JPH10173660A - Highly reliable atm lan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize failure detection and redundant transfer, while holding a load on a terminal to be low by setting plural VC between terminals for preparing for the generation of a fault, selecting the proper VC from among the plural VC according to the monitored result of the VC, and performing communication. SOLUTION: A fault detecting means 1 operates fault detection by using a p-mp connected VC, so that the transmission of signals for fault detection to all opposite terminals can be attained at once. A redundant transferring means 2 automatically operates re-transmission by using a waiting system VC, when a confirmation response is not transmitted from a receiving terminal so that a load on the terminal at a normal time can be reduced, and the loss of data at the time of fault generation can be avoided. A network setting means 3 enables communication between an arbitrary terminal and a switch by a few PVC, by combining the PVC between the terminal and switch with an IP routing table on a central node.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly reliable ATM (asynchronous) for an industrial system.
transfer mode) LAN.

[0002]

2. Description of the Related Art FIG. 15 shows a conventional ATM for an industrial system.
It is a conceptual diagram of LAN. As is clear from the figure, the terminal is provided with an OAM (operation administrator).
VC (virtual circuit) with which an application program communicates by using an application and maintenance function or polling
Is provided. When a failure occurs on the path of the application program VC, the failure detection means 1 continues communication of the application program using the standby VC set on the spare path to reduce the influence of the failure. Redundant transfer means 2 is provided to reduce the number. In some cases, the redundant transfer unit 2 avoids a failure by transferring data of an application program by simultaneously using a plurality of VCs set between terminals. A network setting means 3 for setting a network as described above is provided.

[0003] In the ATM network, an OAM function is provided for controlling and managing the network.
Failure detection can be performed by using the failure management function. The OAM function is provided at five levels from the physical level to the VC level. In the case of the VC level,
Since the number of target VCs can be very large,
OAM functions at the VC level may not be provided. In such a case, by using the VC to be monitored itself or the monitoring VC that passes through the same path as the VC and periodically transmitting a signal, a polling process for checking the state of the VC causes a failure. Perform detection.

FIG. 16 shows a conventional technique for transferring data using a plurality of VCs. One of the plurality of VCs is used as a working VC, and the other VCs are used as standby VCs. Normally, redundant transfer means 2 of the transmitting terminal
Transfers data only by the working VC. The above working VC
When a failure occurs on the path, the failure detecting means 1 of the transmitting terminal detects the failure, and the redundant transfer means 2 of the transmitting terminal selects one of the standby VCs and sets it as a new working VC.
Such a system is called a standby redundancy system. FIG. 10 is a diagram showing another conventional technique for transferring data using a plurality of VCs. The redundant transfer means 2 of the transmitting terminal performs all VC
To transfer data at the same time. The redundant transfer means 2 of the receiving terminal receives only one of the data that has arrived redundantly and discards the other data by the serial number or the like added to the data. Such a method is called a parallel transfer method.

[0005] In the ATM, unless a VC is set between terminals, communication is not possible even if there is a physical communication path between the terminals. For this reason, PVC (permanent VC,
In an ATM LAN using only a fixed connection VC), it is necessary to set a PVC between all terminals that may perform communication.

FIG. 18 shows a V in an ordinary ATM LAN.
The setting method of C is shown. VC is a unique VC identifier within a single fiber; VCI (VC identifier)
ier) and a new VCI is given when the data is relayed to the next fiber by the ATM switch. Such a conversion is described in a VCI conversion table on the ATM switch. In PVC, all A on the PVC path
It was necessary to manually set the VCI conversion table of the TM switch.

