JPH0642672B2 - Priority communication control method - Google Patents

Description

The present invention relates to a priority communication control method, and more particularly to a priority communication control method for controlling transfer of communication right based on communication priority designation information in a token.

[Prior Art] A so-called local area network "LAN" in which a large number of transmission devices (hereinafter referred to as nodes) are connected to share one transmission line and data communication is performed between these nodes.
Is thriving.

An example of the system configuration of this LAN is shown in FIG.

In the figure, reference numeral 1 denotes transmission lines 100 to 160, which are nodes A to G constituting a LAN. Each node A to G (100 to 160)
Host A to G (2
00 to 260) are connected.

Among various communication methods in the LAN, the token passing method is particularly excellent in that the communication service can be uniformly provided to all the nodes even when the network is in a high traffic state.

However, in a bus-type LAN, usually one transmission line is shared by each node, so if transmission is allowed in each node without management, a state occurs in which two or more nodes simultaneously transmit. The so-called "collision" in which data on the transmission line interferes
The phenomenon occurs.

For this reason, a communication control code called "token" which is a communication right transfer instruction is circulated in the network system so that only the node that acquires (receives) this token acquires the transmission right to transmit data. However, the occurrence of this collision phenomenon is prevented.

That is, the node acquires the transmission right only when it receives the token, and executes a series of communication processing at this time if transmission is necessary. Then, this token is passed (transmitted) to the next node at the time when this transmission processing ends, or when the transmission processing is unnecessary.

In this way, the token is handed over to the next node after each transmission of the node that has acquired the token, but this way of passing is considered to circulate all nodes in the network. Each node in the work is evenly provided with communication chances, that is, communication services.

FIG. 8 shows the state of token circulation in the network system shown in FIG.

In the token bus system, each node is connected to one common transmission line, and a token circulates in the node address order, for example, according to a node address unique to each node.

By the way, the network system naturally has a node which becomes inoperable due to power failure or failure. When one node constituting the network system goes down, the token disappears at this node and the token cannot be sent to the next node. For this reason, the token is not circulated as it is, and a serious situation occurs in which communication is impossible at any node in the network.

Furthermore, there is a circumstance that it is not possible to refuse the existence of an inoperable node in a network even though it is not a failure. In other words, in the network, the arrangement of devices and offices connected to it is widely distributed, so it is more convenient for the user to partially start the nodes in the network than to start them all at once. Moreover, it is more convenient that the nodes of the devices for which operations have been completed can be individually powered down. In these cases, the operation of the network will be carried out while partially including the inoperable node.

Considering the above, it should be possible that there is always a change in the configuration of operable and impossible nodes in the network.
Following this, each node in the network always monitors the state of the downstream node to which the token should be passed next, and if it is found that the downstream node has become inoperable,
Immediately, it is necessary to remove this node from the network configuration (remove from the token ring), that is, perform degenerate operation, select another appropriate node as the node to which the token should be passed thereafter, and switch to this.

Furthermore, if a node with an intermediate address value between the node that has passed the token up to now and the own node is newly enabled and ready to enter the network (receive the token), It is necessary to switch the downstream node that should pass the token to this new node.

On the other hand, in the case of the token ring system, the transmission path is connected only to the nodes adjacent to each other, and when the token is received from one node, the token is next sent to the other node. In other words, the tokens are physically passed to the adjacent node in sequence, but since the network has a ring shape, it automatically orbits in the network. Both methods are the same in that the tokens evenly orbit all the nodes in the network.

[Problems to be Solved by the Invention] In this way, each node can receive an equal communication service by the circulation of tokens. For example, it seems that a host computer or a file device is connected to a node in a network. In such cases, the frequency of occurrence of these communication requests is extremely high compared to other general terminals.

Even in such a case, in the conventional communication method, the transmission right (token) circulates to all the nodes only evenly, the transmission of necessary data is delayed, and the processing efficiency of the entire network system is deteriorated. There was a drawback that it would end up.

[Means for Solving the Problems] The present invention has been made for the purpose of solving the above problems, and includes the following configuration as one means for solving the above problems.

