JP2000244506A - Network having duplex transmission line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the reduction of a transmission quality by suppressing the deletion of high-priority information caused by fault occurrence on a network for transmitting high/low-priority information through a duplex transmission line. SOLUTION: The transmission line setting information of a high/low priority is received from a master transmission device 101 and respective slave transmission devices 102 transmit high-priority information 105 to a transmission line 103A and transmit low-priority information 106 to a transmission line 103B. On the assumption that any fault occurs in a transmission part 104A of slave transmission equipment 3 and the equipment is bypassed 108A, the master transmission equipment 101 detects bypass spots on the respective transmission lines from the alive information of the respective slave transmission devices 102 for each transmission cycle and when the number of bypasses on a transmission loop A exceeds the number of bypasses on a transmission loop B, the transmission line setting information is switched so that the transmission of the high- priority information 105 through the transmission line 103B is instructed as shown by a figure (b).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network system having a double transmission line, and more particularly to a transmission device having a bypass function when a transmission unit fails.

[0002]

2. Description of the Related Art Network conditions required for constructing a distributed system include high performance, high reliability and economy.
The ring network has a small number of transmission paths and is easy to construct a wide area network, and is therefore a promising candidate in conjunction with recent advances in LAN technology. As a ring network with such a double shared transmission path, IEICE technical report
SE79-120, "Data Highway System by Optical Fiber Communication (Page 94, FIG. 10)" discloses a method of bypassing a transmission unit when a failure occurs in the transmission unit.

According to this, when a failure occurs in one of the two transmission units of the transmission device, only the transmission unit in which the failure has occurred is separated from the ring transmission line, and the transmission line is secured by bypassing the gap. Transmission of another transmission device connected to the transmission path can be continued, and transmission performance of the entire network can be maintained.

[0004]

However, in the conventional bypass method of the transmission unit, there is no consideration for the importance of information transmitted on the dual shared transmission line. Now, in the transmission device connected to the dual transmission line of the A system and the B system, a failure occurs in the transmission unit A that transmits information having high priority (importance) to the transmission line of the A system,
It is assumed that the transmission unit B that transmits low-priority information to the transmission path of the system is normal. In this case, the high priority information is lost by the bypass of the transmission unit A, while the low priority information of the transmission unit B is continuously transmitted. When the number of bypasses in the network increases, a large amount of high-priority information may be lost as a result, and there is a problem that the transmission quality of the entire system may be significantly reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly reliable network having a double transmission line capable of overcoming the above-mentioned problems of the prior art and suppressing a decrease in transmission quality due to a bypass.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a network system in which a plurality of transmission devices having a function of bypassing a failed transmission unit are connected by a double transmission line. A device (hereinafter referred to as a parent transmission device) monitors a bypass state for each transmission line, and sets a transmission line having a smaller number of bypasses as high priority information and a transmission line having a larger number of bypasses as low priority information transmission line. Each of a plurality of child transmission devices (hereinafter, child transmission devices) distributes and transmits high-priority and low-priority child transmission information for each transmission path in accordance with the setting information.

In each transmission cycle, the child transmission information including the source address (SA) is transmitted from the two transmission units, and the parent transmission device transmits the transmission source address acquired from the child transmission information for each transmission path. It is characterized in that a bypass location is detected by an absent address. Note that the child transmission information may be alive information for each transmission unit of the child transmission device,
It may or may not depend on a data frame containing high / low priority information.

The transmission path setting information may include high / low information priority included in a transmission frame of the parent transmission apparatus,
Initial settings are made so that high-priority information is transmitted to one of the two transmission paths and low-priority information is transmitted to the other. The transmission path setting information may be a management frame issued separately instead of a data frame including high / low priority information.

Further, when the parent transmission device is in a bypass state, one child transmission device which first detects the bypass state has a configuration capable of acting as a parent transmission device.

The operation of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic configuration and operation of a network having a dual transmission line according to the present invention. One parent transmission apparatus 101 and a plurality of child transmission apparatuses 102-1 to 10-5 are connected by ring-type double transmission paths 103A and 103B.
03 to distribute the high / low priority information to the master transmission device 1
In accordance with the transmission path setting information issued from the communication unit 01, each child transmission apparatus 102 separates its own high / low priority information,
04A / B, high-priority information 105 on the transmission path 103 (A / B), and low-priority information 1 on the transmission path 103 (B / A).
06 is transmitted.

