JPH0758965B2 - Network system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to communication network systems, in particular so-called
The present invention relates to a network system suitable for LAN (Local Area Network).

[Background of the Invention]

LAN is known as a network system for interconnecting computers, terminal devices, various office devices, etc. scattered in a relatively narrow area such as the same building or the same premises (for example, , "Information processing"
Vol. 23, No. 12, 1982, pages 1122-1177). Traditional LAN
In, the transmission line is substantially semi-fixed, and dynamically adding or partially removing the transmission line is a star LAN.
Very difficult, except for. Dynamically increasing or decreasing the number of nodes is not easy when the tap is active (for example, when an optical fiber is used for the transmission line). In this sense, conventional
The LAN should be inflexible. Access between LANs is also inconvenient.

Flexibility is especially important when a failure occurs and recovery from it. Generally, if a failure that occurs in a node, a device connected to the node, or a part of a transmission path is left unattended, the entire system will be brought down. In particular, in ring-shaped LAN where active taps are used, most of the partial failures are directly linked to system down, and therefore,
Rapid separation of the obstacle is essential. Moreover, since the tap is an active type, it is necessary to maintain at least only the regenerative relay function even when the node is disconnected. Therefore, a dedicated power supply system for the tap and the transceiver part must be installed in the system. Alternatively, it is necessary to take measures such as duplicating the entire transmission path system including the regeneration relay means. The known so-called loopback as one of the countermeasures against failures is a kind of function that dynamically changes the network configuration, but the degree of configuration change that can be made by it is very limited, and furthermore, it is not possible to transmit it. Since it is necessary to have each node have a loop back function and the same release function while assuming that the road system is duplicated, the system and the individual nodes must have complicated configurations. Even in a bus LAN, it is rare that a partial failure spreads to the entire system. In short, in a conventional LAN, a partial failure has a strong tendency to threaten the entire system, and it cannot be said that the reliability is sufficiently high in that respect, and one of the reasons is the lack of flexibility described above. is there.

[Object of the Invention]

An object of the present invention is to provide a network system which is highly reliable in that the network structure is highly flexible and the obstacles can be easily separated and restored.

[Outline of Invention]

The basic concept of the present invention is to form a required LAN network by interconnecting a plurality of partial networks, each of which can form a ring LAN by itself, through a circuit switching device. Is. Each partial network has a partial ring connection control device which interconnects one and the other end of the transmission line of the partial network to form a ring or of a circuit switching device. Switching connection is made so that each line is connected to a separate line. Therefore, it is also possible to construct an independent ring LAN for each partial network by using a simple circuit switching device that has only the circuit switching function, or to connect multiple partial networks through the circuit switching device. It is possible to easily connect to each other to form a wider area ring LAN, or to dynamically change the configuration of such a wide area LAN, as needed and at any time. it can.

The network connection management control device that manages and indicates the mutual connection relationship of the partial networks may be configured as another partial network which is to be connected to the partial network to form the network.

Further, this network connection management control device may be provided as an internal mechanism of the circuit switching device, or
It may be connected to a set of the line as an external mechanism of the line switching device. The former is suitable for making a dedicated exchange, and the latter is suitable for using an off-the-shelf general-purpose exchange.

Example of Invention

1 (a) to (e) show an embodiment in which the present invention is applied to a ring LAN. In FIG. 1 (a), a circuit switch 1, a network connection management / control device 2,
Partial rings 10, 20, and 30 scattered at three locations form one network system. In the present embodiment, the circuit switch 1 may be a general-purpose one having a normal circuit switching function, but it is desirable that the transmission band has as wide a transmission band as possible. Recently, a wide band exchange of several hundred Mb / s or more has appeared, which is enough.

