JP3533148B2 - Connection bypass system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection bypass system that bypasses a connection when an ATM network failure occurs.

[0002]

2. Description of the Related Art ATM (as as a technique capable of communicating various data such as voice and video on the same network
ynchronous transfer mode) Networks are attracting attention. In this ATM network, it is necessary to promptly detect the occurrence of a line failure and restore the connection.

Conventionally, as disclosed in Japanese Patent Laid-Open No. 9-036884, a detour path is newly searched and set between the occurrence of a failure and the recovery thereof.

Further, in Japanese Patent Laid-Open No. 11-215148, there is provided SVC (switched virtual connection) information as a method for connecting to two terminals, which are network terminating devices, in order to make a detour by designating the other party each time communication is started. It is held in advance. And PVC (permanent virtual
connection: fixed connection type virtual channel), when a connection failure occurs, the SVC information is used to set the connection. Where PV
C is VP (virtual path) and VC (vi
VP as a number corresponding to each rtual channel)
The I (VP identifier) and the VCI (VC identifier) are set in advance.

[0005]

In order to set up a detour path, it is necessary to set up one connection for all target node devices. Therefore, if the detour path is set when a failure occurs in these conventional techniques, it is necessary to sequentially set the connection to all the corresponding node devices. Therefore, the detour processing time is long. Therefore, there is a problem that the service interruption time becomes long. Further, for example, there may be a case where a detour path having a desired band cannot be set in relation to the transmission band.

SUMMARY OF THE INVENTION An object of the present invention is to provide a connection bypass system capable of switching a path to a bypass path only by setting a connection to a part of a node device when a failure occurs.

[0007]

According to a first aspect of the present invention, (a) a basic path connecting a plurality of node devices located between first and second terminals for transmitting ATM cells,
(B) A node device closest to the first terminal and a node device closest to the second terminal of this basic path are used as starting points or ending points, and two or more detours are provided in addition to these node devices. A node device is arranged, only lines between these detour node devices are pre-connected, and a node device closest to the first terminal and a node device closest to the detour node device and the second terminal are provided. The detour path that is released between the detour node devices while the first and second terminals are connected by the basic path, and (c) closest to the first terminal when a failure occurs in the basic path The node device on the side and the node device on the side closest to the second terminal and the node devices on both ends to which the line of the bypass path is connected are connected by a line to connect between the first and second terminals. Switch to communication path by detour path And path switching means is provided in the connection bypass system that.

That is, according to the invention of claim 1, the ATM
A basic path that connects a plurality of node devices located between the first and second terminals that transmit cells and a detour path that detours this basic path are prepared. Among these, the detour path is in a state in which the line between the node device closest to the first terminal and the node device closest to the second terminal of the basic path is released, and the detour path Regarding the other parts constituting the above, the respective node devices and the lines are connected. Therefore, when a failure occurs in the basic path, the path switching means simply connects the line between the node device closest to the first terminal and the node device closest to the second terminal to make a detour. You can switch to the path side path. As a result, the number of connection settings is drastically reduced, and it is possible to quickly switch to the alternative path, as well as the route to the alternative path is set and the bandwidth for that can be secured, so reliability is also improved. Can be made.

According to the second aspect of the invention, (a) a basic path connecting a plurality of node devices located between the first and second terminals transmitting ATM cells; and (b) a first path of this basic path. Node device closest to the terminal and the node device closest to the second terminal as a starting point or an ending point, and two or more detour node devices are arranged in addition to these node devices, and these detour nodes are used. Only the line between the node devices is connected in advance, and the node device closest to the first terminal and the bypass node device and the node device closest to the second terminal and the bypass node device are connected to the first node device. And the detour path that is released while the second terminal is connected by the basic path, (c) the node device closest to the first terminal when the basic path fails, and the second path The side closest to the terminal A route switching means for switching between the first and second terminals to the communication route by the bypass path by connecting the node devices at one end and the node device at the both ends to which the bypass path is connected by a line; Basic path failure recovery detection means for detecting when a failure of the basic path is recovered, and (e)
After the path switching means switches to the communication path by the bypass path, when the basic path failure recovery detecting means detects that the failure of the basic path has been recovered, the node device closest to the first terminal and the second Of the basic path between the first and second terminals by disconnecting the line between the node device closest to the terminal and the bypass path, and connecting the line on the basic path side of these node devices instead. And a switching back means at the time of restoration of the basic path for switching back to the communication path by the connection bypass system.

