JP3507709B2 - Control method of ring network 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 control method for a ring network system in which a transmission line has a ring configuration, and more particularly to a control method for a simultaneous recovery event of ring switching performed when an external control or a failure occurs. .

[0002]

2. Description of the Related Art A plurality of nodes are connected to two fibers or four nodes.
The ring network system connected by the fiber line has a ring switching function for controlling the continuation of communication by switching the transmission path of the communication path set between the nodes. In such a ring network system, in addition to automatically switching the ring when a failure is detected, the ring network system has a control function capable of forcibly switching the ring according to an instruction from an external control device or the like.

This ring switching function is described in ITU-T Recommendation G.264. 841 (07/95), and in the ring switching based on the above recommendation, the node that initiates the switching performs ring switching with respect to another node that requires a switching operation to perform the ring switching. In order to do so, a K byte request signal using K bytes of the SDH frame is transmitted to each node, and other nodes switch communication paths based on this control signal.

Further, according to the above-mentioned recommendation, when the fault is released or by the operation of returning the communication path switched from the external control device to the original state, the ring-switched communication path is returned to the original state and the switchback control is performed. Is also regulated. When performing ring switching back, as in the case of ring switching, the node that initiates the switching back sends a K-byte request signal, and each node that receives this K-byte request signal switches the communication path. It can be returned to the normal state (normal state).

In such a ring configuration network,
A failure may occur in multiple transmission sections (segments) at the same time. In this case, each node that has detected a failure transmits a K-byte request signal to switch the communication path of each node. Here, in the prescribed ring switching function, in accordance with the K-byte request signal, from the network control state in which the ring switching control is being executed for two or more segments that are not adjacent to each other, all switching nodes are in the other segments. Before recognizing the start of the ring switching switchback control by the K-byte control signal (defined in the above-mentioned recommendation), each starts the ring switching switchback control of its own node. Therefore, when the ring network is controlled in the normal state, the entire ring network is in the pass-through state, and it takes time to complete the control.

[0006]

As described above, in the conventional ring network system, the ring switching cancellation control is performed simultaneously from the state of the network that executes the ring switching control in at least two or more and non-adjacent segments. If ITU-T Recommendation G. 841 (07
/ 95), each node performing the cancellation process must perform the process for the switching factor of the other section recognized by the K-byte control signal. At this time, even though all switching factors are canceled in the network, each node executes processing for switching factors that do not exist, and it takes time to control the network to the normal state. .

The present invention solves the above problems, and controls the simultaneous recovery event of the ring network system so as to promptly return the network to the normal state without causing misconnection of traffic (misconnect). The purpose is to provide a method.

[0008]

In order to achieve the above object, the present invention provides a switching control in which a plurality of nodes are connected to each other in a ring shape via a plurality of transmission paths and the switching state in each node is changed. Is applied to a ring network system capable of switching the transmission path of the set communication path to a different transmission path and performing ring switching to continue communication, and the node that initiates the ring switching performs ring switching. A ring switching request signal for transmitting, and another node performs switching control for changing the switching state in the node according to the ring switching request signal, thereby providing a ring network system control method for performing ring switching, Switch the switching state of each node on the ring network in multiple sections. Simultaneous recovery that detects the occurrence of a simultaneous recovery event that tries to recover the ring switching of the plurality of sections at the same time as the control when returning from the state where the ring switching is performed to the normal state where the ring switching is not performed Event detection step, switching state initialization step that resets the switching state of its own node to the initial state when the occurrence of simultaneous recovery event is detected in this step, and resetting the switching state to the initial state for other nodes And a switchback request signal transmitting step for transmitting a switchback request signal for requesting.

Here, the ring switching is a process of switching the transmission path to a route that avoids a section designated by an operation from an external control device connected to each node, or the node detects a failure of the transmission path. It is conceivable that this is a process of switching the transmission path to a route that avoids the faulty section.

The ring switching request signal is ITU
-T Recommendation G. S based on the regulations of 841 (07/95)
It may be a switching request signal transmitted using the K byte signal of the DH frame.

Further, as a concrete example, the simultaneous recovery event detecting step includes a plurality of steps when a ring switching request signal addressed to the own node is received after a request signal for switching back the ring switching is transmitted. There is a method of determining that the simultaneous recovery event of the ring switching has occurred.

