JPH0691541B2 - Bus type LAN - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bus-type LAN, and more particularly to a token-passing bus-type LAN in which transmission is controlled based on a logical ring that represents the order in which tokens are sequentially delegated.

<< Summary of the Invention >> This invention provides a management station on a bus-type LAN, and the management station polls other normal stations at regular intervals, and builds a logical ring consisting of stations that wish to transmit based on the answer, By broadcasting the logical ring data to each normal station at the same time and concentrating the construction and management of the logical ring on the management station, the processing of the normal station is simplified and the data transmission speed is increased accordingly. It is a thing.

<< Conventional Technology and Its Problems >> Conventionally, as one of the transmission control methods of the bus-type LAN, there is a token passing method in which the access right of the transmission path, so-called token, is transmitted one after another in accordance with a preconfigured logical ring. .

In a LAN that uses this token passing method, all communication nodes may be provided with a list of logical ring subscribers depending on the application, and when a subscriber to this logical ring changes, another communication node Must be notified of the change.

As one of the methods, all communication nodes have a logical ring maintenance function, and whenever a station that is subscribed to the logical ring holds a token, it invites new stations to other stations, There is a method of updating the logical ring subscriber station list by a response and notifying this list information to other communication nodes.

Further, the applicant has set up a management station for maintaining and managing the logical ring in the network, and the management station sequentially polls all other communication nodes to obtain information on joining and leaving the logical ring. We have developed a method to collect and update the logical ring subscriber list, and to notify all communication nodes of the latest subscriber list in order by selecting (unpublished).

However, in the former method, since all stations have the logical ring maintenance function, the processing at each station becomes complicated and the processing time becomes long. As a result, the overhead time required for network management is increased, the time required for data transmission is relatively reduced, and the transmission efficiency deteriorates.

Also, in the latter method, the management station individually notifies the logical ring subscriber station list by selecting, and the receiving station that receives it updates the list of its own station, so it takes time to update the list of all stations. There is a problem that the load on the management station is increased and other data transmission is affected in addition to the above-mentioned problem.

<Object of the Invention> The present invention has been made to solve the above problems, and an object of the present invention is to simplify the processing relating to network management between a management station and a normal station, and to improve transmission efficiency accordingly. It is to provide a bus-type LAN that can be improved.

<< Structure and Effect of the Invention >> In order to achieve the above object, the present invention configures a communication node with a management station and a plurality of normal stations in a bus type LAN that is transmission-controlled by a token passing system based on a logical ring. Collection means provided in the management station for collecting the logical ring joining data regarding the normal station by performing regular polling, and storage means provided in the management station and the ordinary station for storing the logical ring joining station list,
Each time polling is performed, the logical ring subscriber station list data updated / stored in the storage means of the management station is broadcasted to other normal stations, and the list data sent from the management station is received. From the list updating means for updating the storage means provided in the normal station based on the list data, and the logical ring subscriber station list stored in the storage means of the normal station each time the list data is received, the normal station generates a token. The present invention is characterized in that a succeeding station updating means for finding a succeeding station to be delegated and using it as a succeeding station address is provided.

The bus type LAN according to the present invention comprises a management station which is provided in a communication node which constitutes the bus type LAN, and the management station polls other normal stations at a constant cycle, and consists of stations which desire to transmit based on the answer. By constructing a logical ring, broadcasting the logical ring data to each normal station, and concentrating the construction and management of the logical ring on the management station, processing related to network management in the normal station is simplified and transmission efficiency is improved. In addition to the improvement, the LAN can be constructed at low cost.

<< Description of Embodiments >> FIG. 1 is a diagram showing an overall configuration of a bus LAN according to the present invention.

In the figure, a bus-type LAN is configured by connecting a management station 1 and ordinary stations 2 to N, which form a communication node, to a transmission line 10 formed of a coaxial cable or the like. The management station 1 is a normal node in the bus type LAN, and is provided with a polling function for other normal stations 2 to N and a management function of logical ring joining or leaving.

FIG. 2 is a block diagram showing the internal structure of the management station 1. As shown in the figure, the management station 1 has a CPU 20, ROM 21, RA
It is composed of an M22, a transmission controller 23, and an internal bus 24 connecting these. The CPU 20 controls the transmission controller 23 according to the program stored in the ROM 21 to transmit / receive various frames to / from the transmission path 10. The RAM 22 is used as a buffer for temporarily holding various data such as a network management information table 30, a local station address area 30c, a subsequent station address area 30d, and transmission / reception data, which will be described later. The internal structure of the normal stations 2 to N is also substantially the same as that of the management station 1 shown in FIG.

FIG. 3 is a diagram showing the configuration contents of the network management information table 30 provided in the RAM 22. Table 30
Various management information about each node 1 to N on the network is stored, and the memory area address in the table 30 corresponds to the node number of each node 1 to N. The structure of each memory area is
As shown at 30-2, it comprises a communicable bit 30a indicating whether or not the corresponding node 2 is communicable, and an area 30b in which other information regarding the node 2 is also stored. The communicable bit 30a is set to ON when the corresponding node 2 joins the logical ring when the logical ring is constructed. At the time of constructing such a logical ring, all the communicable bits 30a of the table 30 are set to either ON or OFF, and the logical ring is constructed by the node set to ON.

Fig. 4 shows own station address area 30c in RAM22.
FIG. 3 is a diagram showing a configuration of a subsequent station address area 30d. In the own station address area 30c, the address of the own station is stored by the process described later, and in the succeeding station address area 30d, the next station to which the token is transferred, that is, the next station to which the token is transferred in the logical ring is transferred. The address is stored.