That is, according to the second aspect of the invention, the ATM
A basic path that connects a plurality of node devices located between the first and second terminals that transmit cells and a detour path that detours this basic path are prepared. Among these, the detour path is in a state in which the line between the node device closest to the first terminal and the node device closest to the second terminal of the basic path is released, and the detour path Regarding the other parts constituting the above, the respective node devices and the lines are connected. Therefore, when a failure occurs in the basic path, the path switching means simply connects the line between the node device closest to the first terminal and the node device closest to the second terminal to make a detour. You can switch to the path side path. As a result, the number of connection settings is drastically reduced, and it is possible to quickly switch to the alternative path, as well as the route to the alternative path is set and the bandwidth for that can be secured, so reliability is also improved. Can be made. According to the second aspect of the present invention, when the failure of the basic path is recovered by the basic path failure recovery detecting means, this is detected, and after the path switching means switches to the communication path by the bypass path, the basic path failure recovery is performed. When the detecting means detects that the failure of the basic path has been recovered, the basic path recovery switchback means bypasses the node device closest to the first terminal and the node device closest to the second terminal. By disconnecting the line to the path and connecting the lines on the basic path side in these node devices instead, the line between the first and second terminals is switched back to the communication path by the basic path. As a result, when the basic path is restored, it is decided to switch back from the detour path to the basic path, so if the basic path has a wider transmission band, restart the signal transmission in a better transmission state. You can

According to the third aspect of the present invention, (a) a basic path connecting a plurality of node devices located between the first and second terminals transmitting ATM cells; and (b) a first path of this basic path. Node device closest to the terminal and the node device closest to the second terminal as a starting point or an ending point, and two or more detour node devices are arranged in addition to these node devices, and these detour nodes are used. Only the line between the node devices is connected in advance, and the node device closest to the first terminal and the bypass node device and the node device closest to the second terminal and the bypass node device are connected to the first node device. And the detour path that is released while the second terminal is connected by the basic path, (c) the node device closest to the first terminal when the basic path fails, and the second path The side closest to the terminal A route switching means for switching between the first and second terminals to the communication route by the bypass path by connecting the node devices at one end and the node device at the both ends to which the bypass path is connected by a line; A bypass path failure detecting means for detecting a failure of the bypass path, and (e) when the failure of the bypass path is detected by the bypass path failure detecting means after switching to the communication path by the bypass path by the path switching means. A basic path failure recovery presence / absence determining means for determining whether or not the failure has been recovered, and (v) a first terminal when the basic path failure recovery presence / absence determining means determines that the failure of the basic path is recovered. By disconnecting the line between the node device closest to the node and the node device closest to the second terminal and the bypass path, and connecting the lines on the basic path side in these node devices instead. And between the second terminal is equipped with a return means base path recovery during cutting switched back to the communication path by the basic path in the connection bypass system.

That is, according to the invention of claim 3, the ATM
A basic path that connects a plurality of node devices located between the first and second terminals that transmit cells and a detour path that detours this basic path are prepared. Among these, the detour path is in a state in which the line between the node device closest to the first terminal and the node device closest to the second terminal of the basic path is released, and the detour path Regarding the other parts constituting the above, the respective node devices and the lines are connected. Therefore, when a failure occurs in the basic path, the path switching means simply connects the line between the node device closest to the first terminal and the node device closest to the second terminal to make a detour. You can switch to the path side path. As a result, the number of connection settings is drastically reduced, and it is possible to quickly switch to the alternative path, as well as the route to the alternative path is set and the bandwidth for that can be secured, so reliability is also improved. Can be made. Further, in the invention according to claim 3, when the bypass path failure detecting means detects the failure of the bypass path and the basic path failure recovery presence / absence determining means determines that the failure of the basic path has been recovered, a switchback at the time of recovery of the basic path is performed. We decided to switch back to the communication path by the basic path by means. in this way,
When a failure occurs in this detour path after switching to the detour path, the path is switched back to this if the original basic path has been restored.
It is possible to secure the reliability of the cell transmission path.

According to the invention described in claim 4, in the connection bypass system according to claims 1 to 3, the bypass path is provided between the node device closest to the first terminal and the node device closest to the second terminal. It is characterized in that a plurality of nodes are provided between the node devices.

That is, the invention according to claim 4 indicates that a plurality of detour paths may be provided. By providing a plurality of detour paths, it is possible to further improve reliability as compared with switching between the basic path and one detour path. Of course, the present invention does not prohibit the case where only one system of bypass path is provided.

According to a fifth aspect of the present invention, in the connection detour system according to the fourth aspect, (a) a free band comparison means for comparing the sizes of free bands that can be transmitted by the respective detour paths, and (b) this It is further characterized by further comprising a bypass path selecting means for selecting a bypass path in order from the bypass path having the largest free band based on the comparison result by the free band comparing means.

That is, according to the invention of claim 5, when a plurality of detour paths are provided, the empty band comparison means compares these empty bands, and from the comparison result, the detour path having the largest empty band is selected in order from the detour path. By making the selection, the transmission condition of the ATM cell in the detour path of the switching destination is improved.

According to a sixth aspect of the present invention, in the connection bypass system according to the fifth aspect, when comparing the sizes of the available free bands of the bypass paths, the free band comparing means determines the total available band from each path. It is characterized by not comparing the band obtained by subtracting the total of the bands reserved for use in 1., but comparing the free band obtained by subtracting the band actually used in the bypass path from the total band.