[0007]

SUMMARY OF THE INVENTION Conventional ATM LAN
In the configuration of the above, when the failure detecting means 1 on the terminal detects a failure on the path of the VC by polling, a monitoring VC passing through the same path as the monitored VC is set, and the monitoring VC is used. Signals for failure detection are periodically transmitted and received. For this reason, when the number of communication partner terminals increases, the transmission / reception load of the failure detection signal increases, which hinders the original business. The redundant transfer means 2 performs communication using a plurality of VCs provided between terminals, and avoids the influence of a fault on the VC. In the standby redundancy system, one of a plurality of VCs is used as an active VC for data transfer of an application program, and the other VCs are used as standby VCs.
When a failure occurs above, data transfer is continued using one of the standby VCs. In the parallel transfer method, data is transferred using a plurality of VCs. Therefore, even if a failure occurs on one VC path, data is transferred without any problem. In the standby redundancy system, data transferred from the occurrence of a failure until the VC is switched is lost, so that retransmission at the application level is required. Further, in the parallel transfer method, since transfer is performed by a plurality of VCs, the transmission and reception load on the terminal increases. The network setting means 3
A VC for performing communication between terminals is set. When using PVC, communication is possible only between terminals for which PVC has been set in advance. When communication such as management communication is required, in order to perform communication between arbitrary terminals and switches,
It is necessary to set a PVC between all the terminals, which requires enormous effort. Also, when setting a PVC, if a loop-shaped PVC is set due to an operation error, the PV
A cell circulating infinitely on C may saturate the network.

[0008] The polling process is performed by the terminal. This terminal uses a VC that communicates with the partner terminal or a monitoring VC that follows the same route as the VC.
A survival signal is transmitted periodically. In this case, the terminal needs to transmit the same number of survival signals as the number of communication partners within one period, receive the same number of survival signals, and monitor the state of the VC. Such processing is performed when the number of partner terminals increases.
A heavy load is placed on the terminal.

In the standby redundancy system, data is transferred by the old working VC until the failure is detected and the standby VC is switched to the working VC after the failure actually occurs. Data is lost due to failure. For this reason, the application program on the terminal must perform retransmission processing after switching the VC, and the retransmitted data suffers a very large delay. In the parallel transfer method, even if a failure occurs in one VC, the transfer can be performed in another VC, so that the transfer is not affected by the failure and the retransmission processing by the application program is unnecessary. However, since the same data is transferred redundantly, there is a disadvantage that the load on the transmitting / receiving terminal and the network increases.

[0010] Further, in the above ATM LAN, when there is a possibility that communication is performed between all terminals, it is necessary to set a very large number of VCs. Assuming that the number of terminals is N, _N C ₂ = N × (N−1) / 2 PVCs
Must be set, and as the number of terminals increases, the setting labor becomes very large. FIG. 19 illustrates such a problem. In order to arbitrarily communicate between six terminals, it is necessary to set 15 PVCs.

Further, since the PVC is manually set, a loop may occur due to a setting error. FIG.
FIG. 4 is a diagram illustrating an example of a loop. VC input as VCI = 4 to port 1 of the ATM switch is
Output as CI = 7. The VC has some A
After passing through the TM switch, VCI = 9 is again input to port 2 of the same ATM switch. At this time,
The setting of the VCI conversion table is incorrect, and the VCI =
If it is specified to output as 7, the cell on the VC goes around the same path indefinitely. If the upstream terminal continues to transmit cells, the number of cells circulating in the loop continues to increase and the network reaches saturation. In the VCI conversion table in the case where a loop occurs, two inputs correspond to one output destination, which corresponds to an mp-p connection (multi point-to-point connection, many-to-one connection) as shown in FIG. It cannot be distinguished from the VCI conversion table for VC. In order to detect a loop, it is necessary to read the VCI conversion tables of all switches and follow the path of each VC.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems.
An object of the present invention is to increase the reliability of an ATM LAN and to improve the efficiency of network settings when an ATM LAN is used in a field requiring fault tolerance.

