JPH11355292A - Atm layer protection system and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently perform high-reliability ATM layer protection with a simple constitution and easy control with respect to a ATM layer protection system and its device. SOLUTION: In the ATM layer protection system which protects a protection section against communication interference by an ATM layer, plural nodes 10A and 10B are provided which mutually hold connection information of an active system and a standby system for the protection section, and the fault detection node 10B which have detected the communication interference of the active system connection at the end point of the protection section generates a connection switching request cell specifying the faulty connection and transmits the cell to the counter node 10A, and the fault detection node and the counter node switch the faulty connection to the standby system connection at the timings of transmission and reception of the connection switching request cell.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM layer protection method and an apparatus therefor, and more particularly to an ATM layer protection method and an apparatus for protecting a communication failure in a protection section by an ATM (VP / VC) layer. In recent years, it has been required to realize a highly reliable ATM network at a low network cost. For this reason, it is required to realize a redundant configuration of an active system and a standby system of the transmission line at a low network cost.

[0002]

2. Description of the Related Art In this respect, in an ATM network, unlike a conventional physical layer in which a transmission line is duplicated (two communication lines are prepared), a transmission line is divided into two in units of VP / VC logical connections. Since the connection can be duplicated, the network cost can be reduced by, for example, selectively duplicating only the connection requiring high reliability. In addition, since the connection can be changed in one or two or more VP / VC units, flexible network protection can be performed.

[0003]

However, conventionally, ATMs
Although the standardization organizations such as ITU-T are discussing the layer protection, the specific processing sequence of the alarm transfer cell and the switching control cell is not specified. In particular, regarding a VC switch that performs VC level handling, when a failure occurs in the VP layer, it is necessary to replace all the VCs accommodated in the VP. Therefore, the failure information of the VP layer and the switching instruction / switch response are transmitted to all VCs. It is required that distribution / collection be performed quickly and reliably.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ATM layer protection method and a device capable of efficiently performing highly reliable ATM layer protection with a simple configuration and control.

[0005]

The above-mentioned problem is solved, for example, by referring to FIG.
Is solved. That is, the ATM of the present invention (1)
The layer protection method is an ATM layer protection method for protecting a communication failure in a protection section by an ATM layer, and includes a plurality of nodes 10 for mutually holding active and protection connection information for the protection section. The failure detection node 10B that has detected the communication failure of the working connection at the end point generates a connection switching request cell specifying the failed connection, transmits the cell to the opposing node 10A, and transmits the connection switching request cell. Then, upon the reception, the failure detection node 10B and the opposite node 10A switch their respective failure connections to the backup system connection.

According to the present invention (1), each node 10 mutually holds the connection information of the working system and the protection system for the protection section, so that the failure detection node 10
By simply transmitting the connection switching request cell specifying the failed connection from B to the opposing node 10A, the ATM layer protection, which is generally complicated, can be performed quickly and reliably independently (by distributed control) for each protection section.

Preferably, in the present invention (2), in the above-mentioned present invention (1), the opposite node 10A switches the faulty connection of its own node to the connection of the standby system upon receiving the connection switching request cell, and also detects the fault detection node. Send a connection switching response cell to 10B,
Upon receiving the connection switching response cell, the failure detection node 10B switches the failure connection of its own node to the connection of the standby system.

[0008] This is an upstream priority switching control for switching a failed connection first from a failed upstream node. Further, the downstream failure detection node 10B is
After confirming the connection switching at 0A, the connection switching of the own node is performed, so that the protection control in the protection section in a secure and secure manner is performed. Further, by exchanging the connection switching request cell and the connection switching response cell, preferably by using the standby route, the conduction of the standby route can be simultaneously confirmed.

Further, the node device 10B of the present invention (3)
In a node device of an ATM communication system for protecting a communication failure in a protection section by an ATM layer, a connection information holding unit 13 for mutually holding active and protection connection information for the protection section, and an end point of the protection section. A failure detection unit 11 for detecting a communication failure in the protection section, a connection switching request cell specifying a failure connection by the failure detection of the failure detection unit, and transmitting the cell to the correspondent node 10A. A switching control unit that switches a failed connection of the own node to a connection of a standby system upon receiving a connection switching response cell from the node.

Further, the node device 10A of the present invention (4)
In a node device of an ATM communication system for protecting a communication fault in a protection section by an ATM layer, a connection information holding unit 13 for mutually holding connection information of a working system and a protection system for a protection section, and a fault detection node 10B. A switching control unit 22 that switches a corresponding failed connection of the own node to a connection of a standby system upon receiving a connection switching request cell specifying a connection.

Preferably, in the present invention (5), in the above-mentioned present invention (3), the switching control unit 22 accommodates all the VCs or all the VPs under the faulty connection by the fault detection of the fault detecting unit 11. A connection switching request cell is generated for each VP or each group VP for which a faulty connection is specified for each backup VP or each group VP, and the cell is transmitted to the opposing node 10A. Upon receiving the connection switching response cell for each node, the corresponding failed connection of the own node is switched to the connection of the standby system.
Therefore, all the fault VCs or all the fault VPs under the fault connection are set for each of the backup VPs or the group V
Switching can be performed efficiently for each P.