An example of the switching control performed by each node in response to the ring switching request signal is that the route in the direction of transmission from the node is based on the active route and the ring switching which have been performed until now. Bridge control is used to connect to both the spare route and the route to be the new transmission route, and the route in the direction received by the node is separated from the working route that had been transmitting until now, and ring switching is performed. The switch control may be performed so as to switch and connect to the backup system route of the route that becomes the new transmission route.

[0013] When the ring network is returned to the normal state from the state where the ring switching is performed in a plurality of sections, the switching back request signal transmitting step in the switching node that is switching among the plurality of nodes, The switching state of the node concerned is returned to the bridge state by canceling the switch control, the step of sending a request signal for requesting another node to return the switching state to the bridge state, and all other After confirming that the node is in the bridge state, the steps of releasing the bridge control and returning the switching state of the switching node to the initial state and returning the switching state to the initial state for other nodes are performed. And a step of transmitting a request signal for requesting.

Further, it is conceivable that the ring-shaped transmission path connecting the plurality of nodes is composed of a working system line and a protection system line, respectively. In this case, the ring network system may be a ring network system that transmits part-time traffic by using the vacant channel of the protection line.

Furthermore, in the case of transmitting part-time traffic, switching among the plurality of nodes is performed when the ring network is returned to the normal state from the state in which the ring switching has occurred in a plurality of sections. The switching back request signal transmission step at the switching node that is in progress requires the step of releasing the switching state of the node to the bridge state by canceling the switch control, and requesting the other nodes to return the switching state to the bridge state. Sending a request signal to confirm that all other nodes have entered the bridge state, and then releasing the bridge control from the switching state of the switching node to the initial state; Send a request signal requesting that the switching state be returned to the initial state. Steps and may be provided with a step of connecting temporarily again the part-time traffic that has been dropped.

By the control as described above, when a simultaneous recovery event switching factor in which a plurality of ring switches are switched back simultaneously occurs in the ring network, the node which judges this causes a transition to the idle state, so In addition, it is possible to appropriately and appropriately control the control state of the network to a state in which ring switching is not performed, and it is possible to prevent erroneous connection of communication paths.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows the configuration of a ring network system to which the control method according to the present invention is applied.

In this system, nodes A, B, C,
Four fibers (hereinafter referred to as four fibers) are formed between the D, E, and F sections, which are CW (clockwise) and CCW (counterclockwise) service traffic fibers and CW and CCW protection fibers. ), The whole is connected in a ring shape.
Here, the service traffic cable and the protection cable do not necessarily have to be separate fibers, and the same cable can be used to connect each node with two cables (hereinafter referred to as “two fibers”). May be used separately.

Here, between A and B, between B and C, and between C and D
The segment A, the segment D-E, the segment EF, and the segment F-A are referred to as segments A, B, C, D, E, and F, respectively. Here, the service traffic fiber and the protection fiber are high-speed lines for time-division-multiplexed digital signal transmission each having a frame structure standardized by SDH, such as STM-16 standardized by SDH. It is configured.

Further, each node has a low-speed side line (for example, S standardized by SDH) that is slower than the service traffic fiber and the protection fiber.
TM-1) is connected.

In the ring network system having such a configuration, in a state where failure detection and switching by an external command are not performed at all (hereinafter referred to as a normal state), the transmission signal between the nodes passes through the service traffic fiber. Is transmitted. Each node constantly monitors the transmission status of both the service traffic fiber and the protection fiber. If a failure occurs in the service traffic transmission system of a certain segment, the transmission path between the segments is switched to the protection fiber and communication is continued (span switching). Of course, this span switching can be forcibly switched by an external command from a control device (not shown) or the like.

On the other hand, when a failure occurs in both the service traffic fiber and the protection fiber in a certain segment, the transmission path is switched to the protection fiber of the transmission path different from the existing communication path to continue the transmission. It is designed to switch the ring. Similar to the span switching, this ring switching can be forcibly switched by an external command from a control device (not shown) or the like.

