JPH07107104A - Atm communication system - Google Patents

Abstract

PURPOSE:To provide a synchronizing system and a routing method being excellent in profitability and service property, in the ATM communication system for connecting each adjacent communication node of plural communication nodes by a loop-like bus and transmitting and receiving a cell. CONSTITUTION:The synchronizing system is provided by providing an elastic buffer 4 in a communication node 1, adjusting a transfer time of a cell between the communication nodes to an integer multiple of a period of the cell, and setting the timing of cell demultiplexing of all the communication nodes to the same. Also, the routing system is provided by providing a storage means 13 for mounting position information of the communication node 1 and slot generator position information, and for performing autonomously transmission and reception of the cell by esch communication node 1, based on the position information. In such a way, cell demultiplexing can be performed without generating pull out by a simple constitution. Also, the transmission and reception, ans routing of the cell can be performed at a high speed by a simple processing method and constitution. Moreover, a multi-point communication and a loop back test can be performed easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM communication system for transmitting / receiving cells using a loop bus.

[0002]

2. Description of the Related Art Conventionally, in an ATM communication system in which a plurality of communication nodes transmit and receive cells to and from each other, various switches such as a space switch, a time switch and a bus switch are used for switching cells.

Among these, the international standardization of the structure of the ATM communication system using the bus switch is being promoted. For example, the distributed queue dual bus subnetwork of a metropolitan proposed by the Institute of Electrical and Electronics Engineers (IEEE) has been proposed. Area Network "DistributedQu"
eue Dual Bus Subnetwork o
fa Metropolitan Area Net
There is a distributed matrix type dual bus (DQDB) system described in "work", IEEE 802.6 (12.1990).

In this ATM communication system, a unidirectional bus is connected from one communication node to an adjacent communication node to transmit a cell, and a single communication node from the communication node receiving this cell to the adjacent communication node. This is configured by connecting a plurality of communication nodes and an adjacent communication node with a unidirectional bus, such as connecting a directional bus and transmitting cells. It is also characterized by having a similar bus in the opposite direction, and each communication node transmits by multiplexing cells on the bus when there is no cell transmitted by another communication node on this dual bus. Further, the cell is received by separating the cell addressed to the own communication node from the bus, and the data transmission / reception between the communication nodes is performed at high speed.

Also, in this ATM communication system, as a synchronization method for finding the beginning of a cell when performing cell demultiplexing, "Introduction to B-ISDN" (Ohm Co.)
The cell synchronization method described on page 120 is used.

[0006]

An ATM communication system using the distributed matrix type dual bus system constitutes a bus in which two buses having different communication directions are physically looped. Also, in order to equalize the bus usage frequency of each communication node, traffic control is performed by providing logical start and end points of the bus. That is, cells flowing on the bus are discarded at the end of each bus.
Further, the starting point and the ending point of this bus can be set to arbitrary positions on the respective buses and can be changed. The logical starting point of this bus is called the slot generator.

Since two buses having different communication directions have a start point and an end point, respectively, when a cell is transmitted from a certain communication node to another communication node, the cell to be transmitted is multiplexed on which bus. It is necessary to decide whether to send it. Conventionally, this transmission direction is selected by providing a table in each communication node, and the central processing unit setting the transmission direction in this table.

In this ATM communication system, cells are demultiplexed at each node, so that cells transmitted to adjacent nodes are delayed by the processing time. Further, transmission delay to adjacent nodes occurs. That is, the phase at the beginning of the cell received by the adjacent node is out of phase with the cell at the transmitting node. For this reason, in the receiving side node, in order to find the beginning of the cell having the shifted phase and perform the cell demultiplexing process, the reception data in each communication node as described in "Introduction to B-ISDN" (Ohmsha) The cell synchronization was achieved by extracting the synchronization signal from and finding the beginning of the cell.

