JPH1188235A - Route switching method, node and network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of cancellation of data in spite of switching a route by switching a first node from a first route to a second route when an idle time from the transmission of data to the first route to the generation of next data desired to transmit becomes over a prescribed transferring time at the time of switching a route. SOLUTION: Information that the fault of a repeating line 4 is restored, e.g. each CPU of terminal housed exchangers 300 and 400 refers to the data transferring longest time of a detour connection from a data transferring longest time table to which a longest time required for transferring data is previously set for each connection. When the passing time of a lapse timer after the detour data transmission amounts to the data transferring longest time, as data transmitted just before is already received by the terminal housed exchangers 300 and 400 on a receiving side, CPU on a transmission side transmits by switching to a normal connection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a route switching method, a node, and a network system.
The present invention can be applied to a frame relay switching network, an ATM switching network, and the like.

[0002]

2. Description of the Related Art Conventionally, in a network, a connection (hereinafter, referred to as a connection) normally set for exchanging data.
If a failure occurs in the trunk line or the exchange on the regular connection) and data cannot be exchanged in the regular connection, another connection to be bypassed (hereinafter, referred to as a bypass connection) is selected and set. Data is exchanged by the bypass connection.

Here, when the above-mentioned fault is recovered, it is necessary to switch from the alternate connection to the regular connection. The operator selects a time that is less, and the operator forcibly switches by command operation.

[0004]

However, in the related art, when the switching process is performed by using the failure recovery as a trigger, if data being transmitted and received remains on the bypass connection, the bypass connection is established by the switching process. There is a problem that the data is discarded because it is disconnected.

[0005] Further, even when the operator forcibly switches by command operation during a time when traffic is small, there is a possibility that the operator may compete with the start of data transmission / reception at the time of command operation, and in this case, data is similarly discarded. There was a problem that would be done.

In the above description of the problem, switching between the detour connection and the regular connection has been described.
Of course, the same problem generally occurs when switching from one connection to another connection.

In the above description of the problem, the connection between the exchanges has been described. However, the same problem also exists in route switching between general nodes and in a network system including nodes.

Therefore, there has been a demand for a route switching method, a node, and a network system that do not cause data discarding even when switching from one route to another route.

[0009]

According to a first aspect of the present invention, there is provided a method for communicating data continuously or intermittently from a first node to a second node via a first route. From the state where the
In the route switching method for switching data to a state in which data is continuously or intermittently communicated via the route, when the above-mentioned route switching factor occurs, the first node is switched to the first node.
When the vacant time from the transmission of data to the first route to the occurrence of the next data to be transmitted is longer than the transfer time between the first and second nodes via the first route In addition, switching from the first route to the second route is performed.

[0010] According to a second aspect of the present invention, when data is continuously or intermittently communicated to the opposing node via the first route, data is transmitted via the second route due to the occurrence of a route switching factor. A node that switches to a state of communicating continuously or intermittently: (1) route switching factor detection means for detecting the occurrence of the route switching factor; and (2) after transmitting data to the first route, A clock for measuring the idle time until the next data to be transmitted is generated; and (3) the time counted by the clock when the occurrence of a route switching factor is detected by the route switching factor detecting means is set to the first route. Over the transfer time to the opposing node when passing through
Route switching control means for switching from the first route to the second route.

According to a third aspect of the present invention, a state in which communication is performed from a first node to a second node via a first route,
In the route switching method for switching to a state of communicating via the second route by the occurrence of the route switching factor, when the route switching factor occurs, the first node transmits the last data to the first route. After waiting for the time required for the last data to reach the second node, switching from the first route to the second route is performed.

According to a fourth aspect of the present invention, there is provided a node which switches from a state of communicating with an opposing node via a first route to a state of communicating via a second route due to occurrence of a route switching factor. 1) route switching factor detecting means for detecting occurrence of the route switching factor;
(2) a clock for measuring the time since the last output of data to the first route, and (3) the first route from the time when the occurrence of a route switching factor is detected by the route switching factor detecting means. Route switching control means for switching from the first route to the second route when the time measured by the clock elapses more than the time required for the last data transmitted to the other route to reach the opposing node. And characterized in that:

A fifth aspect of the present invention is characterized in that a network system having a plurality of nodes includes the nodes according to the second and / or fourth aspects as all or some of the nodes.

