JP2001268101A - Network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that costs increase since there are a large number of limitations and a line duplexing device is dedicated when it is desired to partially adopt a redundant configuration in a system using the dedicated line duplexing device. SOLUTION: In the network system connecting the arbitrary node devices of first and second ring networks through two trunk circuits of first and second trunk circuits 120 and 121, when switching the first or second trunk circuit from a reserve system to an active system, the node device, to which the first or second trunk circuit is connected, is switched into path pattern in transient state temporarily and switched into path pattern in target state later. Thus, high-quality switching of a little data omission is performed and communication can be continued.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM (Asynchro
nous Transfer Mode: relates to redundancy of a communication network system including communication devices such as exchanges.

[0002]

2. Description of the Related Art For example, in the field of railway management systems and road management systems, there is known a network configuration in which a plurality of communication devices are distributed and collected, and information from these communication devices is collected in a management center and managed. . In this type of system, fault tolerance is required due to the nature of highly public systems such as railways and roads. For example, as shown in Japanese Patent Application No. 11-86280 filed earlier by the applicant, FIG.
7 is shown. This system includes a ring network 100 in which node devices 101, 102, 103, and 104 are connected by a ring transmission line, and a node device 1
This is realized by an ATM ring system that performs communication by an ATM switching technology between ring networks 105 formed by connecting 06, 107, 108, and 109 via a ring transmission path. The network management device 10 is connected to the node device 101 via the Ethernet (registered trademark) 20.
And manages all node devices in the ring network 100 and the ring network 105. In a system that performs communication between ring networks, if a failure occurs in a transmission path between rings, communication between the rings is interrupted.Therefore, a redundant transmission path that can be switched as a working system or a standby system is provided between the rings. In the case where a failure occurs in the active transmission line, the connection between the ring networks is made redundant by switching to the backup transmission line to continue communication between the rings.

In the ring network system shown in FIG. 17, a node device 102 and a node device 106 are inter-ring connection node devices for connecting adjacent ring networks, and are switched between the active system and the standby system. They are connected by possible duplicated trunk lines 110. In this trunk line, communication between the ring networks is normally performed using the trunk line 111 of the working system. When a failure occurs in the trunk line 111 of the working system, the trunk line is switched to the trunk line 112 of the standby system. By doing so, communication between the rings is continued. As described above, in the ring network system shown in FIG. 17, when a failure occurs in the working trunk line, the switching between the protection trunk lines can be controlled to continue communication between the rings. As a conventional network system, as shown in FIG. 18, one network management device 10 has a network connection function and an ATM switching device (node device 2) having a duplex configuration.
01, 202: a plurality of ATM switching devices (node devices 203, 2
04, 205).

[0004] In this system, the network management device 10 transmits all network connection devices 201 and 202, node devices 203 and 204 on the ATM ring 206.
The network management device 10 manages the network connection device 201,
202 and is physically connected. The network connection devices 201 and 202 have an Ethernet interface that accommodates the Ethernet 20 and an ATM interface that accommodates the ATM ring 206. One of the network connection devices 201 and 202 is an active system,
The other operates as a standby system, and Ethernet 20 and ATM
It also has a network connection function for connecting the ring 206. The node devices 203, 204, and 205 are ATM switches having an ATM interface that accommodates an ATM ring. In the network system having such a configuration, the network management device 10 and the node device 20
When the network connection devices 201 and 202 having a duplex configuration for relaying the communication between 3, 204 and 205 are operating as the active system and the standby system, respectively, the network management device 10 needs to reach the ATM ring 206. Is registered that the next hop is the network connection device 201.

In this state, if a system switching occurs between the network connection devices 201 and 202 having a duplex configuration, the network management device 10
It is necessary to change the next hop to be the network connection device 202 as the route information to reach 6. Generally, RIP (Routing Infor), which determines an optimal route based on the number of hops to a destination, is a protocol for dynamically switching route information.
mation protocol) is widely used. When RIP is used, the network management device 10 uses the metric of the RIP response message broadcast from the network connection devices 201 and 202 as an identifier, and transmits the RIP response message having a smaller metric to the network. A route via the connection device is selected. In such a system configuration, when switching the system between the network connection devices 201 and 202, the network connection device 201 broadcasts a certain metric value N using a RIP response message. 202 initially uses the lowest metric value for a period of time to RIP
A response message is broadcast, and after a lapse of a predetermined time, the system is switched by using the metric value N used by the network connection apparatus 201.