Preferably, in the present invention (6), in the above-mentioned present invention (4), the switching control unit 22 controls all VCs or all Vs under the fault connection from the fault detecting node 10B.
For each P, a faulty connection is specified for each backup VP or group VP accommodating them. For each VP or for each group VP, a connection switching request cell is received, and the corresponding fault connection of the own node is changed to the backup connection. Switch to Therefore, all the fault VCs or all the fault VPs under the fault connection can be efficiently switched for each VP of the backup system accommodating them or for each group VP.

Preferably, in the present invention (7), in the above present invention (3) or (5), the switching control unit 22 comprises:
The failure connection of the own node is switched to the connection of the standby system without waiting for the connection switching response cell from the opposite node 10A. Therefore, this is not an upstream priority, but the switching process can be performed at high speed in parallel at both nodes. Preferably, in the present invention (8), in the present invention (4) or (6), the switching control unit 22 switches the corresponding failed connection of the own node 10A to the connection of the standby system, and also causes the failure detecting node 10B to The connection switching response cell is transmitted. Therefore, the failure detection node 1
In 0B, the completion of connection switching in the opposite node 10A can be easily confirmed.

The node device 10B of the present invention (9) is a node device of an ATM communication system for protecting a communication failure in a protection section by an ATM layer.
A connection information holding unit 13 for mutually holding connection information of the active system and the protection system for the protection section, and all VCs under the failed connection by detecting a communication failure at an end point of the protection section;
Alternatively, a first line-corresponding unit 3B for generating predetermined intra-device cells for all VPs and outputting them downstream in accordance with the active connection information, and capturing the egress intra-device cells to reserve the cells. One or more second line corresponding units 5A, 6A, etc., which are turned back into the device according to the system connection information;
Each of the returned cells in the device is collected, and a connection switching request cell for each VP or each group VP that specifies a faulty connection is generated for each backup VP or each group VP accommodating the cells, and the cell is opposed. And one or more third line-corresponding units 4B and the like for transmitting to the node.

An example of the operation will be specifically described. The first line corresponding unit 3B is connected to all Vs under the faulty connection (VP3).
C (VC1, VC3) per cell (VP3 / VC
1, VP3 / VC3), and guides them to the downstream second line corresponding units 5A and 6A according to the active connection (routing tag) information. The second line corresponding unit 5A captures the cell (VP3 / VC1) in the device on the outgoing side, and returns the cell to the device according to the connection (routing tag) information of the standby system. In addition, the second line corresponding unit 6A captures a cell (VP3 / VC3) in the device on the egress side and returns the cell to the device according to the connection information of the standby system.

The third line corresponding section 4B is folded back,
A connection switching request cell for each VP that specifies a faulty connection for each backup VP (in this case, each backup VP4) that collects the internal cell (VP3 / VC1) transferred to itself and accommodates the collected cells (VP3 / VC1) VP3 / VC1), and sends the cell to the opposite node 10A. Further, the third line corresponding section 4B '(not shown) collects the internal cell (VP3 / VC3) which has been turned back and transferred to itself, and for each VP of the standby system accommodating it (in this case, standby). System V
A connection switching request cell (VP3 / VC3) is generated for each VP that specifies the failed connection (for P4 '),
The cell is transmitted to the opposite node 10A.

Therefore, even if a complicated standby route search is not performed, the faults VC1 and VC3 under the fault VP3 can be detected by the simple configuration and the flow control of the cell in the device.
It can be efficiently related to P4 and VP4 '. In addition, since the cells in each device are collected and the connection switching request cell for each corresponding VP or each group VP is transmitted,
Do not overwhelm the protection link bandwidth. All failure VP
Can be similarly considered when relating to one or more standby group VPs.

The node device 10A of the present invention (10) is a node device of an ATM communication system that protects a communication failure in a protection section with an ATM layer, and mutually holds active and protection connection information for the protection section. The connection information holding unit 13 that receives the connection switching request cell for each VP or each group VP that specifies the failed connection for each VP or each group VP from the failure detection node 10B, and receives all or all of the corresponding failed connections. VP
One or two or more first line corresponding units 4A, etc., which respectively generate predetermined intra-device cells and output them upstream in accordance with backup connection (routing tag) information;
One or more than one or more of the outgoing-side cell in the device are captured and the corresponding faulty connection is switched from the active system to the standby system, and the captured cell is returned to the device according to the connection (routing tag) information of the standby system. It has second line corresponding units 1B, 2B and the like.

Here, the flow control of the cell in the device inside the node device 10A can be considered in the same manner as described for the node device 10B. Therefore, even if a complicated standby route search is not performed, the fault VC1 and the fault VC1 under the fault VP3 can be controlled by the simple configuration and the flow control of the cell in the device.
VC3 can be efficiently switched to VP4, VP4 'of the standby system.

The node device 10B of the present invention (11) is a node device of an ATM communication system for protecting a communication failure in a protection section by an ATM layer, and mutually holds connection information of an active system and a protection system in a protection section. The connection information holding unit 13 and a connection failure request cell are generated for each of all VCs or VPs under the failed connection by detecting a communication failure at the end point of the protection section, and these are generated according to the active connection information. A first line-corresponding unit 3B that outputs downstream and one or more second line-corresponding units 5A, which capture the egress-side connection switching request cell and turn the cell back into the device according to the backup connection information. 6A etc. and the returned connection switching request Le a in which and a second of the one or more transmitted to the correspondent node 3 of the line interface portion 4B and the like.

