JPH0260106B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a data communication system, and in particular to a data communication system using a multi-link transmission group, in which data retransmission can be carried out quickly when a link failure occurs. This invention relates to a multi-link communication processing method that improves data transfer efficiency.

[Conventional technology]

FIG. 2 is an explanatory diagram of a data communication system using a multi-link transmission group, where 1 is a secondary station, 2 is a primary station, and 3 is a transmission group composed of a plurality of data links.

The secondary station 1 consists of two data links A and B and a transmission group T that manages them, and the primary station 2 consists of two data links A' and B' and a transmission group T that manages them. ′.

The data links A and B of the secondary station are sequentially polled by the primary station, and if there is data waiting for transmission, it is sent to the primary station using an information unit PIU (Pass Information Unit). The PIU consists of "flags, addresses, control fields, data, CRC, and flags."

Conventionally, link failure in a secondary station has been detected by monitoring the communication time with the primary station using a timer. This timer is called the primary station monitoring timer. The method of monitoring non-communication time is to start a timer upon reception of a frame, and if the next frame is not received within a certain period of time set in the timer, the timer times out and a link abnormality is determined.

In this case, the timer setting time is set to be sufficiently longer than the retry interval performed by the primary station when the secondary station does not respond to polling from the primary station. Therefore, a considerable number of PIUs are required between the time the secondary station detects a link failure and the time it retransmits the data on another link.
, and the primary station must keep the remaining PIUs that have already been received on the buffer waiting for sorting until the PIU that was previously unreceivable is properly received. , which caused a decrease in PIU transmission efficiency and buffer usage efficiency.

For example, if a 100 byte PIU is transmitted over a 9600 BPS link and the timer is set to 30 seconds, it will take 36 bytes before the timer times out.
PIU will be sent.

[Problem that the invention seeks to solve]

In traditional multilink data communication systems,
Because the link failure detection at the secondary station was delayed, buffer efficiency at the primary station decreased, and data transfer efficiency decreased. Therefore, it is possible to perform data correction processing at an early stage when a link failure occurs.

[Means for solving problems]

The present invention checks whether retransmission of transmitted data is necessary or unnecessary at the secondary station at an interval equal to the retry interval at the primary station, regardless of whether a link failure is detected. Transmitted data that does not exist is automatically retransmitted from another link, and if transmitted data is duplicated at the primary station, only one is validated. As a means for this purpose, in a multi-link communication system in which data is transmitted between a primary station and a secondary station using a transmission group composed of multiple data links, data within the secondary station is Based on a timer means that is activated by frame reception from the primary station for each link and monitors the passage of time approximately equal to the polling retry interval at the primary station, and a delivery confirmation notification from the primary station for the data transmitted to the primary station. Means for detecting unconfirmed delivery data and means for retransmitting unconfirmed data at the time point when the timer means times up via another data link are provided, and the primary station receives the previously received data by retransmission. This feature is characterized in that correct received data is created by integrating the received data.

〔Example〕

The details of the present invention will be explained below with reference to Examples.

FIG. 1 is a conceptual diagram of one embodiment of the present invention. In the figure, 1 is a secondary station composed of transmission group T consisting of data links A and B, 2 is a primary station composed of transmission group T' consisting of data links A'B', and 3 is a secondary station composed of transmission group T' consisting of data links A'B'. Data links 4 and 5 are retransmission timing timers for data links A and B, respectively, TS is timer set, TR is timer restart, TO is timer out, and D ₁ , D ₂ , and D ₃ represent transmission data. .
Further, the vertical direction of the figure indicates the passage of time from top to bottom, or the order of the operations, which indicates the following contents.

First, transmission data D ₁ and D ₂ arrive at the transmission group T of the secondary station from, for example, a workstation. These data are sequentially stored in a buffer (not shown).

Data link A is polled. A retransmission timing timer 4 is set (T.S).

Data D ₁ and D ₂ are transmitted from data link A.

Next transmission data D ₃ arrives at transmission group T.

Transmission data D ₁ arrives at transmission group T′ of the primary station. D ₁ is passed to a higher level. However, the transmitted data _D2 does not arrive due to a link failure that subsequently occurred.

Data link B is polled. A retransmission timing timer 5 is set (TS).

Send data D ₃ on data link B.

Transmission data _D3 arrives at transmission group T'.