As described above, according to each of the first to fifth aspects of the present invention, data does not remain on the first route at the time of switching, and data can be prevented from being discarded. At the opposing node, the data arriving from the second route does not arrive earlier than the data arriving from the first route, and it is possible to prevent the data arrival order from being reversed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings.

In this embodiment, as shown in FIG. 2, terminals 100 and 200 and terminal accommodation exchanges 300 and 40
0, and the exchanges 500, 600, 700 and 800. Between the terminal 100 and the terminal accommodation exchange 300 and between the terminal 200 and the terminal accommodation exchange 400,
Connected by terminal lines 1 and 2. The terminal exchange 300, the relay exchange 500, the intermediate exchange 600 and the terminal exchange 400, and the terminal exchange 300
And the trunk exchange 700, the trunk exchange 800, and the terminal accommodation exchange 400, respectively.
Connected by 7 and 8.

The terminals 100 and 200 are terminals that exchange data with each other.

The terminal exchange 30 according to this embodiment
Reference numerals 0 and 400 perform exchange control processing between the terminal line 1 and the trunk line 3 or 6, and between the terminal line 2 and the trunk line 5 or 8. Further, the terminal accommodation exchanges 300 and 400 have the same configuration, respectively. Therefore, the detailed configuration of the terminal accommodation exchange 300 will be described below.

As shown in FIG.
Corresponds to a trunk line having an exchange processing unit 310, a central processing unit 320, a data transmission circuit 331, a data reception circuit 332, a failure detection circuit 333, a normal data detection circuit 334, and a data detection circuit 335 for communication between exchanges. Unit 330, a relay line corresponding unit 340 having the same configuration as the relay line corresponding unit 330,
51 corresponding to the terminal line corresponding section 350.
The trunk line correspondence unit 330 is connected to the trunk line 3, the trunk line correspondence unit 340 is connected to the trunk line 6, and the terminal line correspondence unit 350 is connected to the terminal line 1.

The exchange processing unit 310 performs a connection exchange process between the terminal line 1 and the trunk line 3 or 6.

The trunk line corresponding units 330 and 340 control data communication of the trunk lines 3 and 6. The trunk line corresponding units 330 and 340 have the same configuration, and the detailed configuration of the trunk line corresponding unit 330 will be described below. The data transmission circuit 331 in the trunk line correspondence unit 330 receives the data output from the switching unit 310 and transmits the data to the trunk line 3.

The data receiving circuit 332 receives data arriving from the trunk line 3 and exchanges the data.
Output to 0.

The fault detection circuit 333 detects a fault in the trunk line 3. The failure detection circuit 333 sets the data dedicated to failure detection in the data transmission circuit 331, and transmits the data via the trunk line 3 to the trunk exchange 500.
And the response data to the failure detection data transmitted from the transit exchange 500 to the data receiving circuit 332.
, It is confirmed that no fault has occurred in the trunk line 3, and if this response data is not received, a fault in the trunk line 3 is detected. Further, the failure detection circuit 33
When the data receiving circuit 332 receives the failure detection data output from the transit exchange 500, the data transmission circuit 331 sets the response data corresponding to the failure detection data in the data transmission circuit 331, so that the response data is transmitted to the transit exchange 500. Send. Further, even after the failure is detected, the dedicated data for failure detection is periodically output, and it is confirmed whether or not the response data is received, thereby detecting that the failure has been recovered if received.

The normal data detecting circuit 334 detects whether the data received by the data receiving circuit 332 is normal. For example, it detects whether the format or value of the received data is normal, whether the order is correct by comparing with the previous data, whether there is any omission, and the like.

The data detection circuit 335 for communication between exchanges
If the data received by the data receiving circuit 332 is data for communication between exchanges, the data is detected.
For example, information such as failure occurrence and failure recovery is exchanged between the exchanges by the communication between the exchanges. The above is the description of the trunk line corresponding unit 330. The same applies to the trunk line corresponding unit 340.