According to the present invention (11), the first line handling unit 3B generates predetermined connection switching request cells for all VCs or all VPs under the faulty connection, and generates these in the own node 10B. By a method of returning and sending the packet as it is to the opposing node 10A, a functional unit for collecting and editing the connection switching request cell from the third line corresponding unit 4B or the like can be deleted, and the device configuration is simplified.

The node device 10A according to the present invention (12) is a node device of an ATM communication system that protects a communication failure in a protection section by an ATM layer, and mutually holds active and protection connection information for the protection section. Upon receiving connection switching request cells transmitted from the failure detection node 10B for all VCs or VPs under the failed connection from the failure detection node 10B, these are output upstream according to the connection information of the standby system. One or more first line corresponding units 4A, etc., capture the outgoing side connection switching request cells, switch their corresponding connection information from the active system to the standby system, and switch the captured cells to the standby system connection. One or two or more folded back into the device according to the information 2 of the line interface 1B, in which and a 2B or the like.

According to the present invention (12), each connection switching request cell received from the failure detection node 10B is returned as it is in its own node 10A, and each time the corresponding failure connection information of each line corresponding unit is transmitted from the working system. The method of switching to the standby system simplifies the device configuration. Preferably, in the present invention (13), the present invention (9)
Or in (11), the second and third line corresponding units 5A,
6A and the like switch each corresponding failed connection from the active system to the standby system after receiving the connection switching response cell from the opposite node 10A. Therefore, it is possible to confirm the switching at the upstream and perform the switching control with the priority given to the upstream.

Preferably, in the present invention (14), in the above-mentioned present invention (9) or (11), the second and third line corresponding units 5A, 6A, etc. transmit the connection switching response cell from the opposite node 10A. The corresponding failed connection is switched from the active system to the standby system without waiting. Therefore, switching to the standby system in both the failure detection node 10B and the opposing node 10A can be performed quickly.

Preferably, in the present invention (15), in the above-mentioned present invention (10) or (12), the first line handling unit 4A or the like receives the connection switching request cell from the failure detecting node 10B or automatically receives the cell. When one or more loopback cells are collected in the node 10A, its own connection is switched from the active system to the standby system. Preferably, in the present invention (16), the present invention (10) or (1)
In 2), the first line corresponding unit 4A and the like
After the collection of one or more return cells in the communication node 0A, the connection switching response cell is changed to the failure detection node 10B.
To send to. Therefore, the failure detection node 10B can confirm that the opposite node 10A has received the connection switching request cell.

The node device according to the present invention (17) is a node device of an ATM communication system for protecting a communication failure in a protection section by an ATM layer. Alarm cell identification unit that identifies the alarm transfer cell in the section that has been, based on the identification result of the alarm cell identification unit,
While the out-of-section alarm transfer cell is input from the upstream, the out-of-section alarm transfer cell is transferred to the downstream.If the out-of-section alarm transfer cell is not input and the in-section alarm transfer cell is generated, An alarm cell transfer control unit that converts the in-section alarm transfer cell into an out-of-section alarm transfer cell and transfers the cell downstream. Therefore, it is possible to eliminate the waste of redundantly transferring the out-of-section alarm transfer cell downstream, and to facilitate the processing of the out-of-section alarm transfer cell downstream.

[0027]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Note that the same reference numerals indicate the same or corresponding parts throughout the drawings. FIGS. 2 and 3 are diagrams (1) and (2) for explaining the ATM layer protection system according to the first embodiment, and show a case where a switching control function of connection information is distributed and arranged in each line corresponding unit. Is shown.

FIG. 2 shows a schematic configuration of a VP protection section. In FIG. 2, reference numeral 10 denotes a switching node (ATM switch, cross-connect device, etc.) for exchanging user cells and performing protection control for the VP protection section; Is a line corresponding unit, and 21 is an ATM switch (A
SW) and 22 are call controllers for performing call control of user cells (permanent calls, on-demand calls, etc.), 40 is a relay node, and PL is a physical link such as an optical fiber connecting the nodes.

A case where a section between the switching nodes 10A and 10B is defined as a VP protection section, and switching between the active VP and the standby VP is performed in this section will be described. In this case, the physical links PL3, 4 and the like are both used in the active VP, but by providing a margin in their communication capacities, the backup VPs for the respective active VPs in the PL3, 4 are respectively assigned to the PL4. , 3 can be provided. Communication such as communication failure detection notification, connection switching request, and switching response is performed using an OAM cell different from a normal user cell.

FIG. 11 shows a generally used alarm OA.
3 shows a format of an M cell (VP-AIS cell). The OAM cell for alarm comprises a 5-byte header and a 48-byte information area (payload) like the user cell.
“VPI” is the same VPI as the fault VP, and “VCI” is V
A specific value representing the OAM cell for P, "OAM type" is VP
-A specific value indicating an AIS cell or a VP-FERF cell (alarm cell), "Defect type" is a failure type, and "Defect Loc".
“ation” holds a failure location, and “CRC” holds a payload error detection code.

In the first embodiment, an OAM cell for notifying a fault that has occurred in a protection section is a VP trigger cell, and an OAM cell for notifying a fault in the protection section is distinguished from the general (out of section) alarm OAM cell. The OAM cell for communicating the control information for connection switching is referred to as a VP switching request cell and a VP switching response cell. Returning to FIG. 2, a rough flow of the VP protection control according to the first embodiment will be described. The switching nodes 10A and 10B are normally connected to the active system V
A user cell is flowing on P. In this state, if a communication failure occurs on the downlink from the switching node 10A to the relay node 40a, the relay node 40a detects the failure, generates a VP trigger cell, and sends it to the switching node 10B. When a communication failure occurs on the downlink from the relay node 40a to the switching node 10B, the switching node 10B detects the failure and internally generates a VP trigger cell.