The network connection management / control device 2 is a line (hereinafter referred to as a ring configuration circuit) 3, 5 that should form a part of a ring LAN transmission line, and a line for connection control information necessary for network connection operation. (Hereinafter referred to as control line) 4,
It is connected to the circuit switch 1. This device 2 has a transmission medium 6 connected as a part of a LAN transmission line as will be described later, and is provided with a node (not shown) connected to this transmission medium 6 and after the network formation. Is configured to communicate with other nodes in the network and a partial ring connection control device to be described later via this node. Therefore, the network connection management / control device 2 is nothing but a kind of partial ring. The network connection management / control device 2 accepts network connection requests from various partial rings, determines the mutual connection relationship of those partial rings, and sends necessary instructions or information to each part of the network. Therefore, this device 2 has a function of communicating with each partial ring connection control device via the control line 4 in addition to the communication function via the above-mentioned node, and, for example, each partial ring and its connection. It stores information necessary for network connection control, such as a correspondence table with the circuit numbers of various circuits that are used, an interconnection relationship table of existing networks, and the like.

In the present embodiment, the network connection management / control device 2 is a device separate from and independent of the circuit switch 1, but it may be part of the internal mechanism of the circuit switch 1. For example, the transmission line system hardware such as the transmission medium 6 and the node connected thereto is configured as one type of trunk, and the network connection request acceptance means is configured as one type of register, and is used for interconnection relation determining means and network connection control means. The information storage means and the like can be incorporated in the central controller. With this configuration, the control procedure for connecting the partial rings to each other can be considerably simplified, and the overhead required to complete or change the network connection can be shortened.

Each of the partial rings 10, 20, 30 comprises a partial ring connection control device 11, 21, 31 and a partial network 15, 25, 35 to be interconnected to form a ring LAN. Each of these sub-networks has an appropriate number of nodes,
Including these nodes, it has a configuration that functions as one section of the ring LAN. Each of the partial ring connection control devices 11, 21, and 31 accommodates both ends of the transmission line of the corresponding partial network, and also includes ring configuration circuits 12 and 14, 22 and 24, 32 and 34, and control lines 13 and 23. , 33 are connected to the line switch 1, and if necessary, a line connection request is issued to the line switch 1 and both ends of the transmission line of the partial network are extended to the corresponding ring-structured lines, and control is also performed. Network connection management / control device 2 through the ring configuration line after the network for network and network formation
Communicate with. Note that the control lines 13, 23, 33 may not be provided, and one of the ring configuration lines 12 or 14, 22 or 24, 32 or 34 may be used as it.

Ring configuration lines 3,5,12,14,22,24,32,34 are duplicated,
Backup word transmission or loop back may be performed. Further, not only these ring-structured lines but also the control lines may be of one-way transmission type. In that case, two lines having mutually opposite transmission directions are prepared as the control lines 4 of the network connection management / control unit 2, and these and each ring part ring pair line pair 12, 14, 22, 24.
Alternatively, a method of connecting 32 and 34 and exchanging connection control information (removing the control lines 13, 23, 33) can be adopted. The configuration that makes all lines one-way transmission type simplifies exchange control, and is a high-speed LAN that uses optical fibers as transmission lines.
Make it easy to build.

The process of forming a ring LAN in this system is as follows. Suppose first that the partial ring 10 needs to operate as a ring LAN without any network being formed. Therefore, the partial ring connection control device 11 makes a call through the control line 13 to request the connection of the network connection management / control device 2 to the control line 4. Receiving this request, the line switch 1 sets up a communication path 113 between the line 4 and the line 13 unless the line 4 is busy.
Through this connection, the partial ring connection control device 11 issues a network connection request to the network connection management / control device 2 (Fig. 1 (b)).

The network connection management / control device 2 checks the control information such as the table and determines the mutual connection relationship to be established. In this case, each end of the internal transmission medium 6 is connected to the ring-forming lines 3 and 5. Connect each and connect line 3 to 12
To the circuit switch 1 and, at the same time, instructs the partial ring connection control device 11 to issue a request to connect the line 14 to the circuit switch 1 to the circuit switch 1. In response to these requests, the circuit switch 1 establishes a communication path 112 between the lines 3 and 12 and a communication path 114 between the lines 14 and 5, and as a result, a ring LAN (15-14- 114-5-6-3-112-1
2-15) is formed (FIG. 1 (c)). Control line 13
The connection between No. 4 and No. 4 is cut at an appropriate time before and after the completion of the network to prepare for a network connection request from another partial ring. After the network is completed, each node performs communication control based on a predetermined protocol, and communication between nodes is performed as in the conventional ring LAN.