That is, in a priority communication control method of a network system in which a plurality of transmission devices are connected via a communication medium and only the transmission device that has acquired the communication right by the token that is a communication right transfer command obtains the transmission right, A network configuration table that contains priority designation information that designates the priority of tokens, and that stores information about the transmission devices that make up the network, including the priority information for each transmission device, in each transmission device that makes up the network And a priority information holding means for holding the priority information of its own device, and according to the network configuration table, the token is provided only to the transmission device having a priority equal to or higher than the designated priority of the priority designation information in the token. A transmission device that circulates the token while changing the priority designation information in the token when the transmission right acquisition token circulates a predetermined number of times And a token control means for changing.

Then, for example, the token control means, when receiving a token addressed to its own device, a comparison means for comparing whether or not the priority designation information in the received token is equal to or more than the priority information held in the priority information holding means, As a result of the comparison by the comparison means, a transmission right acquisition means for acquiring a transmission right when the priority designation information in the received token is equal to or higher than the priority information held in the priority information holding means, and the transmission right acquisition means transmits When the token that has acquired the right circulates a predetermined number of times, the priority designation information in the token is changed, and the priority information of each transmission device in the network configuration table is equal to or higher than the priority of the changed priority designation information. A first transmission right delegating means for delegating a transmission right by a device to generate a token for a transmission device capable of delegating the transmission right, and the priority in the reception token as a result of the comparison by the comparison means. If the designated information is not equal to or higher than the priority information held in the priority information holding means, the transmission right is addressed to the next transmission device according to the network configuration table without acquiring the transmission right in the own device. Second transmission right delegating means for generating the token and delegating the transmission right.

[Operation] With the above-described configuration, it is possible to provide a network system with high transmission efficiency, in which the opportunity to acquire the communication right is changed according to the communication amount of the transmission device, and the communication right (transmission right) can be efficiently distributed. .

Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of a node according to an embodiment of the present invention. In the figure, 1 is a network transmission line of a LAN, 2 is a node which is a transmission control device, and 3 is various computer equipment and office equipment connected to the node 2.

The node 2 is a transmission circuit 11 / reception circuit 12 that performs data communication with the transmission line 1, a token determination circuit 4 that determines whether or not the data received by the reception circuit 12 is a token, the overall control of the node, and the transmission data A control unit (hereinafter referred to as CPU) 5 for performing processing, decoding of received data, disassembly, timing control of communication operation, etc., a memory circuit 6 for storing transmitted / received data, etc., and an interface circuit 7 with the host 3, An address setting unit 8 and a priority information holding unit 9 configured by a switch or the like for setting a unique address number for a node, comparing priority information in a token with priority information held in the priority information holding unit 9 A network structure for storing the comparison circuit 10, the destination address discrimination circuit 13, the address information of each constituent node of the network, and the priority information held by each node. It is constructed from the table 14. The address value set in the address setting unit 8 and the node information in the network configuration table 14 are read by the CPU 5 and used as a destination address and a source address during transmission / reception.

The data to be transmitted from the host 3 is temporarily stored in the memory circuit 6 in the node 2 and is appropriately formatted (packetized) as communication data, and the destination node address from the network configuration table 14 is set as the destination. After adding the address value and the setting value of the address setting circuit 8 as the source address, the receiving circuit 11 receives the token addressed to the own node, and holds the priority information holding unit 9 of the own device based on the priority information. Information has a high priority and can be transmitted to the transmission line 1 via the transmission circuit 12 only when the transmission right is acquired.

On the other hand, the other node receives the communication data on the transmission path 1, the destination address determination circuit 13 checks the destination address value in the received data, and the setting value of the address setting circuit 8 in the own node, that is, the destination address If it is judged that the data is data, this is notified to the CPU 5, this data is taken into its own node, and after some decomposition and editing processing is performed by the CPU 5,
It delivers to the connected host 3.

Further, in the token passing method, all the data flowing on the transmission line 1 is not only communication data between the hosts 3 but also only between the CPU itself in each node such as a token and the CPU of the partner node. So-called communication control data is also included.