In the ring network system having the above configuration, the control method according to the present invention will be described below with reference to FIGS. 2 to 9. FIG. 2 shows that, in the ring network system having the above-described configuration, FS-R (Forced Switch Ring) switching is performed in two sections, segment C and segment F, by the control method according to the present invention. R switching request is canceled at the same time (F
S-R Release), the sequence until the network is controlled to the normal state.

As shown in FIG. 2, the control signal indicating the content of the request output for switching the ring exchanged between the nodes is the section overhead (SO) of the SDH frame.
H), the K-byte request signal (IT) transmitted using the 8-bit K1 byte and K2 byte, respectively.
UT Recommendation G. It is realized by 841 (07/95).

Here, as shown in FIGS. 3 to 5, the K-byte request signal is a 1st to 4th bit of the K1 byte, and a switching request to another node (Forced Switch Ring: Ring forced switching request, Reverse). Request Ring: Response to a ring switching request (hereinafter referred to as "ring switching response"),
No Request: No request), and the request destination is represented by the 5th to 8th bits. Further, the first to fourth bits of the K2 byte are the request source, and the fifth bit is the direction for the switching section (failure section) (Short: direction for directly transmitting the switching section (hereinafter referred to as Short direction)), Long: switching. Direction of transmission via a section other than the section (hereinafter referred to as the Long direction)),
6th to 8th bits are the switch state of the requesting node (Bridge: state where the sender is connected to both service and protection, Switch: state where the receiver is switched from service to protection, Idle: Bridge control When
It represents a state in which Switch control is not performed).

In FIGS. 3 to 5, as an example of actual transmission using K bytes, No Request is “0000”, Short is “1”, Long is “0”,
Bridge & Switch is "010", Bridge is "001", Id
Although le is transmitted using "000", a code other than this may be used.

First, FIG. 6 shows an example of a normal control state of the network based on the network configuration of FIG. In response to the communication request from the low speed side communication line, each node sets a communication path between the nodes and performs communication.

In FIG. 6, here, communication paths of bidirectional service traffic 57, 58 are set between the node A and the node C, and bidirectional part-time traffic 59 between the node D and the node F. , 60, and bidirectional part-time traffic 61, 62 are set between the node A and the node B, respectively.

The specific setting of the communication path of the service traffic 57 is performed by the node C in which all (or part of) the signals input from the low speed side with respect to the time slot having the multiplexed signal transmitted from the node B. ) It is assumed that switching control for multiplexing (adding) is performed and switching control for separating (dropping) the signals of the time slots multiplexed at node C is performed at node A. By performing such control, the communication path through which the signal input from the low speed side of the node C is transmitted to the node A via the nodes D, E, and F is set as the service traffic 57. Become. Similarly, the reverse direction service traffic 58 is also set as a communication path that is multiplexed in the high-speed line at the node A and separated at the node C by performing switching control between the node A and the node D.

In an actual operation mode, a plurality of communication paths simultaneously set communication paths for service traffic and part-time traffic between various nodes. Then, when receiving the request signal regarding the span switching and the ring switching, each node judges only from the communication path setting status at that time, and switches only the communication path that requires each switching.
Here, for simplicity, the following description will be given assuming that the communication path is set in the form of FIG.

First, it is assumed that the network of FIG. 6 is in a normal control state in which ring switching is not performed at all. From this state, it is assumed that at time T1 in FIG. 2, the node C is performing ring switching to the segment C, and the node F is also performing ring switching control at the segment F.

In this state, node C is node D
On the other hand, in the Short direction (segment C in this case), the request source node C is controlling the Bridge & Switch to the request destination node D, and the K-byte request signal of the ring forced switching request (1a in FIG. 2). Hereinafter, it is abbreviated as “request signal (ring switching: C → D, Short, Bridge & Switch). The same applies hereinafter). Also, in the Long direction,
The requesting node C bridges and swit to the requesting node D
A K-byte request signal (1b in FIG. 2) of a ring forced switching request indicating that ch control is being performed. Hereinafter, abbreviated as "request signal (ring switching: C → D, Long, Bridge &Switch)." ) Is being sent.

