JPS61253945A - Network control system - Google Patents

Abstract

PURPOSE:To follow the variation of a network constitution precisely under simple algorithm by starting a network reconstituting means every fixed number of times of reception of a communication right transfer instruction. CONSTITUTION:A lower node address is set up in a self-node setting address and a token is transmitted by using a lower node address subtracted by '1' as a destination address. If the token is not normally transmitted to the lower node, the self-node decides that the lower node is a communication disabled node, checks whether the lower node address value is the minimum address value fixed on the network or not, and if the value is the minimum address value, tries to transmit the token by using a new lower node address value again subtracted by '1' as the destination address. Thus, the transmission of the token to the node of the address value obtained by successively subtracting '1' from the preceding address is tried and the operation is repeated until the token is received by any one of nodes. Consequently, transmission control devices can be precisely combined under simple algorithm.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a network control method for a network system in which a plurality of transmission control devices are connected to a bus-type communication medium. The communication control device (hereinafter referred to as a node) is Wcnt, and local area network systems, so-called LANs, that perform data communication between these nodes are popular.Among the various communication methods in LAN, the token passing method is a network It is particularly excellent in that it can equally provide communication services to all nodes even under high traffic conditions, and therefore does not cause a drop in transmission efficiency.

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

In the figure, reference numeral 1 indicates transmission lines 100 to 160, which are nodes A to G constituting the LAN. Each 7-dore A to G (100 to 160)
There are hosts A to G (2) that process transmission information, respectively.
00 to 260) are connected. In general, bus LANs share a single transmission path, so if each mate is allowed to send calls without management, a situation will occur where two or more nodes will be transmitting at the same time, and the data on the transmission path will be A so-called "collision" phenomenon occurs in which there is interference between the two.

One method for preventing this is a token passing method. In contrast, in the token passing method, “
Transmission right delegation commands called tokens are exchanged between each node via the transmission path, and only the note that receives the token acquires the right to transmit (transmission right).
The node that receives this token performs a series of communication processes such as transmission processing at that point if necessary (if there is a transmission request), and then performs a series of communication processing such as transmission processing at that point, and when this processing is completed, or if there is no need for transmission processing at all. If there is no such token, a method of passing (sending) the token to the primary node to which it should be delegated is used to prevent collisions.

In this way, each time the transmission process at the node with the transmission request is completed, the "°°token" is passed to the next node and sequentially circulated among the 7 nodes in the network. The constituent nodes are given equal opportunities to acquire transmission rights, that is, opportunities to receive communication services.

There are two types of token cyclic control depending on the network configuration: the token ring method and the token bus method.In the token bus method, usually
The transmission path is formed by a single linear conductor, and transmission data sent from one node is transmitted almost simultaneously to all other nodes connected to the network transmission path (transmission path 1 in Figure 1). Received. Therefore, the destination node address is always attached to the beginning of the transmitted data, including the aforementioned token command, and this is compared with the address value uniquely assigned to each node, and the destination node address is compared with the address value uniquely assigned to each node. If the address matches the node address, the transmitted data is imported as data addressed to the own node, or after the transmitted data is imported indiscriminately, the above address comparison is performed. Treat it as data.

In this token bus system, the node (downstream node) to which a certain node should give a token next is generally r
The node closest to the day node address and with the smallest address value. However, for the node with the least number of addresses,
It is defined as "the node with the highest address value".

Now, as a matter of course, there are parts of a network system that become inoperable due to failure. This cannot be avoided no matter how expensive and highly reliable parts are used. When a failure of one part affects the operation of the entire system, it becomes a big problem.

If one of the nodes making up the network system goes down, the tokens will disappear at this node and will no longer be sent to the next node. Therefore, if things continue as they are, the tokens will not be circulated, and a serious situation will occur in which communication will be impossible at any node in the network.