[0013]

The ATM LAN according to the first configuration of the present invention can be represented by a schematic principle diagram showing the entire configuration of the present invention as shown in FIG. Failure detection means 1
Sets a monitoring VC for one-to-many connection that includes all the paths of the VCs with which the application on the terminal communicates, and uses the monitoring VC for the p-mp connection. The response of the partner terminal to the failure detection signal is transmitted using a p-mp connection monitoring VC set by the partner terminal in the same manner as the terminal. The redundant transfer unit 2 automatically retransmits data using the standby VC only when the acknowledgment from the partner terminal cannot be received within a predetermined time period for the data transmitted using the active VC. . The network setting means 3 divides the network into a plurality of sub-networks,
One representative node and another general node are set in each subnetwork, PVCs are set between the general nodes and the representative nodes, and between the representative nodes, and an appropriate IP (internet protocol) routing table is set on the representative node. Set. In addition, the network setting means includes: a VC identifier; VCI (VC identifier)
ier) values are assigned in ascending or descending order in the downward direction of the VC. The failure detecting means 1 is a p-mp connection VC
, The failure detection signal can be transmitted to all the partner terminals only once. When an acknowledgment is not received from the receiving terminal, the redundant transfer means 2 automatically retransmits the data by using the VC of the standby system, thereby reducing the load on the terminal in normal times and reducing the data load at the time of failure. Loss can be avoided. The network setting means 3 includes a PVC between the terminal and the switch,
By combining the IP routing tables on the representative node, any terminal
Enables communication between switches. Further, the network management setting means 4 sets the VCI in the ascending order or the descending order, thereby enabling a single ATM switch to detect a loop.

ATM LAN according to the second configuration of the present invention
Uses the following means. Each terminal sets a monitoring VC of one-to-many connection (p-mp connection) so as to include all the routes of the VC set for the original communication. The terminal transmits a survival signal for monitoring the state of the VC using the monitoring VC of the p-mp connection. The partner terminal similarly sets a monitoring VC for p-mp connection, and a response from the partner terminal is performed using the monitoring VC. The terminal is
It is possible to transmit the survival signal to many partner terminals only once. Since the reception processing of the survival signal from the partner terminal is performed by the number of partner terminals, the load of the polling process is about half as compared with the case where the monitoring VC of the p-mp connection is not used.

ATM LAN according to a third configuration of the present invention
Is, as shown in FIG. 2, the redundant transfer means 2 of the transmitting terminal 1.
(Not shown) is transferred using the working VC at the time of the first transfer. When receiving the data, the redundant transfer unit 2 (not shown) of the receiving terminal 2 sends an acknowledgment to the transmitting terminal 1. The redundant transfer means 2 of the transmitting terminal 1 retransmits the data using the standby VC if the acknowledgment cannot be received within a certain time after the data is transmitted. When there are a plurality of standby VCs, retransmission is performed using the VCs sequentially or simultaneously. When retransmission is performed, data duplication and order reversal occur. Therefore, the redundant transfer unit 2 of the transmitting terminal 1 assigns a serial number when transferring data, and the redundant transfer unit 2 of the receiving terminal 2 In accordance with the serial number, duplicate data is discarded or the order of data is guaranteed. In normal times, the data transfer by the active VC succeeds, and the transmission terminal 1
Is transferred only once because the redundant transfer means 2 receives the acknowledgment. If a failure occurs on the path of the working VC, the redundant transfer means 2 of the transmitting terminal 1 retransmits the data using the standby VC, so that the data is transferred without any problem only by increasing the transfer delay time. .