In any of the above cases, the switching node 10B that has detected the failure transmits the failure V to the opposite switching node 10A.
The VP switching request cell specifying P is transmitted. In this case, preferably, the continuity test of the standby system can be performed by transmitting the VP switching request cell to the VP (link) of the standby system corresponding to the failed VP. Upon receiving this, the switching node 10A switches the connection information corresponding to the failed VP in the header conversion table to be described later to the active system or the standby system, and then returns a VP switching response cell to the switching node 10B. Also in this case, preferably, the continuity test of the standby system can be performed by transmitting the VP switching response cell to the VP (link) of the standby system corresponding to the failed VP. The switching node 10B is a switching node 10A
It is confirmed that the VP switching control has been normally performed in the switching node 10A by receiving the VP switching response cell from the node, and the connection information corresponding to the failed VP in the header conversion table of the own node is changed from the active system to the standby system. Switch to

When it is determined that the VP switching control in the switching node 10A has failed due to the reception timeout of the VP switching response cell, the information element in the VP switching response cell, or the like, the switching node 10B sends the VP switching request again. Transmit the cell or suspend connection switching. FIG. 3 shows a detailed configuration of the switching node in the first embodiment. In the drawing, 10 is a switching node, 11 is a line corresponding unit, 12 is a header conversion unit (HCV), 13 is a header conversion table, 14 Is a transmission path failure detection unit (ED
T), 15 is an OAM cell generator (SCG), 16 is OA
M cell receiver (SCR), 21 is an ATM switch (AS
W) and 22 are call control units.

The figure shows VPI = 1 as VP due to space limitations.
1, VCI = 1 is simply represented as VC1. The explanation follows this. Further, in this system, VPI is rewritten (replaced) for each node, but VCI is not rewritten for each node because the description is complicated. Of course, the VCI may be rewritten for each node. The routing tag information R for determining the output route of the ASW 21 is treated as being equal to the VPI value on the output side, and is not shown here.

In the figure, the line corresponding units 1B and 2B correspond to the physical links PL3 and PL2 in correspondence with the physical links PL1 and PL2.
Line corresponding parts 3A, 4A and 3B, 4B corresponding to PL4
, And line corresponding units 5A and 6A are provided corresponding to the physical links PL5 and PL6, respectively. Each line handling unit has a common configuration so as to cope with a failure detected in each of the uplink and downlink paths.

The call control units 22A and 22B generate connection information of the active system, respectively, when a permanent call is connected or when an on-demand call is sent / received, and hold this in the header conversion table 13 of the own node. An example of connection information of the active system is as shown in the figure. The header conversion unit 12
The input side of the header conversion table 13 is referred to by the header information of the input cell, the header information of the input cell is rewritten by the corresponding header information of the output side, and the rewritten cell is guided to the corresponding output path by the ASW 21.

Specifically, the operation of cell switching by the working system is as follows. The physical link PL1 accommodates VP1, and VC1 and VC2 are multiplexed here. The line corresponding unit 1B rewrites VP1 / VC1 of the input cell to VP3 / VC1 and guides it to the line corresponding unit 3A on the outgoing route (R = 3), and also converts VP1 / VC2 of the input cell to VP4 / VC2. It is rewritten and is led to the line corresponding unit 4A on the outgoing route (R = 4). On the other hand, the physical link PL2 accommodates VP2, where VC3 and VC4 are multiplexed. The line corresponding unit 2B rewrites VP2 / VC3 of the input cell to VP3 / VC3, guides it to the line corresponding unit 3A on the outgoing route (R = 3), and converts VP2 / VC4 of the input cell to VP4 / VC2. It is rewritten and is led to the line corresponding unit 4A on the outgoing route (R = 4).

As a result, VC1 and VC3 are multiplexed on VP3 of the physical link PL3. The line corresponding unit 3B rewrites VP3 / VC1 of the input cell to VP5 / VC1 and guides it to the line corresponding unit 5A.
Rewrite C3 to VP6 / VC3 and replace it with line
Lead to A. On the other hand, VP4 of physical link PL4 has VC
2, 4 are multiplexed. The line corresponding unit 4B rewrites VP4 / VC2 of the input cell to VP5 / VC2 and guides it to the line corresponding unit 5A.
Is rewritten to VP6 / VC4, and this is led to the line corresponding unit 6A. As a result, VC is added to VP5 of the physical link PL5.
1 and 2 are multiplexed, and VC3 and VC4 are multiplexed on VP6 of the physical link PL6.

Assuming that the above is a downward path, the upward path is normally formed in the opposite way (pairwise). That is, the line corresponding unit 5A sets VP5 / VC1 of the input cell to V
It is rewritten to P3 / VC1 and guided to the line corresponding unit 3B, and VP5 / VC2 of the input cell is rewritten to VP4 / VC2 and guided to the line corresponding unit 4B. Further, the line corresponding unit 6A converts VP6 / VC3 of the input cell into VP3 / VC3.
To the line corresponding unit 3B, and VP6 / VC4 of the input cell is rewritten to VP4 / VC4, and this is guided to the line corresponding unit 4B. On the other hand, the line corresponding unit 3A rewrites VP3 / VC1 of the input cell to VP1 / VC1 and guides it to the line corresponding unit 1B.
VC3 is rewritten to VP2 / VC3, which is led to the line corresponding unit 2B. In addition, the line corresponding unit 4A outputs the VP4 of the input cell.
/ VC2 is rewritten to VP1 / VC2, which is led to the line corresponding unit 1B, and VP4 / VC4 of the input cell is converted to VP2 / VC2.
/ VC4 and leads it to the line corresponding unit 2B.

