causing the server to output a second signal to the line;
  The network system control method according to claim 10, wherein the terminal-side determination unit determines whether the terminal can access the server based on whether the terminal has received the second signal. .   12. The network system control method according to claim 11, wherein the server outputs the second signal to the line only when the server side determination unit determines that the server is accessible to the terminal.   In the normal setting, the server outputs a first signal to the line,
  The network system control method according to claim 9, wherein the terminal-side determination unit determines whether the terminal can access the server based on whether the terminal has received the first signal.   14. The network system control method according to claim 13, wherein the terminal outputs a second signal to the line only when the terminal side determination unit determines that the terminal can access the server. And
  A control method for a network system, which causes the server-side determination unit to determine whether or not the server can access the terminal depending on whether or not the server has received the second signal.   When the server-side determination unit determines that the server can access the terminal connected to the line adjacent to the second NIC, the second NIC is activated in the NIC control unit. The method of controlling a network system according to any one of claims 9 to 14, which is not allowed to be performed.   The server
  Line failure determination unit for determining whether or not the failure has been removed from the line
Further comprising
  When both the first and second NICs are active, the server sends a third signal from one of the first and second NICs to the other. A fourth signal from each of the two NICs to the line,
  The line failure determination unit determines whether or not the failure has been removed from the line depending on whether the server has received the third signal on the other side,
  Whether or not the terminal can access the server depending on whether or not the terminal has received the fourth signal in the terminal-side determination unit of the terminal in which the network address is set to the second value. The network system control method according to any one of Claims 9 to 15, wherein
  If the line failure determination unit determines that the line failure has been removed, the NIC control unit is deactivated only the second NIC,
  When the terminal-side determination unit of the terminal in which the network address is set to the second value determines that the terminal cannot access the server, the setting unit of the terminal A control method of a network system, wherein the network address of the terminal is changed from the second value to the first value.

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