The terminal line corresponding section 350 controls data communication of the terminal line 1. The post-detour data transmission elapsed timer 351 in the terminal line correspondence unit 350 measures an idle time after transmitting data on the detour route. That is, the vacant time from when data is transmitted to when data to be transmitted next is generated is measured.

The central processing unit 320 is a terminal accommodation exchange 3
All controls in 00 are performed.

The configuration of the terminal exchange 300 has been described above. The same applies to the terminal accommodation exchange 400.

The relay exchanges 500, 600, 700
And 800 are between trunk lines 3, 4 and 5 and trunk line 6,
An exchange control process between 7 and 8 is performed. Furthermore, transit exchanges 500, 600, 700, and 800 have the same configuration, respectively. Therefore, the detailed configuration of transit exchange 500 will be described below.

As shown in FIG. 3, the transit exchange 500
An exchange processing unit 510, a central processing unit 520, a relay line corresponding unit 530 having a data transmission circuit 531, a data reception circuit 532, a failure detection circuit 533, and an inter-switch communication data detection circuit 534; 530
And a trunk line corresponding unit 540 having the same configuration as the above. The trunk line correspondence unit 530 is connected to the trunk line 3, and the trunk line correspondence unit 540 is connected to the trunk line 4.

The switching processing unit 510 performs a process of exchanging a connection between the trunk line 3 and the trunk line 4.

The trunk line corresponding units 530 and 540 control data communication of the trunk lines 3 and 4. The trunk line corresponding units 530 and 540 have the same configuration, and the detailed configuration of the trunk line corresponding unit 530 will be described below. The data transmission circuit 531 in the trunk line handling unit 530 receives the data output from the switching processing unit 510, and transmits the data to the trunk line 3.

The data receiving circuit 532 receives the data arriving from the trunk line 3 and exchanges the data.
Output to 0.

The fault detecting circuit 533 detects a fault in the trunk line 3. The failure detection circuit 533 sets the data dedicated to the failure detection in the data transmission circuit 531 so that the data is transmitted to the terminal accommodation exchange 3 via the trunk line 3.
00, and responds to the failure detection data transmitted from the trunk exchange 300 with the data reception circuit 5
32, it is confirmed that no failure has occurred in the trunk line 3, and if this response data is not received, a failure in the trunk line 3 is detected. Further, when the failure detection circuit 533 receives the failure detection data output from the terminal exchange 300 into the data reception circuit 532, the failure detection circuit 533 sets response data for the failure detection data in the data transmission circuit 531. Exchange 300
And sends the response data. Further, even after the failure is detected, the dedicated data for failure detection is periodically output, and it is confirmed whether or not the response data is received, thereby detecting that the failure has been recovered if received.

The inter-switch communication data detection circuit 534
When the data received by the data receiving circuit 532 is data for communication between exchanges, the data is detected. For example, information such as failure occurrence and failure recovery is exchanged between the exchanges by the communication between the exchanges. The above is the description of the detailed configuration of the trunk line corresponding unit 530. The same applies to the trunk line corresponding unit 540.

The central processing unit 520 is connected to the transit exchange 500
Do all the controls in.

The above is the description of the configuration of the transit exchange 500. The same applies to the transit exchanges 600, 700 and 800.

Next, in the operation of this embodiment, switching from the regular connection to the alternate connection is performed because a failure has occurred in the trunk line, and thereafter, the failure is recovered and switching from the alternate connection to the regular connection is performed. This will be described with reference to FIGS.

In FIG. 2, communication is performed between terminal 100 and terminal 200, and 100 to 300 to 500 to 600 to 400 to 2
00 is set. Here, when a failure occurs in the trunk line 4, the failure detection circuit of each of the trunk exchanges 500 and 600 detects that the failure of the trunk line 4 has occurred, and notifies the respective central processing units of the failure. You. Furthermore, if a connection is set up on the trunk line in which the fault has occurred, each central processing unit notifies the terminal accommodation exchange that has set up the connection that communication is not possible due to the fault through inter-switch communication. Is done. Therefore, in this case, the terminal accommodation exchanges 300 and 400 are notified that the communication of the connection between the terminals 100 and 200 cannot be performed.