Further, in this system, the physical link PL3
The backup system at the time of the failure of (VP3) is the physical link PL4 (VP
4), and conversely, a standby system in the event of a failure in the physical link PL4 (VP4) is provided in the physical link PL3 (VP3). The call control units 22A and 22B generate standby connection information corresponding to the working connection information in advance, and store these in the header conversion table 13. However, FIG. 3 mainly shows connection information of a standby system when a failure occurs in the physical link PL3 (VP3).

Hereinafter, the protection operation by the VP layer for the transmission path failure will be specifically described. In the line handling unit 3B, when the VP trigger cell from the relay node 40a is detected by the failure detection unit 14 or the failure detection unit 14 detects a transmission line failure, the fact is notified to the OAM cell generation unit 15 and the OAM cell generation The unit 15 sends out a VP switching request cell specifying that VP3 has a failure. When the VP switching request cell is input, the header conversion unit 12 determines in advance that the fault VP
With reference to a standby routing table (not shown) in which routing tag information of the standby VP for
The routing tag information R of the switching request cell is stored in the standby VP
(In this case, R = 4). Thereby, the VP switching request cell is guided to the line corresponding unit 4B, and is sent to the opposite switching node 10A via the VP4. The connection information of the backup routing table may be provided on the header conversion table 13.

In the line corresponding section 4A, the header converting section 1
2 receives the VP switching request cell, distributes the cell to all the line corresponding units 1B, 2B, 3A, etc., and notifies the call control unit 22A of the reception of the VP switching request cell. Note that the VP switching request cell from the line handling unit 4B is
May be extracted (captured) and notified to the OAM cell generation unit 15 to that effect, and the OAM cell generation unit 15 receiving this may generate a VP switching request cell addressed to all the line corresponding units.

In the line corresponding section 1B, the OAM cell receiving section 16 extracts (captures) the outgoing VP switching request cell distributed and transferred, and uses this as a trigger to change the connection information of the header conversion table 13 from the working system. Switch to the standby system. As a result, the line corresponding unit 1B rewrites VP1 / VC1 of the subsequent input cells to VP4 / VC1 and VP1 / VC2 of the input cells to VP4 / VC2, and leads them to the line corresponding unit 4A.

In the line corresponding unit 2B, the OAM cell receiving unit 16 extracts the outgoing VP switching request cell and, at the same time, switches the connection information of the header conversion table 13 from the active system to the standby system. As a result, in the line corresponding unit 2B, VP2 / V
C3 to VP4 / VC3, and VP2 / VC of the input cell
4 to VP4 / VC4 and replace them with the line
Lead to A. As described above, the use of the failure link PL3 for the down route in the protection section is avoided.

On the other hand, in the line corresponding unit 3A, the OAM cell receiving unit 16 extracts the outgoing side VP switching request cell and, at the same time, shuts down the use of the active system in the header conversion table 13. As a result, in the line corresponding unit 3A, the subsequent input cells VP3 / VC1 and VP3 / VC2 are discarded, for example. Further, in response to the input of the VP switching request cell to the header conversion unit 12, the line corresponding unit 4A switches to use the connection information of the active system and the connection information of the standby system of the header conversion table 13 together. As a result, in the line corresponding unit 4A, the VP4 /
VC2 to VP1 / VC2 and VP4 / V of the input cell
C4 is rewritten to VP2 / VC4, these are led to the line corresponding units 1B and 2B, respectively, and VP4 of the input cell is newly added.
/ VC1 to VP1 / VC1, and VP4 /
VC3 is rewritten to VP2 / VC4, and these are led to the line corresponding units 1B and 2B, respectively. As described above, the normal link PL is applied to the upstream route in the protection section.
The connection route to 1 and 2 was secured.

Further, upon receiving the notification of the reception of the VP switching request cell from the line corresponding unit 4A, the call control unit 22A sends the V to the switching node 10B via the line corresponding unit 4A.
Send a P-switch response cell. In the line corresponding unit 4B,
Upon receiving the VP switching response cell, the header conversion unit 12 distributes the cell to all the line corresponding units 5A, 6A, 3B, etc., and if necessary, informs the call control unit 22 of the reception of the VP switching response cell.
Notify B. Note that the failure detection unit 14 extracts the VP switching response cell from the line handling unit 4A, notifies the OAM cell generation unit 15 of the fact, and receives the notification to the OAM cell generation unit 1
5 may be configured to generate a VP switching response cell addressed to the all-line corresponding unit.

In the line corresponding section 5A, the OAM cell receiving section 16 extracts (captures) the outgoing VP switching response cell distributed and transferred, and uses this as a trigger to change the connection information of the header conversion table 13 from the working system. Switch to the standby system. As a result, the line corresponding unit 5A rewrites VP5 / VC1 of the subsequent input cell to VP4 / VC1 and VP5 / VC2 of the input cell to VP4 / VC2, and leads them to the line corresponding unit 4B.