That is, the conventional digital communication network using the loop-shaped multiplex bus can realize high-speed communication, but requires the following complicated device and processing for realizing the high-speed communication. Is. (1) Since the head positions of packets are shifted by the cell processing time between adjacent communication nodes, a complicated synchronization method is required to synchronize each communication interface unit. Moreover, when the position of the slot generator is changed, the phase of the cell changes before and after the change of the position of the slot generator, so that there is a disadvantage that all communication nodes are out of synchronization. (2) In order to determine the data transmission direction, the communication path and the transmission direction for each communication node are stored in a dedicated table or in a form integrated with another table, and the central processing unit stores this table for each call. It was necessary to update the content and determine the transmission direction. Therefore, when the position of the slot generator is changed, the transmission direction of each call changes, so that it is necessary to rewrite the table held by each communication node. (3) When the communication node is duplicated, the two systems are separately recognized and transmitted at the time of cell transmission. That is,
The central processing unit has to perform transmission processing for each call and each system. (4) When performing point-to-multipoint communication between a plurality of communication nodes, it is necessary to transmit cells to both of the two buses, but no specific method is shown in the above-mentioned documents.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned conventional problems, and a digital communication network using a loop-shaped multiplex bus that realizes high-speed communication with a simple device configuration and processing. Is to provide.

That is, a first object of the present invention is to provide an economical method for synchronizing the communication nodes without using a complicated synchronization method. The second purpose is to use a table for determining the transmission direction of data, that is, a simple and fast routing method in which the transmission direction can be determined immediately even if the position of the slot generator is changed. Is to provide. A third object is to provide a simple and fast routing method even when duplicating communication nodes. A fourth purpose is to provide the necessary scheme for realizing point-to-multipoint communication.
A fifth object is to provide a device and a communication network which provide a method for easily implementing a loopback function in a communication node and which can be easily operated for maintenance such as failure diagnosis.

[0012]

In order to achieve the above-mentioned object, in the present invention, a digital communication network using a communication node and a loop-shaped multiplex bus is provided with the following means. (1) An ATM communication system for transmitting and receiving cells by connecting adjacent communication nodes of a plurality of communication nodes to each other through transmission / reception buses to form a loop structure and demultiplexing cells from each communication node on the bus In (1), a constant cycle or an integer multiple of that cycle is provided with a buffer that absorbs the timing deviation of the cell demultiplexing between the communication nodes adjacent to each communication node, and the total delay time of the cell processing time and the transmission delay time By reading out the buffer in step 1, the phase of the timing of cell demultiplexing in each communication node is made the same in all communication nodes.

(2) In each communication node, as a method of performing routing based on the mounting position information on the bus, a communication node mounting means for storing the position where the node is mounted on the bus and a slot generator are set. A means for storing the position is provided, and a transmission direction determining means for determining the transmission direction of the cell by each communication node is provided from the information on the position where the communication node is mounted and the position information where the slot generator is set.

(3) Duplicated communication nodes are provided at adjacent mounting positions on the multiplex bus, and the same mounting position information is given to these two communication nodes. Further, there is provided a setting position changing means for changing the setting position of the slot generator depending on the normal state and the fault state.

(4) Point-to-point communication is provided with a routing tag according to the mounting position, while
For point-to-multipoint communication, routing tag attaching means for attaching a routing tag dedicated to multipoint communication is provided. Specifically, a unique routing tag is defined for a combination of a plurality of output destination communication nodes, and the cell is routed by this. further,
The receiving unit of each communication node has a table for judging the reception of cells.
A judgment receiving means for receiving the multiplexed cells on the bus according to the contents of the table and the table is provided.

(5) As a return means of each communication node, the cell receiving section is provided on the end point side of the bus with respect to the cell transmitting section.

[0017]

Since each of the above-mentioned means operates as follows, it is possible to construct a digital communication network using a loop-shaped multiplex bus that realizes high-speed communication with a simple device configuration and processing.

(1) The buffer provided on the bus connecting the adjacent communication nodes absorbs the timing difference of the cell demultiplexing between the adjacent communication nodes, and the phase of the cell demultiplexing timing at each communication node. Is the same for all communication nodes, so a complicated synchronization method is unnecessary. Further, since the phase is the same in all communication nodes and the cell phase does not change before and after the slot generator change, synchronization does not occur even when the slot generator is changed.

