JPH0250541A - Bus type lan - Google Patents

Abstract

PURPOSE:To execute high speed data transmission by executing the polling at a constant period for each ordinary station with a control station provided at a bus type LAN, constructing a logical ring composed of a station desiring transmission based on the reply and simultaneous-multiple-address-informing respective ordinary stations of the logical ring data. CONSTITUTION:To a transmission line 10 composed of a coaxial cable, etc., a control station 1 to constitute a communication node and ordinary stations 2-N are connected and thus, a bus type LAN in constituted. The control station 1 is a communication node in a bus type LAN and provides a polling function for other ordinary stations 2-N and the control function of the addition or the leaving of the logical ring. The control station 1 execute the polling at a constant period for other ordinary station, the logical ring composed of a station to desire the transmission based on the reply is constructed, the logical data are simultaneous-multiple-address-informed to respective ordinary stations and collected to the construction of the logical ring and the control station. Thus, the processing concerning the network control at the ordinary station becomes simple and transmission efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (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 representing the order in which tokens are sequentially delegated.

(Summary of the invention) This invention provides a bus-type LAN with a management station, polls other normal stations at regular intervals, and builds a logical ring consisting of stations that wish to make a call based on the responses. By simultaneously broadcasting the logical ring data to each normal station and concentrating the construction and management of the logical ring on the management station, processing at the normal stations is simplified and data transmission is increased accordingly. It is something.

(Prior art and its problems) Conventionally, as one of the bus-type transmission control methods, there is a token passing method in which access rights to the transmission path, or so-called tokens, are transmitted one after another according to a pre-constructed logical ring. be.

In a LAN using this token passing method, all communication nodes may be provided with a list of stations joining the logical ring by an application, and when a change occurs in the stations joining this logical ring, other communication nodes must be notified of changes.

One method is to provide all communication nodes with a logical ring maintenance and management function, and each time a station that has joined the logical ring retains a token, it invites other stations to join the logical ring. There is a method of updating the logical ring joining station list based on the response and notifying other communication nodes of this list information.

In addition, the present applicant has proposed that 7) a management station is provided within the network to maintain and manage the logical ring, and the management station polls all other communication nodes in order to determine whether they join the logical ring or not. We have developed a method to collect withdrawal information, update the logical ring joining station list, and sequentially notify all communication nodes of the latest joining station list using selection (unpublished).

However, in the former method, since all stations have the function of maintaining and managing the logical ring, the processing at each station becomes complicated and the processing time increases.

As a result, the overhead time required for network management increases, the time required for data transmission relatively decreases, and the transmission efficiency deteriorates.

In addition, in the latter method, the management station individually notifies the logical ring joining station list through selection, and the receiving station updates its own list, so it takes time to update the list of all stations. This not only increases the burden on the management station, but also increases the load on the management station, which affects other data transmissions.

(Purpose of the Invention) This invention was made to solve the problem described in "-", and its purpose is to simplify the processing related to network management between the management station and the normal station, and to reduce the transmission An object of the present invention is to provide a bus-type LAN that can improve efficiency.

(Structure and Effects of the Invention) In order to achieve the above object, the present invention configures a communication node by a management station and a plurality of normal stations in a bus-type LAN where transmission is controlled by a token passing method based on a logical ring. a collection means provided in the management station for periodically polling to collect logical ring participation data regarding normal stations; a storage means provided in the management station and the normal stations for storing a list of logical ring participation stations; A transmission means for simultaneously broadcasting the logical ring joining station list data updated and stored in the storage means of the management station to other normal stations, and a transmission means for receiving the list data sent from the management station and converting it into the list data. list updating means for updating a storage means provided in the normal station based on the list;
Each time the list data is received, from the list of stations joining the logical ring stored in the storage means of the normal station, the normal station searches for a subsequent station for requesting a token, and includes updating means for updating the subsequent station as the subsequent station address. It is characterized by

The bus-type LAN according to the present invention includes a management station provided in the communication nodes constituting the bus-type LAN, and the management station polls other regular stations at regular intervals, and the stations that wish to make a call based on the responses are configured. By constructing a logical ring, broadcasting the logical ring data to each regular station, and concentrating the construction and management of the logical ring on the management station,
This has advantages such as simplifying network management processing at a normal station, improving transmission efficiency, and making it possible to construct the entire LAN at low cost.

(Description of Embodiments) FIG. 1 is a diagram showing the overall configuration of a bus-type LAN according to the present invention.

In the figure, a bus-type LAN is constructed by connecting a management station 1 and normal stations 2 to N, which constitute communication nodes, to a transmission path 10 made of a coaxial cable or the like. The management station is
Polling 8 for other normal stations 2 to N, which are communication nodes in a bus-type LAN! management functions for joining or leaving a logical ring.

FIG. 2 is a block diagram showing the internal structure of the management station 1. As shown in FIG. 6, the management station 1 has a CPU 20. ROM
21, a RAM 22, a transmission controller 23, and an internal bus 24 connecting these. C.P.
The U20 controls the transmission controller 23 according to the program stored in the 110M21 to open the transmission line 1.
0, various frames are transmitted and received between them. R.A.
M22 is a network management information table 30, which will be described later.
, own address area 30C, address area 30C, and subsequent station address area 30d, which are used as buffers for temporarily holding transmitted/received data and other various data.

Note that the internal structures of the normal stations 2 to N are almost 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. As shown in FIG. The table 30 stores various management information regarding each node I-N on the network, and the memory area address in the table 30 corresponds to the node number of each node 1-N.

