JPH08331139A - Frame relay network and information transmission method in the network - Google Patents

Abstract

PURPOSE: To secure communication and to improve reliability for a frame network by forming the network with plural lines and immediately switching the line to another line when a network fault or a fault such as congestion occurs in the line on one side in a frame network and an information transmission method in the network. CONSTITUTION: This information transmission method for the frame relay network comprised by connecting its own side terminal equipment 1 and opposite side terminal equipment 3 via an exchange 2 are constituted in such a way that a main line and a sub line are connected between its own side terminal equipment 1 and the exchange 2, and between the exchange 2 and the opposite side terminal equipment 3, respectively, and when the network fault o the fault such as the congestion is detected in its own side terminal equipment 1 or the opposite side terminal equipment 3, the line is immediately switched from the line on one side to the line on the other side to continue information transmission to the network.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame relay network and a data transmission method in the network. In recent years, a frame relay network has been developed as an information transmission method suitable for connection between LANs. Frame relay is similar to packet switching,
By transmitting and receiving information in the frame of the data link procedure (HDLC) and designating the destination in the address part of the HDLC,
This is a switching system that realizes frame-based switching as well as physical multiplexing of physical lines. Since the frame relay network is easy to control, it is easy to increase the speed, and it is expected as a wide area network that can improve the line utilization efficiency of the leased line by frame multiplexing and construct an economical network.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram of a main part of a conventional frame relay network. As shown in the figure, the local terminal device 1 and the remote terminal device 3 are connected via the exchange 2 by single-line lines La and Lb. Since it is a single line, if some trouble occurs between the frame relay network and the terminal device,
Naturally, communication with the other party cannot be performed until the failure is recovered.

By the way, failures in the frame relay network include network failure and congestion. 2 in case of network failure
An example and a case where congestion occurs will be described. FIG. 6 is an explanatory diagram of an example of network failure occurrence in the conventional configuration. As an example of network failure, first, the terminal device 1 of the self side sends an inquiry of the network state confirmation to the exchange 2 (or the terminal device 3 of the partner side) via the line (La). The self-sided terminal device 1 starts the time monitoring by the timer after issuing the inquiry of the network state confirmation. For example, if the network state notification is not returned from the exchange 2 after 15 seconds, the self-sided terminal device 1 has a network failure. Confirm. After that, 1
An inquiry is made every 5 seconds to check the network status, and if the local terminal 1 receives the network status notification from the exchange 2, it is judged that the line has been restored, and data transmission from the local terminal 1 to the exchange 2 is started. .

FIG. 7 is a diagram for explaining another example of occurrence of a network failure in the conventional configuration. Similar to FIG. 6, first, the local terminal device 1
Inquiries about network status confirmation from switch 2 via line (La)
Send to The self-side terminal device 1 starts the time monitoring by the timer after issuing the inquiry of the network state confirmation, and when receiving the network state notification with the flag indicating the network failure from the exchange 2 within 15 seconds, for example. The side terminal device 1 confirms the network failure by this flag and stops the transmission. Further, an inquiry about the confirmation of the network status is sent to the exchange 2 about every 15 seconds, and if the flag indicating the network failure disappears, it is judged that the network has been recovered and the data transmission is started.

FIG. 8 is an illustration of an example of network congestion occurrence in the conventional configuration. Similar to FIG. 7, first, the terminal device 1 of the self side sends an inquiry to confirm the network state to the exchange 2 via the line (La). The self-side terminal device 1 makes a call for the inquiry of the network state confirmation,
The time monitoring by the timer is started, and within 15 seconds, for example, the switch 2 issues a network status notification with a flag indicating network congestion.
Then, the terminal device 1 on its own side confirms the network congestion by this flag and stops the transmission. Further, an inquiry to confirm the network state is sent to the exchange every 15 seconds, and if the flag indicating the network congestion disappears, it is judged that the state has been restored and data transmission is started.