ATM LAN according to a fourth configuration of the present invention
As shown in FIG. 3, a network is divided into a plurality of sub-networks, and a switch or a terminal performing routing at an IP level is arranged as a representative node for each sub-network. In the figure, the node indicated by R is the representative node. By appropriately setting the VC and the routing table between the representative nodes, communication can be performed in any combination. A switch or terminal other than the representative node of the subnetwork is set as a general node, and a VC is set between the general node and the representative node. The general node sends all data to the representative node, and leaves the data transfer to the representative node. When the source node and the destination node are in the same subnetwork, the source node transmits data to a representative node of the subnetwork to which the source node belongs. The representative node determines that there is a destination node in the subnetwork represented by the own node based on the destination IP address of the data, and sends the data to the destination node. If the source node and the destination node are in different subnetworks, the source node transmits data to a representative node of the subnetwork to which the source node belongs. The representative node refers to the destination IP address of the data, selects an appropriate subnetwork, and transfers the data to the representative node of the subnetwork. The representative node to which the data has been transferred sends the data to the destination node.

ATM LAN according to a fifth configuration of the present invention
When determining the VCI of the PVC, as shown in FIG.
The VCI is determined so that the VCI value changes in the ascending order or the descending direction in the downward direction of the VC. A loop detecting means is provided in the ATM switch, and when setting the VCI conversion table, the magnitude relation between the input VCI value and the output VCI value is compared to determine whether a loop has occurred. PVC
When the VCI conversion table is manually set, the loop detection means is activated, and the VCI conversion table is checked as follows. When assigning VCI values in descending order, input VC
If the I value is smaller than the output VCI value, it is determined that a loop has occurred. To assign VCI values in ascending order, input VC
If the I value is larger than the output VCI value, it is determined that a loop has occurred.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 FIG. 5 is a diagram showing a first embodiment of the present invention. On each of the terminals 1 to 4, a failure detecting means 1 (not shown), a redundant transfer means 2 (not shown), and a network setting means 3 (not shown) are provided. Setting means 4 (not shown) is provided. The arrow in FIG. 5 indicates a V for the application on the terminal 1 to communicate with the application on another terminal.
Part of C is shown. A plurality of VCs are set between terminals in preparation for occurrence of a failure. These VCs are set to follow different paths. The figure shows an example of two VCs set between the terminal 1 and the terminal 2. VCs other than those shown in the figure are also set between the terminals 1 and 3 and between the terminals 1 and 4. The redundant transfer unit 2 performs communication by selecting an appropriate one from a plurality of VCs according to the result of monitoring the VC by the failure detection unit 1. The failure detection means 1 periodically exchanges failure detection signals by using a p-mp connection VC that includes all of the VC paths for application communication. In addition, the network setting means 3 performs a PVC connection so that communication between arbitrary terminals and switches can be performed for communication for managing such a network and communication that does not require high speed and reliability. And a communication path using the IP routing table. Further, the network management and setting means 4 arranged on the ATM switch,
When setting a VC, a loop error occurs due to a setting error.
Is prevented from occurring. Details of each means will be described in an embodiment described later.

Embodiment 2 [Failure Detecting Means] FIGS. 6 and 7 are block diagrams showing a second embodiment of the present invention. As shown in FIG. 6, the application program on the terminal 1 performs a task by setting a VC between the terminals 2, 3, 4, and 5 and performing communication. To detect a fault on the path of these VCs, the terminal 1 pm
Set a VC for monitoring p connection. The terminal 1 transmits one survival signal at regular intervals to indicate the soundness of the VC to other terminals. The other terminal sets a monitoring VC of the p-mp connection similarly to the terminal 1, and the monitoring VC also includes a path between the terminal and the terminal 1. The terminal returns a response to the survival signal from the terminal 1 by using the monitoring VC. The terminal can transmit the survival signal to many partner terminals only once. Since the reception processing of the survival signal from the partner terminal is performed by the number of partner terminals, the load of the polling process is about half as compared with the case where the monitoring VC of the p-mp connection is not used.

