JP2000032019A - Network system and its configuration method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the network system where a node exclusively for line concentration for each ring system is not required, the changeover switch is simplified and the cost is reduced by the share. SOLUTION: The network system consists of ring systems A, B, C, D and a relay common node device 20 connecting in common to ring lines 5a, 5b, 5c, 5d of the ring systems A, B, C, D, collects information from the ring lines 5a, 5b, 5c, 5d to relay it to a relay line 30. The relay common node device 20 contains all VC paths in the ring lines 5a, 5b, 5c, 5d by a VP exchange connection path. The relay transmission is realized by the VP exchange control by the relay common node device 20 and the VC exchange control by ring nodes 10a-1,..., 10a-5, 10b-1,..., 10b-5, 10c-1,..., 10c-5 and 10d-1,..., 10d-5 in the ring lines 5a, 5b, 5c, 5d.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a plurality of ring systems for connecting a plurality of node devices via a ring-shaped line and performing communication between communication terminals accommodated in the node devices via the ring line. More specifically, the present invention relates to an improvement in a configuration of a portion for concentrating a ring line of each ring system and performing relay transmission.

[0002]

2. Description of the Related Art For example, ATM is used as one of system construction forms such as a railway management system and a road management system.
(Asynchronous Transfer Mode) A plurality of node devices having an exchange function are arranged in a ring via a transmission line such as an optical fiber, and local communication corresponding to a monitoring camera or a monitor device is provided to each of the node devices. After connecting the terminal, set a plurality of virtual communication paths in a ring shape with respect to the transmission path, by the communication path,
A form is considered in which information between the local communication terminals is transmitted and received via each node device.

FIG. 9 shows a basic configuration of a communication system of this type, in which six node devices 10-1, 10-2,
10-3, 10-4, 10-5, and 10-6 are connected in a ring shape by a transmission line using an optical fiber or the like. These node devices 10-1, 10-2, 10-3, 10-4, 10-5,
Reference numerals 10-6 denote communication devices having an ATM switching function, in particular, node devices 10-1, 10-2, 10-3,
10-4 and 10-5 are ring nodes constituting the above-mentioned ring, and the node device 10-6 is a ring control node for controlling the ring.

Each of the ring nodes 10-1, 10-2, 10-3,
One or a plurality of local communication terminals are connected to 10-4, 10-5 and the ring control node 10-6, respectively. FIG. 2 particularly shows only the local communication terminal 11-1 connected to the node device 10-2 and the local communication terminal 11-2 connected to the node device 10-5.

[0005] Communication between these local communication terminals 11 is as follows.
The ring nodes 10-1, 10-2, 10-3, 10-4, 1
0-5 and a ring-shaped line formed between the ring control nodes 10-6.

That is, in this communication system, each ring node 10-1, 10-2, 10-3, 10-4, 10-5 is connected to the ring control node 10-6 by a bidirectional line 5. Realizes the ring. Specifically, the ring control node 10-6 and the ring node 10-1 are connected to the line 5
They are connected by a bidirectional line consisting of 1-1 and line 52-6. Also, the ring node 10-1 and the ring node 1
The line 0-2 is connected by a bidirectional line including a line 51-2 and a line 52-5. Hereinafter, ring node 1
0-2 and the ring node 10-3, between the ring node 10-3 and the ring node 10-4, between the ring node 10-4 and the ring node 10-5, and between the ring node 10-5 and the ring control node 1.
The same applies between 0-6.

As a result, in this communication system, line 5
A ring composed of 1-1, 51-2, 51-3, 51-4, 51-5, and 51-6 (defined as clockwise);
2-1, 52-2, 52-3, 52-4, 52-5, and 52-6 in a direction (defined as counterclockwise).

In the ring communication system having such a configuration, the communication between the local communication terminals 11 described above is normally realized by bidirectional communication using a clockwise line, and the counterclockwise line is used when a line failure occurs. It is operated in the form of reserve for loopback.

[0009] In recent years, there has been an increasing demand for constructing a network system covering a wider area using a ring communication system as shown in FIG. As a conventional network system that satisfies such demands, there has been one having a configuration as shown in FIG.