That is, in the invention according to claim 6, when comparing the sizes of the available free bands of the bypass path, the free band comparing means subtracts the band actually used in the bypass path from the total band. I'm going to compare the free bandwidth. This is because if each bypass path reserves free bandwidth, there may be cases where there is virtually no free bandwidth even if there is a path with a large apparent bandwidth. In some cases, the bandwidth used by the line is actually small and there is a lot of free bandwidth. Therefore, the actually vacant band is compared to select the detour path, and the transmission condition of the ATM cell in the detour path of the switching destination is improved.

According to the invention described in claim 7, (a) a basic path connecting a plurality of node devices located between the first and second terminals transmitting ATM cells; and (b) a first path of this basic path. Node device closest to the terminal and the node device closest to the second terminal as a starting point or an ending point, and two or more detour node devices are arranged in addition to these node devices, and these detour nodes are used. Only the line between the node devices is connected in advance, and the node device closest to the first terminal and the bypass node device and the node device closest to the second terminal and the bypass node device are connected to the first node device. And the detour path that is released while the second terminal is connected by the basic path, (c) the node device closest to the first terminal when the basic path fails, and the second path The side closest to the terminal A route switching means for switching between the first and second terminals to the communication route by the bypass path by connecting the node devices at one end and the node device at the both ends to which the bypass path is connected by a line; After switching to the detour path by this route switching means, whether to return to the basic path again, and when returning to the basic path, it should be at the time point when the failure of the basic path is restored or the detour path of the switching destination. The connection bypass system is provided with return selection means for arbitrarily selecting whether or not a failure occurs.

That is, according to the invention of claim 7, the ATM
A basic path that connects a plurality of node devices located between the first and second terminals that transmit cells and a detour path that detours this basic path are prepared. Among these, the detour path is in a state in which the line between the node device closest to the first terminal and the node device closest to the second terminal of the basic path is released, and the detour path Regarding the other parts constituting the above, the respective node devices and the lines are connected. Therefore, when a failure occurs in the basic path, the path switching means simply connects the line between the node device closest to the first terminal and the node device closest to the second terminal to make a detour. You can switch to the path side path. As a result, the number of connection settings is drastically reduced, and it is possible to quickly switch to the alternative path, as well as the route to the alternative path is set and the bandwidth for that can be secured, so reliability is also improved. Can be made. Further, in the invention according to claim 7, after switching to the detour path, whether to return to the basic path again, and when returning to the basic path, it should be at the time point when the failure of the basic path has been recovered or to the switching destination. Since the recovery selection means for arbitrarily selecting whether or not the failure of the bypass path occurs is provided, it is possible to select the presence / absence of the switchback and the timing of the switchback according to various circumstances.

[0021]

DETAILED DESCRIPTION OF THE INVENTION

[0022]

EXAMPLES The present invention will be described in detail below with reference to examples.

FIG. 1 shows the configuration of a connection bypass system according to an embodiment of the present invention. In this connection bypass system, the first terminal 101 is a terminal located at a branch of a bank, and the second terminal 102 is a terminal located at another branch of the bank. These first
The first to third node devices 111 to 113 are arranged between the second terminals 101 and 102 as node devices forming a basic path (working path). Further, the fourth node device 114 and the fifth node device 115 are the first
Is prepared as a bypass path (standby path) of the sixth node device 116 and the seventh node device 117.
It is prepared as a detour path. A network management device 131 that manages a network is arranged in this connection bypass system. The network management device 131 has a circuit configuration similar to that of a normal personal computer, and C (not shown).
A PU (Central Processing Unit) also realizes network management by executing a program stored in a storage medium (not shown). The network management device 131 includes a connection management unit 132, a node management unit 133, and a line management unit 134. The line management unit 134 has lines 141 to
For 144 and 152 to 157, the connection number of the connector established in the network, the connection name, the line number used in the connection, the line number used in the bypass path, and the available bandwidth of the bypass path are managed. The free bandwidths of the lines 141 to 144 and 152 to 157 are notified to the connection management unit 132 every time a connection is set.

Here, the line 141 is the first node device 11
The first node device 112 is connected to the second node device 112, and the line 142
Connects the second node device 112 and the third node device 113. The line 143 connects the fourth node device 114 and the fifth node device 115, and the line 144 is the sixth node device.
The node device 116 and the seventh node device 117 are connected. A line 152 is connected between the first terminal 101 and the first node device 111, and when the first terminal 101 and the second terminal 102 are connected by a basic path, First node device 111 and fourth node device 11
The line 153 is not connected during the period 4. In this state, similarly, the first node device 111 and the sixth node device 11
The line 156 is not connected between 6 as well. A line 155 is connected between the second terminal 102 and the third node device 113, and the first terminal 101 and the second terminal 102 are connected.
In this state in which the connection between the third node device 113 and the fifth node device 115 is established, the line 1 is connected between the third node device 113 and the fifth node device 115.
54 is not connected. In this state, similarly, the line 157 is not connected between the third node device 113 and the seventh node device 117.