Embodiment 3 [Regarding Redundant Transfer Means] FIGS. 8 and 9 are block diagrams showing a third embodiment of the present invention. Terminal 1 transmits one active VC as shown in FIG.
And one or more standby VCs are set. The terminal 1 transmits data using the redundant transfer means 2 as shown in FIG. The redundant transfer unit 2 includes an active VC switching unit 5, a data transmission unit 6, and a data retransmission unit 7. VC
The table shows the current working VC and the VCI of the standby VC. The retransmission table records the data to be retransmitted together with the retransmission time. First, a process when the working VC is normal will be described. When receiving the data from the application program, the data transmitting unit 6 refers to the VC table, selects the working VC, and transmits the data using the working VC. At the same time, the data transmitting means 6 calculates a retransmission time by adding an appropriate timeout period to the current time, and stores the retransmission time together with the data in the retransmission table. The transmitted data is received by the terminal 2, and the terminal 2 transmits an acknowledgment to the terminal 1. Upon receiving the acknowledgment, the data retransmission unit 7 of the terminal 1 deletes the corresponding item in the retransmission table.

Next, a case where a failure occurs on the working VC will be described. When receiving the data from the application program, the data transmitting unit 6 refers to the VC table, selects the working VC, and transmits the data using the working VC. At the same time, the data transmitting means 6 calculates a retransmission time by adding an appropriate timeout period to the current time, and stores the retransmission time together with the data in the retransmission table. Transmission data is current V
It disappears due to a failure on C and is not received by terminal 2. For this reason, the terminal 1 reaches the retransmission time without receiving the acknowledgment. The data retransmitting unit 7 extracts data to be retransmitted from the retransmission table, and transmits the retransmitted data using the standby VC selected from the VC table. The retransmitted data is deleted from the retransmission table. As a method of using a plurality of standby VCs at the time of retransmission, a method of sequentially using the standby VCs one by one in addition to a method of using all the standby VCs simultaneously is conceivable. When a certain period of time has elapsed since the occurrence of the failure, the failure detection unit 1 notifies the working VC switching unit 5 of the occurrence of the failure. The working VC switching means 5
The current VC is switched by rewriting the C table.

FIG. 10 shows a format of a packet used for communication. A data packet for transmitting data from the terminal 1 to the terminal 2 includes a type, a serial number, a flag, and transmission data. The flag is used to indicate whether the packet is transmitted for the first time or retransmitted. The terminal 2 does not need to send an acknowledgment for the retransmission packet. The acknowledgment packet is composed of a type and a serial number. The terminal 2 records the serial number of the received data in order to prevent the same data from being processed redundantly when the acknowledgment is lost.

Embodiment 4 [About Network Setting Means (Part 1)] FIG.
Shows the logical configuration of the fourth embodiment of the present invention. The squares in the figure indicate terminals or ATM switches, and the lines connecting them indicate VCs. The network is divided into four sub-networks, each with a network address of 123.456.1.0, 123.456.2.0, 123.456.3.0,12
3.456.4.0. Let the address of the representative node of each subnetwork be 123.456.x.1. Each representative node is shown in FIG.
2 has an IP level routing table as shown in FIG. First, from the terminal 11 in the subnetwork 1,
The operation of each node when transmitting data to the terminal 12 in the same sub-network will be described. Since the terminal 11 is a general node, it always transfers data to the representative node (123.456.1.1) when transmitting data. The representative node transfers the data to the terminal 12 because the destination address 123.456.1.7 of the data is in the subnetwork of the representative node. As a result, data is transmitted from the terminal 11 to the terminal 12.