In FIG. 1A, high priority information 105 is transmitted on a transmission line 103A, and low priority information 106 is transmitted on a transmission line 103B. Now, it is assumed that a failure has occurred in the transmission unit 104A of the child transmission device connected to the transmission path 103A. Then, the bypass mechanism of the child transmission device operates, and the transmission path 10
3A and the transmission section 104A are separated, and the transmission path 103A is bypassed by the bypass 108A. The parent transmission device 101 monitors the bypass state of each transmission device 102 for each transmission line for each transmission line, and transmits the high-priority information to the transmission line 103.
When the bypass number of A exceeds the bypass number of the transmission line 103B, the transmission line setting information of the A system and the B system is switched.

FIG. 2B shows the state after the switching of the transmission path setting information. According to the switching setting from the parent transmission apparatus 101, each transmission apparatus 102 has the high priority information 105 on the transmission path 103B and the high priority information 105 on the transmission path 103A. The low priority information 106 is transmitted. As a result, the child transmission device in which the failure has occurred distributes the spontaneous high-priority information 105 to the transmission unit 104B for transmission.

FIG. 2 is a schematic functional block diagram showing a characteristic part of the transmission apparatus according to the present invention, wherein (a) is a parent transmission apparatus,
(B) is a child transmission device. The parent transmission device 101 includes transmission units 104A and 104B, a bypass control unit 113, an access control unit 114, and a priority control unit 115. The two transmission units 104A and B perform transmission and reception with the transmission paths 103A and 103B, respectively. The bypass control unit 113 includes the transmission unit 103A
When a failure of / B occurs, the switching unit 109 is operated to bypass the failure side. The access unit 114 receives transmission information from each transmission device 102 from the transmission units 104A and 104B, and sends out spontaneous transmission information every transmission cycle.

The priority control unit 115 is a feature of the present invention. The priority control unit 115 sets a transmission path for associating high / low priority information with transmission paths A / B, and a transmission path for transmitting high priority information. A
When the number of bypasses of / B) exceeds the number of other transmission paths (B / A), the transmission path setting of the A-system and the B-system is switched, and the transmission-path setting information is placed on the spontaneous transmission frame, and each child transmission apparatus 102
Notify.

The child transmission device 102 includes two transmission units 104
A, B, bypass control unit 113, access unit 114
And an information distribution control unit 116. Access unit 1
14 checks and branches the transmission frame, the transmission frame addressed to itself, and the transmission right of the parent transmission device 101. In addition, it transmits its own transmission frame every transmission cycle.

The information distribution control section 116
The transmission path setting information from one transmission frame is checked for each transmission path, and spontaneous high / low priority information is distributed for each of the transmission paths 103A and 103B according to the transmission path setting. Further, in the event of a failure of the parent transmission device 101, the function of the information distribution control unit 116 of the child transmission device 102 can be changed to the parent priority control unit 115 in order to take over the function of the parent.

As described above, the network of the present invention transmits different information to each of the dual transmission lines, and secures the transmission line of another transmission device by bypassing the failed transmission unit. Transmission efficiency can be improved. In particular, when two transmission paths are selectively used for high-priority and low-priority information transmission, transmission of a high-priority information is distributed to transmission paths with failures, that is, transmission paths with a small number of bypasses. The device can transmit high-priority information, thereby suppressing a decrease in transmission quality in the entire network and improving network availability.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, one embodiment of the present invention will be described in detail. In the embodiment of the network according to the present invention, as shown in FIG. 1 and FIG. 2, one parent transmission apparatus 101 and a plurality of distributed child transmission apparatuses 102
Are sequentially connected in series to form a loop network, and the two transmission paths 103A and 103B are selectively used according to the priority of transmission information. Transmission devices 101 and 102
Are two transmission units 104 that transmit and receive the transmission paths 103A and 103B.
The transmission unit 104A or 1 having A and B and having a failure
There is provided a switching unit 109 for disconnecting the transmission line 04B from the transmission line 103 and connecting the transmission line 04B with the bypass 108. The loop of the transmission line 103A is called an A system, and the loop of the transmission line 103B is called a B system.

FIG. 3 is a transmission time chart showing the loop access method of the network according to the present embodiment. Here, for the sake of simplicity, the case of GA polling is shown for a single loop in a double loop transmission line as a token path type loop access method.