On the other hand, at the opposite node D, the request signal (ring switching: D → C, Short, Bridge & Switch) (2b in FIG. 2) and the request signal (ring switching: D → C, Long, Bridge).
& Switch) (2a in FIG. 2) is being transmitted. Similarly, the node F sends a request signal (ring switching: F → A, Short
t, Bridge & Switch) (3b in FIG. 2) and request signal (ring switching: F → A, Long, Bridge & Switch) (3 in FIG. 2)
a), the node A sends a request signal (ring switching: A
→ F, Short, Bridge & Switch) (4b in Fig. 2) and request signal (ring switching: A → F, Long, Bridge & Switch)
(4a in FIG. 2) is being transmitted.

At the nodes B and E, which are intermediate nodes, the received request signal in the Long direction (ring switching:
Long, Bridge & Switch) (1b, 2a, 3b, 4 in FIG. 2)
a) is passed through and is transmitted to the adjacent node.

In the switching nodes C and D, a request signal in the Long direction for ring switching of the segment F (ring switching: Long, Bridge & Switch) (4a in FIG. 2,
3b) is received, but the request signal (ring switching: Short, Bridge & Switch) (1a, 2b in FIG. 2) is also received in the short direction in the segment C, so the request signal in the long direction (ring switching: Long). , Bridge & Switch) (4 in Fig. 2)
a, 3a) are held without passing through. Similarly, the switching nodes A and F request signals in the Long direction for ring switching of the segment C (ring switching:
Long, Bridge & Switch) (1b, 2a in FIG. 2) is received, but is held without passing through.

As a result, the network control is in a state in which the ring switching control for the two segments is performed. The control state of the network at this time is shown in FIG. As a result of the control, the service traffic (57, 58 in FIG. 6) is restored (switches the service to protection) in (65, 66 in FIG. 7). Part-time traffic (59, 60 in Figure 6)
Controls part-time traffic (Figure 7
63, 64).

Next, at time T2 in FIG. 2, it is assumed that release events occur simultaneously in the switching nodes C and F in the control state of FIG. The nodes C and F execute the maintenance controls 14 and 15 for maintaining the control state of the nodes and hold the request signal for performing the link switching F (ring switching: A → F, Long, Bridge & Switc).
h) (4a in FIG. 2), request signal (ring switching: D → C, L
on, Bridge & Switch) (2a in FIG. 2) are respectively passed through and transferred to nodes D and A which are the next nodes (5a and 6a in FIG. 2). At this stage, the control state of the network is the same as the control state of FIG. 7.

At time T3 in FIG. 2, node D
Is a request signal from the node C regarding the ring switching F (ring switching: A → F, Long, Bridge & Switch) (5 in FIG. 3).
By receiving a), it is recognized that the switching request in the segment C has been canceled, and the ring bridge & switch control 16 necessary for the ring switching F is performed (in the communication path setting state of FIG. Switching operation is not performed because there is no path that requires switching.) Then, the request signal (ring switching: A to F, Long, Bridge & Switch) (Fig. 3
No. 5a) is passed through to the node E and is received from the opposite direction, and the request signal related to the ring switching F (ring switching: F → A, Long, Bridge & Sw).
itch) (3b in FIG. 3) to node C.

On the other hand, the node C requests the signal from the node D (ring switching: F → A, Long, Bridge & Switch).
Upon confirming that the opposite node D has recognized the switching request cancellation of the segment C by receiving (3b in FIG. 3), the ring bridge & switch control 18 for performing the ring switching F is executed (see FIG. 7). In the setting status of the communication path,
The bridge control 70 and the switch control 69 are left as they are. ) And request signal (ring switching: F → A, Long, Br
idge & Switch) (3b in FIG. 3) is passed through and transmitted to the node B.

On the other hand, the intermediate node E sends a request signal from the node D (ring switching: A → F, Long, Bridge & Switch).
When (5a in FIG. 3) is received, the ring bridge & switch control 21 for performing the ring switching F (the switching operation is not performed in the communication path setting state in FIG. 7 because there is no switching required path), The received request signal (ring switching: A → F, Long, Bridge & Switch) (5a in FIG. 3) is passed through and transmitted to the node F.

