JPS63193742A - Data communication control system - Google Patents

Abstract

PURPOSE:To the setting of a various kinds of protocols and the monitoring of an opposite state in a high-order layer and to reduce load on the processing of the protocol by the high-order layer, by providing a monitoring timer, and enabling the transition of an opposite station to an innactive state to be detected. CONSTITUTION:A side receiving a frame just before between the physical layers of stations which perform communication with each other operates a frame transmission monitoring timer from its own station, and when no data frame transmission request is issued from its own station within a prescribed time, transmits a response frame, meanwhile, the station which transmits the frame just before, after transmitting the frame, operates a frame reception monitoring timer, and when no frame is received from the opposite station within the prescribed time, assumes that the opposite station is set at the inactive state, and informs it to the high-order layer. In such a way, it is possible to detect whether an opposite node is set at an active state or the inactive state in com municating at a physical layer level.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data communication control system in a local area network or the like.

[Conventional technology]

Generally, a communication network performs data transfer with other nodes according to a protocol. Protocols have a hierarchical structure; for example, they consist of a physical layer, data link layer, and transport layer that control communication functions, a layer that controls higher-level communication processing functions, and a layer that controls higher-level information processing functions. ing.

FIG. 2 is an operation flowchart of the physical layer in a conventional hierarchical structure, in which step 1 is a check for acceptance of a data transmission request from an upper layer, step 2 is data frame transmission processing, step 3 is a check for data frame reception, and step 4 indicates data frame reception notification processing to the upper layer.

Next, the operation will be explained. In the conventional physical layer, after starting processing in step 1, it is checked whether there is a data frame transmission request from an upper layer that is a user layer of the physical layer, or if a valid frame is received from the communication medium in step 3, If there is a transmission request in step 1, frame transmission processing is executed to the medium in step 2, and if a frame is received in step 3, the upper layer is notified of this in step 4.

[Problem that the invention seeks to solve]

Conventional communication control methods at the physical layer are based on the methods described above, and because the physical layer cannot determine whether the partner node is active or inactive, various protocols are implemented in the upper layer. I had to set it up and monitor the status of the other station. Therefore, in addition to placing a burden on upper layer protocol processing, there are also problems such as when a failure occurs, it is not possible to determine whether an abnormality has occurred at the physical layer level or in the upper layer protocol.

This invention was made in order to solve the above-mentioned problems, and it is a data communication system in which it is possible to detect at the physical layer level whether the partner node during communication is in an active state or an inactive state. The purpose is to obtain a method.

[Means for solving problems]

In this invention, the steps of transmitting a data frame to the partner node (step 12), starting the timer T1 for monitoring reception of data frames from the partner node (step 21), and It includes a step in which the timer TI expires due to no reception from the node (step 22), and a step in which the inactive state of the partner node is detected (step 27), and a data frame is not received from the partner node. a receiving stage (step 13), and a stage of starting timer T2 for monitoring data frame transmission from the local node (step 4).
1), a step in which the timer T2 expires because there is no transmission from the local node within a predetermined period of time (step 42), and a response frame indicating that the local node is in an active state is sent to the other node. and a step of transmitting (step 46).

[Effect]

In the communication control system according to the present invention, immediately before the physical layer of stations communicating data, the side that has received a frame (step 13) operates a frame transmission monitoring timer from its own station (step 41); If there is no data frame transmission request from the own station within a certain period of time (step 42), a response frame is transmitted (step 46).On the other hand, the station that has just transmitted the frame does not receive a data frame transmission request (step 1) after transmitting the frame.
2) Activate the frame reception monitoring timer (step 21)
), if no frame is received from the other station within a certain period of time (step 22), the other station is assumed to be in an inactive state and the upper layer is notified (step 27).

〔Example〕

An embodiment of the present invention will be described below with reference to the flowcharts in FIGS. 1(a) and 1(b). , this operation is performed under the control of the node of the data communication device, that is, the computer,
FIG. 1(a) shows a flowchart after the own node performs transmission processing to the partner node, and FIG. 1(b) shows a flowchart after receiving from the partner node. Although this is a flowchart of the operation of the own node, the other node also becomes the own node and performs similar processing, and operates so as to mutually detect the state of the other node.

In the figure, the start of the frame reception monitoring timer T1 in step 21 means to start counting a predetermined period of time for waiting for a data frame or a response frame from the partner node. Also, starting the frame transmission monitoring timer T2 in step 41 means waiting for frame transmission from the local node,
After a predetermined period of time, it starts measuring the time for transmitting a response frame that informs the other node of its own active state.