(2) In each communication node, the transmission direction determining means autonomously determines the transmission direction of the cell based on the mounting position information on the bus of the communication node and the mounting position information of the communication node in which the slot generator is set. Therefore, a table for storing the relationship between the communication path and the transmission direction is not required, and the time for restarting communication when the slot generator is changed can be shortened.

(3) Since the two duplicated communication nodes are arranged adjacent to each other and given the same mounting position information, each communication node can transmit cells without being aware of the duplicated communication node system. Further, in the event of a failure, the slot generator setting position changing means autonomously changes the slot generator setting position, so that switching of the duplicated communication nodes can be realized quickly and easily.

(4) A routing tag dedicated to multipoint communication defined by a combination of a plurality of output destination communication nodes and cells multiplexed on the bus in accordance with the contents of the table and table for judging cell reception. Since the receiving unit of each communication node can autonomously receive the cell by the determination receiving unit that receives the, the point-multipoint communication can be easily performed without the central processing unit performing complicated reception processing.

(5) Cell Since the transmitted cell can be received by the cell receiving section of the own communication node, the loopback function can be realized without newly providing a loopback test device. That is, maintenance and operation such as failure analysis of each communication node becomes easy.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ATM communication system according to an embodiment of the present invention will be described in detail below with reference to the drawings. <First Embodiment: Synchronization Method> FIG. 1 is a diagram showing a schematic configuration of each communication node of an ATM communication system according to the present invention. 2 is a diagram showing a network configuration of an ATM communication system in which a plurality of communication nodes are connected, and FIG. 3 is a diagram showing transmission / reception timings of cells in each communication node in the network.

As shown in FIG. 1, the communication node 1 is connected to a multiplex bus 2 (hereinafter bus A) and a multiplex bus 3 (hereinafter bus B) in the opposite direction to the bus A, for each of the buses A and B. Elastic buffer 4 (hereinafter ES) that absorbs the phase difference of the transmission data and outputs the output data to the output line 16.
The data input from the input line 17 is bus A2 and bus B
3 is composed of a multiple access control unit 5 which controls to multiplex and communicate cells. A communication terminal as shown in FIG. 2, for example, is connected to the output line 16 and the input line 17.

FIG. 2 shows a case where a communication network is formed by connecting the communication nodes 1 in a plurality of loops and connecting the communication terminal 20 to each communication node. The buses A2 and B3 of the adjacent communication nodes 1 are connected to each other to configure the entire loop. At this time, the bus A and the bus B each have a bus start point (slot generator) and a bus end point, and the data flowing between the bus start point and the bus end point is discarded at the bus start point.

At this time, as shown in FIG. 3, the cells transmitted to the adjacent communication node are out of phase by the sum of the cell processing time in the multiple access control section and the data transmission delay time. Absorb the phase shift,
Align the phases of cells flowing on the buses A2 and B3,
The reception timing of each node (the leading phase of the reception cell after the phase shift is absorbed by ES4) is made equal. That is, the timing of cell multiplexing processing for the bus A2 and the bus B3 of each communication node is as shown in FIG. 3, and all the communication nodes can operate at the same reception timing for both the bus A2 and the bus B3.

This makes it possible to determine the timing of cell multiplexing processing of each communication node without paying attention to cell synchronization. Further, since the timing of cell multiplexing processing does not change even if the position of the slot generator changes, a complicated cell synchronization circuit as in the past is not required, and even when the position of the slot generator is changed, loss of synchronization does not occur. Absent.

<Second Embodiment: Cell Transmission / Reception System> In the following description, the position of the slot generator that defines the beginning of the multiplex bus is defined as the bus in the ATM communication system configured by connecting a plurality of communication nodes shown in FIG. An example of the cell transmission / reception system will be described by exemplifying the case where the node A (2s) is provided at A2 and the node F (3s) is provided at the bus B3.