In the past, it was sometimes acceptable for systems to fail due to failures, but in recent years, fault tolerance has become more important as a measure of system reliability. In order to strengthen this resistance, it is necessary to take measures such as, for example, disconnecting a failed part from the system and continuing operation with the remaining parts, or reintroducing parts that have recovered from a failure during operation. be done.

Furthermore, in a network, there are circumstances in which it is impossible to deny the existence of inoperable nodes even though they are not out of order. In other words, since the devices and offices connected to a network are spread out over a wide area, it is more convenient for users to start up nodes in the network partially rather than all at once. It is more convenient to be able to individually power down the 7-cards of devices that have finished their operation. In these cases, the network will be operated while including some inoperable nodes.

Considering the above, it should be assumed that changes in the configuration of operable and inoperable nodes in the network can always occur.
On the other hand, each node in the network constantly monitors the status of the downstream node to which it should pass the token to the primary node, and if it becomes clear that the downstream node is inoperable, it immediately changes this node to the network configuration. It is necessary to select another suitable node as the node to which the token should be passed from now on, and switch to this node.

For example, in the system shown in FIG.
FIG. 3 shows an example of token circulation when node F150 is an inoperable node.

As shown in the figure, it is necessary to circulate the tokens while avoiding inoperable notes.

Furthermore, if a node with an address value intermediate between the node that has previously passed tokens and its own node becomes operational and is ready to enter the network (receive tokens), it will receive tokens. It is necessary to switch the downstream node to which it should be passed to this new node.

The above operation can be rephrased as the definition of a node that should be replaced with the token described above.Among the nodes that are in an operable state, the node that is closest to the node address and is the smallest.

If there is no corresponding node, then the node with the maximum address among the operable mates is selected.

Now, in the past, there have been few methods that have been able to sufficiently follow the changes in the configuration of nodes in a network as described above, and therefore, for example, there have been many cases where the failure of some nodes leads to the failure of the entire network.

Furthermore, even if a device has a means for dealing with the above-mentioned configuration variations, its processing procedure is extremely complicated, and in particular, the overhead of communication control firmware is large, so a simple algorithm is required.

Purpose of the present invention was made in view of the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a network control method that can reliably follow changes in network configuration and can do this using a simple algorithm. do.

EMBODIMENT OF THE INVENTION An embodiment of the present invention will be described in detail below with reference to one drawing.

FIG. 4 is a block of notes according to an embodiment of the present invention.
1 in the figure is the LAN network transmission line shown in Figure 1;
2 is a node which is a transmission control device, and 3 is various computer equipment and office equipment connected to the node 2 (corresponding to the hosts 230 to 260 shown in FIG. 1).

The node 2 includes a transmitting/receiving circuit 4 that performs data communication with the transmission path l. A control unit (hereinafter referred to as CPU) 5 that performs overall control of the node, processes transmitted data, decodes and disassembles received data, and controls the timing of communication operations, etc., a memory circuit 6 that stores transmitted and received data, etc. It is comprised of an interface circuit 7 between the nodes, and an address setting section 8 consisting of a switch and the like that sets a unique address number for each node. The address bias set in the address setting unit 8 is read out by the CPU 5 and used as the destination address and source address during transmission and reception.

The data to be transmitted from the host 3 is temporarily stored in the memory circuit 6 in the node 2, and then appropriately formatted (packetized) as communication data. After adding the set value as the source address, it receives a token addressed to its own node, and when it acquires the right to transmit, sends it to transmission path l.

- 10,000, the other node receives one communication data on the transmission path l, checks the destination address value in the received data, and determines that it is the setting value of the address setting circuit 8 in the second node, that is, the data is addressed to the second node. Once determined, this data is taken into the computer, subjected to some decomposition and wjA collection processing by the CPU 5, and then delivered to the connected host 3.

In addition, in the token passing method, all the data flowing on the transmission line l is not only the communication data between the hosts 3, but also the communication data only between the CPU in each notebook such as a token and the CPU of the other party's mate. It also includes so-called communication control data.