[0006]

As described above, failures in the frame relay network include network failure and congestion. In the case of a network failure as shown in FIGS. 6 and 7, whether the network failure is confirmed due to a time out or the network failure is confirmed by a failure flag, the terminal device on the self side or the partner side promptly transmits data. Is obliged to stop. Therefore, the network side must be repeatedly checked from its own side to the other side, and the line must be stopped until the network status notification is returned and the time is monitored, or the failure flag is cleared and the system is restored.

On the other hand, as shown in FIG. 8, when congestion occurs in the frame relay network, transmission of a specific line and a plurality of lines is disabled, or the transmission amount is significantly reduced. This kind of congestion is based on the concept of congestion in the frame relay network, and it is considered that the maximum transmission amount of all lines may be equal to or higher than the physical speed. For this reason, there is a very high possibility that congestion will occur depending on the settings made by the user. Then, when a plurality of them occur, there is no other way but to reduce the data transmission amount on the transmission path.

In these cases, the reliability seems low despite the procedure in which the frame relay was made for the purpose of connecting between LANs. An object of the present invention is to change a conventional single-line frame relay network to a double line in a transmission method in a frame relay network, and promptly switch to another line when a failure such as a network failure or congestion occurs in one line. To secure communication and improve reliability of the frame relay network.

[0009]

SUMMARY OF THE INVENTION The present invention provides an information transmission method in a frame relay network configured by connecting a self-side terminal device and a remote-side terminal device through an exchange,
The self-sided terminal device and the exchange, and the exchange and the other-sided terminal device are connected by a main line and a sub-line, respectively, network failure or network congestion at the own-sided device or the other-sided terminal device. When the failure of (1) is detected, the one line is immediately switched to the other line, and the information transmission to the network is continued.

Here, the terminal device on the other side or the terminal device on the other side sends an inquiry of network state confirmation to the network, monitors the return of the network state notification from the other side for a certain time, and within the certain time, When the network status notification is not returned, it is determined that the network has failed and the line is switched from one to the other. Further, when the own terminal device or the other terminal device sends a network state confirmation inquiry to the network, when the other side returns a network state notification including a flag indicating network failure or network congestion within a fixed time. Determines that a network failure or network congestion is made by the flag and switches the line from one to the other.

Further, the self-side terminal device or the partner-side terminal device electrically detects disconnection of the line, determines that there is a network failure, and switches the line from one to the other.
Furthermore, the self-side terminal device or the partner-side terminal device monitors the congestion state of the line by the number of received notifications, and when a certain congestion state is reached, switches the line from one to the other.

Furthermore, the terminal device on the other side or the terminal device on the other side monitors the congestion state of the line by the number of reception notifications within a certain time, and when the number of reception notifications reaches a certain number, the line can be switched from one to the other. You can do it. Further, the own terminal device or the other terminal device determines the congestion state of the line by the total data amount of the received frame, and when the total data amount within a fixed time exceeds a fixed amount, switches the line from one to the other. It is designed to be switched.

Further, the self-side terminal device or the partner-side terminal device is adapted to switch the line from one side to the other when the abnormal message is received from the partner side and the abnormal message is not resolved within a certain period of time. . Further, the own terminal device or the partner terminal device receives an abnormal message from the partner and switches the line from one to the other when the number of received abnormal messages exceeds a certain amount.

Furthermore, when the abnormal terminal receives an abnormal frame from the other party and the discard rate of the received information increases, the own terminal apparatus or the other party terminal apparatus monitors for a predetermined time and does not recover within a certain time. At this time, the line is switched from one to the other. Furthermore, the self-side terminal device or the partner-side terminal device monitors for a predetermined period of time when the retransmission rate of information transmission in the upper application connected to each of them is significantly increased, and when it does not recover within a fixed time Is designed to switch lines from one to the other.