[0006]

However, in a conventional system in which one of the duplexed trunk lines connecting the ring networks can be switched as the active system and the other as the standby system, the conventional system can be used when the line redundancy switching fails or when the line redundancy control is performed. If the inter-ring connection node device that is responsible for the failure itself fails, not only is it not possible to switch the line duplex due to a circuit failure, but also it is not possible to perform normal communication between rings due to the failure of the inter-ring connection node device. was there. Therefore, the first object of the present invention is to
In order to solve this problem, by arranging the redundant accommodation function of the line as the node function of the ring network,
An object of the present invention is to provide a network system capable of configuring a flexible network capable of taking a redundant configuration between lines accommodated in arbitrary nodes and performing high-quality switching with little data loss. Further, in a system in which network connection devices are configured in a duplex configuration, if system switching is performed again within a certain period when system switching is performed, the network connection device that has become the active system due to the previous switching has the smallest metric. Because the value is used, the next active network connection device is the RIP
There is a problem in that the network management device cannot select a route that again passes through the active network connection device, even though the broadcast is performed using the response message.

Therefore, a second object of the present invention is to solve this problem by changing the metric value depending on whether or not the other network connection device of the duplexed network connection device is alive, thereby enabling a certain period of time. It is an object of the present invention to provide a network system capable of switching a path even if a plurality of system switchings occur in a network.

[0008]

According to a first aspect of the present invention, there is provided a network system comprising: a first ring network in which a plurality of switching devices are connected on a transmission line; and a plurality of switching devices. A second ring network connected on the transmission line is connected via two relay lines, a first relay line and a second relay line, and the first relay line or the second relay line is connected. The switching device has a working state path pattern for switching a path so as to connect one of the transmission lines connected to the node device and the trunk line connected to the node device, and one of the transmission lines connected to the node device. A standby state path pattern in which a path is switched so as to connect a path and the other transmission path connected to the node device, and a transmission path connected to the node device and the other transmission path connected to the node device. In addition to connecting to the transmission line, the switching of the trunk line is performed by switching the three path patterns, namely, the transition state path pattern that switches the path so that the information transmitted from the trunk line can be pulled in. By doing so, communication can be continued. In the network system according to claim 2 of the present invention, the first
Is switched from the working system to the protection system, or from the protection system to the working system,
The switching device to which the first trunk line or the second trunk line is connected switches to the path pattern in the transition state once, and then switches to the path pattern in the target state. Switching can be performed and communication can be continued.

In a network system according to a third aspect of the present invention, a network in which a plurality of node devices are connected on a transmission line, a management device for managing each node device in the network, and a transmission line arranged on the transmission line A first network connection device for connecting to the management device, the network connection device reaching the transmission path via its own device depending on the presence or absence of the other network management device at the time of system switching Weighting the route information to be notified. The network management device selects the route information having the smallest weight from the route information, and connects to the transmission path via one of the network connection devices according to the route information. Since the weight of the route information is changed depending on the presence or absence of the other network management device, the route can be switched immediately even if a plurality of system switches occur within a certain period. Claim 4 of the present invention
In the network system according to the first aspect, when the first and second network connection devices operate as active network connection devices, the weight is set to N and the route information is notified. If it exists, if its own device is switched from the active system to the standby system, the weight is set to M (M> N) and the route information is notified, and the own device is switched from the standby system to the active system. In this case, system switching is performed by notifying the route information with the weight set to N, and at the time of system switching, if there is no active network connection device, the own device is switched from the standby system to the active system. In the case of switching, the route information is notified with the weight set to N−1, and after the system is switched, if the existence of the network connection device is confirmed, the network connection device of the working system at this time is checked. By notifying the routing information themselves as N, performs system switching. Thus, even if a plurality of system switchings occur within a certain period, the path can be switched immediately.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a basic configuration diagram of the network system according to the first embodiment of this invention. In FIG. 1, node devices 101, 102, 103, and 104 are arranged in a ring network 100,
These node devices are connected in a ring by a ring transmission line. Similarly, node devices 106, 107, 108, and 109 are arranged in the ring network 105, and these node devices are connected in a ring by a ring transmission line. Between the ring network 100 and the ring network 105, the node device 102 and the opposing node device 106 are connected by a relay line 120. Similarly, the node device 103 and the opposing node device 109 are connected by the relay line 121. One or a plurality of local terminals can be accommodated in the node devices that construct the ring networks 100 and 105. In particular, in FIG. 1, the local terminals 122 accommodated in the node device 104 and the local terminals 122 accommodated in the node device 108. Only the local terminal 123 is shown. In the system shown in FIG. 1, the node devices 101, 102, 10
ATM exchanges are used as 3, 104, 106, 107, 108 and 109. ATM switch is VP
(Virtual Path) and VC (Virtual Channel)
l: a virtual channel), which is connected to an ATM transmission line realized by a two-level network, and fetches a fixed-length cell (ATM cell) taken from an input port into the AT.
VPI (Virtual Path Identifier) included in the M cell
ifier: virtual path identifier) and VCI (Virtual Chan)
nel Identifier (virtual channel identifier).