Next, the operation of each node when data is transmitted from the terminal 11 in the subnetwork 1 to the terminal 41 in the subnetwork 4 will be described. Since the terminal 11 is a general node, it always transfers data to the representative node (123.456.1.1) when transmitting data. Since the destination address 123.456.4.4 of the data is in another subnetwork, the representative node searches the routing table to determine the transfer destination. Since the destination node is in the subnetwork 4 (123.456.4.0), the address of the transfer destination representative node is 123.456.2.1. At the transfer destination node, the routing table is searched in the same way, and the data is 123.456.1.1 → 123.456.2.1 → 123.456.3.1 →
It is transmitted in the order of 123.456.4.1. Representative node 123.456.
In 4.1, the destination address of the transferred data is 123.456.4.
4 is in the sub-network of the representative node, so that the representative node transfers the data to the terminal 41. As a result, data is transmitted from the terminal 11 to the terminal 12.
Thereby, the data is transmitted from the terminal 11 to the terminal 41. In this embodiment, there are four sub-networks, but if there are three general nodes in each sub-network, the total number of nodes is 16. P according to the invention
When communicating between arbitrary nodes by VC, PV
C is required to have ₁₆ C ₂ = 16 × 15/2 = 120 lines. According to the present invention, it is only necessary to set three PVCs between the representative node and twelve PVCs between the representative node and the general node.

Embodiment 5 FIG. [About Network Setting Means (Part 2)] FIG.
FIG. 3 and FIG. 14 are diagrams showing a fifth embodiment of the present invention. In this embodiment, the value of the VCI changes in the ascending or descending order in the downward direction of the PVC in order to easily detect the occurrence of the loop due to the erroneous recognition of the VCI of the PVC. FIG. 13 is an example of the cause of the occurrence of the loop. In the figure, two VCs, PVC1 and PVC2, are set in a network composed of four ATM switches. Also, in FIG.
This shows the contents of the CI conversion table. The upper table is a correct setting example. Now, it is assumed that the setting of the table shown in the lower part is made due to an incorrect setting of the items indicated by hatching.
In this setting, the output of PVC2 in switch 1 is set to PV
C1 is merged, and the output of PVC1 in switch 2 is merged with PVC2. As a result, FIG.
A loop-shaped PVC having two inputs, such as 4, is set. When operation of the system starts as it is, PVC
1, the cell input from the upstream terminal of PVC2 goes around the loop infinitely, so that the ATM switch and the fiber on the loop become saturated. The loop detecting means on each ATM switch inspects the VCI conversion table every time the VCI conversion table is changed to prevent a loop. In the present embodiment,
When the loop detecting means on the switch 1 checks the entry of the PVC 2, the input VCI value 6 which should be in descending order is converted into the larger output VCI value 13, so that it is possible to detect that a loop has occurred. When a loop is detected, the loop detection means issues an alarm by any method to notify the operator of the occurrence of the loop.

[0026]

Since the present invention is configured as described above, it has the following effects.

According to the first configuration of the present invention, fault detection and redundancy transfer for high reliability can be realized while keeping the load on the terminal low. Further, it is possible to reduce the labor for setting the PVC when setting such a network, and to prevent the occurrence of a loop due to a setting error.

Further, according to the second configuration of the present invention, a terminal can transmit a survival signal to a number of partner terminals only once. Since the reception processing of the survival signal from the partner terminal is performed by the number of partner terminals, the load of the polling process is about half as compared with the case where the monitoring VC of the p-mp connection is not used.

Further, according to the third configuration of the present invention, when there is a problem in the transfer on the active VC, the standby V
Since the transfer using C is performed, the load on the terminal and the network is small in normal times, and the data can be transferred without any problem simply by increasing the transfer delay time.

Further, according to the fourth configuration of the present invention, compared to the case where VCs are set for all terminal combinations, by setting a much smaller number of VCs and the routing table, it is possible to set any terminal / Communication between switches becomes possible.

According to the fifth configuration of the present invention, VC
Can be detected only by a simple comparison process in one switch.

[Brief description of the drawings]

FIG. 1 is a schematic principle diagram showing an overall configuration of the present invention.

FIG. 2 is a diagram showing an outline of a redundant transfer unit of the present invention.

FIG. 3 is a diagram showing a network configured by network setting means of the present invention.

FIG. 4 is a diagram showing a network setting means according to the present invention;
FIG. 9 is a diagram showing an example of a VCI provided to the.

FIG. 5 is a diagram showing a first embodiment of the present invention.