In the line corresponding unit 6A, the OAM cell receiving unit 16 extracts the outgoing side VP switching response cell, and switches the connection information of the header conversion table 13 from the active system to the standby system in response to this. As a result, in the line corresponding unit 6A, VP6 / V
C3 to VP4 / VC3 and VP6 / VC of the input cell
4 to VP4 / VC4 and replace them with the line
Lead to B. As described above, the use of the failure link PL3 for the up route in the protection section is avoided.

On the other hand, in the line corresponding section 3B, the OAM cell receiving section 16 extracts the outgoing VP switching response cell and, at the same time, shuts down the use of the active system in the header conversion table 13. As a result, the line corresponding unit 3B discards the subsequent input cells VP3 / VC1 and VP3 / VC2, for example. Further, in response to the input of the VP switching response cell to the header conversion unit 12, the line corresponding unit 4B switches to use the connection information of the active system and the connection information of the standby system of the header conversion table 13 together. As a result, in the line corresponding unit 4B, the VP4 /
VC2 to VP5 / VC2 and VP4 / V of the input cell
C4 is rewritten to VP6 / VC4, these are led to the line corresponding units 5A and 6A, respectively, and VP4 of the input cell is newly added.
/ VC1 to VP5 / VC1, and VP4 /
VC3 is rewritten to VP6 / VC4, and these are led to the line corresponding units 5A and 6A, respectively. As described above, the normal link PL is applied to the down route of the protection section.
Connection routes to 5 and 6 were secured.

Incidentally, the header conversion tables 13 of the line corresponding sections 3A and 3B hold connection information of the standby system when a failure occurs in the physical link PL4 (VP4). In the first embodiment, the VP switching request cell is generated by the OAM cell generation unit 15 of the line corresponding unit 3B.
It is also possible to use a P trigger cell or a predetermined device cell, and insert a VP switching request cell in the line corresponding unit 4B.

Further, the generation of the VP switching request / response cells, the transmission / reception control thereof, and the switching control of each header conversion table 13 in each line corresponding unit based on the above are collectively performed by the call control units 22A and 22B. You may be comprised so that it may perform. Further, the contents of each header conversion table 13 may be configured to be reset by the call control units 22A and 22B when necessary.

In the first embodiment, the switching node 10B switches the connection information of its own node from the active system to the standby system after receiving the VP switching response cell from the switching node 10A. For example, when transmitting the VP switching request cell to the switching node 10A, the connection information of the own node may be switched from the active system to the standby system.

FIG. 4 is a diagram for explaining the ATM layer protection method according to the second embodiment, and shows a case where the connection information switching control function is centrally arranged in a switching control unit. In the figure, 23 is a switching control unit, 24 is a control unit that performs switching control, 25 is an OAM cell receiving unit (CRV), 26 is an OAM cell transmitting unit (CXT),
27 is a line switching table holding information on backup VPs corresponding to the failed VP for all VPs of the switching node 10;
Reference numeral 8 denotes a header conversion table that holds active and standby connection information for the all-line corresponding unit 11 of the switching node 10.

The inset (a) shows the configuration of the line corresponding unit 11 (3B). The basic configuration may be the same as that of FIG.
However, the OAM cell generator 15 generates a VP trigger cell based on the failure detection of the failure detector 14. Also, the VP trigger cell from the relay node 40a receives the header conversion unit 1 as it is.
2 is input. On the other hand, the header conversion table 13 holds the setting information of the connection information (including the routing tag information) from the switching control unit 23. This setting information includes information of R = 7 (may be fixed) to which the switching control unit 23 is connected as routing tag information R for the VP trigger cell, the VP switching request cell, and the VP switching response cell.

When a failure occurs in the physical link PL3 (VP3), a VP trigger cell is input to the header conversion unit 12 of the line corresponding unit 3B. The VP trigger cell is a header conversion unit 12
Is assigned routing tag information (R = 7), and ASW
At 21, it is routed to the switching control unit 23 and input to the OAM cell receiving unit 25. The control unit 24 refers to the line switching table 27 with the VP trigger cell VP3, and
VP4 corresponding to the OAM cell transmitting unit 26 is obtained.
The VP switching request cell that specifies the failed VP3 is transmitted. The routing tag information (R =
4) is provided, routed to the line corresponding unit 4B by the ASW 21, and transmitted to the switching node 10A. At this time, the transmission method of the VP switching request cell is 1 or 2
A method of continuously transmitting the above VP switching request cell and monitoring a response time from the opposite node 10A, and a method of constantly generating a VP switching request cell are conceivable.

In the switching node 10A, the line corresponding unit 4
The VP switching request cell input to A is sent to the switching control unit 23. The control unit 24 refers to the line switching table 27 based on the failure VP3 of the VP switching request cell, and obtains a spare VP4 corresponding to the failure VP3. Furthermore, the corresponding standby connection information is extracted from the header conversion table 28,
These are set in the header conversion table 13 of each line corresponding unit 11. The setting is performed for each line corresponding unit 11 using, for example, a specific device cell. After the setting is completed,
4 sends out a VP switching response cell.

The VP switching response cell is input to the line corresponding unit 4B of the switching node 10B via the backup VP4. The VP switching response cell is provided with routing tag information (R = 7) by the header conversion unit 12 and received by the OAM cell receiving unit 25 of the switching control unit 12 via the ASW 21. The control unit 24 refers to the line switching table 27 and the header conversion table 28 based on the failure VP3 of the VP switching response cell, reads out the connection information of the standby system, and uses the cell in the device to read the header information of each line corresponding unit 11 using the cell in the device. Set in the conversion table 13.