In this system, the master transmission apparatus 101 in the loop network becomes a master (primary station mode in which no relay operation is performed), and the child transmission apparatus 102 (secondary station mode in which relay operation is performed) is generally GA (master station). A signal T indicating a transmission right called “Go Ahead” is supplied. When the transmission device 102 having the transmission request detects the transmission right T on the transmission path, it does not relay the transmission right downstream (that is, avoids simultaneous transmission by the transmission devices downstream from its own transmission device). Send When the frame transmission is completed, the transmission state returns to the relay state, so that T is transferred from the own transmission apparatus to the downstream transmission apparatus.

By sequentially shifting the transmission right T to the downstream without delay, transmission requests from all the transmission apparatuses are efficiently processed. When transmission of all transmission devices is completed, the parent transmission device 10
No. 1 requires generation of T again, which is called a transmission cycle, and has a fixed length in this example. In this figure, an example is shown in which all the transmission devices have a transmission request, and no transmission unit bypass occurs in the ring transmission path. The horizontal axis represents time, and the vertical axis represents the physical Each position is shown.

FIG. 4 shows an example of the format of the transmission information. The transmission information of the present embodiment includes an information frame Da.
ta, transmission right T, and the frame format is HDLC
(High level Data Link Control). Therefore, the symbol F in the figure is a flag indicating a frame boundary, D
A indicates a destination address, SA indicates a source address, C indicates a control byte, I indicates data, and FCS indicates an error detection unit.

The content of the control byte C is composed of PL and M,
The PL indicates the transmission priority of the data I, and two types of high and low can be set. For example, 1 is high priority information and 0 is low priority information. M is data for identifying the transmission frames of the parent transmission device and the child transmission device. The parent transmission device 101 sets the parent identifier in M of the transmission frame of its own, and sets 1 in the PL of the frame of the high priority information and 0 in the PL of the frame of the low priority information.
Is transmitted, for example, a transmission frame of high priority information is transmitted to the A system loop, and a transmission frame of low priority information is transmitted to the B system loop.

The transmission priority of the PL of the parent transmission frame distributed to the A-system and the B-system becomes transmission path setting information according to the present invention. That is, the transmission priority of the transmission paths A and B (high / low)
Irrespective of another management frame, the priority information of the transmission information of the parent transmission apparatus 101 is used as it is. According to this embodiment, the system configuration is simple, and the transmission performance of the network does not deteriorate.

The child transmission apparatus 102 knows which loop should transmit high priority information from the PL data of the transmission frame having the M identifier received from the A and B systems. Further, the child transmission device 102 confirms that its own transmission unit 104 is operating normally (alive state).
In order to notify the data frame No. 1, a Data frame in which the own address is added to the source address SA is issued in the transmission cycle. If there is no spontaneous transmission information, the destination address DA or data I
Becomes empty. The parent transmission apparatus 101 specifies a bypass occurrence portion from SAs that cannot be received among source addresses SA of all received information.

Next, the parent transmission device 101 and the child transmission device 10
2 will be described in detail. FIG. 5 shows the functional configuration of the parent transmission device, and more specifically shows FIG. 2A. The parent transmission device 101 accommodates a plurality of information devices 215 via a device interface 214, and enables transmission with any other information devices in the network. The transmission unit 206 and the reception unit 207 constituting the transmission unit 104 are provided for each of the transmission paths 103A and 103B, and execute transmission and reception of transmission information.

The access units 114A and 114B are connected to the transmission path 103
This function is for sharing A and B between a plurality of transmission devices, and performs a process of branching in own information from a reception transmission line and inserting spontaneous information into a transmission transmission line, as described later.
The transmission control 211 has a function of executing a transmission protocol process for transferring information, and is usually realized by software processing of a processor. The memory 212 is a storage part for processing programs of the processor and transmission information.

The network configuration control unit 201 is a function for controlling the switching of the transmission path. The network configuration control unit 201 previously stores the SAs (source addresses) of all the transmission devices, monitors the SAs of all the received frames, and determines whether or not the transmission unit is bypassed. And the bypass generation unit detection 202 that detects the location of the occurrence, and compares the number of bypass cases of the A-system and B-system transmission lines from the information of the location of the occurrence of the bypass. A transmission path setting 204 for setting high / low transmission priorities corresponding to transmission paths so as to distribute low priority information to a large number of transmission paths, and the transmission priorities, that is, transmission path setting information (in this embodiment, A transmission path notification 203 is provided for notifying each transmission apparatus by putting the high / low priority of the transmission information of the parent transmission apparatus) on the PL bit of the C field (control byte) of the Data frame.

The bypass control unit 113 and the switching unit 109 will be described later. The respective functional units except for the transmitting / receiving units 206 and 207 are connected to each other by an internal bus 213 so that information can be exchanged.