Based on the above hardware configuration and the principle of token passing described above, each node in the network transfers tokens to downstream nodes one after another, so that communication that shares one transmission line is performed. is there.

The network system configuration of this embodiment will be described below with the configuration shown in FIG.

The structure of the transmission frame circulating in the network system of this embodiment is shown in FIGS.

In the figure, 200 is a token frame, 201 is a source address (hereinafter referred to as SA), 202 is a destination address (hereinafter referred to as DA), 203 is a token code representing a token frame, 204 is a priority designation code, and 205 is A transmission code representing a data frame, and 206 is transmission information.

The data transmission control of this embodiment will be described below with reference to the flow chart of FIG.

First, in step S1, it is monitored whether or not a transmission frame is received from the transmission line 1. When the transmission frame is received, the process proceeds to step S2, and the destination address discrimination circuit 13 is set in the DA 202 and the address setting circuit 8 in the reception frame. Compared with the own node address value. If the two values do not match, that is, if the transmission frame is not addressed to the own node, the process returns to step S1 to prepare for reception of the transmission frame addressed to the next node.

In the case of the transmission frame addressed to the own node, the process proceeds to step S4, and the transmission code area (203, 205) in the transmission frame received by the token discriminating circuit 4 being energized is examined to see whether it is the token code 203 or not. When the token frame is received, the process proceeds to step S5 and the comparison circuit 1
0 is activated and the priority designation code 204 and the data held in the priority information holding unit 9 are compared. As a result, when the priority of the own node is higher, the process proceeds to step S7, the transmission right is acquired by the reception token, and in step S8 there is data to be transmitted from the host 3 or the own node, that is, a transmission request is made. It is checked whether or not there is, and if there is a transmission request, step S9.
The node address peculiar to the destination node to which the data is to be transmitted is set to DA202, the own node address set by the address setting circuit 8 is set to SA201, and then the transmission code 205 and the transmission information 206 are set. Generate a transmission frame 250, step S1
At 0, the data transmission frame 250 is transmitted to the transmission destination node according to a predetermined transmission control procedure.

When the data transmission process is completed, the process proceeds to step S11 to execute the priority designation process described later to obtain the priority designation code to send the token and the downstream node address, and then in step S12, the SA201 sends its own node address. , A token code is set in 203, and the node address DA202 and the priority designation code 204 are set to the destination node address and the priority designation code determined by the priority designation processing in step S11.
This token frame 200 is generated, and this is transmitted to the transmission line 1
, And after transferring the transmission right, the process returns to step S1.

On the other hand, the token frame 200 received in step S6
If the priority designation code 204 is higher than the priority of holding in the priority information holding unit 9 of the own node, it is a token sent by mistake, and it is not permitted to acquire the transmission right, and step S12 Then, the token frame is immediately generated and the token is sent to the downstream node. If there is no transmission request in step S8, the process proceeds to step S11 to send the token to the downstream node.

If the token is not received in step S4, the process proceeds to step S20, the data transmission frame 250 addressed to the own device is received in the own node according to a predetermined transmission control procedure, and the transmission information received in step S21 is the host 3 If it is the information to be sent to the host 3, if it is the information to be sent to the host 3, the process proceeds to step S22, and after some decomposition and editing of this information, it is sent to the host 3 connected to this node, The procedure returns to step S1 to prepare for the next data transmission.

If it is not the data to be transmitted to the host 3, that is, if it is the communication data between the nodes, the process proceeds to step S30,
The process corresponding to each received data is performed, and then the process returns to step S1.

The communication data between the nodes includes the node address of the joining node sent by group broadcast communication when each node newly joins the network, the priority designation information held in the nodes, and the like. In this case, this priority designation information is stored in the network configuration table 14.
Also included is a request for transmission of network configuration table information from a newly joining node.

Thus, in this case, the priority designation information added to the token information has a filter-like role of selecting a node that can receive the communication service.

The token priority designation process in the above description will be described below with reference to the flow chart of FIG.