On the other hand, the first terminal 101 and the second terminal 10
When the two are connected by the first detour path, the line 153 is connected between the first node device 111 and the fourth node device 114, and the third node device 113 and the fifth node are connected. A line 154 will be connected between the devices 115. Further, when the first terminal 101 and the second terminal 102 are connected by the second detour path, the line 156 is connected between the first node device 111 and the sixth node device 116. , The line 157 is connected between the third node device 113 and the seventh node device 117.

The first to seventh node devices 111 to 117 are connected to the control line 161. This control line 161
Are connected to the node management unit 133. Control line 16
1, the network management device 131 uses the lines 141 to 144, 1
The state of 52 to 157 is grasped. For example, 1st-7th
It is assumed that a line failure has occurred in any of the node devices 111 to 117. In this case, the trap is notified to the network management device 131 via the control line 161. When the node management unit 133 detects a failure, the line management unit 134 is notified of the content thereof. The line management unit 134 manages the connection number, and when the detour is necessary due to the occurrence of a failure, the line management unit 134 issues a detour instruction to the connection that should be detoured to the connection management unit 132.

Upon receipt of the detour instruction, the connection management unit 132 sets a line with a large free band among the first detour path and the second detour path as a detour path and restores the connector. . Two detour paths are provided in the case of this embodiment, but more paths can be provided freely. If any of the bypass paths have a failure, the bypass is not executed at that time. After that, when the detour destination line is restored, the re-detour process is performed.

FIG. 2 shows an example of a connection management table used by the connection management unit for management. The connection management table 171 defines a connection for connecting the first terminal 101 and the second terminal 102 shown in FIG. 1 as the first connection number 241. The connection name is "PVC
-1 ". In this connection, the bandwidth used is" 1 ".
000 "and the basic or working path is line 15
2, 141, 142, 155 are used. At this time, the first node device 111 connects the line 152 and the line 141, and the second node device 112.
Connects the line 141 and the line 142, and the third node device 113 connects the line 142 and the line 155.

Regarding the detour path, the first detour path and the second path
There are two detour paths available. Lines 152, 153, 143, 154, 1 for the first detour path
55, and the lines 152, 156, 144, 157, 155 are used for the second detour path. In this state, the fourth node device 114 connects the lines 153 and 143, and the fifth node device 115 connects the lines 143 and 154. In addition, the sixth node device 11
6 connects the lines 156 and 144, and the seventh node device 117 connects the lines 144 and 157.

FIG. 3 shows a line management table managed by the line management unit. Line management table 17
2 is the line status of each line 141, 142, ..., Connection number of basic path, connection number of detour path,
The total bandwidth, used bandwidth and free bandwidth are described. Figure 1
The line management unit 134 shown in FIG.
When the connection of the basic path is set to 2, 141, 142, 155, the bandwidth used in the connection is calculated and the used bandwidth is added respectively. Then, the used bandwidth is subtracted from the total bandwidth of each line to obtain these free bandwidths.

The free bandwidths of these lines shown in the line management table 172 are notified to the connection management unit 132. Upon receiving this notification, the connection management unit 132 manages the smallest value among the free bandwidths of the respective lines forming the bypass path as the bypass path when setting the bypass path. For example, in the case of the first detour path of this embodiment, the free band of the line 153 is “6500” and the free band of the line 143 is “75”.
00 "and the free bandwidth of the line 154 is" 7500. "Therefore, the free bandwidth of this detour path is" 650. "
In the same way, in the case of the second bypass path, the free band “5000” of the line 156 is the smallest value, and is set to this value.

FIG. 4 shows a part of the contents of the node management table managed by the node management unit. The node management table 173 includes the node devices 111, 112 ...
Node number, the port number of each port, the state of the port, and the total bandwidth. This Figure 4
At the time point indicated by, a failure (Error) has occurred in the port of the second node device 112 on the side connected to the line 141, for example. The line 142 of this second node device 112
The port on the side connecting with is normal (Good). This is the line 141 in the line management table 172 shown in FIG.
It corresponds to the line status of. The operation of this connection bypass system will be described below, taking as an example the case where a failure occurs in the port of the second node device 112 that is connected to the line 141.

FIG. 5 shows the flow of processing when a failure occurs in the node management unit. Node management unit 133
Is waiting for the failure occurrence trap to be transmitted through the control line 161 shown in FIG. 1 (step S30).
1). When a failure occurs in the port of the second node device 112 that is connected to the line 141 and a failure occurrence trap is sent (Y), the node management unit 133 causes the node management table 173 shown in FIG. Port number to use "1
The port state of 12-141 "is changed from" Good "(normal) to" Error "(fault) as shown in this figure (step S302).