In the terminal exchanges 300 and 400, when a notification that a fault has occurred in the trunk line 4 is detected by the inter-switch communication data detection circuit, the respective central processing units are notified thereof. Furthermore, in each central processing unit, by instructing a detour circuit control unit (not shown) to set detour connections from 100 to 300 to 700 to 800 to 400 to 200, switching from a regular connection to a detour connection is performed. Done.

Thereafter, when the trunk line 4 is restored, the restoration is detected by the respective failure detection circuits of the trunk exchanges 500 and 600, and the respective central processing units are notified of the restoration. Further, in each of the central processing units, when a failure occurs in the trunk line 4, the terminal accommodation exchanges 300 and 400, which have set up the connection, are notified by the inter-exchange communication that the failure in the trunk line 4 has been recovered.

In each of the terminal accommodating exchanges 300 and 400, when the notification that the failure of the trunk line 4 has been recovered is detected by the respective inter-exchange communication data detection circuits, the respective central processing units are notified of that. You.

In this embodiment, when the central processing units of the terminal exchanges 300 and 400 are informed that the failure of the trunk line 4 has been recovered, the maximum necessary for transferring the data is returned. The maximum data transfer time (hereinafter, referred to as Tmax) of the detour connection is referred to from a data transfer maximum time table portion (not shown) in which the time is preset for each connection. Note that Tmax may be set differently for each connection as described above, but may be common for all connections.

Furthermore, at this time, the central processing unit in the terminal-side exchange 300 or 400 on the transmitting side in the communication of the detour connection checks whether or not the time counted by the elapsed timer after transmission of the detour data has reached Tmax.

Here, if the time counted by the elapsed timer after the detour data transmission has reached Tmax, that is, the vacant time from the last transmission of data by the transmitting terminal exchange 300 or 400 is equal to or greater than Tmax. In the case of, the data transmitted most recently to the terminal-side exchange 400 or 300 on the receiving side has already been received, and there is no problem even if the connection is switched. The connection is switched to the regular connection and transmitted.

If the next data transmission is performed before the time elapsed by the timer after the bypass data transmission reaches Tmax, the time measured by the bypass data transmission elapsed timer is cleared immediately after the data transmission. It will be timed again from the beginning. That is, the next data transmission interval is T
If the value is less than max, the time is cleared and the time is restarted each time. During this time, communication is performed by the bypass connection.

From the above results, even if recovery from the failure is detected, communication is performed on the detour connection until the interval between data transmitted from the exchange 300 or 400 on the transmitting side to the detour connection becomes equal to or greater than Tmax. When the data interval reaches Tmax, the connection is switched from the bypass connection to the regular connection, and the subsequent communication is performed using the regular connection.

On the other hand, the receiving-side terminal exchange 400 or 300 on the receiving side exchanges the terminal-containing exchange 300 or 400 on the transmitting side.
Is switched from the bypass connection to the regular connection and transmitted, so that the signal is forcibly received by the regular connection. At this time, by confirming that the data received from the normal connection is normal data by the normal data detection circuit, no data remains in the detour connection, and no reverse of the data arrival order has occurred. You can also confirm that.

As described above, according to the one embodiment,
Rather than switching connections immediately after failure recovery is detected, the interval between data sent by the sending exchange to the alternate connection must be the maximum required to reach the receiving exchange via the alternate connection. If it is longer than the time, the connection is switched from the detour connection to the regular connection, so that no data remains on the detour connection at the time of switching, and data can be prevented from being discarded. The data arriving from the connection does not arrive earlier than the data arriving from the detour connection, and it is possible to prevent the data arrival order from being reversed.

Further, according to the above-described embodiment, in the case of communication in which burst transmission and transmission stop are repeated, such as a moving image transmitted in units of frames, reception of burst data is not interrupted by switching. It is possible to switch from the detour connection to the regular connection.