(1) Transmission Method FIG. 4 is a diagram showing a detailed configuration of each communication node 1 (configuration of a cell transmission unit and a cell reception unit). The communication node 1 transmits a cell input from the input line 17 to the bus A2 or the bus B3 via the cell multiplexing processing unit 5, and receives the cell from the bus A2 or the bus B3 to output the output line 1
It is composed of a cell receiving section 7 for outputting to the cell 6.

Here, the cell transmitting unit 6 assigns the routing information providing unit 8 which provides the input cell with the routing information indicating the relationship between the input and the destination, and the cell as the bus A2 or the bus B.
On the bus of the communication node 1 and the transmission direction selection unit 9 that assigns the transmission direction of the cell to the transmission direction selection unit 9 that is divided into three. It comprises a mounting position information storage unit 12 for storing the mounting position and a slot generator position storage unit 13 for storing the position information on the bus of the communication node in which the slot generator is set, and the cell receiving unit 7 is the cell transmitting unit 6 The same mounting position information storage unit 12, a reception determination unit 15 that determines whether or not cells received from the bus A and the bus B can be received, and the cells received from the bus A2 or the bus B3 are multiplexed on the output line 16 and output. The cell output unit 14 is configured to operate. Although the mounting position information storage unit 12 is provided in both the cell transmission unit 6 and the cell reception unit 7 in this embodiment, since the stored information is the same, one unit may be provided in the common unit of the communication node 1. .

FIG. 5 shows the structure of the table 50 for accumulating the routing information provided in the routing information addition unit 8 in the cell transmission unit 6, and the output destination of the input cell is designated by this table. After that it is sent on the bus.

FIG. 6 shows the values set in the mounting position information storage unit 12 and the slot generator position storage unit 13 provided in each communication node in the system configuration (same as FIG. 2) when a plurality of communication nodes are connected. FIG. 8 is a diagram showing an example, and based on this value, the transmission direction instructing unit 10 determines whether to transmit a cell to the bus A2 or the bus B3 according to the procedure shown in FIG.

A detailed operation example of the cell transmission direction determination method according to the present invention will be described below with reference to FIGS. 4 to 7. First,
A mounting position, which is information indicating the physical arrangement of each of the communication nodes A to F, is assigned along the direction in which the cells flow on the bus A2, and is set in the mounting position storage unit 12 by a processor (not shown) (hereinafter, mounting position storage The value set in the section 12 is T.). In this embodiment, as shown in FIG. 6, T = 0, 1, 2, 3, for nodes A, B, C, D, E, F.
4 and 5 are the mounting position storage units 12 of the respective communication nodes 1.
Set to.

Next, the position of the slot generator is defined by the mounting position of the communication node where the slot generator is set on the bus A2, and is set in the slot generator position storage unit 13 from a processor (not shown) (hereinafter, slot generator position storage will be described). The value set in the section 13 is SG.). In this embodiment, since the slot generator 2s of the bus A2 is set in the communication node A, SG = 0 is set in the slot generator position storage unit 13 of each communication node 1 as shown in FIG.

Next, the routing information adding unit 8 adds the routing information (hereinafter referred to as R) defined by the mounting position of the receiving node to each cell and stores it in the routing information storage unit 11. More specifically, according to the routing information addition table 50 shown in FIG.
VPI / VC which is the header information of the cell input from 7.
Output VPI / V for the cell where I is Hin0 (501)
Converted to Hout0 (502) as CI, and
The mounting position information R0 (503) of the destination communication node is added as the routing information.

The transmission direction instructing section 10 determines the transmission direction from the values of T, SG and R by the procedure shown in FIG. That is, first, the magnitudes of the values of T and SG and R and SG are compared. Here, when T and R are both smaller than SG (yes in both 701 and 702), and when both T and R are equal to or larger than SG (both in 701 and 703 are no).
Compares T with R, and if T is less than R (704ye
s) sends cells to bus A2 (705), otherwise (704no) sends cells to bus B3 (70).
6). On the other hand, if T is smaller than SG and R is equal to or larger than SG (701yes, 702no), the cell is transmitted to the bus B3. Also, T is SG or more and R is SG
If it is smaller (701 no, 703 yes), the cell is transmitted to the bus A2. This procedure can be easily realized by firmware or software control by a logic circuit or a processor.