FIG. 6 shows the flow of processing for the occurrence of a failure in the line management unit. The line management unit 134 monitors that the port status of the node management table 173 changes from "Good" to "Error" (step S3).
21). When such a change is detected (Y), the corresponding line status of the line management table 172 shown in FIG. 3 is changed from “Good” to “Er” as shown in FIG.
to “ror” (step S322). Then, in this example, the connection management unit 132 is notified that the line 141 has failed (step S323).

FIG. 7 shows the flow of processing for the occurrence of a failure in the connection management unit. When the connection management unit 132 receives a notification of the occurrence of a failure from the line management unit 134 (step S341), if there are a plurality of detour paths in the failed connection, these connection bandwidths are compared. Then, the detour path having many free bands is selected as a detour (step S342). If only one detour path is set, this will be selected. In the present embodiment, by checking the location of the first connection number 241 in the connection management table 171 shown in FIG. 2, the lines 152, 153, 143, 15 of the first bypass path with a large free bandwidth of the bypass path.
4, 155 is selected as a detour. The connection management unit 132 requests the line management unit 134 to acquire the line status of the selected detour path (step S34).
3). Then, after that, the line management unit 134 waits for the result of whether or not the detour is possible (step S344).

Returning to FIG. 6, the description will be continued. Line manager 1
If there is a request from the connection management unit 132 to acquire the line status of the selected detour path (step S324: Y), the line 34 is connected to the line management table 17 shown in FIG.
The line status is acquired from No. 2 and returned to the connection management unit 132 (step S325).

Returning to FIG. 7 again, the description will be continued. The connection management unit 132 uses this result to select the first selected
It is checked whether or not the detour is possible (step S344). If there is a line whose line status is "Error", detouring is not possible. When it is determined that all the line states are “Good” and the detour is possible (Y), the relevant node device is instructed to perform the connection setting for switching to the detour (step S345).
In the case of this example, the first bypass path is set. However, the fourth node device 114 and the fifth node device 115
Are already connected as part of the path of the first detour path. Therefore, first, the first node device 111 is caused to perform connection setting of the lines 152 and 153 instead of the line 141. Next, the third node device 113 is caused to perform connection setting of the lines 155 and 154 instead of the line 142. Of course, these node devices 11
The time before and after the control of the connection setting for Nos. 1 and 113 is not particularly limited.

When the detour path is set, the connection management unit 132 notifies the line management unit 134 of the connection setting change (step S346). Then, after that, when data about the free band is sent from the line management unit 134 (step S347: Y), the free band is changed (step S348), and the process ends (end).

The above is the case where the detour path is set successfully from the result of the line status acquisition. When it is determined that the detour is impossible in step S344 (N), it is determined whether or not the detour is impossible in all the prepared selectable detours (step S349). In the case of this example, the second bypass path still remains. In such a case (N), the next detour path with many free bands is selected (step S350). Then, in step S343, the line management unit 13 acquires the line state of the detour path.
4 will be requested and the same processing will be performed. Step S
If the detours to all the detour paths are not possible at the present time in 349 (Y), the process for the time being ends (END).

By the way, even if one of a plurality of detour paths exists, the detour path can be used if there is no subsequent failure of the line. Of course, if the basic path is restored, it is not necessary to perform such re-routing processing. Here, the line status of the line 143 of the first bypass path is "Error".
In this section, we will explain the processing at the time of line restoration such as re-diversion processing, assuming that the line state is restored to "Good" and it becomes possible to make a detour when it is not possible to switch to this detour path. .

FIG. 8 shows the flow of processing of the node management unit when the line is restored. Node management unit 13
3 monitors the line restoration through the control line 161 shown in FIG. 1 (step S371). Then, for example, when the line 143 of the first detour path is restored (Y), the node management unit 133 causes the node management table 17 shown in FIG.
The port status of the corresponding port number of 3 is changed from "Error" to "Good" (step S372).

FIG. 9 shows the flow of processing of the line management unit when the line is restored. The line management unit 134 monitors that the port status of the node management table 173 changes from "Error" to "Good" (step S3).
91). Then, when such a change is detected (Y), the corresponding line status of the line management table 172 shown in FIG. 3 is changed from "Error" to "Good" (step S392). Then, the connection number of the bypass path is obtained (step S393). In this embodiment, the connection number 241 that sets the first bypass path
Will be obtained. The line management unit 134 then requests the connection management unit 132 to acquire the status of the corresponding connection of the first connection number 241 (step S394).

FIG. 10 shows the flow of processing of the connection management unit when the line is restored. When the connection management unit 132 receives a status acquisition request for the connection with the connection number 241 from the line management unit 134 (step S411: Y), the first connection number 241 in the connection management table 171 is received.
Lines 152, 141, 142 that form the basic path in
It reads 155 and requests the line management unit 134 to acquire these line states (step S412). When the line management unit 134 receives this line state acquisition request (see FIG. 9).
(Step S395: Y), the line management table 172 is checked to check these lines 152, 141, 142, 15
It returns to the connection management unit 132 whether the five-line status is "Error" or "Good" (step S3 in FIG. 9).
96). If the line 141 has not been recovered yet, "Error" will be returned for this line state.

