JP3289416B2 - Token passing method LAN data transfer method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a token-passing LAN (local area network) characterized by the time criticality required for factory automation and the like (the regularity of transferring data to a destination within a certain required time). Data transfer method.

[0002]

2. Description of the Related Art For example, a conventional token-passing LAN data transfer method disclosed in Japanese Unexamined Patent Publication No. 3-159436 discloses a synchronous data (a voice or the like that requires a time criticality severe in data transfer delay). Node 2a (bandwidth management station) that manages the bandwidth of (high-priority data) and the destination node 2 as the destination of data transfer
b (calling station) and destination node 2 as a data transfer destination
c (called station) and token passing method LA
In N1, the destination node 2b first receives a synchronous data transmission request from a communication application (communication application software implemented on a LAN), and transmits a bandwidth use request frame 11 requesting a transmission band for the synchronous data to the management node 2a. . Bandwidth request frame 11 from management node 2a
And a request response frame 12 indicating reception of the request and, if possible, a band use permission frame 13 indicating band allocation (step S11). Next, when receiving the bandwidth use permission frame 13, the destination node 2b transmits a connection request frame 14 for requesting connection (logical connection) setting to the destination node 3c. When the acknowledgment frame 15 indicating the connection setting is received from the destination node 3c if possible, the synchronous data frame 20a is transmitted to the destination node 3c.
(Step S12). And destination node 2
When the transmission of the synchronous data frame 20a is completed, b transmits a band return frame 16 indicating the end of the band use to the management node 2a. The return response frame 17 indicating the reception of the bandwidth return frame 16 is received from the management node 2a (the above procedure S13).

[0003] The token passing system LAN is an ISO
(International Organization for Standardization) Token ring type of standard 8802 /
Token bus type or token ring type FDDI (Fiber Distributed D) of ISO standard 9314
In a data interface (ta Interface) network, transmission right information called a "token" circulates in one direction on a transmission line, and a node receiving the token performs media access control to obtain a right to use the transmission line.

The above-mentioned conventional token passing system LA
In the data transfer method of N, the transmission node refers to the management node every time the destination node receives the synchronization data so that the band use efficiency does not decrease even in the dynamic traffic (when the length of the synchronization data or the arrival interval is undefined). A method of deciding the assignment (data transfer band centralized management method) is adopted.

[0005]

The above-described conventional data transfer method of the token passing LAN uses a method in which the destination node refers to the management node and determines the allocation of the transmission band every time the destination node receives the synchronous data. In addition, the procedure for multiplexing countermeasures in the event of a management node failure is complicated and the scale is increased. In addition, the overhead required for frame communication before and after the synchronous data transfer (steps S11 and S13 in FIG. 5) increases and the responsiveness deteriorates. In addition, synchronous data having high urgency cannot be transferred quickly in a token arrival wait associated with frame communication (procedure S11 in FIG. 5) before synchronous data transfer. In addition, a response time for determining synchronous data transfer within a request time by referring to the management node every time is required, and a control program of a communication application is complicated, for example, a request and a response are described at different timings. Further, frame communication before and after synchronous data transfer (steps S11 and S13 in FIG. 5)
Makes the protocol (communications protocol) processing complicated. In particular, a bandwidth use status monitoring procedure such as the non-return of the allocated bandwidth due to the node power interruption or the loss of the bandwidth return frame is required in addition to the normal data transfer procedure. The conventional data transfer method has the above problems.

The problem to be solved by the present invention is to eliminate the need for a management node in the token-passing LAN data transfer method, measure the amount of synchronous data of the own node, notify the other nodes, and notify the other nodes of the amount of synchronous data. To provide a method (data transfer band distribution management method) for determining discard and transmission processing of the synchronous data.

[0007]

According to the present invention, there is provided a data transfer method in a token-passing type LAN which combines a plurality of nodes. It is characterized by adopting a distributed management system.

[0008] Each of the plurality of nodes measures, at a predetermined timing, the amount of synchronous waiting data accumulated in its own node and other nodes. Further, when measuring the amount of synchronous data waiting to be transmitted, as a synchronous data amount notification frame for notifying another node of the amount of synchronous data to be transmitted accumulated in the own node,
It is measured using a concatenated or additive token frame or broadcast frame.