As is clear from FIG. 1, in the first embodiment of the present invention, any node device constituting the ring network (in FIG.
3, 106, 109), a plurality of trunk lines are accommodated in a redundant configuration. In other words, a configuration is provided between the ring networks 100 and 105 in which two sets of relay lines are provided which can switch to the protection line and continue communication when the working line becomes disconnected. According to such a configuration, for example, the node device 10 operating as the active system
When the relay line 120 between the node device 103 and the node device 106 is interrupted due to some kind of failure, the relay circuit 1 between the node device 103 and the node device 109 which are on standby as a standby system.
21 starts up as an active system, and these node devices 10
The communication can be maintained by using the relay circuit 121 between the communication device 3 and the node device 109. Next, how communication paths are set for communication between a plurality of ring networks will be described. Communication of the network system is performed via a communication path formed in a ring transmission line and a trunk line. FIG. 2 is a diagram showing a communication path set in the first embodiment of the present invention. In FIG. 2, as an example, local terminals 122 accommodated in two ring networks, respectively.
3 shows a communication path in which communication between the terminal and the local terminal 123 is performed via the relay line 120. Here,
The communication paths formed on the ring transmission line and the trunk line are shown.

The information transmitted from the local terminal 122 is transmitted via the terminal accommodation line 321 to the node device 104,
Communication path 304, node device 101, communication path 301,
The communication path 317 passes through the node device 102, the node device 106 of the other ring network, and the communication path 30
9, node device 107, communication path 310, node device 1
08, arrives at the local terminal 123 through the terminal accommodation line 323. Conversely, information from the local terminal 123 passes through the terminal accommodation line 324, passes through the node device 108, the communication path 311, the node device 109, the communication path 312, and the node device 106, and passes through the communication path 318, the node device 10
2, communication path 302, node device 103, communication path 30
3. Arrival at the local terminal 122 through the node device 104 and the terminal accommodation line 322. In this way, the communication path when a plurality of ring networks are connected by a trunk line is
This is a communication path in which communication paths in each ring network are connected by a communication path of a trunk line. The communication path in the ring network forms a communication path between two points by using all the one-way communication paths.
306, 307, 308 and communication paths 313, 314,
The communication paths in the reverse direction on the ring transmission lines 315 and 316 are communication paths for performing loopback in response to a communication failure in the ring. Since the loopback is well known, the description of the operation is omitted here.

The trunk line 121 (communication paths 319 and 32)
0) is a standby line when the relay line 120 (communication paths 317 and 318) breaks down, and at this time, no communication path for relay is set. Trunk line 120
When the (communication paths 317, 318) are disconnected or the relay node devices 102, 106 are down, the path settings in the node devices 103, 109 become valid, and the communication between the ring networks becomes the relay line 121. (Communication paths 319 and 320). Here, before describing the switching of the trunk line in the network system, a control path in the ring network and between the ring networks for giving the instruction will be described. The control path is a path formed on a transmission path for giving a command such as switching of a communication path to a node device constituting the network system. Then, among the plurality of node devices in the ring network system, at least one node device serves as a control node device and controls other node devices via this control path. However, as a control restriction in the ring network system, the control node device in the ring network is given the authority to control only the node devices in the same ring network.

In other words, when performing control over another ring network, a command is given to a control node device for controlling a node device in the ring network to which the node device to be controlled belongs, and the control node device is controlled. Then, control is again performed on the node device to be controlled. First, a control path in the ring network will be described. FIG. 3 is a diagram showing a control path in the ring network. Here, a ring transmission path is not shown, but a control path formed in the ring transmission path is shown. 3, 101, 102, 103, 10
Reference numeral 4 denotes a node device constituting the ring network, and reference numerals 405, 406, and 407 denote control paths formed on the respective ring transmission lines. In FIG. 3, the node device 101 is a control node device that controls the inside of the ring network, and has an in-ring control function 401 required for ring control. This not only has a basic ring control function, but also has a control for operating the node devices connected to the trunk line as the active system or the standby system, respectively, in relation to the present invention. The other node devices 102, 103, and 104 have control functions 402, 403, and 404 necessary to receive control from the control node device 101.