The connection management unit 132 is the line management unit 1.
When this reply is received from 34 (step S41 in FIG. 10).
3: Y), these lines 152, 141, 142, 15
It is determined whether the path can be restored according to step 5 (step S414). In the case of this example, the line state of the line 141 is "Error", and the basic path cannot be restored (N). Therefore the connection manager 1
32 checks the connection management table 171 to determine whether detour is possible (step S41).
5). In this example, detours are possible. Therefore, the lines 152, 153, 143, 154, which form the first detour path,
It reads 155 and requests the line management unit 134 to acquire these line states (step S416). If there is no detour (step S415: N),
At this point, the process ends (end). Although different from this example, the lines 152, 141, and 14 that form the basic path
When there is no abnormality in all of 2, 155 and the recovery is possible (step S414: Y), step S34 of FIG.
The processing will proceed to 5 and thereafter.

In this example, since the line status of the line 141 is "Error", the line management unit 134 is shown in FIG.
As in step S395, the line status acquisition request is received (step 397: Y in FIG. 9). Therefore, the line management unit 13
4 returns the line status of the lines 152, 153, 143, 154, 155 forming the first bypass path in the line management table 172 to the connection management unit 132 (step S399 in FIG. 9). Here, since the line status of the line 143 has been restored and the status has changed from “Error” to “Good”, all the line statuses of the lines 152, 153, 143, 154, 155 are returned as “Good”. Become.

The connection management unit 132 waits for this reply in step S413 of FIG. In the case of this example, the connection management unit 132 uses the lines 152, 153,
All the line statuses of 143, 154 and 155 are "Good"
Therefore, it is judged that restoration is possible (step S41).
4: Y). Therefore, the processing after step S345 in FIG. 7 is started for the detouring by the first detouring path. When the detour path is set in this process, the connection management unit 132 notifies the line management unit 134 of the connection setting change (step S346 in FIG. 7). Therefore, in step S398 shown in FIG. 9, the line management unit 134 receives this setting change and advances the processing to step S327 in FIG.

In the example described above, re-detouring of the first detour path is shown, but detouring may be performed by the second detour path.

Modification

FIG. 11 shows a connection management table in a modification of the present invention. Compared to the connection management table 171 of the embodiment shown in FIG. 2, this connection management table 171A has an item of “switchback mode”, and the column corresponding to the first connection number 241 is “at the time of failure”. It is shown that the "Switchback" mode is currently selected. The "revertive mode" is a mode that determines whether or not to switch back to the basic path after the basic path is restored when the alternative path is switched to in the event of a failure. In the connection bypass system of this modified example, three modes of "no switchback", "switchback after restoration", and "switchback at failure" are defined, and one of these modes can be appropriately selected. It has become.

The "no switching back" mode is a mode that is fixed in a state where the detour path is switched. This mode is selected because it is not necessary to switch back to the basic path when there is no need to substantially distinguish between the basic path and the detour path, as in the case of completely equal transmission bands. . When this "no switchback" mode is selected, the connection is not switched back even when a failure occurs in the bypass path of the bypass destination. Therefore, the connection remains disconnected unless the detour path is restored.

The "switchback after restoration" mode is a mode for switching back to the original basic path when it is restored. In the case where the basic path has a wider transmission band and the inconvenience such as the discarding of ATM cells does not occur, there is a merit of waiting for the recovery of the basic path and switching back to this. In the case of the embodiment, a failure has occurred in the line 141 of the basic path. Therefore, when the “switchback after recovery” mode is set, the connection management unit 132 receives a request for connection switchback from the line management unit 134, and the lines 152, 141, 142, and 155 that form the basic path. After checking the status, if all of them are “Good”, the connection is connected using this basic path.

"Switchback mode" is "Switchback on failure"
When it is in the mode, it is when the urgency of the switchback is less than in the "Switchback after recovery" mode, and it switches back to the original path when a failure occurs in the path after switching. I am trying. For example, in the above-mentioned embodiment, the line 14 is switched after the switching to the first bypass path is performed.
A case where a failure occurs in 3 will be described. When the connection management unit 132 receives the connection switchback request from the line management unit 134, after checking the line states of the lines 152, 141, 142, and 155 that form the basic path, all of them become "Good" (normal). If so, you will use this basic path to connect. The above enables efficient use of the network.

In the embodiment and the modified examples, the basic path (working path) and the detour path (backup path) in the relatively simple network between the first terminal 101 and the second terminal 102.
I explained. In a system in which a network is complicatedly formed between these terminals 101 and 102, one basic path can be considered as a plurality of basic paths routed. In such a case, the present invention can be applied to a detour path for each basic path after division.