Next, in the state of FIG. 1 (c), the network connection request from the partial ring 30 goes through the same process as in the case of FIG. 1 (b), and the control line 33-communication path 133-control It is assumed that the call is issued through the line 4 (Fig. 1 (d)). The network connection management / control device 2 determines a mutual connection relationship to be newly established in the same manner as in the above-mentioned case, and based on this, the partial ring connection control device via the path (3-112-12). Instructing 11 to issue a request to the circuit switch 1 for disconnecting the connection between the lines 14 and 5 and connecting the line 14 to the line 32, and also through the path (4-133-33). The ring controller 31 is instructed to issue a request to connect the line 34 to the line switch 5 to the line exchange 1. The circuit switch 1 sets the respective communication paths in response to these requests, and thus the new ring LAN (15-14-132-32-35-34-134-5-5-6-3-1).
12-15) are formed (FIG. 1 (e)). At the time of reconfiguring the network, the connection (3-112-12) may be disconnected once and then reconnected. If the line is bidirectional, the network connection management / control unit 2 can issue connection requests for the lines 14 and 5, and the lines 34 and 5; however, the line switch is usually used. As long as it is of the type
32 connections) can not be requested. If the network connection management / control device 2 is incorporated as an internal mechanism of the circuit switch 1, there will be no restriction on the connection procedure as described above. The separation of the partial rings can be easily performed by the same process.

By the way, the overhead for network reconstruction is unavoidable, and in some cases, it reaches several tens of ms.
I can't ignore it. As a countermeasure, the network connection management / control device 2 sends appropriate instruction information to all the nodes included in the operating network to prevent access to the network before starting the reconfiguration operation. , Release information is sent after the reconfiguration is completed. When the loopback mechanism is provided, the loopback may be performed in advance at the connection point with the line whose connection is changed for reconfiguration, and then the reconfiguration operation may be started.

As shown by reference numeral 21 in FIG. 2, each partial ring connection control device is configured so that a small-scale ring-shaped LAN can be configured with only each partial ring as required.

The network fault diagnosis function can be assigned to each partial ring connection control device for each partial ring, but it is better to have the network connection management / control device 2. The process of finding and disconnecting the obstacle ring in the case of such a configuration is shown in FIGS. 3 (a) to (e). As shown in FIG. 3 (a), when the partial rings 10, 20, 30 form one ring-shaped LAN via the network connection management / control device 2, the partial network 35 fails. (X mark) is generated. The network connection management / control device 2, which has detected the occurrence of a failure, first instructs each of the partial ring connection control devices 11, 21, 31 and cooperates with them to disconnect the interconnection of all lines (third part). Figure (b)). Then, the network connection management / control device 2 and the partial ring 10 are reconfigured in the network, but no fault is detected at this time (FIG. 3 (c)). Then the partial ring
30 is incorporated into the network, where a fault is detected (Fig. 3 (d)). As a result, since it is found that the partial ring 30 has a fault, the partial ring 30 is separated from the network and the next partial ring 20 is incorporated into the network (Fig. 3 (e)). The resulting partial ring is separated from the network, and the network is reconstructed with only the partial ring having no obstacles. This reconnection process may be performed in a fixed order led by the network connection management / control device 2, or may be performed by each partial ring connection control device randomly issuing a network connection request. Good. Alternatively, it is also possible to identify the failed partial ring by connecting each partial ring to the network connection management / control device 2 individually in sequence.

A plurality of network connection management / control devices may be accommodated in one circuit switch. As an example of such a case, in FIG. 4 (a), the partial rings 10 and 20 are connected to the network connection management / control device 2, and a single ring LAN (6
-3-12-15-25-25-22-5-6) is formed. Further, in FIG. 4 (b), the partial ring 10 is connected to the network connection management / control device 2 to form a first ring-shaped LAN.
(6-3-12-15-15-14-5-6), and at the same time, the partial ring 20 is connected to the network connection management / control device 2 ', and the second ring LAN (6'-5 ′ -24-25-2
2-3'-6 ') is formed. Other partial rings, not shown, can be requested by the network connection management / control unit 2 or 2'to join any desired ring LAN. It is possible to take any form as required. For example, a number of partial rings that require access to a particular device can be distributed over multiple networks to level the traffic.