FIG. 1 is an example of the construction of a network system composed of three ring systems A, B and C based on the configuration shown in FIG. In the figure, a ring system A includes six ring nodes 10a-1, 10a-2, 1
0a-3, 10a-4, 10a-5, and 10a-6. Among them, the ring node 10a-6 concentrates information on the ring system A and relays and relays communication to the external line 14. Used as a dedicated node. Similarly, the ring system B and the ring system C respectively have six ring nodes 10b-1, 10b-2, 10b-3, 10b-4,
10b-5, 10b-6 and ring nodes 10c-1, 10c
-2, 10c-3, 10c-4, 10c-5, and 10c-6, of which the ring nodes 10b-6 and 10c-6 collect information on the ring systems B and C, and provide external lines. It is used as a line concentrator / relay-only node for relaying communication to.

Further, a relay control device for relaying information from the ring nodes 10a-6, 10b-6, and 10c-6 dedicated to the line concentrator / relay to the exchange 40 via the relay line 30 is connected to the external line 14. 15 are interposed.

As can be seen from the configuration shown in FIG. 10, in this conventional network system, one ring node (10a-6, 10b-6, 10c-) is provided for each of the ring systems A, B, and C. 6) is used for line collection, and relay control device 15 for further collecting such information.
It was necessary to provide. According to such a configuration, the number of nodes dedicated to line consolidation increases in accordance with the number of ring systems, and each ring node has to be arranged at a base that performs relaying, resulting in poor node utilization efficiency.

[0013] In addition, in the above-described information collection and relay of the ring system, the relay system may be duplicated from the viewpoint of improvement of communication reliability. Special equipment for controlling the relay system was required.

[0014]

As described above, the above-mentioned conventional network system has the following problems.
One ring node is used as a node dedicated to concentrating, and a relay device that relays information from each node dedicated to concentrating to a relay line is arranged.

When performing duplication of the relay system, a special device for switching and controlling these relay systems is arranged.

When a network covering the area is constructed in a ring shape, the efficiency of node utilization is low because it is necessary to arrange each ring node corresponding to a line concentrator at a relay point. ,
In addition, a dedicated node for the line concentrator is required for each ring system, or a special device for switching and controlling the duplexed relay system is required, so that the configuration is complicated and the cost is increased. There was a problem.

An object of the present invention is to eliminate the above-mentioned problems, and to provide a network system which does not require a dedicated node for each ring system, has a simple configuration and is inexpensive, and a construction method thereof. And

Another object of the present invention is to provide a network system capable of controlling the switching of these relay systems without using any special device even when the relay systems are duplicated, and a method of constructing the network system. Is to do.

[0019]

To achieve the above object, according to the present invention, a plurality of node devices are connected by a ring-shaped line, and the ring terminal is connected between communication terminals accommodated in the node devices. In a network system including a plurality of ring systems that perform communication via a line, the ring system is arranged in common with each of the ring systems, the respective ring lines of each of the ring systems are concentrated, and communication information on each of the ring lines is collected. And a relay common node device for relaying to the relay line.

According to a second aspect of the present invention, in the first aspect of the present invention, the ring line and the trunk line are provided with an asynchronous transfer mode (ATM) in which a virtual path (VP) and a virtual channel (VC) can be set at two levels of virtual routes. ) Line, and the relay common node device exchanges all VCs in the ring lines of each ring system by the VPs.
It is characterized by being accommodated by a P exchange path.

According to a third aspect of the present invention, there are provided a plurality of ring systems for connecting a plurality of node devices by a ring-shaped line and performing communication between communication terminals accommodated in the node devices via the ring line. In the method for constructing a network system, a common relay node device for concentrating each ring line of each ring system and relaying communication information on each ring line to a relay line is arranged in common to each ring system. It is characterized by having done.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the ring line and the trunk line are provided with an asynchronous transfer mode (ATM) capable of setting two-level virtual routes of a virtual path (VP) and a virtual channel (VC). ) Line, and the relay common node device exchanges all VCs in the ring lines of each ring system by the VPs.
It is characterized by being accommodated by a P exchange path.

[0023]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of a network system according to an embodiment of the present invention. This network system has four ring systems A, B, each covering an area indicated by a dotted line.
C, D and the respective ring circuits 5a, 5b, 5c, 5d of the ring systems A, B, C, D are connected in common, and information from the respective ring circuits 5a, 5b, 5c, 5d is collected. And a relay common node device (hereinafter abbreviated as a common node) 20 for relaying to the relay line 30 and an exchange 40 interposed in the relay line 30.