First, in step S60, the token cycle number register in the memory circuit 6 is read, and in step S61 it is checked whether the register is "0". Here, if the register is “0”, that is, if the token circulation is the first order, step S
In step S63, the priority designation level is selected as "3", and in the subsequent step S63, the network configuration table 14 has a value equal to or higher than the own node address among the nodes having the priority designation level "3" or higher. And the node closest to its own node address is selected as the downstream node. When there is no corresponding node, the node having the smallest node address and the priority designation level of "3" or higher is selected as the downstream node.

Then, in step S64, the token cycle number register is incremented by 1, and in step S65 it is checked whether or not the token cycle number register is "3". If "3", the token cycle number register is set to "0" in step S66. Then, the process ends. If the token cycle number register is not "3" in step S65, the process is terminated.

If the register is not "0" in step S61, the process proceeds to step S67 to check whether the register is "1". If the register is "1", that is, the token circulation is 2
In the case of the order, the process proceeds to step S68, the priority designation level is selected as "2", and in the following step S69, the own node address is selected from the nodes having the priority designation level "2" or more from the network configuration table 14. A node having the above value and closest to its own node address is selected as a downstream node. When there is no corresponding node, the node having the lowest node address and the priority designation level of "2" or higher is selected as the downstream node. Then, the process proceeds to step S64.

When the register is not "1" in step S67, that is, when the token circulation is the third cycle, the process proceeds to step S70, the priority designation level is selected to "1", and in the following step S71, the network configuration table 14 is used. Among the nodes whose priority designation level is “1” or higher, the node having the value equal to or higher than the self-node address and closest to the self-node address is selected as the downstream node. When there is no corresponding node, the node having the lowest node address and the priority designation level of "1" or higher is selected as the downstream node. Then, the process proceeds to step S64.

The token circulation of the present embodiment by the above processing is shown in FIGS. 5A to 5C, taking the case where the network system configuration is that shown in FIG. 6 as an example.

In this embodiment, the holding level of the priority information holding unit 9 of each node is the level shown in the table below.

The node acquiring the transmission right at the level "3" is shown in FIG. 5A, the node acquiring the transmission right at the level "2" is shown in FIG. 5B, and the node acquiring the transmission right at the level "1" is shown in FIG. Nodes that acquire the transmission right at this time are shown by diagonal lines in FIG. 5 (C).

As shown in the figure, the higher the level number, the higher the priority. In this way, level 3 nodes (for example, node C12
0) can acquire the transmission right three times more frequently than the level 1 node (for example, the node F150), and the level 2 node can acquire the transmission right twice as much as the level 1 node. .

In a node where the host connected to the node is connected to a device with a high communication load such as a host computer or a file device, by setting the node priority to a higher level, communication will be performed compared to other nodes. It is possible to proceed with the processing remarkably fast. The priority information holding unit 9 of the above-mentioned node
Is composed of a display switch, and any level from level 1 to level 3 can be set depending on the model of the connected host 3.

However, this priority information holding unit 9 does not necessarily have to set a fixed priority level by hardware, but can set a dynamic priority level to an optimum value by software. For example, at the start-up of the network, each node is temporarily activated with the communication priority set to a specific value (default value). And
When each node becomes able to communicate, a specific node (for example, node C120) sends priority setting data as communication data for each node, and each node sends the sent priority setting data to, for example, a RAM. It may be stored in the priority information holding unit 9 configured by.

The specific node (node C120) should be a node connected to a device having a non-volatile memory such as a file device as the host 3, and the priority information for all the nodes in the network should be registered in advance in this file device. Good.

FIG. 7 (A) shows an example of setting the priority level of the network at the time of start-up, after which the sending (setting) of the priority level information 208 to each node is completed, and the resetting of the priority level is completed. Is shown in FIG. 7 (B).

The set priority is shown in the frame of each node.
x is a default value which is a specific value.

From the state shown in FIG. 7A, the optimum priority information may be set in each node in consideration of the traffic volume of the network, etc., for example, the priority information shown in FIG. 7B. This setting is performed, for example, by the node C120 to which the file device is connected as the host 3 transmits the transmission frame 300 shown in FIG. 6, and the priority levels x ₁ to x ₆ are set to each node. Shows.

In this embodiment, if the priority of all the nodes is set to the highest level, the tokens evenly circulate through all the nodes during all crawls, and the same control as the conventional token circulate can be performed.