Based on the above hardware configuration and the above-mentioned principle of token passing, each node in the network receives and passes tokens to downstream nodes one after another, allowing communication to be performed using a shared transmission path. be.

Now, in each node, generally the downstream node to which the token should be passed (i.e., the node specified by the destination address attached when sending the token) is fixed once the token has circulated on the network. There are many cases where this is done.

Now, in each node, the downstream node that should send the token (i.e., the node that adds the destination address when sending the token) is fixed once the token has circulated on the network. There are many cases where this is done.

On the other hand, in the tree embodiment, the following RECO
A method is adopted in which each node is required to perform an NFIGURATION (reconfiguration) operation, and downstream nodes are flexibly changed in response to changes in the network configuration.

Data transmission control in this embodiment will be explained below with reference to the flowchart shown in FIG. 885.

First, in step SlO, the transmission data on the transmission path l is monitored to check whether a token has been received. If the token is not received, the process proceeds to step Sll, where it is checked whether the destination address is the set address value of the eye node and the transmission data is addressed to the eye node. If the transmission data is addressed to the eye node, this data is transmitted at step 512. The received data is received and sent to the host 3 as necessary.

When a token is received, the process advances from step 510 to step 513, where there is data to be sent from the host 3,
It is checked whether or not there is a transmission request. If there is a transmission request, data transmission processing is executed in step 514 and the process proceeds to step 515. If there is no transmission request in step 513, the process directly proceeds to step 515.

In step S15, it is checked whether the received token is the first token after the power of the eye node is turned on.

If it is the first token, the process advances to step 321.

This represents the token delegation operation after the node has started transmitting (for example, powered on) and has received the token for the first time. This means that the downstream node is not yet recognized, and this is to deal with this.

If it is determined in step S15 that it is not the first token, the process proceeds to step 516, and in step S16, due to an unforeseen situation such as a failure or power down, the token that has been circulating until then disappears, and the first token transfer after subsequent recovery processing is performed. It is checked whether the token is in operation or not, and if it is the first token delegation, the process proceeds to step 521. This often occurs in systems where communication rights are delegated by tokens. This is because if the 7-de is powered down, the token disappears and the uke cannot pass the token to the subsequent 7-do.

In such a case, generate a token on any 7-card,
This is because it is necessary to restart token circulation or perform recovery processing.

If it is determined in step S16 that this is not the first token received after the token disappears, the process proceeds to step 317, and the process proceeds to step 317, where the token is circulated to the node at a certain periodic token transfer operation, or at a certain time periodic token transfer operation. It is checked whether or not this is the case, and if a certain period has elapsed, the process proceeds to step 521. This is to deal with a node newly joining the network. In other words, if a node with an address value closer to the eye node than the previous downstream node starts up and becomes operational, and the nodes before and after this new entrant mate are unaware of this, the token will remain with this new node forever. It is not passed to the participant node, so RECONFIGURATI, which will be described later, is performed at a certain period.
Perform the ON operation.

This is to recognize these newly joining nodes and allow them to join the network.

If the fixed period has not elapsed in step S17, the process proceeds to step 318, and a token is transmitted using the address value of a downstream node (not shown) in the memory circuit 6 as the destination address. Then, in the following step 519, it is checked whether the token delegation was performed normally. The means for identifying this varies depending on the transmission control procedure of each network, but 1. For example, when a token is received, the node that receives the token sends an ACK, which is an acknowledgment.
This is done by returning a response, or by the receiving node starting a new communication operation and then determining that the source address of the communication data sent to the transmission path I is this downstream node address.

If the token has been successfully transferred, the process returns to step SIO to prepare for the next data transmission.

If the token is not successfully transferred in step S19, it is checked in step 520 whether or not the token has been sent for the second time, and if it is the first time, the process proceeds to step 818.
Execute the token retransmission process. If the token is made twice in step 520, proceed to step 521;
This is to deal with the case where the partner node to which the token has been previously passed suddenly goes down (failure or power off), and is to search for a new node to which the token should be transferred.