When a plurality of network connection management / control devices are provided in this way, it is sufficient to provide one or several of them with a failure diagnosis function for partial rings. For example, in FIG. 4 (a), if the network connection management / control device 2'has the above-mentioned diagnosis function, the network is usually constructed as shown in FIG. 4 (a)-(a). e) the partial ring according to the process described above
When it is discovered that a failure has occurred in 20, the separated partial ring 20 is connected to the network connection management / control device 2 ', as shown in FIG. Fault diagnosis is performed while the remaining partial ring configures the network together with the network connection management / control unit 2 and maintains the communication function.

It is also possible to construct a ring LAN that spans multiple circuit switches. In FIG. 5 (a), ring-structured trunk lines 6 and 8 and a control trunk line 7 are provided between the circuit switches 1 and 1 '. The partial ring 20 and the network connection management / control device 2 are connected to the ring LAN (6-
3-24-25-22-5-6) is formed, and the partial ring 10 is accommodated in the circuit switch 1'via the ring constituting lines 12 and 14 and the control line 13. The partial ring 10 calls the control line 4 of the network connection management / control device through the control line 13 for making a network connection request. The line switch 1'extends the line 13 to the communication line 113 and the relay line 7, and the line switch 1 further connects the relay line 7 to the communication line.
The communication path between the partial ring control device 11 and the network connection management / control device 2 is extended from 107 to the line 4 (FIG. 5 (b)). Hereinafter, except that the relay lines 6 and 8 are used, the line 3 is connected in the same manner as in the case of FIG. 1 (e).
12 and 14 and 24 are connected to complete a new ring-shaped LAN including the partial ring 10 (FIG. 5 (c)).

[Background of the Invention]

As is clear from the above description, the network system of the present invention has a great flexibility in the network configuration, and therefore various measures can be taken easily even when a failure occurs. The reliability as is also greatly improved. Furthermore, the dedicated power supply system for the active node may be taken from the common power supply for each partial network (for example, each floor), and when it fails, the partial ring can be disconnected. Also in this respect, the reliability is improved.

Moreover, a partial ring connection control device in which one and the other ends of the transmission lines of the partial network are interconnected so as to form a ring or are switched and connected so as to be connected to respective separate lines of the circuit switching device. As a result of providing each of the partial networks, the circuit switching device only needs to have the circuit switching function, and does not need to have the function of configuring each partial network into a ring and operating it. The structure is simplified, an off-the-shelf general-purpose exchange can be used, and the addition and removal of partial networks can be easily dealt with. Moreover, even if the circuit switching equipment loses its function altogether due to a catastrophic failure, each sub-network has its own independent ring-shaped structure.
Can function as a LAN.

[Brief description of drawings]

1 (a) to (e), FIG. 2 and FIG. 3 (a) to
(E), FIG. 4 (a)-(b) and FIG. 5 (a)-
(C) is a block diagram of each example of the present invention. 1,1 ′ …… Circuit exchange, 2,2 ′ …… Network connection management / control device, 10,20,30 …… Partial ring, 11,21,31 …… Partial ring connection control device, 15,25, 35 …… Partial network work.

Claims (4)

[Claims] 1. A plurality of partial networks that can be connected to each other to form a ring-shaped LAN, a circuit switching device, and a plurality of partial networks that are respectively connected to the plurality of partial networks and one of the transmission lines of the partial networks. The other end is interconnected with a plurality of partial ring connection control devices which are switch-connected so that the other ends are interconnected to form a ring or are connected to respective separate lines of the circuit switching device. A network system including a network connection management control device for managing and instructing connection relations. 2. A network system according to claim 1, wherein the network connection management control device is configured as another partial network which is connected to the partial network to form a network. 3. A network system according to claim 1 or 2, wherein the network connection management control device is provided as an internal mechanism of the circuit switching device. 4. A network system according to claim 1 or 2, wherein the network connection management control device is connected to a set of lines of the circuit switching device.