Further, according to the present invention, in a frame relay network configured by connecting a self-side terminal device and a partner-side terminal device through an exchange, the self-side terminal device and the exchange, and the exchange and the exchange. When the main terminal device or the remote terminal device detects a failure such as a network failure or network congestion by connecting to the remote terminal device by a main line and a sub line, respectively, the other line is immediately connected to the other line. The present invention provides a frame relay network configured so as to switch to the line and continue information transmission to the network.

[0016]

1 is a block diagram of the essential parts of a frame relay network according to the present invention. As shown in the figure, in the present invention, the local terminal device 1 and the remote terminal device 3 are connected via the exchange 2 by a plurality of main lines L1a and L1b and sub lines L2a and L2b. . That is, conventionally, as shown in FIG. 5, the local terminal device 1 and the remote terminal device 3 were connected by the single line of the lines La and Lb via the exchange 2, but in the present invention, a network failure occurs as a double line. It deals with the occurrence of network congestion. As a result, according to the present invention, when a failure occurs in one line, switching to the other line can eliminate a network failure or a communication congestion state and improve reliability.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, according to the present invention, a main line L1a and a sub line L2a are provided between the own side terminal device 1 and the exchange 2, and a main line L1 is provided between the exchange 2 and the partner side terminal device 3.
b, a sub-line L2b is provided in the frame relay network. As a code in the figure, "STATUS-ENQ" is a "network status confirmation inquiry" frame sent from the local terminal device to the exchange, and "STATUS" is the local terminal device (or partner terminal device) from the exchange. It is a "network status notification" frame sent back to.

That is, as a query for confirming the network status from the local terminal device to the exchange, a "network status confirmation query" (STA
When TUS-ENQ) is sent, a "network status notification" (STATUS) for notifying the status of the network is always returned from the exchange at regular intervals. Specifically, as shown in the figure, S
When the exchange calls TATUS-ENQ and the exchange receives STATUS-ENQ, it sends STATUS to its own terminal device within about 15 seconds, and when the exchange receives STATUS, it receives STATUS within about 15 seconds.
-The ENQ is called and the exchange receives the STATUS-ENQ. Hereinafter, this step is repeated.

As described above, after the response sequence is activated, the network and the exchange are operating normally by repeatedly performing processing on the network at regular intervals (about 15 seconds) until the network stops. Make sure that. On the other hand, when there is no STATUS response from the exchange in response to the STATUS-ENQ inquiry from the self-sided terminal, the self-sided terminal fails in the main line L1a between the self-sided terminal and the exchange. When it is determined that it has occurred, the sub line L2a is switched to and data is transmitted and received.
That is, the terminal device on its own side stops the data transmission / reception on the main line L1a and transmits / receives the data on the sub line L2a to guarantee the data communication. The inquiry control and the line switching by the inquiry control as described above are performed by a driver (firmware, not shown) in the terminal device without being noticed by a host (for example, a user).
Is done automatically.

FIG. 2 is an explanatory diagram showing an example of occurrence of a network failure in the configuration of the present invention. First, the terminal device of its own side sends a network status confirmation inquiry (STATUS-ENQ) to the exchange through the main line, and at the same time starts the time monitoring by the timer. If a network status notification is not returned from the exchange after about 15 seconds have passed, the terminal device on the own side confirms that the network has failed and switches to the sub line. However, the main line will also continue to check the network status. After switching to the sub-line, the local terminal device sends a network status confirmation inquiry (STATUS-ENQ) to the exchange and starts the time monitoring by the timer. When the network status notification is returned from the exchange within about 15 seconds, the terminal device on the own side confirms that the sub line is normal and starts data transmission to the exchange. As with the main line, the sub-line always asks the network status confirmation from the terminal device on the own side.