In the ring system A, for example, five ring nodes 10a-1, 10a-2, 10a-3, 10a-4, and 10a-5 are connected in a ring by the ring circuit 5a using an optical fiber or the like. Be composed. These ring nodes 1
ATM switching devices are used as 0a-1, 10a-2, 10a-3, 10a-4, and 10a-5, for example.

The ATM switching device is a VP (Virtual Path:
Virtual path) and VC (Virtual Channel)
ATM realized by two-level network
In the switching network, a fixed-length cell (ATM cell) input from an input port is converted into a V-cell included in the ATM cell.
It has a function of switching to an output port in accordance with a PI (Virtual Path Identifier) and a VCI (Virtual Channel Identifier). Although not particularly shown in the figure, each ring node 10a-1, 10a-2, 10a-3, 1
One or a plurality of local communication terminals are connected to 0a-4 and 10a-5, respectively.

The configuration itself of the ring system A is such that the ring node 5a is not closed as one ring, but is accommodated in the common node 20 so that the information on the ring node 5a can be relayed to the relay line 30. Except for this point, it is basically the same as the ring system shown in FIG.

The configurations of the ring system B, ring system C and ring system D are basically the same as those of the ring system A. That is, the ring system B
Are five ring nodes 10b-1, 10b-2, 10b-3, each accommodating one or a plurality of local communication terminals.
This is an ATM ring system in which 10b-4 and 10b-5 are connected by a ring line 5b. Ring system C is
5 each containing one or more local communication terminals
Ring nodes 10c-1, 10c-2, 10c-3, 10
A consisting of c-4 and 10c-5 connected by a ring circuit 5c
It is a TM ring system. The ring system D includes five ring nodes 10d-1, 10d-2, 10d-3, and 10d- each accommodating one or a plurality of local communication terminals.
AT consisting of 4, 10d-5 connected by a ring circuit 5d
It is an M-ring system.

Next, the ring circuits 5a, 5b, 5c, and 5c of the ring systems A, B, C, and D in the common node 20 will be described.
The accommodation form of 5d and the relay line 30 will be described with reference to FIG. As shown in FIG. 1, the common node 20 includes a control unit 201 and a switch unit 202.
The control unit 201 sets the input port and the output port of the cell to V
It has a switching table registered in association with PI and VCI, and controls the cell exchange operation in the switch unit 202 according to this switching table.

The switch unit 202 performs a cell exchange operation of transmitting an input cell through an output port corresponding to the input port of the cell. The input / output ports of the switch unit 202 include the ring circuits 5 of the ring systems A, B, C, and D.
a, 5b, 5c, 5d, and each of these ring systems A,
Trunk lines 30a, 30b, 30 corresponding to B, C, D
c and 30d are accommodated as shown in FIG.

For example, in the ring system A, a ring line 5a-1 connected to the ring node 10a-1 and a ring line 5a-6 connected to the ring node 10a-6 are terminated. Although omitted in FIG. 2, the ring circuit 5a
-1 and the ring node 10a-6, the ring node 1
Ring circuits 5a-2, 5a-3, 5a-4, 5a via 0a-1, 10a-2, 10a-3, 10a-4, 10a-5, respectively.
-5 are connected to each of these ring circuits 5a-1, 5a-2, 5
a-3, 5a-4, 5a-5, and 5a-6 form one ring circuit 5a as a whole (see FIG. 3).

In the switch unit 202, the ring circuit 5
a (5a-1, 5a-2, 5a-3, 5a-4, 5a-5, 5a-
A VP path 51 is formed between 6) and the above-mentioned trunk line 30a (provided corresponding to the ring system A), and a VP switching connection path is formed so as to form a VP path 52 in the ring line 5a. Settings have been made.

The VP path 51 is connected to each of the ring nodes 10a-1, 10a-2, 10a-3, 10a- in the ring system A.
This is a virtual path that can set a VC path used for communication between local communication terminals via 4, 10a-5. In the figure, on this VP path 51, the local communication terminal 11 accommodated in the ring node 10a-3 in the ring system A
A state is shown in which a VC path is set for a-3 and relay transmission with the relay line 30a is performed via the common node 20.

As can be seen from the figure, the ring node 10a-3 has a switch unit 102 for performing the cell switching operation related to the above-described relay transmission and the like, and has the input port and the output port of the cell corresponding to VPI and VCI. And a control unit 101 for controlling the cell switching operation in the switch unit 102 in accordance with the switching table registered and attached to the other ring nodes 10a-1 and 10a-2 in the ring system A. , 10a-4 and 10a-5 have the same configuration.