FIG. 6 is a functional block diagram of the child transmission device.
(B) is shown more specifically. Functions equivalent to those of the parent transmission device 101 are denoted by the same reference numerals, and detailed description is omitted. The child transmission device 102 accommodates a plurality of information devices 215 via a device interface 214, and enables transmission with any other information devices in the network.
The access units 114A and 114B are a transmission unit 206 and a reception unit 207.
Via the receiving transmission line, to take in the information addressed to itself,
A process for inserting spontaneous information into the transmission line is performed.

Network configuration control section 301 of child transmission apparatus 102
Is a function for controlling switching of the transmission paths 103A and 103B.
Transmission path setting information detection 302 for detecting transmission path setting information (transmission priority) from the PL bit of the C field of the parent transmission frame, and according to the transmission path setting information, the spontaneous high / low priority transmission information is transmitted to the A system. Transmission line allocation 303 for allocating which of the transmission lines to the transmission lines B and B, and the child transmission device 102
Is composed of the transmission path notification 203 which is not functioning.

The network configuration controller 3 of the child transmission device 102
01 is provided with the same function as the network configuration control unit 201 of the parent transmission device 101, and the child transmission device 102 that first detects that a failure has occurred in the parent transmission device 101 and that no parent transmission frame exists in the loop. Alternatively, it may be made to act instead. That is, the transmission path setting information detection 302 of the child transmission apparatus 102 that first detects the disappearance of the parent transmission frame instructs the transmission path notification 203 to start the function and the transmission path allocation 303 to change the function to the transmission path setting 203. Itself changes its function to bypass occurrence detection 202, becomes the parent transmission apparatus 101, and continues network transmission.

FIG. 7 is a functional block diagram of the access unit of the transmission device. Information received from the transmission paths 103A and 103B is taken into the access units 1145A and 1145B, and the access control 40
1. The data is supplied to the reception data buffer 402. The access control 401 is inserted in the transmission line 103 in series, and controls whether the own transmission apparatus transmits information or relays received information as it is. In the token pass type loop access method, this function is indispensable for acquiring the transmission right T and erasing the transmission information in a loop. The reception data buffer 402 is a temporary memory that includes a reception information filter at a stage before the input and selects and stores only target information.

On the other hand, a transmission right pattern buffer 403 and a transmission data buffer 404 which are temporary memories of transmission information.
Is the selector 4 together with the relay output of the access control 401.
05, only one of them is selected and output to the transmission path 103. These transmission timings are controlled by the access control 401. Each functional module except the selector 405 and the transmission right pattern buffer 403 is connected to the internal bus 213, and exchanges information with the network configuration control units 201 and 301, the transmission control 211, and the memory 212 shown in FIGS. It is possible.

FIG. 8 is a functional block diagram of the bypass unit of the transmission device. The bypass control unit 113 includes a transmission unit 206,
The transmission units 104A and 104B composed of the reception unit 207 are monitored, and if transmission or reception is not performed in each transmission cycle, that is, if a failure occurs in the transmission unit 104, the switching unit 10
By controlling 9A / B, the transmission unit 104A / B in which a failure has occurred is disconnected from the transmission line 103, and the transmission line 104A / B is connected by a bypass 108 therebetween.

FIG. 9 shows an operation flow of the parent transmission device according to one embodiment. First, the parent transmission apparatus 101 performs initial setting of transmission path setting information (s101). In each transmission cycle, the parent transmission device 101 transmits a parent transmission frame (Data frame) to the transmission paths 103A and 103B (s1).
02). The parent transmission frame carries a parent identifier M and a transmission priority (high / low) PL, and the PL after distribution to the transmission path is transmission path setting information. Next, transmission data from each child transmission device 102 is received from the transmission paths 103A and 103B (s10
3).

At the timing when the parent transmission frame has been received in one cycle, an absent source address SA is calculated from all the received data, and a bypass occurrence location is detected (s104).
Next, the number of bypasses of the transmission lines 103A and 103B are compared to determine whether or not the switching of the transmission line setting information is necessary (s10).
5). The transmission path 103A for which a high priority is currently set
If the number of bypasses of / B is larger than the other (B / A), switching is required, and the transmission path setting information of the A system and the B system is switched (s10).
6). Otherwise, keep the current transmission path setting information,
It returns to s102.