Similarly, at time T3, node A
Request signal from node F (ring switching: D → C, Long, Br
idge & Switch) (6a in FIG. 2) is received, it is detected that the switching request for segment F has been canceled, and this time ring bridge & switch control 17 for ring switching C is performed (for the communication path in FIG. 7). In the setting state, bridge control 68
The switch control 67 is left as it is. ). And request signal (ring switching: D → C, Long, Bridge & Switch)
(6a in FIG. 2) is transferred to the node B, and the held request signal (ring switching: C → D, Long, Bridge &
Switch) (1b in FIG. 3) is transmitted to the node F.

On the other hand, the node F receives the request signal (1b in FIG. 3) from the node A and can confirm that the opposite node A has recognized the switching request cancellation of the segment F,
A ring bridge and ring switch control 19 based on the ring switching request for the segment C is executed (the switching operation is not performed in the communication path setting state of FIG. 7 because there is no switching required path), and a request signal (ring switching) is performed. : C →
D, Long, Bridge & Switch) (1b in FIG. 3) is passed through and transmitted to the node E.

Similarly, the intermediate node B sends a request signal from the node A (ring switching: D → C, Long, Bridge & Switch).
(6a in FIG. 2) is received to perform the ring bridge & switch control 20 (the switching operation is not performed in the communication path setting state in FIG. 7 because the switching required path does not exist), and the received request signal (FIG. 2). 6a) of each, pass through,
Send to node C. The control state of the network is the same as the control state of FIG.

At time T4 in FIG. 2, the ring bridge & switch control 2 is performed at the node B and the node E, respectively.
2 and 23, and the received request signal (ring switching: Brid
ge & Switch) is passed through and transmitted to node A and node D, respectively.

However, although the node C controls the ring switching release of the segment C,
Since a request signal (ring switching: D → C, Long, Bridge & Switch) (6a in FIG. 2) indicating that ring switching is newly performed for the segment C addressed to the own node from the CW direction, a plurality of signals are received. It is determined that the simultaneous recovery event has occurred for the ring switching factors of the segments (here, segment F and segment C). At this time, in the node F as well as the node C, the segment F
Regarding the ring switching factor of the segment C and the segment C, it is determined that a simultaneous recovery event has occurred.

Therefore, the node C and the node F recognize that it is necessary to perform control for causing the own node to transition to the idle state and the network to transition to the normal state.
As a result, the nodes C and F drop switches (return switch control) to all the nodes of the network.
In order to put it in the state, the local node performs drop switch control 24
And 25, the control state of the own node is set to a ring bridge, and a request signal (no request: Bridge) in which the source and the request destination are not specified is in the CW direction (7a in FIG. 4) and the CCW direction (in FIG. 4). 7b) to the adjacent node.

At this time, in the request signal in which the transmission source and the request destination are not specified, 5-8 bits of K1 byte and 1-4 bits of K2 byte indicating the transmission source and the transmission destination are numerical values not set as node names. It may be anything as long as it is “0” in this embodiment.

Nodes A, B, D, and E that have received the request signal (No request: Bridge) (7a in FIG. 4) or (7b in FIG. 4) whose source and request destination have not been specified are dropped. Switch control 27, 29, 26, 28 is performed to bring the control state of the node to the ring bridge state.
Then, the nodes E and B further pass through the received request signal (no request: Bridge).

The control state of the network up to this point is shown in FIG.
Shown in. In FIG. 8, the drop switch control states 73 and 75 and the bridge control states 74 and 76 of the nodes A and C are shown. 77 and 78 indicate bidirectional flow of service traffic.

At time T5 in FIG. 2, nodes A and D
In this case, since request signals (no request: Bridge) 7b and 7a are received from both the CW direction and the CCW direction, all nodes (nodes A, B, C, D, E, and In F), the drop switch control ends, and it can be determined that the bridge control state is set. Then, the drop bridge controls 30 and 31 of the own node are respectively executed. Then, the nodes A and D send a request signal (no request: Idle) indicating that their nodes do not control the bridge and the switch in the CW direction (9a, 8 in FIG. 2).
a) and CCW direction (9b, 8b in FIG. 5). FIG. 9 shows the drop switch control 79 and the drop bridge control 80 of the node A.