The control node device 101 and each node device 10
Control paths 405, 40 connecting 2, 103, 104
Reference numerals 6 and 407 are fixedly configured in advance by the numbers of the node devices and the like, and are configured to be able to constantly perform control processing. Also, as shown in FIG. 2, the communication path for user information forms an upper and lower communication path by using a one-way path in the ring network, but the control paths 405, 40 in the ring network.
6 and 407, up and down control paths are formed using the same path. FIG. 3 shows only a one-way control path, but the control node device 101 switches the direction of the control path in accordance with the status of the transmission path in the ring network to thereby control the path in the ring network. Control communication becomes possible even when there is a failure in a part. For example,
When a failure occurs in the ring transmission path between the node device 103 and the node device 104, the control of the node device 104 by the control path 407 cannot be performed.
To the control path 408 in the opposite direction indicated by the dotted line.
Switch to the path. As described above, each node device in the ring network can perform various operations with respect to the process for maintaining the ring network performed by the control node device therein.

Next, a control path set between a plurality of ring networks will be described. The control path between the ring networks is set between the control node devices of each ring network, and information can be exchanged between the control node devices of each ring network. As a result, control is also performed by giving a control command to the control node device of the other ring network to the node device of the other ring network that cannot be directly controlled by the control node device of the one ring network. This makes it possible to match the states of the lines of a plurality of ring networks and synchronize the switching operation. FIG.
FIG. 4 is a diagram illustrating a control path set between a plurality of ring networks. 4, 101, 102, 103,
Reference numerals 104, 106, 107, 108, and 109 denote node devices constituting a ring network.
02 is a ring control function for controlling the ring network. Each of the ring control functions 501 and 502 has a function of controlling each node device in the ring network similarly to the intra-ring control function 401 of FIG. 3, and further has a function between the respective ring control functions 501 and 502. Control path 50 for controlling between ring networks
3, 504, and has an inter-ring control function for adjusting the line status of each ring network and synchronizing the switching operation.

The control paths 503 and 504 are different from the control paths in the ring network shown in FIG. 3 and are constituted by communication paths as shown by solid lines and dotted lines, respectively. For this reason, even if a failure occurs in the ring network, the so-called detour function (loopback) operates effectively, and recovery can be performed without performing any special operation. Further, the two control paths 503 and 504 are set so as to pass through each of the two trunk lines having a redundant configuration.
The configuration is such that control information can be exchanged between ring networks. For this reason, in each of the ring control functions 501 and 502, the inter-ring control signal is always transmitted to the path of these two paths.
Duplicate information received from each route can be handled. Further, ring control functions 501 and 502
Are configured to give the final decision authority to one of them so that the switching process can be performed smoothly and at high speed. Thus, it is necessary to define the configuration to which the final decision authority is to be given, but the switching process can be performed at a high speed. Here, returning to the description, switching of the trunk line in the network system will be described.

There are three types of path setting patterns for switching the trunk line, and in the node device to which the trunk line is connected, one of the patterns is set in accordance with a command from the control node device. FIG. 5 shows a path setting pattern for switching trunk lines in each node device. FIG. 5A shows a pattern in which the path is switched so that one transmission path connected to the node device and the other transmission line connected to the node device are connected, and the relay line is in a standby state. It is a path pattern at the time. FIG.
(B) is a pattern in which the path is switched so as to connect one of the transmission lines connected to the node device and the trunk line connected to the node device, and the path pattern when the trunk line is in the working state. It is. FIG. 5 (C) shows a pattern when the trunk line transitions between the working state and the standby state, and is a path pattern that temporarily transitions so as not to reduce the communication quality during operation as much as possible. is there. The transition of the path pattern includes a transition from (A) to (B) via (C) and a transition from (B) to (A) via (C). In the transition from B) to (C) and the transition from (C) to (B), the flow of cells is switched by switching the path, which may affect the communication. Influence is reduced.

Next, the procedure for actually switching the trunk line will be described step by step. FIGS. 6 to 12 show the procedure for switching the trunk line during normal operation, and the switching of the relay circuit is performed by combining the transitions of the path patterns in FIG. Here, the state from the state where the upper trunk line in the figure is the working system to the lower trunk line being switched to the working system is shown. Also,
FIG. 13 shows the respective processing sequences of the intra-ring control function and the inter-ring control function accompanying the switching operation of the trunk line. As described with reference to FIG. 4, in the control between the rings, one of the control node devices has the final authority of the switching so that the switching of the trunk line can be performed quickly. The device 101 has the authority. FIG. 6 shows a state in which communication is performed via the upper trunk line. 6, 101, 102, 103, 104 and 106, 10
7, 108, and 109 are node devices, and 122, 12
3 is a local terminal, 301, 302, 303, 3
04 and 309, 310, 311 and 312 are communication paths, 317, 318, 319 and 320 are communication paths of trunk lines, and 321, 322, 323 and 324 are terminal accommodation lines. Note that, for the sake of simplicity of the drawing, the detour path in the reverse direction used when a failure occurs in the ring network is omitted. In addition, in FIG. 7 to FIG. 12 described below, since the configuration itself is the same, reference numerals are not given to all components, and only components deemed necessary for the description are denoted by reference numerals.