In the above-described embodiment, the case where the present invention is applied to switching from a detour connection to a regular connection has been described. However, it is needless to say that, in general, the same applies to a case where a certain connection is switched to another connection.

In the above embodiment, the case where the present invention is applied to connection switching between exchanges has been described. However, the present invention can be similarly applied to route switching between general nodes and in a network system including nodes.

In the above embodiment, the interval between data transmitted from the transmitting-side exchange to the bypass connection is as follows:
Switching from the detour connection to the regular connection when the time is longer than the maximum time required to arrive at the receiving exchange via the detour connection has been described. As soon as it is detected, the sending exchange forcibly stops the data sent to the bypass connection, and the maximum time required for the last data transmitted before the shutdown to reach the receiving exchange via the bypass connection. After waiting as described above, the detour connection may be switched to the regular connection and the next data may be transmitted.

Further, in the above-described embodiment, a case has been described in which data dedicated to failure detection is transmitted in the detection of a failure or recovery of a line. However, like a line using a modem, a signal such as a CD (carrier detection) is transmitted. The failure may be detected at the level.

[0055]

As described above, according to the present invention, no data remains on the first route at the time of switching, so that data discarding can be prevented. Data arriving from the second route does not arrive earlier than data arriving from the first route, and it is possible to prevent the data arrival order from being reversed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a detailed configuration of a terminal accommodating exchange 300 according to an embodiment.

FIG. 2 is a block diagram showing a configuration of the embodiment.

FIG. 3 is a block diagram showing a detailed configuration of a transit exchange 500 according to the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Terminal line, 3, 6 ... Relay line, 310 ... Exchange processing part, 320 ... Central processing unit, 330, 340 ... Relay line corresponding part, 350 ... Terminal line corresponding part, 331 ... Data transmission circuit, 332 ... Data reception Circuits 333: Failure detection circuit, 334: Normal data detection circuit, 335: Inter-switch communication data detection circuit, 351: Detour data elapsed timer.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04M 3/22 H04L 11/08 H04Q 9/00 311 11/20 C

Claims (5)

[Claims] 1. A state in which data is continuously or intermittently communicated from a first node to a second node via a first route, the data being transmitted via a second route due to the occurrence of a route switching factor. In the route switching method for switching to a state in which communication is performed continuously or intermittently, when the above-mentioned route switching factor occurs, the first node transmits data to the first route and then transmits the next data to be transmitted. Switching from the first route to the second route when the idle time until data is generated is equal to or longer than the transfer time between the first and second nodes when the data passes through the first route. A route switching method characterized by the following. 2. From a state where data is continuously or intermittently communicated to an opposing node via a first route, data is continuously or intermittently transmitted via a second route due to the occurrence of a route switching factor. A node for switching to a state in which communication is performed in the first route, a route switching factor detecting means for detecting the occurrence of the route switching factor, and a process for transmitting data to the first route until the next data to be transmitted is generated. The clock for measuring the idle time and the occurrence of the route switching factor are detected by the route switching factor detecting means, and the time measured by the clock elapses more than the transfer time to the opposing node when passing through the first route. Route switching control means for switching from the first route to the second route when the first route is performed. Node. 3. A route switching system for switching from a state in which communication is performed from a first node to a second node via a first route to a state in which communication is performed via a second route due to occurrence of a route switching factor. In the above, when the route switching factor occurs, after the first node transmits the last data to the first route and waits for the time required for the last data to reach the second node, Switching from a first route to a second route. 4. A node that switches from a state of communicating with an opposing node via a first route to a state of communicating via a second route due to the occurrence of a route switching factor. , A clock for measuring the time since the last output of data to the first route, and a time when the occurrence of the route switching factor is detected by the route switching factor detecting means. Switching from the first route to the second route when the time measured by the clock elapses more than the time required for the last data transmitted to the first route to reach the opposing node. A node having route switching control means. 5. A network system having a plurality of nodes, wherein the network system according to claim 2 or 4 is included as all or a part of the nodes.