In step S21, RECONFIC-URA, which is a network reconstruction process that newly detects a token delegation light, is performed.
Execute the D1ON operation, successfully delegate the token, and return to step 510.

Step S 21 (7) RECONFIGURATIO
The details of the ON operation will be explained below with reference to the flowchart of FIG.

First, in step Sl, the downstream node address is set to the set address of the second node, regardless of the previous downstream node address, in the subsequent step S2, this downstream node address is subtracted by 1, and in step S3, this downstream node address is Send the token as the destination address. Then, in the following step S4, it is checked whether the token transfer was successful or not. The means for identifying this is the same as step 519.

If the token is not successfully sent to the downstream node (if the transmission fails), the process proceeds to step S6, assuming that the other node is an inoperable (communication) node, and the downstream node address value is the minimum specified by the network. Check whether it is the address value or not, and if it is the minimum address value, step S
Returning to step 2, the downstream node address value is subtracted by one again, and token transmission is attempted using this new downstream node address value as the destination address.

In this way, the address value is gradually subtracted and the token is attempted to be sent to the node with that address value.
- Repeat this operation until a token is received on the card.

If the token delivery is not successful even if the subtracted address value reaches the minimum address value specified in the network, the process proceeds from step S5 to step S7, and the downstream node address f1 is determined in the network. The process returns to step S3 as the maximum node address value. Thereafter, the token receiving, passing, and address value wc'x operations are repeated.

If the token transfer is successful, the process proceeds from step S4 to step S7, where this operation is stopped.
The downstream node address value at that time is stored, and the address value at that time is used as the downstream node address from now on.

YES in step 515.16 to take more time to process the RECONF I GIJRA T I ON operation.
, specific cases such as NO in step 320 and step 3
17: YES, so that it is done only at regular intervals, and when other normal token transfers are made, the previous REGO
The next node address value obtained by the NFIGURATION operation is set as a fixed value, and by using it as is, consideration is given so as not to reduce the data transmission efficiency of the network.

As explained above, according to this embodiment, token transfer can be performed reliably in any case, and even if token transfer cannot be performed normally, the network can be regenerated with almost no loss in data transmission efficiency. Can be constructed.

As explained above, according to the present invention, in a network system, it is possible to reliably disconnect a transmission control device that has become inoperable due to a failure or otherwise, and to incorporate a transmission control device that is newly operable. This can be done using a simple algorithm.

[Brief explanation of drawings]

FIG. 81 is a diagram showing the configuration of a bus type network system. FIGS. 2 and 3 are conceptual diagrams showing how tokens circulate in the token bus system. FIG. 4 is a block diagram of an embodiment according to the present invention, FIG. 5 is a flowchart showing the data transmission fWJ 11 of this embodiment, and FIG. 6 is a flowchart of network reconfiguration operation of this embodiment. Here, l...network transmission path, 2...notebook, 3...host, 4...transmission/reception circuit, 5...C
PU, 6... memory circuit, 7... interface circuit, 8... address setting circuit. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A network control method for a network system in which a plurality of transmission control devices are connected to each other via a bus-type communication medium and data communication is performed by delegating communication rights using a communication right delegation command having a destination address, which is unique to the transmission control device. an address setting means for setting the address value of the address setting means, and a value obtained by subtracting a certain number from the setting value with the setting value of the address setting means as an initial value, and the value obtained by subtracting a certain number from the setting value, and the value is the destination address of the communication rights transfer instruction. If the address value is smaller than the minimum address value determined by the network system, the address value obtained by subtracting a certain value from the maximum address value determined by the network system is used as the unique address value. Communication rights delegation command is issued to the transmission control device. network reconfiguration means for attempting transmission of the communication rights, and the transmission control device activates the network reconfiguration means every time it receives the communication right transfer command a certain number of times.