With the configuration and operation as described above, when the transmission direction of the cell is determined by the routing information adding unit,
It is not necessary to have a table of communication paths and data transmission directions as in the past. Further, even when the position of the slot generator is changed, the operation can be performed only by rewriting the contents of the slot generator position storage unit 13, and it becomes unnecessary to update the data transmission direction for each communication path as in the conventional case. Therefore, the time required to restart communication can be shortened.

(2) Reception Method For example, when a cell is to be transmitted from the communication node B to the communication node E, the communication node B adds the mounting position information of the communication node E as the routing information R to the transmission cell. That is, the cell is transmitted with R = 4. Since the mounting position information T = 1 and the slot generator position information SG = 0 are stored in the communication node B, it is decided to send the transmission cell to the bus A by the procedure shown in FIG. In the communication node E, the reception determination unit 15 compares the cell routing information R received from the bus A and the bus B with the mounting position information T set in the mounting position information storage unit 12, and determines the reception of the cell. If the mounting position information T and the routing information R of the received cell match as a result of the determination, the cell received as the cell addressed to the own node is output to the output line 16 via the cell output unit 14. In this embodiment, since the mounting position information T = 4 of the communication node E is received, the cell having the routing information R = 4 is received. Further, the communication nodes C, D and F do not receive the cell with the routing information R = 4. Accordingly, the communication node E can receive the cell transmitted from the communication node B.

<Third Embodiment: Duplication of Communication Nodes> FIG. 8 is a diagram showing a system configuration (arrangement of communication nodes and setting of mounting position information) when the communication node 1 is duplicated. The present embodiment shows a configuration in which the communication node F and the communication node G are duplex communication nodes.

When duplicating the communication nodes, first, the communication nodes F and G to be duplicated are mounted at the adjacent positions, and the bus is not interrupted between the communication nodes F and G under normal conditions. In addition, the slot generators 2s and 3s are prohibited from being set to the communication node G on the bus A2 and are prohibited from being set to the communication node F on the bus B3. The communication node F is used as mounting position information.
And the same value is set in the communication node G. In this embodiment, T = 5 is set for both the communication node F and the communication node G. As a result, other communication nodes give the same routing information to the communication node to be duplicated without being aware of the duplication, and determine the transmission direction of the cell as in the case of the second embodiment. It is possible to send and receive cells.

When a failure occurs in the communication node F, the central processing unit removes the prohibited items in the normal state, and the positions of the slot generators 2s and 3s are set to the communication node G on the bus A as shown in FIG. By setting the communication node E on the bus B, the communication node F in which a failure has occurred is separated from the buses A and B. Even at this time, it is not necessary to change the method of assigning the routing information and the method of determining the transmission direction in each communication node, and only by rewriting the content of the slot generator position storage unit 13 to SG = 5, even if a failure occurs, Similarly, the transmission direction of the cell can be determined and the cell can be transmitted and received.

<Embodiment 4: Multipoint communication>
The operation of one embodiment of point-multipoint communication will be described with reference to FIGS. 10 to 12.

FIG. 10 is a diagram showing the configuration of the communication node 1a for performing point-multipoint communication. Also,
FIG. 11 is a diagram showing the configuration of a table in the routing information addition unit 8-1 inside the communication node 1a.
Shows a procedure for determining the transmission direction in the transmission direction instruction unit 10-1 inside the communication node 1a.

Regarding the cell for point-to-point communication in the routing information adding unit 8-1, the first to third embodiments
Similarly, the routing information (R) 1103 defined by the mounting position of the receiving node is added, and for the cell of the point-multipoint communication, the reception which is the routing information dedicated to the multipoint communication and is the target of the point-multipoint communication A connection number (hereinafter referred to as MC) 1106 for each combination of nodes is defined and given.