When a synchronous data transmission request is issued, transmission of the synchronous data for which the transmission request has been generated is based on the synchronous data amount waiting to be transmitted. It is determined whether or not the synchronization is completed within the required time, and if the completion is not completed within the required time, the synchronization data for which the transmission request is generated is discarded. The data is stored in the own node as the transmission waiting synchronization data. Further, when a transmission request for synchronous data occurs, if the transmission of the synchronous data for which the transmission request has occurred is not completed within the request time, a rejection response is returned to the source of the transmission request, and If the transmission is completed, an acknowledgment is returned to the source of the transmission request. Further, when a transmission request having the different request time is generated for each synchronization data, the transmission of the synchronization data for which the transmission request has occurred is not completed within the request time based on the transmission waiting synchronization data amount. The synchronous data for which the transmission request is completed is discarded, and the synchronous data for which the transmission request is completed within the request time is stored in the own node as the transmission waiting synchronous data.

[0010] When the token arrives at the own node, the transmission-waiting synchronous data stored in the own node is transmitted.
In addition, when the token arrives at the own node, the transmission-waiting synchronous data that does not satisfy the request time is discarded from the transmission-waiting synchronous data accumulated in the own node.

[0011]

According to the data transfer method of the token passing system LAN of the present invention, in the above procedure, each node first measures the synchronous data amount of its own node at an appropriate timing, and converts the synchronous data amount information into token information or broadcast control information. It forms a concatenated or token frame or broadcast frame and transmits it to another node. The same synchronous data amount information is received from another node (the above-mentioned synchronous data amount notification procedure). Next, the transmission elapsed time of the synchronous data is predicted from the amount of synchronous data of the self-other node, and if the transmission request of the communication application can be completed within a different request time that can be specified for the synchronous data, an acknowledgment is returned; Return the response immediately (the above-mentioned synchronous data discarding procedure). When each node arrives at the token, the node further performs synchronous data transmission processing not to be discarded in the above-described discarding procedure, forms a synchronous data frame, and transmits it to another node. Here, the synchronous data having passed a different request time which can be specified for the synchronous data waiting for transmission from the communication application is discarded (the synchronous data transmission processing procedure).

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A token-passing LAN according to an embodiment of the present invention, as shown in FIG. 1, employs a token-passing LAN 1 that connects a plurality of nodes 2 as data transmission destinations or destinations. (For example, A node 2) stores the synchronous data amount (a numerical value representing the time required for transmitting all the synchronous data, for example, the number of synchronous data or the total number of octets or a combination thereof) at an appropriate timing. Is transmitted to another node (for example, the B and C nodes 2). The synchronous data amount notification frame 10 is received from the B and C nodes 2 in the same manner (the synchronous data amount notification procedure S1). Next, A node 2
Predicts, at an appropriate timing, the elapsed time until the synchronous data can be transmitted in response to the transmission request of the communication application by using the synchronous data amount of the own and other nodes. If the sum of the estimated elapsed time and the delay time during the synchronous data LAN transfer exceeds the required time for the synchronous data, the synchronous data is discarded (the synchronous data discarding procedure S
2). Further, when the token arrives, the A node 2 transmits the synchronous data frame 20 for storing and storing the synchronous data without discarding processing to the B and C nodes 2 (the synchronous data transmitting processing procedure S3).

The token passing system LA of the above embodiment
The data transfer method of N is a method of measuring the amount of synchronous data of the own node, notifying the other nodes, and determining the discarding and transmission processing of the synchronous data from the amount of synchronous data of the own node and other nodes (data transfer bandwidth distribution management method). Take.