Next, the nodes C and F receive the request signal (no request: Idle) (8b, 9b in FIG. 5) from the CCW direction, and the request signal passed through by the node B or node E (no request). : Idle) 7b and 7a are received. Since the nodes F and C can receive the K-byte request signals 7a and 7b from both directions of the nodes, all the nodes (nodes A, B, C, D,
Regarding F), it is determined that the drop switch control ends and the bridge control state is entered. Then, the drop bridge control 32 and 33 of the own node are executed, and the node F transmits a request signal (no request: Idle) in the CW direction (11a in FIG. 5) and the CCW direction (11b in FIG. 5). .
Further, the node C transmits a request signal (no request: Idle) in the CW direction (10a in FIG. 5) and the CCW direction (10b in FIG. 5). FIG. 9 shows the drop bridge control 81 of the node C.
And drop switch control 82.

The nodes E and B receive the request signals (no request: Idle) 11b and 10b addressed to their own nodes from the adjacent nodes, and perform drop bridge control 3 of their own nodes.
5 and 34, and the node E sends a request signal (no request: Idl
e) in the CW direction (13a in FIG. 2) and in the CCW direction (FIG. 2)
13b) is transmitted. The node B sends a request signal (no request: Idle) in the CW direction (12a in FIG. 2) and CCW.
Direction (12b in FIG. 2).

At this point, in all nodes, the communication path of the service traffic is in the idle state, but the part-time traffic remains dropped. Therefore, the restartable control of part-time traffic is started next.

The part-time traffic (61, 62 in FIG. 6) dropped for the restoration control of the service traffic is DCC (Data Communication Channel) after the drop bridge and drop switch control for the service traffic shown in FIG. 9 is completed. The message signal is used to transmit the information that the respective nodes can be re-established.

As shown in FIG. 2, the node D has 45, 46,
Node A is 47, 48, node C is 49, 50, node F is 51, 52, node B is 53, 54, and node E is 5.
5 and 56 are transmitted as DCC signals. At this point, each node can process another switching factor and reprocess the pending switching factor.

At time T6 in FIG. 2, the part-time traffic is reestablished. The node D will be described. In node D, CW, CCW
In both directions of the DCC message signal 4
DCC message signals 50 and 55 transmitted from the destination node C and node E that transmitted 4 and 46 to the own node
When the node receives the request, it performs resettable control 40 of the part-time traffic on both sides of the own node, and becomes the initial control state (no switching factor) as the node. Similarly, when the part-time traffic reset control 37, 41, 38, 36, 39 for the node E, the node F, the node A, the node B, and the node C is completed, the normal control state shown in FIG. .

Here, in the sequence shown in FIG. 2, the part-time traffic is reestablished after receiving DCC message signals 50 and 55 from both sides of the own node. However, the present invention is not limited to this, and the part-time traffic may be reestablished for each segment from the side receiving the DCC message signal.

Therefore, according to the above control method, the whole network is in the pass-through control state with respect to the simultaneous recovery event, and there is no switching factor,
For the situation where protection switching cannot be performed, the above method is newly used to stabilize the network state promptly without affecting service traffic and without causing misconnection of traffic (misconnect). It is possible to control the normal state.

[0059]

As described above, according to the present invention, with respect to the simultaneous recovery event of the ring network system, erroneous connection of traffic (misconnect) is not caused.
It is possible to provide a control method for a ring network system that can quickly control a network to a normal state.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a ring network system to which a control method according to an embodiment of the present invention is applied.

FIG. 2 is a state transition diagram showing a state in which the network is controlled to a normal state from the time when FS-R switching requests in two sections are simultaneously canceled by the control method of the present invention in the same embodiment.

FIG. 3 is a diagram showing request output contents of each node shown in FIG.

FIG. 4 is a diagram showing request output contents of each node shown in FIG.

FIG. 5 is a diagram showing request output contents of each node shown in FIG.

FIG. 6 is a block diagram showing a normal control state of the network based on the network configuration of FIG. 1.

7 is a block diagram showing a control state of the network at times T1, T2, and T3 in FIG.

FIG. 8 is a block diagram showing a control state of the network at time T4 in FIG.

9 is a block diagram showing a control state of the network at time T5 in FIG.