Specifically, in the routing information addition table 110 shown in FIG. 11, for a point-to-point communication cell (cell whose input VPI / VCI is Hin1 (1101)), Hout1 is output as VPI / VCI.
It is converted to (1102), and R1 (1103) which is the mounting position information of the communication node of the transmission destination of the point-to-point communication is further added as the routing information. Also,
Point-cell for multipoint communication (input VPI / V
Output V for cells whose CI is Hin2 (1104))
It is converted into Hout2 (1105) as PI / VCI, and further MC0 (1106) which is information of the combination of the communication nodes of the destinations of point-multipoint communication is added as routing information.

The transmission direction instruction unit 10-1 determines the transmission direction from the routing information R or MC and T, SG stored in the routing information storage unit 11-1 according to the procedure of FIG. If the cell to be transmitted is a point-multipoint communication cell, it is transmitted in both directions of the buses A2 and B3 (1201yes), and if it is a point-point communication cell (1201no), the same procedure as in FIG. 7 is performed. Determine the transmission direction by the procedure. Here, in the case of a point-multipoint communication cell, the cells are A2 bus and B3.
The reason for transmitting in both directions is to omit the process of determining the transmission direction for each destination.

On the receiving side, as in the first to third embodiments, the reception determination table 18 for determining whether or not the cell can be received from the received routing information of the cell is the routing information (R and MC) of the cell to be received by the communication node. Is held in a table format and the cell is received when the received routing information of the cell matches the value held in the table.

For example, in the case of performing point-multipoint communication from the node B to the node E and the node A in the configuration of FIG.
A connection number is defined as a destination combination and is set in the routing information addition table of the node B. Also, the defined connection numbers are set in the reception determination tables 18 of the nodes A and B, respectively. In the example, if MC = 6 is defined as the connection number, the routing numbers used for point-to-point communication are 1 to 5, so that the routing information can be used exclusively for point-to-multipoint communication. Then, the node B transmits this cell in both directions of the bus A2 and the bus B3 according to the procedure shown in FIG. The node A receives this cell from the bus B3, and since MC = 6 is set in the reception determination table 18, the cell is received. The node E receives this cell from the bus A2 and stores MC = 6 in the reception determination table 18.
Is set, so the cell is received. This enables point-to-multipoint communication. Here, since the connection number is defined by the combination of the destination communication nodes, the same connection number can be used even if the source communication nodes are different, as long as the destination communication nodes have the same combination.

<Fifth Embodiment: Folding Method> Hereinafter, FIG.
The operation of one embodiment of the folding method according to the present invention will be described with reference to FIGS.

FIG. 13 shows the input line 17 to the output line 16
It is a figure which shows the structure of the communication node 1b at the time of providing the return | turnback function in FIG. At this time, since the cell receiving unit in the communication node is placed after the cell transmitting unit, the return may be performed by adding the routing information having the own communication node as the destination in the routing information adding unit 8.

Further, the transmission direction instructing section 10-2 determines the transmission direction according to the procedure shown in FIG. Specifically, first, the central processing unit connects the return route selection unit 19 to the bus A bus B.
Is set as the return route, and when T is equal to R (1401yes), the cell is transmitted to the bus A2 or the bus B3 according to the return route set in the return route selection unit 19. The reception determining units 15 of the bus A2 and the bus B3 are connected to the multiplex buses at the output side of the cell multiplex processing unit 5 and determine the reception of cells.

As a result, from the input line 17 to the output line 16
The cell can be easily folded back without providing a special circuit for realizing the folding function, and at this time, it can be selected whether to fold back through the bus A2 or the bus B3. That is, since the bus can be returned using the operating bus, it becomes easy to carry out maintenance operation such as failure analysis of the communication node.

