JPH07123111A - Data relay frame processing method - Google Patents

Abstract

(57) [Summary] [Purpose] Even if the data repeater receives an abnormally long frame, it enables the use of the network as the entire system. A data repeater 10 that is connected to a transmission path that constitutes each network and that processes and relays a data frame transmitted between communication terminal stations of the network.
In the frame processing method, the length of the received data frame is detected, and if the length of the frame is longer than a predetermined length due to an abnormality in the communication terminal station or transmission path, the relay function of the relay device is used. A part of (the functions of the reception unit 11, the relay control unit 12, and the transmission unit 13) is stopped to stop the relay of the data frame.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame processing method for a plurality of network-connected data repeaters.

[0002]

2. Description of the Related Art Conventionally, in this type of repeater, when a normal data frame composed of a destination address, a source address, a data length, data and a frame check sequence is received from a communication terminal station of one network. After performing frame processing such as waveform shaping, the frame is transmitted to the communication terminal station of the other network.
When the length of the received frame is longer than the predetermined length (see FIG. 4 (a)), for example, as shown in FIG. 4 (b),
Similar to the normal frame, frame processing is performed for 4 ms to 7.5 ms to relay the frame to the communication terminal station on the other network, and 9.6 μs to 1
After interrupting the frame at an interval of 1.6 μs, the remaining part of the frame was subjected to frame processing again and relayed to the communication terminal station of the other network. The function of this repeater is generally called a MAU (medium connection unit) Java lock-up protection function. The repeater prevents the receiver from entering the Java state when it detects an abnormally long frame. Was there.

[0003]

However, in the frame processing method of the repeater, the receiving section does not enter the Java state, but the frames are continuously sent to the transmission line at the interruption intervals, so that the network is exclusively used. As a result, the network becomes unusable as a whole system, which not only deteriorates the use efficiency, but also causes a system down in the worst case.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a frame processing method for a data repeater, which enables use of the network as a whole system even if an abnormally long frame is received. And

[0005]

In order to achieve the above object, according to the present invention, there is provided a data repeater which is connected to each network and which processes and relays a data frame transmitted between communication terminal stations of the network. In the frame processing method, there is provided a frame processing method of a data repeater, which detects the length of the received data frame, and stops the relay of the data frame when the length of the frame is longer than a predetermined length. .

[0006]

When a transceiver, a communication terminal station or a repeater receives an abnormally long frame caused by a failure or an abnormality in the transmission path, the repeater receives a part of the relay function, for example, from the network that transmitted the frame. Disables frame input, stops frame relay, or disables the frame while receiving the above frame, processes the frame received from another network, and relays it. Further, or all or until the reception of the abnormally long frame is finished, the relay of all the data frames is stopped.

Therefore, the abnormally long frame received by the repeater is not relayed to the communication terminal station of the transmission partner network, and the deterioration of the usage efficiency in the entire network can be prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings of FIGS. 1 is a block diagram showing a schematic configuration of a repeater using the frame processing method according to the present invention.
FIG. 3 is a system configuration diagram in which a transmission system is configured by connecting the repeater to each network.

In FIG. 1, a repeater 10 includes a receiver 11 for receiving a data frame transmitted from a communication terminal station connected to each transmission line, and a relay for performing frame processing such as waveform shaping of the received frame. A control unit 12 and a transmission unit 13 that transmits the frame-processed data frame to a communication terminal device connected to another transmission path of a transmission partner.

The receiving unit 11 has a receiving port (not shown) connected to each transmission path, receives a data frame from each network through the receiving port, and relays the received frame to the relay control unit 12 Output to. The relay control unit 12 uses the reception unit 11 as a part of frame processing.
The length of the frame input from is detected, and when the frame is shorter than the predetermined length, the frame is processed and output to the transmission unit 13. Also, the relay control unit 1
2 ignores frame input from the receiving port that receives the frame when the frame is longer than a predetermined length, and ignores the frame input from other receiving ports during this period. Transmitter 1 corresponding to the port
It is also possible to output to the network (that is, the network to which the reception port is connected) from the transmission port 3 (not shown).

The transmission unit 13 has a transmission port (not shown) connected to each transmission line, and the relay control unit 12 is provided.
The frame output from is transmitted to the communication terminal station of the transmission partner via a predetermined transmission port. The reception port and the transmission port are paired and connected to each transmission line. In the embodiment, the reception port and the transmission port are connected to the first transmission line and the second transmission line, respectively. Has been done.

FIG. 2 shows an example of a transmission system constructed by connecting the repeater 10 thus constructed to each transmission line. The frame processing operation of the repeater will be described with reference to FIG. In the first embodiment, the communication terminal station 22 is the transmission source and the communication terminal station 42 is the transmission partner. First, when a data frame is transmitted from the communication terminal station 22 connected to the transmission line 21 that constitutes the network 20, the frame is transmitted to the first repeater 10 via the transmission line 21. In the first repeater 10, the receiving unit 11 receives the frame, and the relay control unit 12 detects the length of the frame input from the receiving unit 11. And
If the frame is shorter than the predetermined length, the relay controller 1
2 performs frame processing such as waveform shaping on the frame and outputs the frame to the transmission unit 13. In the transmitting unit 13, the frame-processed data frame is transferred to the transmission line 31.
To the second repeater 10 via.