In the above description, an example has been described in which the node to which the token is next passed is changed and the priority designation code 204 in the token frame 200 is changed in each cycle in which the token circulates to its own node. Alternatively, it may be controlled to change every plural cycles.

On the other hand, the flow chart of Fig. 9 shows the network reconfiguration when a new node enters the network, and when the node that has constituted the network is dropped from the network due to the power stage or failure. Will be described below.

This process is performed at the same time as the token sending process of step S12 in FIG.

First, in step S40, the token is transmitted, and in step S4
In step 1, it is checked whether the token transfer is successful.
The means for identifying this is different depending on the transmission control procedure of each network, but for example, the node that receives the token returns an ACK response, which is a positive response, or the receiving node starts a new communication operation. Next, it is performed by determining that the source address of the communication data sent to the transmission line 1 is this downstream node address.

If the token transfer is successful, the process ends here.

If the token transfer is not normally performed in step S41, it is checked in step S42 whether or not the token has been transmitted for the second time, and if it is the first time, the process returns to step S40.
Execute the token re-send process. If the token is transmitted twice in step S42, the process proceeds to step S43. This is to deal with the case where the other node which has passed the token so far suddenly goes down (failure or power is turned off) and seeks out a new node to which the token should be transferred.

In step S43, the downstream node address is set to the set address of the self node regardless of the downstream node address so far, in step S44 this downstream node address is incremented by 1, and in step S45 this downstream node address is set as the destination. The token is transmitted with the priority level "1" (or x) as the address. Then, in a succeeding step S46, it is checked whether or not the token is successfully delivered. The means for identifying this is step S4.
The same as 1.

If the token is not normally sent to the downstream node (if the transmission fails), the partner node determines that the node cannot operate (communicate) and proceeds to step S48 to set the downstream node address value to the network. It is checked whether or not it is the maximum address value, and if it is not the maximum address value, the process returns to step S44, the downstream node address value is incremented by one again, and the token transmission is attempted using this new downstream node address value as the destination address.

Thus, the address value is gradually added, and then the token is transmitted to the node having the address value, and this operation is repeated until the token is received by any node.

If the token value is not successfully delivered even if the added address value reaches the maximum address value specified in the network, the process proceeds from step S47 to step S48 to set the downstream node address value to the minimum value specified in the network. The process returns to step S45 as the node address value. After that, the token passing and the address value adding operation are repeated.

If the token is successfully delivered, the process proceeds from step S46 to step S49, where this operation is stopped, the downstream node address value at that time is stored in the network configuration table 14, and the address time at that time is stored in the downstream node. Address.

Since the processing of the above operation requires time, this processing is not performed every time, but is performed only in a fixed cycle. When other normal token transfer is performed, the network configuration table 1
A new downstream node may be determined from the nodes stored in 4.

In addition, a node newly entering the network configuration needs to have its node circulate the token, and in order to realize this, the transmission frame on the transmission path 1 is monitored. For example, if the own node address is SA201, When the token code 203 is detected between the DAs 202, the data is sent out on the transmission path immediately to cause a "collision" with respect to the token frame 200, and the processes from step S43 onward in FIG. 9 may be executed.

If the nodes of the network are powered on at different times and start up in an inconsistent state, the count value of how many tokens are currently circulating in the network will vary. Becomes In this case, when the above-described embodiment is executed, it is not possible to perform unified control such that the entire network provides the communication service of the nodes having the same priority level or higher, but at least between the node and the node. As shown in FIGS. 5A to 5C, the higher the priority setting of the node, the more the transmission right can be acquired, and the communication opportunity can be obtained.

Furthermore, for such a network, it is possible to provide a unified priority service as a network by adding a synchronization means for making the count values of the token circulation cycle of all nodes the same.

To give an example of this synchronization means, global addressing provided in many networks (that is, means that can broadcast to all nodes in the network)
There is a method of sending a communication control command for initializing the cyclic count value of the token from a specific node in the network by using. Each node in the network that has received this communication control command initializes the cycle number count value of the token managed by the node until then to a unified specific value.