[0054]

As described above, claims 1 to 3 are as described above.
According to the invention described in claim 7, a basic path connecting a plurality of node devices located between the first and second terminals transmitting ATM cells and a detour path bypassing the basic path are prepared. Every other time, the detour path is in a state where the line between the node device closest to the first terminal of the basic path and the node device closest to the second terminal is released, and the detour path is The other parts of the configuration were configured such that each node device was connected to the line. Therefore, when a failure occurs in the basic path, the path switching means causes the node device closest to the first terminal and the second node device
It is possible to switch to the route on the detour path side simply by connecting the line with the node device closest to the terminal, and it is possible not only to switch to the detour path quickly but also to route to the detour path. Since it is fixed and the band for that can be secured, the reliability can be improved.

According to the second aspect of the present invention, when the failure of the basic path is recovered by the basic path failure recovery detecting means, this is detected, and after the path switching means switches to the communication path by the bypass path. When the recovery of the failure of the basic path is detected by the basic path failure recovery detection means, the node device closest to the first terminal and the side closest to the second terminal are recovered by the basic path restoration switchback means. Disconnect the line between the node device and the bypass path,
Instead, by connecting the lines on the basic path side in these node devices, it was decided to switch back to the communication path by the basic path between the first and second terminals. It is possible to switch back to the basic path, and when the basic path has a wider transmission band, it is possible to restart signal transmission in a better transmission state.

Further, according to the third aspect of the invention, when the alternative path failure detecting means detects the failure of the alternative path and the basic path failure recovery presence / absence determining means determines that the failure of the basic path has been recovered, Since it is decided to switch back to the communication path based on the basic path by the switchback means at the time of path restoration, the reliability of the transmission path of the ATM cell can be secured by sequentially switching the paths.

According to the fourth aspect of the invention, by providing a plurality of detour paths, it is possible to further improve reliability as compared with switching between the basic path and one detour path.

Further, according to the invention of claim 5, when a plurality of detour paths are provided, the empty band comparison means compares these empty bands, and from the comparison result, the detour path having the largest empty band is detoured in order. Since the route is selected, the transmission condition of the ATM cell on the detour path of the switching destination can be improved.

According to the sixth aspect of the present invention, when comparing the sizes of the available free bands of the detour path, the free band comparison means determines the band actually used in the detour path from the total band. Since I decided to compare the deducted free bandwidth, actively select a detour path where the bandwidth used on the line is actually small and the free bandwidth is high even if there is almost no free bandwidth. Therefore, it is possible to improve the transmission condition of the ATM cell on the detour path of the switching destination.

Further, according to the invention described in claim 7, whether or not to return to the basic path again after switching to the detour path by the path switching means, and failure of the basic path when returning to the basic path Since the connection bypass system is equipped with a recovery selection means that allows the user to arbitrarily select whether the switch is to be restored or a failure occurs in the bypass path of the switching destination, the connection bypass system is equipped with a switchback presence / absence and a switchback depending on various circumstances. It becomes possible to freely select the timing.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing a configuration of a connection bypass system in an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a connection management table used for management by a connection management unit in the present embodiment.

FIG. 3 is an explanatory diagram showing a line management table managed by a line management unit in the present embodiment.

FIG. 4 is an explanatory diagram showing a part of the contents of a node management table managed by a node management unit in this embodiment.

FIG. 5 is a flow chart showing a flow of processing when a failure occurs in the node management unit in the present embodiment.

FIG. 6 is a flowchart showing a flow of processing for occurrence of a failure in the line management unit in the present embodiment.

FIG. 7 is a flowchart showing a processing flow for occurrence of a failure of the connection management unit in the present embodiment.

FIG. 8 is a flow chart showing the flow of processing of the node management unit at the time of line restoration in the present embodiment.

FIG. 9 is a flow chart showing the flow of processing of the line management unit at the time of line restoration in the present embodiment.

FIG. 10 is a flowchart showing a processing flow of a connection management unit at the time of line restoration in the present embodiment.

FIG. 11 is an explanatory diagram showing a connection management table in a modified example of the present invention.

[Explanation of symbols]

101 first terminal 102 second terminal 111 First Node Device 112 Second Node Device 113 Third Node Device 114 Fourth Node Device 115 Fifth Node Device 116 Sixth Node Device 117 Seventh Node Device 131 Network management device 132 Connection management unit 133 node management unit 134 Line Management Department 141-144, 152-157 lines 161 control line 171, 171A Connection management table 172 Line management table 173 node management table

Continuation of the front page (56) Reference JP 62-242441 (JP, A) JP 11-355310 (JP, A) JP 2000-59374 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 12/28

Claims (7)