According to the second embodiment, the existing AT
Since a node device that does not support the M layer protection can be dealt with only by adding the transmission / reception function of the VP trigger cell and the switching control unit 23, the ATM is not required.
The cost of introducing layer protection can be kept low. Further, the memory amount of each header conversion table 13 can be reduced.

The functions of the switching control unit 23 may be provided in the call control units 22A and 22B, respectively. When transmitting the VP switching request cell to the switching node 10A, the switching node 10B may switch the connection information of the own node from the active system to the standby system. FIG. 5 is a diagram for explaining the ATM layer protection method according to the third embodiment, and shows a case where the switching management node 50 at the center of the system performs the ATM protection control of each switching node 10 in a concentrated manner.

In the figure, 50 is a switching management node, 51
Is a line corresponding unit, 52 is an ATM switch (ASW), 53
Is a control unit for performing ATM layer protection control of the system, and 54 is a fault V for all switching nodes 10 of the system.
A line switching table holding information on the backup VP corresponding to P, and 55 is a header conversion table holding the connection information of the working system and the protection system for all the line handling units 11 of all the switching nodes 10 of the system. is there.

The switching management node 50 is the switching node 1010
Based on the call connection information (working connection information) sent from each of the call control units 22 such as A and 10B, the backup connection information is generated and managed. In the figure, when a failure occurs in the physical link PL3 (VP3), the line corresponding unit 3B
The VP trigger cell is input to the header conversion unit 12 of FIG. VP
The trigger cell is provided with routing tag information (R = 8) by the header conversion unit 12, is routed to the line corresponding unit 8A by the ASW 21, and is connected to the physical link PL8 and the network 1.
00, the switching management node 50 via the physical link PL12
To the line corresponding unit 12B.

The control unit 53 determines the fault VP of the VP trigger cell.
3, a backup VP4 corresponding to the failed VP3 is extracted by referring to the line switching table 54, and the switching node 1
The VP switching request cell is transmitted to 0B. Line corresponding part 8A
In, the VP switching request cell is routed to the line corresponding unit 4B of the backup VP4 corresponding to the failed VP3, and sent to the switching node 10A. Subsequent VP protection control may be the same as that described with reference to FIG.

Instead of transmitting the VP switching request cell from the switching node 10B to the switching node 10A, the switching management node 50 may transmit the VP switching request cell also to the switching node 10A. Switching node 10B in this case
Switches the connection information of its own node from the active system to the standby system upon receiving the VP switching request cell from the switching management node 50, and the switching node 10A receives the VP switching request cell from the switching management node 50 Switch the connection information of the node from the active system to the standby system. And
If necessary, each of the switching nodes 10A and 10B returns a VP switching response cell to the switching management node 50.

FIGS. 6 and 7 show an AT according to the fourth embodiment.
Diagram (1) illustrating the M-layer protection method,
(2), for each VP accommodating one or more VCs,
Or A for each group VP containing one or more VPs
This shows a case where TM layer protection control is performed efficiently. Although the former case will be described here, the latter case can be similarly considered.

In the figure, reference numeral 17 denotes an OAM cell transmission unit (S
CT), 18 is a cell collection unit (SCG) in the VC device, 19
Is a VP switching request cell generation unit (KCG). In the line handling unit 3B of FIG. 7, when a failure is detected on the physical link PL3, the fact is notified to the OAM cell generation unit 15. The OAM cell generation unit 15 outputs the header conversion table 1
3, a cell in the VC device is generated for each fault VC accommodated in the fault VP. For example, cells in the VC device (VP3 / VC1, VP3 / VC3) are generated. If the link PL3 is VP13 / VC11, VP13
Assuming that / VC13 has been multiplexed, cells in the VC apparatus (VP13 / VC11, VP13 / VC13) are further generated. These cells in the VC device are input to the header conversion unit 12, and are guided to the outgoing line corresponding units 5A and 6A according to the active system routing tag information.

In the line corresponding unit 5A, the cell (VP3 / VC1) in the outgoing VC device is extracted (captured) in the OAM cell receiving unit 16 and returned to the incoming side via the in-device cell transmitting unit 17. The folded cell in the VC device (VP
3 / VC1) is provided with standby routing tag information by the header conversion unit 12, and is guided to the line corresponding unit 4B. Also, if the cell in the VC device (VP13 / VC11)
Is turned back, the cell (VP13)
/ VC11) is provided with standby routing tag information by the header conversion unit 12, and for example, the line correspondence unit 4C (not shown)
It is led to.

In the line corresponding unit 6A, the outgoing VC internal cell (VP3 / VC3) is extracted by the OAM cell receiving unit 16 and returned to the incoming side via the internal cell transmitting unit 17. The folded cell in the VC device (VP3 / VC
In 3), the header conversion unit 12 adds the backup routing tag information and is guided to the line corresponding unit 4B. If the cell in the VC device (VP13 / VC13) is turned back here, the cell in the VC device (VP13 / VC1)
3) is led to, for example, a line corresponding unit 4C (not shown) in the header conversion unit 12 according to the standby routing tag information.