These processes are controlled so as to be included in the process of step S30 in FIG.

As a result, from the subsequent token circulation, all the nodes operate based on the same token circulation period value, so that a unified communication service with priority can be performed in the network.

In the above description, the token bus type network is used as a reference, but the present invention is not limited to this, and the present embodiment can be applied to a token ring type network configuration.

As described above, according to the present embodiment, token transfer can be performed reliably in any case, and even if token transfer cannot be performed normally, the network transmission can be performed without substantially impairing the data transmission efficiency. Can be rebuilt.

[Effects of the Invention] As described above, according to the present invention, each transmission device that constitutes a network is provided with a network configuration table that stores information about the transmission device that constitutes the network, and the priority designation in the token is performed. By making the token circulate only to the transmission device having a priority equal to or higher than the designated priority of the information, changing the priority designation information in the token when the token circulates a predetermined number of times, and also changing the transmission device that circulates the token. It is possible to provide a network system with high transmission efficiency, which can change the chance of acquiring the communication right according to the communication amount of the transmission device and efficiently distribute the communication right (transmission right).

[Brief description of drawings]

FIG. 1 is a block diagram of a node constituting a network system of an embodiment according to the present invention, FIGS. 2 (A) and 2 (B) are configuration diagrams of transmission frames used in this embodiment, and FIG. A general data transmission control flow chart in an example node, FIG. 4 is a priority designation processing flow chart in this embodiment, and FIGS. 5A to 5C are transmission right acquisition state diagrams of each node in this embodiment. FIG. 6 is a network reconfiguration processing flow chart in this embodiment, and FIGS. 7A and 7B are priority information setting state diagrams in each node of another embodiment according to the present invention, and FIG. Is a token circulation transition diagram of the token passing system, and FIG. 9 is a network reconfiguration processing flow chart of the present embodiment. In the figure, 1 ... Transmission line, 2,100 to 170 ... Node,
3 ... Host, 4 ... Token discrimination circuit, 5 ... CP
U, 6 ... Memory circuit, 8 ... Address setting circuit, 9 ...
... Priority information holding unit, 10 ... Comparison circuit, 11 ... Reception circuit, 12 ... Transmission circuit, 13 ... Destination address determination circuit, 14 ... Network configuration table, 203 ... Token code, 204 ... Priority designation code, 205 ...
… Transmission code.

Claims (2)

[Claims] 1. A priority communication control method for a network system, wherein a plurality of transmission devices are connected via a communication medium and only a transmission device which has acquired a communication right by a token which is a communication right transfer command obtains the transmission right. A network that stores the information of the transmission devices that make up the network, including the priority specification information that specifies the priority of the token, and that contains the priority information of each transmission device in each transmission device that makes up the network. A work configuration table, priority information holding means for holding priority information of the own device, and a transmission device having a priority equal to or higher than the designated priority of the priority designation information in the token according to the network configuration table. Only the token is circulated, and when the transmission right acquisition token circulates a predetermined number of times, the priority designation information in the token is changed to circulate the token. Priority control method characterized by comprising a token control means for changing the transmission apparatus. 2. The token control means, when receiving a token addressed to its own device, a comparison means for comparing whether or not the priority designation information in the received token is greater than or equal to the priority information held in the priority information holding means. A transmission right acquisition means for acquiring a transmission right when the priority designation information in the reception token obtained by the comparison means is equal to or higher than the priority information held in the priority information holding means, and the transmission right acquisition means When the token that has acquired the transmission right has circulated a predetermined number of times, the priority designation information in the token is changed, and the priority information of each transmission device in the network configuration table is equal to or higher than the priority of the changed priority designation information. First transmission right delegating means for delegating a transmission right by generating a token addressed to a transmission device that the self device can delegate the transmission right, and the priority in the reception token as a result of the comparison by the comparison means. If the designated information is not equal to or higher than the priority information held in the priority information holding means, the transmission right is addressed to the next transmission device according to the network configuration table without acquiring the transmission right in the own device. 2. The priority communication control method according to claim 1, further comprising: second transmission right transfer means for generating the token and transferring the transmission right.