As shown in FIG. 2, the synchronous data amount notifying procedure S1 is performed by connecting a synchronous token frame (FIG. 2 (a)) or an additive token frame (FIG. 2 (b)) in which the synchronous data amount information is piggybacked on the token information. A broadcast frame (FIG. 2 (c)) is formed to be superimposed on the broadcast (broadcast) control information (header), and the notification of the synchronous data amount information is transferred between the nodes. Here, the token frame is a management frame indispensable for medium access control of the token passing LAN, whereas the broadcast frame is a data transfer frame addressed to all nodes. When each node receives the token frame at its own node, in the case of the concatenated format of FIG. 2A, the sub-node corresponding to its own node in the concatenation subfield of the number of synchronous data in the first to Nth nodes (N is the maximum number of nodes) Write the number of synchronization data in the local node to the field,
It is transmitted to other nodes as synchronous data amount information. On the other hand, the number of synchronous data in the other node is read from the subfield corresponding to the other node and stored in the storage area corresponding to the node (the number of synchronous data in the own node can be determined from the number of synchronous data waiting in the own node). In the case of the addition type format shown in FIG. 2B, the value read from the synchronous data number total field and the number of synchronous data in the own node are added, and the result is written into the synchronous data number cumulative field, and is transmitted to another node as synchronous data amount information. Send. On the other hand, the difference between the numerical value read from the synchronous data total field before writing by the own node this time and the numerical value previously written by the own node in the synchronous data total field is regarded as the synchronous data total in the other node. It is stored in the storage area for the number of synchronous data. Also, each node transmits the node number of its own node and the number of synchronous data waiting to be transmitted at appropriate transmission triggers (for example, when the token is circulated an appropriate number of times before releasing the token), as in the case of the broadcast frame format in FIG. Is stored in each field, and transmitted to another node as synchronous data amount information. On the other hand, when a broadcast frame is received from another node, the number of synchronous data waiting for transmission to be read from the field is identified by the node number field and stored in the storage area corresponding to the node. Note that, instead of the number of synchronous data waiting to be transmitted, another synchronous data amount such as the total number of synchronous data octets may be used.

As shown in FIG. 3, in the synchronous data discarding procedure S2, each node first receives a synchronous data transmission request from the communication application (procedure S101). Next, the cumulative total (Qi, iQi, i)
= 1 to N) and the average delay time (d) during synchronous data LAN transfer, and the required time (T) for the synchronous data
It is determined whether the transmission of the synchronous data can be completed within T (step S102). If it can be completed within T, the synchronous data is added to a synchronous data queue (queue), and an acknowledgment is returned to the transmission request of the communication application. If you can't finish within T
The synchronous data is discarded, and a rejection response is returned (step S
103, S104).

As shown in FIG. 4, in the synchronous data transmission processing procedure S3, each node first receives a token frame from the LAN and determines whether or not there is synchronous data in its own node in a transmission waiting state (the above steps S201 and S202). . Next, if there is synchronous data waiting to be transmitted in step S202, the current time (t) and the average delay time (d) during synchronous data LAN transfer
The time (a) at which the synchronous data is passed from the communication application is subtracted from the sum of the two, and the difference between the difference and the required time (T) for the synchronous data is compared. The transmission of the synchronous data ends within T Determine if you can. When the synchronization can be completed within T, the synchronization data is transmitted to the LAN. If the process cannot be completed within T, the synchronous data is discarded, and the communication application is notified of the discard (see steps S203 to S203).
205). Further, it is determined whether or not there is synchronous data in the transmission waiting state in the own node (step S206). If not, the asynchronous data is transmitted and the token is released (steps S208 and S209). If there is, the node compares the elapsed time from the reception of the token frame with the token holding time (defined by the token passing LAN protocol) and makes a determination. If the elapsed time exceeds the token holding time, the token is released. If not,
The determination processing procedure of step S203 is repeated (step S2
07, S209). On the other hand, if there is no transmission waiting synchronous data in step S202, the asynchronous data in the transmission waiting state in its own node (low-priority data such as file transfer that does not require time criticality that is not severe in data transfer delay)
To release the token (step S208,
S209).

Synchronous data discard and transmission processing procedures S2 and S3
Then, the communication application gives each node a request time (T) for the synchronous data accompanying the transmission request of the synchronous data. Even if a different request time is specified for each synchronous data, each node retains the request time and request time passed from the communication application, transmits the synchronous data within the required time at an appropriate timing, and discards if it cannot be performed. I do.