(57) [Claims] 1. A basic path connecting a plurality of node devices located between first and second terminals for transmitting ATM cells, a node device closest to the first terminal on the basic path, and Each node device closest to the second terminal is used as a starting point or an end point, two or more detour node devices are arranged in addition to these node devices, and only the line between these detour node devices is connected in advance, Between the node device closest to the first terminal and the bypass node device and between the node device closest to the second terminal and the bypass node device, the first and second terminals are connected by a basic path. A detour path that is released in a connected state, a node device that is closest to the first terminal when a failure occurs in the basic path, and a node device that is closest to the second terminal Of the path A connection bypass, comprising: route switching means for switching one of the node devices at both ends to which the line is connected by a line to switch between the first and second terminals to a communication route by a bypass path. system. 2. A basic path connecting a plurality of node devices located between a first terminal and a second terminal for transmitting an ATM cell; a node device closest to the first terminal on the basic path; Each node device closest to the second terminal is used as a starting point or an end point, two or more detour node devices are arranged in addition to these node devices, and only the line between these detour node devices is connected in advance, Between the node device closest to the first terminal and the bypass node device and between the node device closest to the second terminal and the bypass node device, the first and second terminals are connected by a basic path. A detour path that is released in a connected state, a node device that is closest to the first terminal when a failure occurs in the basic path, and a node device that is closest to the second terminal Of the path Route switching means for switching one of the node devices at both ends to which a line is connected by a line and switching between the first and second terminals to a communication route by a bypass path, and when the failure of the basic path is restored A primary path failure recovery detection means for detecting a failure of the basic path after switching to the communication path by the bypass path by the path switching means, and the recovery of the failure of the basic path by the basic path failure recovery detection means, 1
By disconnecting the line between the node device closest to the second terminal and the node device closest to the second terminal and the bypass path, the lines on the basic path side of these node devices are connected instead. A connection detouring system, comprising: a switching-back means for switching back between the first and second terminals to a communication path by a basic path when the basic path is restored. 3. A basic path connecting a plurality of node devices located between first and second terminals transmitting ATM cells, a node device closest to the first terminal on the basic path, and Each node device closest to the second terminal is used as a starting point or an end point, two or more detour node devices are arranged in addition to these node devices, and only the line between these detour node devices is connected in advance, Between the node device closest to the first terminal and the bypass node device and between the node device closest to the second terminal and the bypass node device, the first and second terminals are connected by a basic path. A detour path that is released in a connected state, a node device that is closest to the first terminal when a failure occurs in the basic path, and a node device that is closest to the second terminal Of the path Route switching means for connecting one of the node devices at both ends to which the line is connected by a line and switching between the first and second terminals to a communication path by a bypass path, and a bypass path for detecting a failure of the bypass path After the failure detection means and the path switching means have switched to the communication path by the bypass path, when the failure of the bypass path is detected by the bypass path failure detection means, it is determined whether or not the failure of the basic path is recovered. Basic path failure recovery presence / absence determining means, and when the basic path failure recovery presence / absence determining means determines that the failure of the basic path has been restored, the node device closest to the first terminal and the second terminal By disconnecting the line between the node device on the closest side and the detour path and connecting the line on the basic path side in these node devices instead, the basic line between the first and second terminals is established. Connection bypass system characterized by comprising a return means base path recovery during cutting switched back to the communication path by the scan. 4. The plurality of detour paths are provided between a node device closest to the first terminal and a node device closest to the second terminal.
The connection bypass system according to claim 3. 5. A free band comparing means for comparing the sizes of transmittable free bands of the respective bypass paths, and a bypass path is selected in order from the bypass path having the largest free band from the comparison result by the free band comparing means. 5. A detour path selecting means for performing the following.
Connection bypass system described. 6. The free band comparison means, when comparing the sizes of the free bands that can be transmitted by the bypass paths, subtracts the band obtained by subtracting the total band reserved for use from each path from the total band that can be transmitted. 6. The connection detour system according to claim 5, wherein instead of comparing, a free band obtained by subtracting a band actually used in the detour path from a total band is compared. 7. A basic path connecting a plurality of node devices located between first and second terminals transmitting ATM cells, a node device closest to the first terminal on the basic path, and Each node device closest to the second terminal is used as a starting point or an end point, two or more detour node devices are arranged in addition to these node devices, and only the line between these detour node devices is connected in advance, Between the node device closest to the first terminal and the bypass node device and between the node device closest to the second terminal and the bypass node device, the first and second terminals are connected by a basic path. A detour path that is released in a connected state, a node device that is closest to the first terminal when a failure occurs in the basic path, and a node device that is closest to the second terminal Of the path A path switching unit that connects each of the node devices at both ends to which the line is connected by a line and switches the communication path between the first and second terminals to a communication path by a bypass path, and the path switching unit switches to the bypass path. After the operation is performed, whether to return to the basic path again, and when returning to the basic path, it is possible to arbitrarily select whether to return to the time when the failure of the basic path is restored or when the failure of the bypass path of the switching destination occurs. A connection detour system, comprising: return selection means for enabling the recovery.