[0053]

As described above, according to the present invention, first, in an ATM communication system in which communication nodes are connected by a multiplex bus, each communication node determines the time required for transmission of cells between adjacent communication nodes. Processing time, that is, equal to the cell cycle or an integer multiple of the cell cycle, it is possible to uniquely determine the timing of cell processing operation in all communication nodes, and the complicated synchronization method of the prior art. Is unnecessary. Further, in the ATM communication system in which the communication nodes are connected by the multiplex bus, when the multiplex bus is configured in a loop, it is possible to change the position of the slot generator without causing the loss of synchronization.

Second, in an ATM communication system in which communication nodes are connected by multiple buses, mounting position information and slot generator position information are given to each communication node when the multiple buses are configured in a loop, and routing between communication nodes is performed. According to the mounting position information of each communication node,
At that time, since the algorithm for determining the transmission direction of the cell is defined, it is not necessary to always transmit the cell in both directions as in the past, or to set the transmission direction of the cell on the table, reducing communication traffic and routing information. Effective in simplifying management.

Thirdly, in an ATM communication system in which communication nodes are connected by multiple buses, redundant communication nodes are mounted in adjacent positions when the multiple buses are configured in a loop, and the same communication node is used for these two communication nodes. By providing the mounting position information, it becomes possible to perform cell routing to the duplicated communication nodes with the same routing information, and there is no need to change the routing information even when a failure occurs, and communication with high serviceability. The system can be configured.

Fourthly, point-multipoint communication can be supported by defining a connection number for a combination of a plurality of communication nodes in an ATM communication system in which communication nodes are connected by a multiple bus and thereby performing cell routing. It will be possible.

Fifth, in an ATM communication system in which communication nodes are connected by a multiple bus, a cell receiving section in a communication node is placed after a cell transmitting section, and an algorithm for performing backtracking is determined, so that cell folding can be easily performed. Since it is possible to perform this, it is not necessary to provide a special circuit for realizing the folding function as in the conventional case, and it is effective in downsizing and cost reduction.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a communication node of an ATM communication system according to the present invention.

FIG. 2 is a block diagram of an ATM communication system in which communication nodes are connected in a loop by multiple buses.

FIG. 3 is a diagram showing the timing of cell multiplexing processing of each communication node.

FIG. 4 is a block diagram of a cell transmitter and a cell receiver of the communication node.

FIG. 5 is a table configuration diagram of routing information inside the cell transmission unit of the communication node.

FIG. 6 is a diagram showing a configuration in which an ATM communication system is connected and a method of providing mounting information to each communication node.

FIG. 7 is a flow chart showing a procedure in which the communication node determines the transmission direction of the multiplex bus.

FIG. 8 is a block diagram of an ATM communication system in which communication nodes are duplicated. (Normal)

FIG. 9 is a block diagram of an ATM communication system in which communication nodes are duplicated. (At the time of obstacle)

FIG. 10 is a configuration diagram of a cell transmission unit and a cell reception unit of a communication node that similarly performs point-multipoint communication.

FIG. 11 is a table configuration diagram of routing information inside a cell transmission unit that similarly performs point-multipoint communication.

FIG. 12 is a flow chart showing a procedure for determining a transmission direction when performing point-to-multipoint communication.

FIG. 13 is a configuration diagram of a cell transmitting unit and a receiving unit with a loopback function in the communication node.

FIG. 14 is a flow chart showing a procedure for determining a transmission direction when the communication node performs a loopback.

[Explanation of symbols]

1, 1a, 1b ... Communication node, 2 ... Multiplex bus (bus A), 3 ... Multiplex bus (bus B),
2s, 3s ... Slot generator, 4 ... Elastic buffer (ES), 5 ... Cell multiplexing processing unit,
6 ... Cell transmission unit, 7 ... Cell reception unit, 8, 8-1 ... Routing information addition unit, 9 ...
Transmission direction selection unit, 10, 10-1 ... Transmission direction instruction unit,
11, 11-1 ... Routing information storage unit, 12.
..Mounting position information storage unit, 13 ... Slot generator position storage unit, 14 ... Cell output unit, 15 ... Reception determination unit, 16 ... Output line, 17 ... Input line,
18 ... Receiving judgment table, 19.
..Folding route selection section