On the other hand, the VP formed in the ring circuit 5a
The path 52 is a virtual path that can set a VC path for looping back communication by the VC path in the VP path 51, and is set in the opposite direction to the VP path 51.

Further, a control path 53 can be set in the ring line 5a as shown by a dotted line in FIG. The control path 53 is connected to the control unit 201 of the common node 20 and each of the ring nodes 10a-1, 10a-2, 10a-3, 10a-4,
Each of the ring nodes 10a-1, 10a-2, 1 is set from the common node 20 to the respective ring nodes 10a-1, 10a-2, 1
0a-3, 10a-4, and 10a-5. As an example of this control, the control unit 201 of the common node 20 sends the ring nodes 10a-1, 10a-2, 10a-
A loopback instruction is sent to the control unit 101 of the corresponding ring node among 3, 10a-4, and 10a-5, and the VC path in communication in the VP path 51 at the ring node is changed to a VC path in the VP path 52. Control to loop back to

The way of accommodating the ring circuits 5b, 5c, 5d and the trunk line 30 of the other ring systems B, C, D in the common node 20 is the same as the way of accommodation in the ring system A. That is, in the ring system B, the switch unit 202 terminates the ring line 5b-1 connected to the ring node 10b-1 and the ring line 5b-6 connected to the ring node 10b-6, and also sets the ring line 5b (5b -1,5b-2,5b-3,5b-4,5b-5,5
b-6) and the relay line 30b (provided corresponding to the ring system B), a VP path 51 is formed, and a VP path 52 and a control path 53 are formed in the ring line 5b. , VP exchange connection path is set.

As for the ring system C, the switch section 202 terminates the ring line 5c-1 connected to the ring node 10c-1 and the ring line 5c-6 connected to the ring node 10c-6, 5c (5c-1, 5c-2, 5c-3, 5c-4, 5c-5, 5
A VP path 51 is formed between c-6) and the relay line 30c (provided corresponding to the ring system C), and a VP path 52 and a control path 53 can be formed in the ring line 5c. , VP exchange connection path is set.

Further, as for the ring system D, the switch section 202 terminates the ring line 5d-1 connected to the ring node 10d-1 and the ring line 5d-6 connected to the ring node 10d-6. 5d (5d-1, 5d-2, 5d-3, 5d-4, 5d-5, 5
d-6) and the trunk line 30d (provided corresponding to the ring system D), a VP path 51 is formed, and a VP path 52 and a control path 53 are formed in the ring line 5d. , VP exchange connection path is set.

Next, the communication operation of the network system will be described. Here, a case where the local communication terminal in the ring system A communicates with the relay line 30a via the common node 20 will be particularly described.

FIG. 3 shows only the relay part corresponding to the ring system A among the relay parts of the ring systems A, B, C and D in the common node 20 of the network system and the line configuration of the ring system A. FIG.

In the figure, a relay line 30a for concentrating and relaying information of the ring system A is accommodated in the common node 20 together with the ring line 5a of the ring system A. The ring line 5a includes a line 5a-1 between the common node 20 and the ring node 10a-1, a ring node 1
Line 5a-2 between 0a-1 and 10a-2, ring node 10a
Line 5a-3 between -2 and 10a-3, line 5a-4 between ring nodes 10a-3 and 10a-4, and ring nodes 10a-4 and 10
A line 5a-5 between the node a-5 and a line 5a-6 between the ring node 10a-5 and the common node 20. The local communication terminals in the ring system A include a local communication terminal 11a-1 housed in the ring node 10a-1,
Local communication terminal 1 accommodated in ring node 10a-4
Only 1a-4 is shown.

In this circuit accommodation mode, the common node 20 uses the VP in the switch unit 202 as described with reference to FIG.
An exchange connection path is set, and all VC paths in the ring system A are accommodated by this VP exchange connection path. As a result, once the VP exchange connection path is set in the common node 20, even if the communication path increases or decreases due to the addition or removal of the ring node, the operation of setting the path in the common node 20 each time is performed. Is no longer needed.