[0018]

According to the data transfer method of the token passing system LAN of the present invention as described above, the synchronous data amount of the own node is measured and notified to other nodes, and the synchronous data is discarded based on the synchronous data amount of the own and other nodes. And a method for determining the transmission processing, so that it is more fault-tolerant and can be easily implemented as compared with the conventional method in which the transmission source node refers to the management node and determines the allocation of the transmission band every time the synchronization data is received.
Further, the efficiency of use of the LAN is improved, and the delay in transferring the synchronous data to the LAN can be reduced. Also, by synchronizing the synchronous data amount information with the token information and the broadcast control information, the use of the LAN band accompanying the synchronous data amount notification is minimized.
It can be easily designed with a commercially available LAN control LSI conforming to O8802 or 9314 standard LAN. In addition, the present invention facilitates a control program of a communication application, for example, by immediately responding to a synchronous data transmission request of the communication application and describing it synchronously. Furthermore, there is an effect that a different request time is designated for each synchronous data from the communication application, and the system construction on the LAN can be flexibly performed.

[Brief description of the drawings]

FIG. 1 is a sequence diagram of a data transfer method for a token passing LAN according to an embodiment of the present invention.

FIG. 2 is a format diagram showing a concatenated / additional token frame and a broadcast frame that piggyback synchronous data amount information on token information and broadcast control information.

FIG. 3 is a flowchart showing a synchronous data discarding process procedure shown in FIG. 1;

FIG. 4 is a flowchart showing a synchronous data transmission processing procedure shown in FIG. 1;

FIG. 5 is a sequence diagram of a data transfer method of a conventional token passing LAN.

[Description of References] 1 LAN 2 Node 10 Synchronous data amount notification frame 20 Synchronous data frame In the drawings, the same reference numerals indicate the same or corresponding parts.

Continued on the front page (72) Inventor Kazuki Odaka 5-1-1, Ofuna, Kamakura City Mitsubishi Electric Corporation Communication Systems Laboratory (72) Inventor Yuji Atsui 5-1-1, Ofuna, Kamakura City Mitsubishi Electric Corporation (72) Inventor Tetsuo Ideguchi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (56) References JP-A-1-99344 (JP, A) JP-A-3-159436 (JP, A) JP-A-4-324473 (JP, A) JP-A-5-145564 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 12/42

Claims (6)

(57) [Claims] Claims: 1. A token passing machine for connecting a plurality of nodes.
In the data transfer method in the switching system LAN , each of the plurality of nodes is stored in its own node and another node at a predetermined timing.
The transmission synchronization data amount is measured, and when a transmission request of the synchronization data is generated , the transmission request
The transmission of the generated synchronous data is performed when the transmission request is generated.
Completion within the required time required to send synchronous data
Determines whether, if not completed within the required time, generation of the transmission request
Synchronized data is discarded and completed within the required time
The synchronous data for which the transmission request has occurred,
It is stored in the local node as waiting synchronization data.When the token arrives at the local node, it is stored in the local node.
A data transmission method for transmitting the synchronous data to be transmitted . 2. A method for measuring an amount of synchronous data waiting for transmission.
The amount of synchronous data waiting to be transmitted
As a synchronous data amount notification frame to notify the node,
The method of data transfer according to claim 1, wherein the this <br/> be measured using a sintered type or addition-type token frame. 3. The amount of synchronous data waiting to be transmitted is measured.
The amount of synchronous data waiting to be transmitted
The synchronous data amount notification frame notified to the node
2. The data transfer method according to claim 1, wherein the measurement is performed using a load cast frame . 4. When a synchronous data transmission request is issued,
The transmission of the synchronous data in which the transmission request has occurred
If not completed in time, the sender of the transmission request will be rejected.
If a response is returned within a specified time
2. The data transfer method according to claim 1, wherein an acknowledgment is returned to the source of the request. 5. When a token arrives at its own node, its own
Of the synchronous data waiting for transmission stored in the
Discard the synchronous data waiting to be transmitted that does not satisfy the required time
2. The data transfer method according to claim 1, wherein: 6. The transmission of the request time different for each synchronous data.
When a communication request is generated, the
The transmission of the synchronous data in which the transmission request has occurred
The transmission request that is not completed within the request time
Term data is discarded and completed within the required time
For the synchronous data for which the transmission request has occurred, the transmission
2. The data transfer method according to claim 1, wherein the data is stored in the own node as waiting synchronization data .