In data link A, retransmission timing timer 4 times out (TO). Therefore D ₁ ,
Prepare to resend D ₂ .

Data link B is polled. Retransmission timing timer 5 is retriggered (T.
R.).

Transmit data D ₁ and D ₂ from data link B again.

Transmission data D ₁ and D ₂ arrive at transmission group T'. Since D ₁ has already been received, it is discarded. In transmission group T', the previously received data and the retransmitted data are discarded.
D ₃ and D ₂ are integrated according to their sequence numbers, and correct data D ₂ and D ₃ are extracted.

Figure 3 shows 1 of the data link control mechanism of the secondary station.
An example configuration is shown. In the figure, 4 is a retransmission timing timer, 6 is a data link establishment/release processing unit, and 7 is a retransmission timing timer.
8 is a receiving frame processing section, 8 is a transmission processing section, 9 is a timer processing section, and 10 is a conventional primary station monitoring timer.

The data link establishment/release processing unit 6 controls the establishment and release of the data link, issues a request to start the primary station monitoring timer 10 and the retransmission timing timer 4 when the data link is established, and stops these timers when the data link is released. issue a request to do so.

The received frame processing unit 7 receives the frame from the primary station using the HDLC procedure, identifies the frame information, issues a request to restart the primary station monitoring timer 10 and the retransmission timing timer 4, and also requests the primary station monitoring timer 10 and retransmission timing timer 4 to restart. The sequence number of the transmission data whose delivery has been confirmed at the station is notified to the transmission processing 8, and delivery confirmation processing is performed.

The transmission processing unit 8 temporarily stores transmission request data from the workstation, and transmits a frame in response to polling from the primary station. Furthermore, a delivery confirmation notification is sent from the primary station for the transmitted data, and when a retransmission request is received, the transmission data for which a delivery confirmation notification has not yet been received from the primary station is retransmitted via another data link.

The timer processing section 9 performs management control of the primary station monitoring timer 10 and the retransmission timing timer 4.
That is, both timers are started in response to a timer start request from the data link establishment/release processing section 6 at the time of data link establishment, and when the primary station monitoring timer 10 times out due to a link failure,
A data link release request is sent to the data link establishment and release processing section 6, and when the data link is released as a result and a timer stop request is issued, both timers are stopped. Furthermore, even if either of the two timers times out, a retransmission request is issued to the transmission processing section 8, and if there is data (frame) whose delivery has not been confirmed by the primary station, it is caused to be retransmitted.

As long as frame transmission is being performed normally, each data link is periodically polled and receiving data from the primary station, and the received frame processing unit 7 issues a timer restart request accordingly. , both timers never time out.

When the primary station monitoring timer 10 times out, the relevant data link is released and the timer is stopped, and retransmission is performed using another data link, but when the retransmission timing timer 4 times out, only retransmission is performed. In the case of retransmission, as in normal frame transmission, retransmission timing monitoring is required, so the retransmission timing timer is automatically restarted.

〔Effect of the invention〕

As described above, according to the present invention, data retransmission is performed early in the event of a link failure, so data transmission efficiency is improved, and buffer efficiency at the primary station is also improved.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of an embodiment of the present invention, Fig. 2 is an explanatory diagram of a data communication system using a multilink transmission group, and Fig. 3 is a configuration diagram of an embodiment of a data link control mechanism of a secondary station. It is. In the figure, 1 is a secondary station, 2 is a primary station, 3 is a transmission group composed of multiple data links, 4 and 5 are retransmission timing timers,
D ₁ , D ₂ , D ₃ are transmission data, TS is timer set,
TR stands for timer restart, and TO stands for timeout.

Claims (1)

[Claims] 1. In a multilink communication system in which data is transmitted between a primary station and a secondary station using a transmission group consisting of multiple data links, the secondary station has a primary link for each data link of the secondary station. a timer means that is activated by frame reception from the station and monitors the passage of time approximately equal to the retry interval of polling at the primary station; and a timer means that monitors the passage of time approximately equal to the polling retry interval at the primary station, and a timer means that detects unconfirmed data based on a delivery confirmation notification from the primary station for data transmitted to the primary station. a means for detecting;
When the timer means times out, there is provided a means for retransmitting unconfirmed data at the time through another data link, and the primary station integrates the previously received data with the data received by retransmission to receive the correct data. A multi-link communication processing method characterized by creating data.