As a specific example of the setting of the VP switching connection path, in the figure, the trunk line 30a and the ring line 5a (5a
-1, 5a-2, 5a-3, 5a-4, 5a-5, 5a-6), and a VP path 51 is formed on the ring circuit 5a itself.
The path 52 is set. The VP path 51 further includes a local communication terminal 11 accommodated in the ring node 10a-1.
VC path 511 (511-) for performing relay transmission of a-1
1,511-2,511-3,511-4,511-5,511-
6) and a VC path 512 for relay transmission of the local communication terminal 11a-4 accommodated in the ring node 10a-4.
(512-1, 512-2, 512-3, 512-4, 512-
5, 512-6) are set.

On the other hand, the VP path 52 has a VC path 521 (521-1, 521-1) used for looping back the ring.
1-2, 521-3, 521-4, 521-5, 521-6) are set in the opposite direction to the VC paths 511 and 512 in the VP 51.

In the above path setting state, for example, information transmitted from the local communication terminal 11a-1 is exchanged and output to the VC path 511-2 by the ring node 10a-1, and then the VC paths 511-3 and 511 are output. -4,511-5,511-6
To the common node 20, and is condensed at the common node 20 and relayed to the relay line 30 a. Also, the local communication terminal 11 from the trunk line 30a
The information addressed to a-1 is exchanged and output to the VC 511-1 by the common node 20 and transferred to the ring node 10a-1, and the local communication terminal 11a-1 is transmitted by the ring node 10a-1.
Is output to

Similarly, information transmitted from the local communication terminal 11a-4 is transmitted to the VC path 51 by the ring node 10a-4.
After being exchanged and output to 2-5, the packet is transferred to the common node 20 through the VC path 512-6, where the signal is condensed and relayed to the relay line 30a. Also,
Information destined for the local communication terminal 11a-4 from the trunk line 30a is exchanged and output to the VC 512-1 by the common node 20, and then to the ring node 10a-4 through the VC paths 512-2, 512-3, 512-4. The packet is transferred and output to the local communication terminal 11a-4 by the ring node 10a-4.

In this communication, the local communication terminal 11
The communication information of a-1 or 11a-4 is stored in the VP path 51 as an ATM cell having a format as shown in FIG.
Transferred on. That is, the ATM cell is a cell
It consists of a header part and a payload part.
In the header part, GFC (Generic Flow Control), VPI, VCI, PT (Payload Type:
Payload type), CLP (Cell Loss Priority), and HEC (Header Error Control) are carried, and information to be transmitted is carried in the information field of the payload portion.

On the VP path 51, each of the ring nodes 10a-1, 10a-2, 10a-3, 10a-4, 10a-5
Performs a cell switching operation according to the respective values of VPI and VCI in the ATM cell. Also, the common node 20
Performs the above-mentioned VP exchange connection control with the trunk line 30a by performing a cell exchange operation only by referring to the value of the VPI in the ATM cell.

As can be seen from the above description, in the relay communication between the local communication terminal in the ring system A and the other ring systems B, C, D, the information on the upper and lower sides of the communication is the reverse of the ring. (See FIG. 3). Even if a failure occurs in the ring system A due to such a path connection setting, the two ring nodes adjacent to the failure transfer the communicating VC path 511 or 512 to the VC path 521 in the VP path 52. By returning (loopback), communication can be rescued.

For example, if a failure occurs in the ring node 10a-3 during communication with the local communication terminal 11a-1 (see FIG. 3), the ring node 10a-2 and the ring node 10
a-4, the information transmitted from the local communication terminal 11a-1 is transmitted to the VC path 511-2, V
C path 521-5, 521-6, 521-1, 521-2, VC
The faulty node 10 is routed through paths 511-5 and 511-6.
The data can be transferred to the common node 20 without passing through a-3.

In the description of FIG. 3, the ring system A
Similarly, the communication in each of the ring systems B, C, and D can be realized through one VP exchange path via the common node 20. In the description of FIG. 3, the ring systems A, B,
The description has been made on the assumption that the VP path exchange is performed by associating the ring circuits 5a, 5b, 5c, 5d of C and D with the trunk lines 30a, 30b, 30c, 30d one-to-one. The association is not always necessary. As a modified example, for example, a VP resource (band) obtained by combining two of the ring circuits 5a, 5b, 5c, and 5d is connected to the relay line 30a,
When the band is less than one of the bands 30b, 30c, and 30d, an operation of relaying the two ring lines to the one relay line is also possible.