FIG. 6 is a diagram showing a system according to an embodiment of the failure detection means of the present invention.

FIG. 7 is a diagram showing an embodiment of the failure detection means of the present invention.

FIG. 8 is a diagram showing a configuration for applying the redundant transfer means of the present invention;
FIG. 4 is a diagram illustrating setting of VC.

FIG. 9 is a diagram showing a configuration of an embodiment of a redundant transfer unit of the present invention.

FIG. 10 is a diagram showing a format of a packet used in the embodiment of the redundant transfer means of the present invention.

FIG. 11 is a configuration diagram of a network according to an embodiment of a network setting unit of the present invention.

FIG. 12 is a diagram showing an IP routing table used by each ATM switch in the embodiment of the network setting means of the present invention.

FIG. 13 is a diagram showing a situation where a loop VC is set in the embodiment of the network setting means of the present invention.

FIG. 14 is a diagram showing a loop VC generated in the embodiment of the network setting means of the present invention.

FIG. 15 is a conceptual diagram of a conventional ATM LAN for an industrial system.

FIG. 16 is a diagram showing redundant transfer means in a conventional ATM LAN.

FIG. 17 is a diagram showing another redundant transfer means in a conventional ATM LAN.

FIG. 18 is a diagram illustrating an example of a VCI conversion table on an ATM switch.

FIG. 19 is a diagram showing a PVC configured to be able to communicate between arbitrary terminals by network setting means in a conventional ATM LAN.

FIG. 20 is a diagram illustrating an example of a loop VC.

FIG. 21 is a diagram illustrating an example of a many-to-one connection VC.

[Explanation of symbols]

1 failure detection means, 2 redundant transfer means, 3 network setting means, 4 network management setting means, 5 active VC switching means, 6 data transmission means, 7 data retransmission means.

Claims (5)

[Claims] An AT that has a physical configuration in which a plurality of communication paths can be selected between terminals and performs communication by selectively or in parallel using VCs set on the plurality of paths in preparation for a failure.
In the M LAN, a failure detection means for detecting a failure on a VC path by an OAM function or other means, a redundant transfer means for selecting a plurality of VCs according to a state of a network and transferring data, and A high-reliability ATM LAN characterized by having network setting means for making various settings necessary for communication of the present invention without error. 2. A one-to-many connection (p-m) so that each terminal includes all the VC paths set for the original communication.
2. A highly reliable ATM L according to claim 1, further comprising a fault detecting means for setting a monitoring VC (p connection) and executing a fault detection protocol using said monitoring VC.
AN. 3. A transmission terminal according to claim 1, wherein the redundant transfer means of the transmitting terminal comprises an active VC.
, And the redundant transfer means of the receiving terminal returns an acknowledgment signal each time data is received, and the redundant transfer means of the transmitting terminal transmits the data for a certain period of time after transmitting the data. If an acknowledgment cannot be received,
2. The high-reliability ATM LAN according to claim 1, wherein said data is retransmitted by using a serial number, and the receiving terminal manages the order of the data by the serial number added by the transmitting terminal. 4. An ATM L for performing communication using PVC.
An invention related to a network setting means of an AN, wherein a network is divided into a plurality of sub-networks, and a switch or a terminal for performing routing at an IP level for each of the sub-networks is arranged as a representative node. Can be set in an appropriate combination to enable communication in any combination. A switch or terminal other than the representative node of the subnetwork is used as a general node, and a VC is set between the general node and the representative node. 2. The highly reliable ATM L according to claim 1, wherein the data is sent to the representative node, and the transfer of the data is left to the representative node.
AN. 5. When setting VC, the value of VCI monotonically decreases or increases monotonically in the downward direction.
10. A method for setting a VCI, wherein the switch has a network setting means for checking a magnitude relationship between the VCI before and after the conversion and setting a VCI conversion table to prevent a VC loop. Highly reliable AT described in 1.
M LAN.