[Explanation of symbols]

A, B, C, D, E, F ... Nodes (segments) 45 to 56 ... DCC signals 57, 58, 65, 66, 77, 78 ... Bidirectional flow of service traffic 59, 60, 61, 62, 63 , 64 ... Bidirectional flow of part-time traffic 67, 69 ... Switch control 68, 70, 74, 76 ... Bridge control 71, 72 ... Pass-through control 24, 25, 28, 29, 73, 75, 79, 82 ... Drop Switch control 30, 31, 32, 33, 80, 81 ... Drop bridge control

Claims (10)

(57) [Claims] 1. A plurality of nodes are connected to each other in a ring shape via a plurality of transmission paths, and switching control for changing a switching state in each node is performed, so that different transmission paths of a set communication path are transmitted. It is applied to a ring network system that can perform ring switching by switching to a route and continuing communication. The node that initiates the ring switching sends a ring switching request signal for performing the ring switching, and another node In a method of controlling a ring network system that performs ring switching by performing switching control that changes a switching state in a node according to a switching request signal, a switching state of each node on the ring network is changed in a plurality of sections. The ring has not been switched from the state that the ring has been switched. As a control when returning to the normal state, a simultaneous recovery event detection step of detecting that a simultaneous recovery event in which the ring switching of the plurality of sections is about to be recovered at the same time has occurred, and the simultaneous recovery event occurrence at this step When a switch is detected, a switching state initialization step for returning the switching state of the own node to the initial state and a switchback request for sending a switchback request signal requesting other nodes to return the switching state to the initial state And a signal sending step. 2. The ring according to claim 1, wherein the ring switching is a process of switching a transmission route to a route that avoids a section designated by an operation from an external control device connected to each node. Network system control method. 3. The ring switching is a process of switching a transmission path to a route that avoids a failure section when a node detects a failure in the transmission path.
A method for controlling the described ring network system. 4. The ring switching request signal is ITU-T Recommendation G.264. The control method for a ring network system according to claim 1, wherein the signal is a signal transmitted by using a K byte signal of an SDH frame based on the regulation of 841 (07/95). 5. The simultaneous recovery event detecting step, when a ring switching request signal addressed to the own node is received after transmitting a request signal for switching back the ring switching,
2. The method of controlling a ring network system according to claim 1, wherein it is determined that a simultaneous recovery event of switching a plurality of rings has occurred. 6. The switching control performed at each node in response to the ring switching request signal is such that, for a route in the direction of transmission from the node, switching is performed by switching the working route and ring that have been transmitting until now. Bridge control is used to connect to both the spare route and the route to be the new transmission route, and the route in the direction received by the node is separated from the working route that had been transmitting until now, and ring switching is performed. The control method of the ring network system according to claim 1, wherein switch control is performed so as to switch and connect to a standby system of a route that newly becomes a transmission route. 7. A step of transmitting the switchback request signal in a switching node of the plurality of nodes that is switching when the ring network is returned to the normal state from a state where ring switching is performed in a plurality of sections. Resets the switching state of the node to the bridge state by releasing the switch control, and sends a request signal requesting another node to return the switching state to the bridge state, After confirming that the other node has entered the bridge state, the step of releasing the bridge control and returning the switching state of the switching node to the initial state, and returning the switching state to the other node to the initial state Sending a request signal requesting the request. Method of controlling a ring network system. 8. The control of the ring network system according to claim 1, wherein the ring-shaped transmission path connecting the plurality of nodes is applied to a ring network system including a working line and a protection line. Method. 9. The method of controlling a ring network system according to claim 8, wherein the control method is applied to a ring network system for transmitting part-time traffic by using a vacant channel of the protection line. 10. When the ring network is returned to the normal state from a state where ring switching is performed in a plurality of sections, a switching back request signal transmitting step in a switching node that is performing switching among the plurality of nodes, , A step of releasing the switching state of the node to return to the bridge state by canceling the switch control, a step of transmitting a request signal for requesting another node to return the switching state to the bridge state, and all other After confirming that the node has changed to the bridge state, the step of releasing the bridge control and returning the switching state of the node to the initial state, and the step of returning the switching state to other nodes to the initial state are performed. The step of sending a request signal to request and the part-time traffic that was temporarily dropped. The method of claim 9, wherein the ring network system, characterized in that it comprises a step of again connected.