FIG. 6 shows the pattern of FIG. 5B in which the node devices 102 and 106 set a path on the trunk line, and FIG. 5B shows that the node devices 103 and 109 flow information through the ring network. A). As a result, the information transmitted from the local terminal 122 passes through the terminal accommodation line 321 and passes through the node device 10.
4, communication path 304, node device 101, communication path 30
1, through the node device 102, the communication path 317, the other ring network node device 106, the communication path 309, the node device 107, the communication path 310, the node device 108, the terminal accommodation line 323, and the local terminal 12
Sent to 3. Conversely, information from the local terminal 123 passes through the terminal accommodation line 324,
Communication path 311, node device 109, communication path 312,
The data is sent to the local terminal 122 through the communication path 318, the node device 102, the communication path 302, the node device 103, the communication path 303, the node device 104, and the terminal accommodation line 322 through the node device 106. When switching between the active system and the standby system of the trunk line in the system having such a configuration, the node devices 102, 103, 1
This is realized by performing path changes 06 and 109.

First, in the first stage of the switching operation, as shown in FIG. 13, the control node device 101 which has started the process of switching the trunk line transmits a signal 601 for instructing the relay node device 103 to change the path. send. Upon receiving this signal, the node device 103 changes the path pattern to that shown in FIG. 5C as shown in FIG. At this stage, there is no change in the cells flowing between the ring networks just by merging the paths in the direction of the communication path (relay line) 320, and the communication between the ring networks via the relay line in FIG. Is performed. Then, the node device 103 on which the path transition has been completed is, as shown in FIG.
By sending a response 602 indicating that the processing has been completed, the first-stage switching operation is completed. Next, in the second stage of the switching operation, as shown in FIG. 13, the control node device 101 sends a signal 603 for prompting the control node device 107 of the adjacent ring network to transition the path of the relay node device 109. The control node device 107 having received the signal 604 instructs the relay node device 109 to change the path.
Send. Upon receiving this signal, the node device 109 changes the path pattern to that shown in FIG. 5B, as shown in FIG. However, in practice, the node device 109 changes from FIG.
Instead of directly transiting to (B), FIG.
The state transitions to the path pattern of FIG. 5B via (C).

At the moment when the node device 109 changes from FIG. 5C to FIG. 5B, a change in the information path occurs, and a communication path (relay circuit) 320 between the node device 109 and the node device 103 is generated. Information begins to flow. In other words, the information from the local terminal 123 to the local terminal 122 up to that point is transmitted via the terminal accommodation line 324 to the node device 10.
8, communication path 311, node device 109, communication path 31
2, while passing through the communication path 318, the node apparatus 102, the communication path 302, the node apparatus 103, the communication path 303, the node apparatus 104, and the terminal accommodation line 322 through the node apparatus 106, After the transition, the node device 1 is connected via the terminal accommodation line 324.
08, the communication path 311, the node device 109, the communication path 320, the node device 103, the communication path 303, the node device 104, and the terminal accommodation line 322 to be sent to the local terminal 122. At this time, there is a possibility that information is lost, but at the time of switching, only one cell is lost at most, and there is almost no possibility of cell loss in communication with a normal low-speed interface. And
The node device 109 that has completed the path transition sends a processing completion response 605 to the control node device 107 as shown in FIG. The control node device 107, which has confirmed the completion of the transition of the relay node device 109, sends a processing completion response 606 to the control node device 101, whereby the second-stage switching operation ends.

Next, in the third stage of the switching operation, as shown in FIG. 13, the control node device 101 sends a signal 607 for instructing the relay node device 103 to change the path. Upon receiving this signal, the node device 103 changes the path pattern to that shown in FIG. 5B, as shown in FIG. As a result, the path patterns of all the node devices 102, 103, 106, and 109 are as shown in FIG. However, the path path remains the path switched in FIG. 8 and does not affect the flow of information. Then, the node device 103 that has completed the path transition,
As shown in FIG. 13, the third-stage switching operation is completed by sending a processing completion response 608 to the control node device 101. Further, in the fourth stage of the switching operation, as shown in FIG. 13, the control node device 101 sends a signal 609 urging the transition of the path of the relay node device 106 to the control node device 107 of the adjacent ring network. Upon receiving this, the control node device 107 sets the relay node device 106
A signal 610 for instructing a path transition is sent to. The node device 106 that has received this signal changes the path pattern to that shown in FIG. 5C as shown in FIG. even here,
Only merging the paths in the communication path (relay line) 317 direction does not change the path route and does not affect the flow of information.