FIG. 10 shows an operation flow of the child transmission device. A parent transmission frame is received for each transmission cycle (s201), and transmission path setting information (PL) for each transmission path
(S202), and assigns the spontaneous high / low priority information to the transmission paths 103A and 103B corresponding to the transmission path setting information (PL) (s203), and according to the allocation, the transmission paths 103A and 103B.
Is transmitted (s204). The child transmission frame carries the source address SA and transmits the child transmission frame, which is used for detecting a failure occurrence location of the parent transmission device 101.

[0039]

According to the network of the present invention, when a plurality of transmission apparatuses are connected by a double transmission path and the high priority information and the low priority information of each transmission apparatus are transmitted for each transmission path, Each time a bypassed transmission unit is detected and control is performed so that high-priority information is transmitted on a transmission path with few bypasses, loss of high-priority information due to a failure can be suppressed, improving transmission quality and transmission efficiency. Has the effect of doing

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing one embodiment of a schematic configuration and operation of a network having a dual transmission line according to the present invention.

FIG. 2 is a configuration diagram showing one embodiment of schematic functions of a parent transmission device and a child transmission device.

FIG. 3 is a transmission time chart of a network showing a loop access method according to an embodiment.

FIG. 4 is an explanatory diagram of a format of transmission information according to one embodiment.

FIG. 5 is a functional configuration diagram of a parent transmission device according to one embodiment.

FIG. 6 is a functional configuration diagram of a child transmission device according to one embodiment.

FIG. 7 is a functional configuration diagram of an access unit according to one embodiment.

FIG. 8 is a functional configuration diagram of a transmission unit bypass mechanism according to one embodiment.

FIG. 9 is an operation flowchart of a parent transmission device according to one embodiment.

FIG. 10 is an operation flowchart of a child transmission device according to one embodiment.

[Explanation of symbols]

101: parent transmission device, 102: child transmission device, 103: transmission line, 104: transmission unit, 105: high priority information, 106
... low priority information, 108 ... bypass, 109 ... switching unit,
113: bypass control unit, 114: access unit, 115
.. Priority control unit, 116 information distribution control unit, 201 network configuration control unit, 202 bypass detection unit detection, 203 transmission line notification, 204 transmission line setting, 206 transmission unit, 20
7 receiving unit, 211 transmission control, 212 memory, 21
3: Internal bus, 214: Device interface, 215:
Information equipment, 301: network configuration control unit, 302: detection of transmission path setting information, 303: transmission path allocation.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takao Nouchi 5-2-1 Omikacho, Hitachi City, Ibaraki Prefecture Inside the Omika Plant, Hitachi, Ltd. (72) Inventor Takushi Hamada 5-chome, Omikamachi, Hitachi City, Ibaraki Prefecture No. 1 Hitachi, Ltd. Omika Plant (72) Inventor Yoshiaki Adachi 5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Omika Plant (72) Inventor Isao Terakado Omika, Hitachi City, Ibaraki Prefecture 5-2-1, Machi-machi Process Computer Engineering Co., Ltd. (72) Inventor Kazuo Kono 5-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture F-term (reference) 5K014 AA02 AA04 BA00 CA02 CA06 DA06 EA00 FA11 GA01 5K030 GA12 HC01 HD06 KX29 LE05 MB04 MD02 9A001 BB03 CC06 CC07 CC08

Claims (4)

[Claims] In a network in which a plurality of transmission devices having a function of bypassing a transmission unit in which a failure has occurred are connected by a double transmission line, one parent transmission device (hereinafter referred to as a parent transmission device) is provided for each transmission line. The bypass state is monitored, the one with the smaller number of bypasses is set as the transmission line of the high priority information, and the one with the larger number of the bypasses is set as the transmission line of the low priority information. A network having a dual transmission line, wherein each of the child transmission devices distributes and transmits child transmission information of high / low priority for each transmission line. 2. The child transmission information including a source address (SA) is transmitted from two transmission units in each transmission cycle, and the parent transmission device acquires from the child transmission information for each transmission path. A network having a dual transmission path, wherein a bypass point is detected by an address absent from the source address. 3. The transmission path setting information according to claim 1, wherein the transmission path setting information is a high / low information priority included in a transmission frame of the parent transmission apparatus, and a high priority is assigned to one of two transmission paths. A network with a dual transmission line that is initialized to transmit information and, on the other hand, low priority information. 4. The method according to claim 1, 2 or 3, wherein when the parent transmission device is in a bypass state,
A network having a double transmission path in which one child transmission device that first detects it has a configuration capable of acting as a parent transmission device.