Next, the operation of the physical layer in the 4-communication control system according to the present invention will be explained according to the flowchart of FIG. After the physical layer starts processing, it checks in step 11 whether there is a data transmission request from an upper layer or whether a valid frame is received from the communication medium in step 13. If there is a data frame transmission request from the upper layer in step 11, the data frame is sent out in step 12, and then the frame reception monitoring timer (hereinafter referred to as
(abbreviated as T1). Thereafter, in step 22, the T1 timer is checked, and in step 23, the data frame received from the partner station is checked. Step 22
When the T1 timeout has elapsed, the process proceeds to step 27 and notifies the upper layer that the partner station is inactive. This operates the frame reception monitoring timer T1 after transmitting a frame, and if no frame is received from the partner node within a certain period of time, the partner node is considered to be in an inactive state. If the data frame in step 23 is received, the process proceeds to step 14 and notifies the upper layer that the data frame has been received, starts the frame transmission monitoring timer (hereinafter abbreviated as T2) in step 41, and receives the transmission request from the local station. Enter the check. This is the reception monitoring timer T1
This indicates that the partner node is in an active state because there was a transmission from the partner node within the time. If the response frame in step 24 is received, proceed to step 41 and T2
Start the timer and start checking the transmission request from the local node. Now that it has been detected that the partner node is active, you can send data to the partner node.
It will wait for transmission instructions from the upper layer. If there is a new transmission request from the higher rank Ray in step 25,
Step 26? -Stop the TI timer and start the data frame transmission process again. This is the reception monitoring timer T
1. During standby, there is a request for a data frame from the local node, so in order to first fulfill this request, the process returns to step 12 and performs data frame transmission processing. If there is no transmission request in step 25, the process returns to step 22 and checks the '7T1 timer.

On the other hand, when a valid data frame is received in step 13, a data frame reception notification is sent to the upper layer in step 14, and a T2 timer is started in step 41.
After this, the T2 timer is checked in step 42, and the data is read from the upper level in step 43.

First, when the waiting time for monitoring data frame transmission from the own node in step 42 has elapsed and T2 timeout has occurred, the process proceeds to step 46, where a response frame of an arbitrary physical layer level is sent, and the process returns to step 21. The frame reception monitoring timer TI is restarted, and the process proceeds to the above-mentioned post-frame transmission process. Although there is no special data frame transmission request from the local node, the remote node is informed that the local node is active. While waiting for data frame transmission monitoring, if there is a data frame transmission request from the upper layer in the check in step 43 before the T2 timeout, the data frame is transmitted in step 47, and the process returns to step 21 to restart the frame reception monitoring timer. The process starts and moves to the processing after frame transmission described above.

When a new data frame is received, step 457
Stop the T2 timer, return to step 14, notify the upper layer of data frame reception, and return to step 4.
Execute processing from step 1. This is because a data frame was received from the partner node while the T2 timer was being monitored, so the T2 timer is first stopped (step 45) in order to process this reception. If no data frame is received from the partner node here, the process returns to step 42 and continues with T.
2 Check for timeout.

In this way, the inactive state of the partner node can be detected. Regarding the occurrence of a failure in the own node, there is no problem because the upper layer of the own node can self-determine the occurrence of a failure. On the other hand, even if the own node reaches the T2 timeout in step 42, if the response frame transmission in step 46 is not executed, then [Effects of the Invention] As described above, according to the present invention, the other node (Step 12)
, a step of starting a timer TI that monitors the reception of data frames from the partner node (step 21), and a step in which the timer T1 expires when there is no reception from the partner node within a predetermined time (step 22). , thereby detecting the inactive state of the partner node (step 27).
), a step of receiving a data frame from the partner node (step 13), a step of starting timer T2 for monitoring data frame transmission from the own node (step 41), and a step of starting timer T2 within a predetermined time. A step in which timer T2 expires due to no transmission from the station node (step 42), and a step in which a response frame indicating that the local node is in an active state is transmitted to the phase and half-cycle nodes (step 46). After receiving the frame, one station will receive a frame reception monitoring timeout.
Since the transition to the inactive state of the partner station can be detected, there is no need to configure various protocols in the upper layer to monitor the state of the partner, and the burden on protocol processing in the upper layer is lightened, making it inexpensive and easy to use. This has the effect of providing a reliable communication control system against failures.

[Brief explanation of the drawing]

Figures 1 (A) and (B) show operation flowcharts of the communication control method of the present invention, in which (A) is a flowchart after transmission, (B) is a flowchart after reception, and Figure 2 is a flowchart for conventional communication. It is a flowchart of control. Agent Masu Oiwa tS<and 2 others) Rare 1
(I) Item 51F! ](Ron

Claims (1)

[Claims] In a data communication control method between nodes consisting of a computer, there are two steps: transmitting a data frame to the other node, starting a timer to monitor the reception of data frames from the other node, and transmitting data from the other node within a predetermined time. The method includes the step of causing the timer to expire due to no reception of the data frame, and the step of detecting the inactive state of the partner node as a result of this, and the step of receiving a data frame from the partner node, and the step of receiving the data frame from the own node. A step of starting a timer for monitoring frame transmission, a step of the timer expiring when there is no transmission from the local node within a predetermined period of time, and thereby informing the other node that the local node is in an active state. and transmitting a response frame indicating the data communication control method.