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Nakano 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Stock company, Information & Communications Division, Hitachi, Ltd. (72) Inventor Miho 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Information & Communication Division

Claims (12)

[Claims] 1. An ATM communication system in which a plurality of communication nodes and communication nodes are connected to each other in a loop by a transmission means, wherein the transmission means demultiplexes cells to transmit and receive cells of each communication node. An ATM communication system characterized in that each communication node is provided with cell buffer means, and the cells are read from the buffer means so that the phases of the read cells correspond to all the communication nodes. 2. An ATM communication system in which a plurality of communication nodes and communication nodes are connected in a loop by a bus, and cells are multiplexed / demultiplexed on the bus to transmit / receive cells of each communication node, An ATM communication system characterized in that each communication node is provided with a buffer means for cells, and the cells are read from the buffer means so that the phases of the read cells correspond to all the communication nodes. 3. A time interval for reading cells from the buffer means is a time including a cell processing time of each communication node and a transmission delay time between adjacent communication nodes or an integral multiple thereof. The ATM communication system according to claim 1 or 2. 4. An ATM communication system in which a plurality of communication nodes and communication nodes are connected in a loop by a transmission means, and the transmission means demultiplexes cells to transmit and receive cells of each communication node. First communication means for storing information identifying each communication node on the loop, second storage means for storing information on the communication node that is the starting point on the loop, and the first and second communication means. 2. An ATM communication system comprising: a transmission direction determining means for determining a transmission direction of a cell based on the information of the second storage means. 5. A communication system in which a plurality of communication nodes and communication nodes are connected to each other in a loop by a bus, and an ATM communication system for demultiplexing cells on the bus and transmitting and receiving cells of each communication node, In each communication node, first storage means for storing information for identifying each communication node on the loop, second storage means for storing information for the communication node that is the starting point on the loop, and first and second And a transmission direction determining means for determining the transmission direction of the cell based on the information in the storage means. 6. The ATM according to claim 4, wherein the information stored in the first storage means and the second storage means is a mounting order or a mounting position of each communication node on the loop. Communications system. 7. The information stored in the first storage means is information on the mounting position of the communication node, and the information stored in the second storage means is information on the position of the slot generator that determines the head of the bus. The ATM communication system according to claim 6, which is characterized in that. 8. An ATM communication system in which a plurality of communication nodes and communication nodes are connected in a loop by a transmission means, the transmission means demultiplexes cells to transmit and receive cells of each communication node. , A plurality of communication nodes having a redundant configuration are adjacently mounted on a loop, and the routing information including the information stored in the first storage means and the second storage means in the plurality of communication nodes are associated with each other, 8. The ATM communication system according to claim 4, further comprising changing means for changing the start point of the loop and the information in the second storage means in case of a failure. 9. An ATM communication system in which a plurality of communication nodes and communication nodes are connected in a loop by a transmission means, the transmission means demultiplexes cells to transmit and receive cells of each communication node. 9. The ATM communication system according to claim 4, wherein each communication node is provided with a broadcast communication control means based on routing information indicating a plurality of destination communication nodes. 10. An ATM communication system in which a plurality of communication nodes and communication nodes are connected in a loop by transmission means, and the transmission means performs demultiplexing of cells to transmit / receive cells of each communication node. An ATM communication system characterized in that the cell receiving means of each communication node is provided on the loop downstream of the cell transmitting means of the communication node. 11. The ATM communication system according to claim 10, wherein each communication node is provided with a loopback means for designating its own communication node as a destination communication node.
M communication system. 12. A communication system in which a plurality of communication nodes and communication nodes are connected to each other in a loop by a transmission means, wherein the transmission means demultiplexes cells to transmit and receive cells of each communication node. Buffer means according to claims 1 to 3, transmission direction determining means according to claims 4 to 7, changing means according to claim 8, broadcast communication control means according to claim 9, and loopback according to claims 10 to 11. An ATM communication system characterized in that a plurality of means are provided in combination or all are provided from each group of means.