Then, the node device 1 whose path transition has been completed
06 sends a processing completion response 611 to the control node device 107 as shown in FIG. Relay node device 1
The control node device 107 that has confirmed the completion of the transition in step 06 sends a processing completion response 612 to the control node device 101, thereby ending the switching operation in the fourth stage. Next, in the fifth stage of the switching operation, as shown in FIG. 13, the control node device 101 sends a signal 613 for instructing the relay node device 102 to change the path. The node device 102 that has received this signal changes the path pattern to that shown in FIG. 5A as shown in FIG. However, actually, the node device 10
5 does not directly transit from FIG. 5B to FIG. 5A, but transits from FIG. 5B through FIG. 5C to the path pattern of FIG. 5A. This node device 102 is shown in FIG.
At the moment when the state transitions from (C) to FIG. 5 (A), a change in the information path occurs, and information stops flowing through the communication path (relay line) 317 between the node device 102 and the node device 106.
Information starts to flow on a communication path (relay line) 319 between the node device 103 and the node device 109. That is, the information from the local terminal 122 to the local terminal 123 up to that point passes through the terminal accommodation line 321 and is transmitted to the node device 10.
4, communication path 304, node device 101, communication path 30
1, through the node device 102, the communication path 317, the other ring network node device 106, the communication path 309, the node device 107, the communication path 310, the node device 108, the terminal accommodation line 323, and the local terminal 12
3 has been transferred to the node device 104 and the communication path 30 via the terminal accommodation line 321.
4, node device 101, communication path 301, node device 1
02, the communication path 302, the communication path 319, the communication path 319, and the other ring network node apparatus 109, communication path 312, node apparatus 106, communication path 309, node apparatus 107, communication path 310, node apparatus 108, Local terminal 1 through terminal accommodation line 323
23.

Then, the node device 1 for which the path transition has been completed
In step 02, as shown in FIG. 13, a process completion response 614 is sent to the control node device 101, thereby ending the switching operation in the fifth stage. As described above, at this point, the communication path is a path passing through the lower trunk line in the figure, but finally, as a sixth step, as shown in FIG. A signal 615 urging the control node device 107 to change the path of the relay node device 106 is sent. Control node device 10 receiving this
7 sends a signal 616 instructing the relay node device 106 to change the path. Node device 1 receiving this signal
In step 06, as shown in FIG. 12, the path pattern is changed to the path pattern shown in FIG. 5A, and the trunk line in the figure is returned to the standby state. Then, the node device 106 that has completed the path transition,
As shown in FIG. 13, a response 617 indicating the completion of the process is sent to the control node device 107. The control node device 107, which has confirmed the completion of the transition of the relay node device 106, sends a processing completion response 618 to the control node device 101, thereby completing the process of switching the relay line. In this way,
The control node device having the final authority performs path transition of the relay node device in the ring network while exchanging signals with the control node device of the other party, and switches the relay circuit.

As described above, by transiting the respective steps of FIGS. 6 to 12 in the form of transitions of the path patterns of the individual node devices, it is possible to reduce the communication performed via the relay line in the figure. It can be shifted to perform communication via a relay line shown in the lower part of the figure. In addition, there is a possibility that communication information between ring networks may be lost due to this switching operation only in the second and fifth stages of the switching operation in FIGS. This does not matter whether one cell is lost or not at the moment of switching. As described above, by the switching operation of the present invention, the switching of the trunk line in operation is performed by using the path switching function inherent in the node device.
An inexpensive switching system can be realized. In addition, regarding such a path switching function, the trunk line 12
0, 121 and node devices 102, 103, 106, 10
Although the path switching is automatically performed by detecting the failure 9, the path switching may be forcibly performed by operation from the network management apparatus 10 for the purpose of, for example, maintenance and inspection. . In this case, communication path switching control is performed from the network management device 10 via the node device 101. However, if a failure occurs in the node device 101, such an operation may not be performed from the network management device 10.

For this reason, as shown in FIG. 14, it is conceivable to connect the network management device 10 to a plurality of node devices of the ring network. In this case, in a normal state, control is performed via the node device 201, and when a failure occurs in the node device 201, the node device 2
It is conceivable to perform the operation by switching to 02. Such an operation will be described below as a second embodiment of the present invention. The network system according to the second embodiment of the present invention is a network system in which a network management device manages a node device on an ATM ring via one of the duplicated network connection devices. This is a network system that can immediately reflect the change in the route information to the network management device when the system is switched between the connected devices, even immediately after the system is switched. FIG. 14 is a configuration diagram of a network system according to the second embodiment of the present invention, which includes a network management device 10 that manages node devices on the ATM ring 206,
The network management device 1 via the Ethernet 20
0 and the network connection devices 201 and 202 connected to the ATM ring 206, and the node devices 203, 204 and 205 connected to the ATM ring 206.
Consists of The configuration of the system shown in FIG. 14 is the same as the configuration of the conventional system shown in FIG. 18. Here, among the network connection devices 201 and 202 having the duplex configuration, 201 is the active system, 202 Is operating as a standby system.