When the frame is longer than a predetermined length, the relay control unit 12 receives a predetermined frame from the reception unit 11 that receives the frame (in the embodiment, the reception port to which the transmission line 21 is connected). Ignore the frame input from the other receiving port (in the embodiment, the transmission line 31
To the transmission port of the transmission unit 13 (in the embodiment, the transmission port to which the transmission path 21 is connected) corresponding to the above-mentioned ignored predetermined reception port. Also outputs the received data frame. The relay control unit 12 that ignores frame input
The condition for returning to the normal relay operation is, for example, the input of a normal frame within a fixed period. It is desirable that the fixed period is, for example, about 500 bits to 16000 bits. Moreover, it is desirable that the condition for an abnormally long data frame is 1.6 ms or more.

When the second repeater 10 also receives the data frame from the transmission line 31, the frame length is detected as described above, and the frame input is ignored or the frame is networked according to the detection result. It controls whether to transmit to the communication terminal station 42 via the transmission path 41 which constitutes 40. Therefore, in this embodiment, when the repeater receives an abnormally long data frame, this frame input is ignored, so that the frame is transmitted to the transmission path, the next-stage repeater, and the communication terminal station of the transmission partner. It is not relayed, which can improve the usage efficiency of the entire network.

The frame processing method according to the present invention is
The object can be achieved not only by the above-mentioned first embodiment but also by the methods of the following second and third embodiments. In other words, in the second embodiment, the frame length is detected by the receiving unit 11, and if an abnormally long frame is detected here, the receiving unit 11 invalidates the received frame and sends it to the relay control unit 12. Set to cancel. Further, when the reception of the abnormally long frame is completed, it is set to return to the normal mode in which the frame can be sent from the receiving port that received the frame to the relay control unit 12.

As a result, the relay control unit 12 is in a data input waiting state, and when the receiving unit 11 receives a frame from a receiving port other than the receiving port that received the abnormally long frame, normal relay operation is performed. It can be carried out. Therefore, in this embodiment, when an abnormally long frame is received, the receiving unit ignores the frame,
As in the first embodiment, the usage efficiency of the entire network is improved, and normal frames from other receiving ports are relayed to the transmission partner, so that data transmission of the frames can be reliably performed.

Further, in the third embodiment, when the transmitting unit 13 is caused to detect the frame length and an abnormally long frame is detected here (see FIG. 3A), the transmitting unit 13 transmits the frame. Is set to stop as shown in FIG. 3 (b). In this case, the condition for an abnormally long data frame is 1.6 ms or more. As a result, all the data frames received from all the receiving ports of the receiving unit 11 are not relayed to the transmission partner, and the transmitting unit 13
When the input of the abnormal frame from the relay control unit 12 is completed, returns to the normal mode at that time.

Therefore, in the present embodiment, when the abnormally long frame is received, the transmitting unit stops the transmission of the frame, so that the abnormal frame is the transmission partner as in the first embodiment. It will not be relayed to the communication terminal station,
This can improve the usage efficiency of the entire network. That is, in these embodiments, when the relay receives a data frame having an abnormally long frame length due to an abnormality in the communication terminal station, the transmission path, or the like, a part of the relay function of the relay is stopped. Since the original relay operation of the repeater cannot be executed, the relay of the abnormal frame is stopped, and the network can be used as the entire system.

[0019]

As described above, the present invention provides a frame processing method for a data repeater, which is connected to each network and frame-processes and relays a data frame transmitted between communication terminal stations of the network, The length of the received data frame is detected, and if the length of the frame is longer than a predetermined length, the relay of the data frame is stopped. Therefore, even if an abnormally long frame is received, the network system is down. And the network can be used as the entire system.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a repeater using a frame processing method according to the present invention.

FIG. 2 is a system configuration diagram in which a transmission system is configured by connecting the repeater shown in FIG. 1 to each network.

FIG. 3 is a diagram showing an input / output frame of a repeater according to a third embodiment of the present invention.

FIG. 4 is a diagram showing an input / output frame of a repeater according to a conventional example.

[Explanation of symbols]

 10 Repeater 11 Receiver 12 Relay Controller 13 Transmitter 20,40 Network 21,31,41 Transmission Line 22,42 Communication Terminal Station

Claims (4)

[Claims] 1. A frame processing method of a data repeater, which is connected to each network and processes and relays a data frame transmitted between communication terminal stations of the network, to detect a length of the received data frame. Then, when the length of the frame is longer than a predetermined length, the relay of the data frame is stopped, and the frame processing method of the data relay. 2. The relay, when receiving the data frame longer than the predetermined length, invalidates the frame input from the network that transmitted the frame and processes the frame received from another network. The frame processing method of the data relay device according to claim 1, wherein the relay is performed by relaying. 3. The relay device, when receiving a data frame longer than the predetermined length, invalidates the frame while the reception of the frame continues, and for a frame received from another network, 2. The frame processing method for a data relay device according to claim 1, wherein the frame processing is performed for relaying. 4. The relay device, when receiving a data frame longer than the predetermined length, stops relaying all the data frames until the reception of the frame is completed. Data relay frame processing method.