FIG. 3 is a diagram for explaining another example of occurrence of a network failure in the configuration of the present invention. Similar to the above, first, an inquiry (STATUS-ENQ) for confirming the network status is sent from the local terminal device to the exchange via the main line, and at the same time, the time monitoring by the timer is started. When a network status notification with a failure flag is returned from the exchange within about 15 seconds, the terminal device on the own side confirms the flag and confirms the network failure and switches to the sub line. However, the main line will also continue to check the network status. After switching to the sub-line, the local terminal device sends a network status confirmation inquiry (STATUS-ENQ) to the exchange and starts the time monitoring by the timer. When the network status notification is returned from the exchange within about 15 seconds, the terminal device on the own side confirms that the sub line is normal and starts data transmission to the exchange. As with the main line, the sub-line always asks the network status confirmation from the terminal device on the own side.

FIG. 4 is an explanatory view of an example of occurrence of network congestion in the configuration of the present invention. Similar to the above, first, an inquiry (STATUS-ENQ) for confirming the network status is sent from the local terminal device to the exchange via the main line, and at the same time, the time monitoring by the timer is started.
When a network status notification with a failure flag is returned from the exchange within about 15 seconds, the terminal device on the own side confirms the flag, confirms network congestion, and switches to the sub line. However, the main line will also continue to check the network status. After switching to the sub line, the local terminal device sends an inquiry to the exchange to check the network status (S
TATUS-ENQ) is sent and the time monitoring by the timer is started. When the network status notification is returned from the exchange within about 15 seconds, the terminal device on the own side confirms that the sub line is normal and starts data transmission to the exchange. Similarly to the main line, the sub-line always asks the network state confirmation from the terminal device on the own side.

The network failure or network congestion in the embodiments of FIGS. 2 to 4 is confirmed by the time monitoring by the timer of the self-side terminal device, and when there is no notification from the network even after a certain period of time, the line is not notified. However, as described below, various methods other than time monitoring are possible. 1. The hardware (not shown) of the local terminal device electrically judges the disconnection of the line and switches the line from one to the other. Normally, the line is always connected, so if the line is disconnected, it can be determined that the network is out of order.

2. The own terminal device switches the line by monitoring the congestion state of the line based on the number of received notifications and making a judgment. The terminal device of its own side grasps the state of the network based on the number of received network congestion information, and when it judges that normal data transmission cannot be performed, it switches from one line to the other line. In this case, when monitoring the number of reception notifications, the line can be switched by judging the number of reception notifications within a certain monitoring time.

3. The terminal device on the own side judges the congestion state of the line by the total data amount of the received frame, and switches the line from one to the other when the data amount exceeds a certain amount. In this case, the line can be switched by judging the total data amount within the fixed monitoring time of the received frame. 4. When the abnormal terminal is received from the partner terminal apparatus, the own terminal apparatus starts a timer, and switches the line from one to the other when the abnormal message does not disappear within a predetermined time.
In this case, if the number of received abnormal telegrams exceeds a certain amount, the line can be switched from one to the other. It is also possible to switch lines by monitoring the number of abnormal telegrams within a fixed time. Furthermore, it is also possible to switch the line by judging the network status based on the total data amount of the received abnormal message.

[5] When the abnormal terminal receives an abnormal frame from the other terminal and the discard rate increases, the local terminal monitors for a predetermined time, and switches the line from one to the other when the abnormal frame is not recovered within a certain time. 6. When the retransmission rate in the higher-level application connected to the terminal device on its own side significantly increases, it is monitored for a predetermined time, and when it does not recover within a certain time, the line is switched from one to the other.

[0027]

As described above, according to the present invention,
In the transmission method in the frame relay network, the conventional single-line frame relay network is made into multiple lines, and when a failure such as a network failure or congestion occurs in one line, it is promptly switched to another line to ensure communication. The reliability of the frame relay network can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of a frame relay network according to the present invention.

FIG. 2 is an explanatory diagram of an example of network failure occurrence in the configuration of the present invention.

FIG. 3 is a diagram illustrating another example of network failure occurrence in the configuration of the present invention.

FIG. 4 is an explanatory diagram of an example of occurrence of network congestion in the configuration of the present invention.

FIG. 5 is a configuration diagram of a main part of a conventional frame relay network.

FIG. 6 is an explanatory diagram of an example of network failure occurrence in the conventional configuration.