The operation of the network system according to the second embodiment will be described below. FIG. 14 shows a state where the active network connection device is selected as a route to reach the ATM ring in the normal operation state.
Here, a dotted arrow indicates a route through which route information is sent from the network connection device, and a solid arrow indicates a route (access route) for reaching the ATM ring selected by the network management device. In the normal operation state, the active network connection device 201 periodically switches the ATM ring 2.
The route information is reported on the Ethernet 20 by RIP with the metric value “N = 3” as the route to reach 06. The network management device 10 receives the path information from the network connection devices 201, 201. In this situation, the network management device 10
Since only 01 reports the route information by RIP,
Since a route via the network connection device 201 is selected as a route to reach the ATM ring 206, the network connection device 201 operates as an active system. Thereafter, when the network connection device 201 switches from the working system to the protection system and the network connection device 202 switches from the protection system to the working system, the network management device 10 sets the access route to the ATM ring 206 as shown in FIG. Control for switching is performed as shown. still,
Here, it is assumed that the presence of the network connection device 201 can be confirmed from the network connection device 202.

That is, in FIG. 15, the network connection device 201 that is switched from the active system to the standby system is
The route for arriving at the ATM ring 206 was previously set to the metric value “3”, but the metric value is set to “1”.
6 ", and the route information is reported on the Ethernet 20 by RIP. Here, the metric value is “16” representing unreachable, but there is no particular problem if the metric value is larger than the original metric value “3”. Also, the network connection device 202 that can switch from the standby system to the active system
Performs the existence check of the network connection device 201,
If the presence is confirmed, the ATM ring 206 is periodically checked.
The route information is reported on the Ethernet 20 by RIP on the route having the metric value “3” for reaching the route information. The network management device 10 receives the route information from the network connection devices 201 and 202, and based on the route information, arrives at the ATM ring 206.
Here, since the metric value from the network connection device 201 is “16” and the metric value from the network connection device 202 is “3”, a route that passes through the network connection device 202 is selected. It switches from the standby system and operates as the active system.

FIG. 16 shows the network connection device 2
02, the presence of the network connection device 201 cannot be confirmed, and the network connection device 201 is switched from the active system to the standby system.
Ring 2 when the system switches from the standby system to the working system
10 shows a state of control for switching the access route to the address 06. In FIG. 16, the network connection device 202 that switches from the standby system to the working system checks the existence of the network connection device 201, and if the existence cannot be confirmed, periodically sets the route for arriving at the ATM ring 206 as a metric value. Is set to “N−1 = 2”, and the routing information is reported on the Ethernet 20 by RIP. The network management apparatus 10 receives the path information from the network connection apparatus 202, and based on the path information and the path information sent by the network connection apparatus 201 when it is alive, performs an ATM operation.
In order to reach the ring 206, the network connection device with the lowest cost (small metric value), in this case, the metric value sent by the network connection device 201 when alive is “3”, and the metric value from the network connection device 202 is Since it is "2", a route via the network connection device 202 is selected, so that the network connection device 202 switches from the standby system and operates as the active system.

Thereafter, if the existence of the network connection device 201 can be confirmed, the network connection device 202 changes the metric value to “3” and reports the route information by RIP. The fact that the existence of the network connection device 201 can be confirmed means that the system can be switched. As described above, in the network system according to the second embodiment of the present invention, when the system can be switched, the active network connection device outputs a constant metric value (“3” in this example). Since the data is transmitted to the network management device, the smaller metric value cannot be used as in the case where the system is switched by using the smallest metric value for a certain period as in the past. Therefore, the system cannot be switched during that period. As described above, according to the network system of the present embodiment, by changing the metric value depending on whether or not the network connection device of the redundantly configured partner is alive, even if the system has just been switched, At the time of switching, the change of the route information can be immediately reflected in the network management device.

[0032]

As described above in detail, according to the first or second aspect of the present invention, a line accommodated in an arbitrary node is provided by arranging a line redundant accommodation function as a node function of a ring network. It is possible to configure a flexible network that can take a redundant configuration between them, and perform high-quality switching with little data loss. According to the third or fourth aspect of the present invention, the metric value is changed according to the existence or non-existence of the other network connection device in the redundant configuration, whereby the system can be switched a plurality of times within a certain period. Even if it occurs, the path can be switched.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a network system according to a first embodiment of this invention.

FIG. 2 is a diagram showing a communication path set in the first embodiment of the present invention.