FIG. 5 is a diagram conceptually showing the logical ring constructed in this way. In this logical ring, the tokens are transferred in the memory area address order in the table 30 to which the corresponding node is allocated. When the token completes one cycle and reaches the last normal station N, the token returns to the first management station 1.

FIG. 6 is a flowchart showing the processing performed when the token is returned in the management station 1.

In the figure, when a token is received, first, if there is transmission data in the management station itself (Yes at step 401), a data transmission process is performed (step 402).

When the data transmission is completed, or when there is no transmission data (No at step 401), a process of grasping the logical ring joining status of the normal station is performed.

In this process, a polling frame is transmitted to each normal station according to the address order described in the network management information table 30 (step 403), and when a response frame is received from the transmission partner station (step 404 affirmative), If the content of the response frame is to join the logical ring (Yes at step 405), the normal station sets the corresponding communicable bit 30a to on (step 4).
07).

If the response content does not indicate that the user wants to join the logical ring (No at step 405), or if the response frame is not received from the transmission partner station after a certain period of time (No at step 404, affirmative at step 406), the normal station handles it. The communicable bit 30a is set to off (step 408). In this way, by updating the communicable bit 30a, a new logical ring is constructed.

Next, when the polling process for one normal station is completed, the number of normal stations that have performed the polling process is counted. If the count value is less than the preset number of times, polling is performed for the next station. Perform processing (Step 40)
Negative, step 402).

The number of normal stations that are polled here is set in Table 30 every time a token comes to the management station.
This is because if the polling process is performed for all the stations described in, the overhead of the management station becomes too large and the transmission efficiency of the network decreases. Therefore, the number of stations to be polled when the token goes around once is set in advance, and every time the token goes around, polling is performed only for the set number of stations. When a token comes around, based on the table 30, polling is performed from the station next to the station polled last time last time.

In this way, when polling has been performed a predetermined number of times and ended (step 409), the updated communicable bit 30a data of the network management information table 30 is transmitted to all normal stations by simultaneous broadcast notification (step). 41
0).

Next, the management station sends a token to the succeeding station based on the logical ring, that is, the network management information table 30, confirms that the succeeding station has received the token (step 411), and ends the series of processes.

FIG. 7 shows the subsequent station address area in the normal stations 2 to N.
It is the flowchart which showed the update processing of 30d.

In the figure, when the normal stations 2 to N receive the communicable bit 30a data from the management station 1 by the simultaneous broadcast notification, they rewrite and update the network management information table 30 according to the contents. (Step 501).

Next, the address of the memory area in the network management information table 30 where the data related to the own station is stored is set to the offset counter provided in the internal RAM 22 (step 502).

Here, it is determined whether or not the value set in the offset counter is equal to the maximum value of the communication node address in the information table 30, and if it is equal to the maximum value, that is, the end address (Yes at step 503), The offset counter is cleared, that is, returned to the start address (step 504).

If it is not equal to the maximum value (No at step 503), the offset counter is incremented (step 50).
Five).

Next, it is judged whether or not the value set in the offset counter matches the address of the own station, and if they match (Yes at step 506), it means that all stations have not joined the logical ring. , Error handling is performed.

If they do not match (No at step 506), the communicable bit 30a of the memory area corresponding to the address set in the offset counter is read from the table 30 (step 507).

When the communicable bit 30a read here is off (No at step 508), the process proceeds to step 503.

When the read communicable bit 30a is on (Yes in step 508), the value set in the offset counter is set in the subsequent station address area 30d (step 509), and the process ends.

In this way, each normal station can update the subsequent station address simultaneously and in a short time.

The above processing in the management station and each normal station is performed every time the token goes around the logical ring and returns to the management station, and it becomes possible to update the logical ring subscription list for all normal stations in a short time. .

Further, since the overhead of the management station is small and the processing in the normal station is simple, the processing relating to the logical ring construction is shortened, and the data transmission can be performed at a high speed.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a bus LAN according to the present invention, and FIG.
FIG. 4 is a block diagram showing the internal structure of the management station 1, FIG. 3 is a block diagram of the network management information table, and FIG. 4 is RAM 22.
FIG. 5 is a configuration diagram of a local station address area 30c and a subsequent station address area 30d provided in FIG. 5, FIG. 5 is an explanatory diagram of a logical ring, FIG. 6 is a flowchart showing the operation of the management station, and FIG.
The figure is a flowchart showing the operation of the normal station. 1 …… Management station (node) 2 to N …… Normal station (node) 10 …… Transmission path 20 …… CPU 21 …… ROM 22 …… RAM 23 …… Transmission controller 24 …… Internal bus 30 …… Network management Information table 30a …… Communicable bit 30c …… Own station address area 30d …… Succeeding station address area

Claims (1)

[Claims] 1. In a bus-type LAN in which transmission is controlled by a token passing system based on a logical ring, a communication node is composed of a management station and a plurality of normal stations, and is provided in the management station to perform regular polling. Collection means for collecting logical ring subscription data about stations, storage means provided in the management station and normal stations for storing a list of logical ring subscription stations, and updated / stored in the storage means of the management station at each polling A means for sending a broadcast notification of the logical ring subscriber station list data to other normal stations simultaneously, and a means for receiving the list data sent from the management station and storing the list data in the normal stations based on the list data. From the list updating means to be updated and the list of logical ring subscribers stored in the storage means of the normal station each time list data is received, the normal station Locate a subsequent station to delegate the token, bus-type LAN, characterized in that and a subsequent station updating means for a subsequent station address.