The configuration of each memory area is, for example, memory area 30.
2, it consists of a communicable focus 30a that displays whether or not the corresponding node 2 is communicable, and an area 30b where other information regarding the node 2 is stored. This communicable bit 30a is turned on when the corresponding node 2 joins the logical ring when the logical ring is constructed. When constructing a logical ring like this,
All of the communicable bits 30a of the table 30 are set either on or off, and nodes set on form a logical ring.

FIG. 4 is a diagram showing the configuration of the local station address area 30C and the succeeding station address area 30d provided in M22 to R. The address of the own station is stored in the own station address area 30c through processing described later, and the address of the next station to which the token is to be transferred is stored in the subsequent station address area 30d, that is, the address of the next station to which the token is to be transferred in the logical ring. Address is stored.

FIG. 5 is a diagram conceptually showing the logical ring constructed in this way. The order in which tokens are delegated in this logical ring is the order of the memory area addresses in the table 30 to which the corresponding nodes are allocated. When the token goes around once and reaches the last regular station N, it returns to the first management station ■.

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

In the figure, after receiving the token, first, if the management station itself has data to be transmitted (step 401ft), data transmission processing is performed (step 402).

After the data transmission is completed, or if there is no data to be transmitted (No in step 401), processing is performed to ascertain the logical ring participation status of the normal station.

In this process, a polling frame is sent to each normal station according to the address order listed in the network management information table 30 (step 403), and when a response frame is received from the destination station (step 4041).
If the content of the response frame indicates a desire to join the logical ring (step 405, affirmative), the normal station sets the corresponding communicable bit 30a on (step 4G?).

In addition, if the response content does not indicate a desire to join the logical ring (step 405 negative), and if no response frame is received from the station after a certain period of time (step 404 negative, step 406 affirmative), the normal station turns off the corresponding communicable bit 3Qa (step 408). In this way, the communicable bit 30a is updated, and a new logical ring is constructed.

Next, when the polling process for one normal station is completed, the number of normal stations that have been polled is counted, and if the counted value is less than the preset number of times, polling is continued for the next station. Perform processing (Step 4)
09 negative, step 402).

The reason for setting the number of normal stations to be polled here is that each time a token comes to the management station, it is
This is because if polling processing were performed on all of the stations listed in , the overhead of the management station would become too large and the transmission efficiency of the network would decrease. Therefore, the number of stations to be polled each time a token comes around is set appropriately in advance, and each time a token comes around, polling is performed only for the set number of stations, and then When a token comes around, polling is performed from the station following the last polled station based on the table 30.

In this way, when polling is completed a predetermined number of times (step 409), the updated communicable focus 30a data of the network management information table 30 is transmitted to all normal stations by simultaneous broadcast notification ( step 410).

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 processing.

FIG. 7 is a flowchart showing the updating process of the subsequent station address area 30d in the normal stations 2 to N.

In the figure, when the normal stations 2 to N receive the communicable bit 30a data from the management station 1 by broadcast notification, they rewrite and update the network management information table 30 according to the contents. The offset counter provided in M22 is set to address 7 of the memory area in which data related to the own station in the network management information table 30 is stored (step 502).

Here, it is determined whether 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, it is the last address (step 503tt determined), Clear the offset counter, that is, return it to the first address (
Step 504).

If it is not equal to the maximum value (step 503, negative), the offset counter is incremented (step 50
5).

Next, it is determined whether the value set in the offset counter matches the address of the own station, and if they match (
Step s06), all stations have not joined the logical ring, and error processing is performed.

If they do not match (step 506 negative), table 30
, ill! of the memory area corresponding to the address set in the offset counter. Can be trusted 30a
is not read (step 507).

If the communicable bit 30a read here is off (No in step 508), the process advances to step 503.

If the read communication enable bit 30a is on (
Ste:)1508 affirmative), subsequent station address area 30d
Then, the value set in the offset counter is set (step 509), and the process ends.

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

The following processing at the management station and each regular station is performed each time the token goes around the logical ring and returns to the management station, making it possible to update the logical ring participation list for all regular stations in a short time. Become.

In addition, since the overhead of the management station is small (and the processing at the normal station is also mta), the processing related to logical ring construction is shortened, and data transmission can be made faster accordingly.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of the bus type AN according to the present invention.
Fig. 2 is a block diagram showing the internal structure of the management station l, Fig. 3 is a configuration diagram of the network management information table, and Fig. 4 is a block diagram showing the internal structure of the management station l.
A configuration diagram of the local station address area 3 (Lc and subsequent station address area 30d provided in AM22), FIG. 5 is an explanatory diagram of the logical ring, FIG. 6 is a flowchart showing the operation of the management station, and FIG. 7 is a normal diagram. 1. Management station (node) 2 to N... Normal (node) 10... Transmission line 20...・CPU 21...ROM 22...RAM 23...Transmission controller 24...Internal bus 30...Network management information table 30a
・・・・・・Communication possible bit

Claims (1)

[Claims] 1. In a bus-type LAN in which transmission is controlled by a token passing method based on a logical ring, a communication node is composed of a management station and a plurality of normal stations, and a communication node provided in the management station and periodically polled. a collection means for collecting logical ring joining data regarding normal stations; a storage means provided in the management station and the normal station for storing a logical ring joining station list; A transmitting means for simultaneously broadcasting the stored logical ring joining station list data to other regular stations; list updating means for updating the storage means, and each time list data is received, the normal station searches for a subsequent station to which it will transfer a token from the logical ring joining station list stored in the storage means of the normal station, and updates the address of the subsequent station. A bus-type LAN comprising: a means for updating subsequent stations; and a means for updating subsequent stations.