FIG. 7 is a diagram illustrating another example of the occurrence of a network failure in the conventional configuration.

FIG. 8 is an explanatory diagram of an example of network congestion occurrence in the conventional configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Own side terminal device 2 ... Exchange 3 ... Other party terminal device L1a, L1b ... Main line L2a, L2b ... Sub line

Claims (12)

[Claims] 1. An information transmission method in a frame relay network configured by connecting a self-sided terminal device and a remote-sided terminal device via an exchange, wherein the self-sided terminal device and the exchange, and the exchange and the exchange When a failure such as a network failure or network congestion is detected in the local terminal device or the remote terminal device by connecting to the remote terminal device by a main line and a sub line, respectively, immediately from one line to the other line A method for transmitting information in a frame relay network, characterized in that the line is switched to another line and information transmission to the network is continued. 2. The self-side terminal device or the partner-side terminal device sends an inquiry to confirm the network status to the network, monitors the return of the network status notification from the partner party for a certain period of time, and monitors the network within the certain period of time. The method of transmitting information in a frame relay network according to claim 1, wherein when the status notification is not returned, it is determined that the network has failed and the line is switched from one to the other. 3. The self-side terminal device or the partner-side terminal device sends a network status confirmation inquiry to the network, and a partner-side terminal device returns a network status notification including a flag indicating network failure or network congestion within a fixed time. 2. The information transmission method in the frame relay network according to claim 1, wherein when it is determined, it is determined that the network is faulty or congestion based on the flag and the line is switched from one to the other. 4. The frame relay network according to claim 1, wherein the self-side terminal device or the remote-side terminal device electrically detects disconnection of a line, determines that a network failure has occurred, and switches the line from one to the other. Information transmission method. 5. The terminal device according to claim 1, wherein the terminal device on the other side or the terminal device on the other side monitors the congestion state of the line by the number of received notifications, and switches the line from one side to the other side when a certain congestion state is reached. Information transmission method in frame relay network. 6. The self-side terminal device or the remote-side terminal device monitors the congestion state of the line by the number of received notifications within a fixed time, and switches the line from one to the other when the fixed number of received notifications is reached. 1. An information transmission method in the frame relay network described in 1. 7. The terminal device on the other side or the terminal device on the other side determines the congestion state of the line based on the total amount of data of the received frame, and when the total amount of data within a certain time exceeds a certain amount, one of the other ends. The method for transmitting information in a frame relay network according to claim 1, wherein the line is switched to. 8. The terminal device according to claim 1, wherein the terminal device on the other side or the terminal device on the partner side receives an abnormal message from the partner and switches the line from one to the other when the abnormal message is not resolved within a certain time. Information transmission method in a frame relay network. 9. The terminal device according to claim 1, wherein the self-side terminal device or the partner-side terminal device receives an abnormal message from the partner and switches the line from one to the other when the number of received abnormal messages exceeds a certain amount. Information transmission method in the described frame relay network. 10. The self-side terminal device or the remote-side terminal device, when an abnormal frame is received from the remote side and the discard rate of the received information increases, monitors for a predetermined time and restores within a fixed time. The method for transmitting information in a frame relay network according to claim 1, wherein when not performing, the line is switched from one to the other. 11. The self-side terminal device or the other-side terminal device performs monitoring for a predetermined period of time when a retransmission rate of information transmission in a higher-order application connected to each of them is remarkably increased, and within a certain period of time. The method for transmitting information in a frame relay network according to claim 1, wherein the line is switched from one to the other when the line is not restored. 12. A frame relay network configured by connecting a self-sided terminal device and a remote-sided terminal device through an exchange, wherein the self-sided terminal device and the exchange, and the exchange and the remote-sided terminal device. The main line and the sub line are connected to each other, and when a fault such as a network failure or network congestion is detected at the local terminal device or the remote terminal device, one line is immediately switched to another line. , A frame relay network configured to continue transmitting information to the network.