By the way, in this network system in which the communication in all the ring systems A, B, C, and D is realized through one VP exchange path by using the common node 20, for example, the relay line is duplicated. Also in this case, all communications in the ring systems A, B, C, and D can be switched by switching only the VP exchange path.

Hereinafter, the duplication of the trunk line in this network system will be described. The duplication of the relay line in this network system can be realized by, for example, a configuration as shown in FIG. In this example, each of the ring circuits 5a, 5b, 5c,
5d, two adjacent common nodes 20a and 20a
b is interposed. These common nodes 20a and 20
b accommodates the trunk lines 30-1 and 30-2, respectively. The trunk line 30-1 includes trunk lines 30a-1, 30b-1, and 30b-1 for the ring systems A, B, C, and D, respectively.
c-1 and 30d-1 and the trunk line 30-2 has trunk lines 30a-2 and 30a-2 for the ring systems A, B, C and D, respectively.
30b-2, 30c-2, and 30d-2.

In the common node 20a, the trunk line 30
a-1, 30b-1, 30c-1, and 30d-1 are respectively connected to ring circuits 5a, 5b, and 5 of the corresponding ring systems A, B, C, and D by VP paths 51 shown by dotted lines in FIG.
VP exchange paths are connected to c and 5d. on the other hand,
In the common node 20b, the trunk lines 30a-2, 30b-2,
30c-2, 30d-2 and ring systems A, B, C, D
VP exchange path connection is not performed with each of the ring circuits 5a, 5b, 5c, and 5d.
The path setting is made such that the VP path 51 is passed through.

FIG. 6 is a conceptual diagram showing the VP path setting status in the common node 20a and the common node 20b in FIG. 5 in more detail.
A VP exchange connection path that can be responsible for concentrating and relaying is in a setting state, and the common node 20b is in a setting state in which the VP path is simply set to through.

In this path setting state, for example, information from the trunk line 30a-1 is transmitted from the common node 20a on the ring line 5a-1 to the ring node 10a-1 through the VP path 51 (in the direction of the arrow in FIG. 5). ) Is exchanged, and each ring node 10a-1, 10a-2, 10a-3, 1
After passing through 0a-4 and 10a-5, the signal is input to the common node 20b through the ring circuit 5a-6. The common node 20b simply outputs the input information on the VP path 51 and outputs it to the ring line 5a-7, and the common node 20a transmits the information sent from the ring line 5a-7 to the relay line 30a-1. Relay transmission to. Other trunk lines 30b-1, 3
Communication is also performed between Oc-1 and 30d-1 and the ring lines 5b, 5c and 5d in a similar flow via the common nodes 20a and 20b.

In the above communication state, the common node 20a
The cell switching operation is monitored by the control unit 201, and as a result of the monitoring, if a failure occurs in the trunk line 30a-1, the control unit 201 of the adjacent common node 20b and the control path 53
VP path setting (see FIG. 6) is changed to a setting state as shown in FIG.

In FIG. 7, the common node 20a, which has been responsible for concentrating and relaying, is now replaced by the ring circuits 5a, 5b, 5c,
The VP path between 5d and the trunk line 30-1 is cut off, and the VP path is reset to the through state on the ring lines 5a, 5b, 5c and 5d, and has not been directly involved in concentrating / relaying until now. The common node 20b is connected to the ring circuits 5a, 5b, 5c, 5
A VP path is set between d and the trunk line 30-1. By such a VP path setting change, communication at the time of failure of the trunk line 30-1 can be rescued.

Here, when the entire trunk line 30-1 fails, the common node 20a for line concentrator / relay is connected to the line concentrator / relay.
Although the example in which the function of the common node 20b not used for the relay is completely switched has been described, the occurrence of a failure in each of the trunk lines 30a-1, 30b-1, 30c-1, and 30d-1 in the trunk line 30-1 is considered. On the other hand, the relationship between the functions of the common node 20a for concentrating / relaying and the function of the common node 20b for non-concentrating / relaying is maintained as it is. It is also possible to change the path setting.