FIG. 3 is a diagram showing a control path set in the ring network according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating control paths set between ring networks according to the first embodiment of this invention.

FIG. 5 is a diagram showing a path setting pattern for switching a relay circuit according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a procedure for switching trunk lines according to the first embodiment of the present invention.

FIG. 7 is a diagram showing a procedure for switching trunk lines according to the first embodiment of the present invention.

FIG. 8 is a diagram showing a procedure for switching trunk lines according to the first embodiment of this invention.

FIG. 9 is a diagram showing a procedure for switching trunk lines according to the first embodiment of this invention.

FIG. 10 is a diagram showing a procedure for switching trunk lines according to the first embodiment of this invention.

FIG. 11 is a diagram showing a procedure for switching trunk lines according to the first embodiment of this invention.

FIG. 12 is a diagram showing a procedure for switching trunk lines according to the first embodiment of the present invention.

FIG. 13 is a processing sequence diagram of a trunk line switching according to the first embodiment of this invention.

FIG. 14 is a configuration diagram of a network system according to a second embodiment of this invention.

FIG. 15 is a view for explaining system switching when both network connection devices can be confirmed in the second embodiment of the present invention.

FIG. 16 is a view for explaining system switching when one network connection device cannot be confirmed in the second embodiment of the present invention;

FIG. 17 is a configuration diagram of a conventional network system.

FIG. 18 is a configuration diagram of another conventional network system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Network management apparatus 20 ... Ethernet 101,102,103,104 ... Node apparatus 106,107,108,109 ... Node apparatus 120,121 ... Relay circuit 122,123 ... -Local terminals 201, 202 ... network connection devices 203, 204, 205 ... node devices 301, 302, 303, 304 ... communication paths 305, 306, 307, 308 ... communication paths 309, 310, 311, 312: communication path 313, 314, 315, 316: communication path 317, 318, 319, 320 ... communication path 321, 322, 323, 324: terminal accommodation line 401: ring Internal control function 501: Ring control function 600: Transmission line

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K014 CA03 CA07 5K030 GA11 HA08 HC14 HD07 JL07 LB08 LE17 MD02 MD07 5K031 AA08 CB10 CB12 CB13 DA02 DA06 EB02 EB05 9A001 BB04 CC03 DD10 JJ18 KK56 LL02 LL09

Claims (4)

[Claims] 1. A first ring network connecting a plurality of node devices on a transmission line, a second ring network connecting a plurality of node devices on a transmission line, and any node device of the first ring network A first trunk line connecting the first ring network to an arbitrary node device of the second ring network; and connecting an arbitrary node device of the first ring network to an arbitrary node device of the second ring network. In a network system having a second trunk line, a node device to which the first trunk line or the second trunk line is connected is connected to one of a transmission line connected to the node device and a relay line connected to the node device. A working state path pattern for switching a path so as to connect a line, one transmission path connected to the node device and the node device A standby path pattern for performing path switching so as to connect the other transmission path connected to the other node, and connects one transmission path connected to the node device to the other transmission line connected to the node device. In addition to the above, a network system that switches a transition state path pattern for performing path switching so as to draw in information transmitted from a trunk line. 2. When the first trunk line or the second trunk line is switched from an active system to a standby system or from a standby system to an active system, the first trunk line or the second trunk line is switched. 2. The network system according to claim 1, wherein the node device to which the line is connected switches to the path pattern in the target state after switching to the path pattern in the transition state once. 3. A network in which a plurality of node devices are connected on a transmission line; a management device for managing each node device in the network; and a plurality of node devices arranged on the transmission line, each connecting the management device to the network. The first and second network connection devices notify the management device of path information for reaching the transmission path via the own device to the management device. Path information notifying means, monitoring means for monitoring the presence of the other network connection device, and path information variable for managing the path information by weighting and variably setting the weight depending on the presence or absence of the other network connection device. Setting means, wherein the management device is configured to provide the route information notified from the first and second network connection devices. Network system, characterized in that with reference to the weighting, equipped with a route selection means for selecting a path of the reporting via the smallest path information weights. 4. The first and second network connection devices, when their own device operates as an active network connection device, notify the routing information with a weight of N, and at the time of system switching, the active network When the connection device exists, if the own device is switched from the working system to the protection system, the weight is set to M (M> N) and the route information is notified, and the own device is switched from the protection system to the working system. In the case of switching, the route information is notified with a weight of N. If there is no active network connection device at the time of system switching, if the own device has switched from the standby system to the active system, Notifies the path information with a weight of N-1. After the system is switched, if the existence of the network connection device is confirmed, at this time, the weight of the active network connection device is set to N.
4. The network system according to claim 3, wherein the route information is notified.