Further, when the common node 20a itself fails during communication in the VP path setting state in FIG.
The communication can be relieved by changing the VP path setting as shown in FIG. That is, in FIG. 8, the control unit 201b of the common node 20b that has detected the occurrence of the failure of the common node 20a
Ring circuit 5 whose VP path was in a through state until then
a, 5b, 5c, 5d and the VP path between the trunk line 30-1 and the failed common node 20a.
Ring circuits 5a-7, 5b-7, 5c-7, 5 on the side close to
The VP path is set so that d-7 is in the loopback state. At this time, on the side opposite to the side close to the common node 20a, each of the ring circuits 5a, 5b,
Needless to say, the ring nodes farthest from the common node 20b (the ring nodes adjacent to the failed common node 20a) need to be loop-back-controlled on 5c and 5d.

[0061]

As described above, according to the present invention,
The common node device for relaying each ring line of each ring system and relaying the communication information on each ring line to the relay line is arranged in common in each ring system. It is not necessary to arrange a ring node, thereby improving the efficiency of ring use, and providing a network system which does not require a dedicated line concentrator node for each ring system, has a simple configuration, and is inexpensive.

Further, in the present invention, since the switching control by the ATM VP switching path is performed in the relay common node device, no special device is used even when the relay system is duplicated. This has the advantage that the switching control of these relay systems can be easily dealt with.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a network system according to an embodiment of the present invention.

FIG. 2 is a diagram showing an accommodation form of a ring line and a relay line in a common node.

FIG. 3 is a diagram showing a relay portion with a ring system A in a common node and a line configuration of the ring system A;

FIG. 4 is a diagram showing a cell format of an ATM cell.

FIG. 5 is a diagram showing a redundant structure of a trunk line of the network system according to the present invention.

FIG. 6 is a diagram showing a VP path setting status of the common nodes 20a and 20b in FIG. 5;

FIG. 7 is a diagram showing an example of VP path setting change control from the VP path setting state in FIG. 6;

8 is a diagram showing another example of the VP path setting change control from the VP path setting state in FIG.

FIG. 9 is a diagram showing a general configuration of a ring system.

FIG. 10 is a diagram showing a conventional example of a network system from a plurality of ring systems.

[Explanation of symbols]

10a-1, ..., 10a-5 Ring nodes of ring system A 10b-1, ..., 10b-5 Ring nodes of ring system B 10c-1, ..., 10c-5 Ring nodes of ring system C 10d-1, ... , 10d-5 Ring node 101 of ring system D 101 Control unit 102 Switch unit 5a (5a-1,..., 5a-7) Ring line of ring system A 5b (5b-1,..., 5b-7) of ring system B Ring line 5c (5c-1,..., 5c-7) Ring line of ring system C 5d (5d-1,..., 5d-7) Ring line of ring system D 51, 52 VP path 511 (511-1,. , 511-6, 512-1, ..., 51
2-6), 521 (521-1,..., 521-6) VC path 53 Control path 11a-1, 11a-3, 11a-4 Local communication terminal 20, 20a, 20b Relay common node device 201, 201a , 201b Control unit 202, 202a, 202b Switch unit 30 (30a, 30b, 30c, 30d) Trunk line 30-1 (30a-1, 30b-1, 30c-1, 30d-1)
Trunk line 30-2 (30a-2, 30b-2, 30c-2, 30d-2)
Trunk line 40 exchange 14 external line 15 relay controller

Claims (4)

[Claims] 1. A network system comprising a plurality of ring systems for connecting a plurality of node devices via a ring-shaped line and performing communication between communication terminals accommodated in the node devices via the ring line. And a relay common node device that is arranged in common to each ring system, concentrates each ring line of each ring system, and relays communication information on each ring line to a relay line. Network system. 2. A ring circuit and a relay line are constituted by an asynchronous transfer mode (ATM) line capable of setting two levels of virtual routes, a virtual path (VP) and a virtual channel (VC). 2. The network system according to claim 1, wherein all VCs in a ring line of each ring system are accommodated by a VP exchange path exchangeable by said VP. 3. A method for constructing a network system comprising a plurality of ring systems for connecting a plurality of node devices by a ring-shaped line and performing communication via the ring line between communication terminals accommodated in the node devices. In the above, each of the ring systems of each ring system, the relay common node device for relaying the communication information on each ring line to the relay line, is arranged in common in each of the ring systems How to build a network system. 4. A ring circuit and a relay line are constituted by an asynchronous transfer mode (ATM) line capable of setting two levels of virtual routes, a virtual path (VP) and a virtual channel (VC). 4. The network system construction method according to claim 3, wherein all VCs in a ring line of each of said ring systems are accommodated by a VP exchange path exchangeable by said VP.