In the line corresponding section 4B, each folded cell in the VC device (VP3 / VC1, VP3 / VC3)
Is collected by the cell collection unit 18 in the VC device. The VC device cell collection unit 18 generates connection switching request information for each VP (VP3) accommodating the fault VCs 1 and 3 based on the collected cells in the VC device, and notifies the VP switching request cell generation unit 19 of this. , The VP switching request cell generation unit 19 transmits the corresponding VP switching request cell to the opposite switching node 10A.

Although not shown, also in the line corresponding unit 4C, each folded cell in the VC apparatus (VP13 / V
C11, VP13 / VC13) are collected, and a VP switching request cell for each VP (VP13) accommodating the faulty VCs 11, 13 is generated based on the collected cells in the VC device,
It is transmitted to the opposite switching node 10A. There are several methods for transmitting the VP switching request cell to the switching node 10A. For example, when the first VC device cell arrives at the VC device cell collection unit 18, a VP switching request cell of the corresponding VP is transmitted, and subsequent arrival of the VC device cell for the same VP is ignored. Alternatively, a corresponding VP switching request cell is transmitted when a predetermined number of cells in the VC apparatus are received, and subsequent arrival of cells in the VC apparatus for the same VP is ignored. Alternatively, when the cells in all the VC devices are received, the corresponding VP switching request cell is transmitted. Alternatively, a certain VC is determined in advance as a representative VC, a VP switching request cell is transmitted upon reception of a cell in the VC device of the VC, and arrival of cells in the VC device with respect to other VPs is ignored. In any case, by transmitting the VP switching request cell for each VP, it is possible to avoid an increase in traffic on the link PL4.

In the line corresponding unit 4A of FIG. 6, the VP switching request cell from the line corresponding unit 4B is extracted by the failure detector 14, and the fact is notified to the OAM cell generator 15. Upon receiving this, the OAM cell generation unit 15 outputs the fault VC
Each VC device cell corresponding to 1 and 3 is generated. For example, cells in the VC device (VP3 / VC1, VP3 / VC3) are generated. Each VC device cell is input to the header conversion unit 12, and is guided to the line corresponding units 1B, 2B according to the all-line corresponding units 1B, 2B, 3A, etc., or the backup routing tag information.

In the line corresponding section 1B, the cell (VP3 / VC1) in the outgoing VC device is extracted (captured) by the OAM cell receiving section 16, and triggered by this, the header conversion table 1
The connection information corresponding to the third fault VC1 (VP3) is rewritten (or switched) from the current “VP1 / VC1” → “VP3 / VC1” to the spare “VP1 / VC1” → “VP4 / VC1”. Thereafter, the extracted cell (VP3 / VC1) in the VC device is looped back to the ingress side by the cell transmission unit 17 in the device, and further guided to the line corresponding unit 4A through the header conversion unit 12 by the routing tag information of the standby system. I will

In the line handling unit 2B, the outgoing VC device cell (VP3 / VC3) is extracted by the OAM cell receiving unit 16, and this triggers the connection corresponding to the fault VC3 (VP3) in the header conversion table 13. The information is rewritten from the current “VP2 / VC3” → “VP3 / VC3” to the spare “VP2 / VC3” → “VP4 / VC3”. After that, the cells (VP3
/ VC3) is looped back to the ingress side by the intracellular cell transmission unit 17, and further guided to the line corresponding unit 4A via the header conversion unit 12 by the backup routing tag information.

Although not shown, the line handling unit 4D also handles each VP accommodating the fault VCs 11 and 13 (VP1
The same processing as described above is performed for the VP switching request cell of 3). As described above, the downlink connection information is switched from the working system to the protection system. In the line corresponding unit 3A, the cell (VP3 / VC1, VP3)
3 / VC3) is extracted by the OAM cell receiving unit 16, and triggered by this, the fault VC1, 3
The working connection information corresponding to (VP3) is closed. After that, the cells (VP3
/ VC1, VP3 / VC3) are returned to the incoming side by the intra-device cell transmitting unit 17, and further guided to the line corresponding unit 4A by the backup system routing tag information via the header converting unit 12, or discarded.

In the line corresponding section 4A, each folded cell in the VC device (VP3 / VC1, VP3 / VC3)
Is collected by the cell collection unit 18 in the VC device. The VC device cell collection unit 18 generates connection switching response information for each VP (VP3) accommodating the fault VCs 1 and 3 based on the collected cells in the VC device, and notifies the VP switching response cell generation unit 19 of this, Upon receiving this, the VP switching response cell generating unit 19 stores the corresponding VP switching response cell in the opposite switching node 1.
0B. Note that the same method as described above may be used for transmitting the VP switching response cell to the switching node 10B. At the same time, a fault VC is added to the active connection information in the header conversion table 13.
As the connection information corresponding to 1, 3
P4 / VC1 "→" VP1 / VC1 "and" VP4 / V
“C3” → “VP2 / VC3” is added.

Although not shown in the figure, the line handling unit 4D also stores the VPs (VP1
The same processing as described above is performed for the VP switching request cell of 3). As described above, the uplink connection information is also switched from the active system to the standby system. Returning to FIG. 7, in the line corresponding unit 4B, the VP switching response cell from the line corresponding unit 4A is extracted by the failure detecting unit 14, and to that effect, the OA
The M cell generation unit 15 is notified. OAM cell generator 15
Generates, for example, cells (VP3 / VC1, VP3 / VC3) in the VC device corresponding to the faults VC1, 3. Each V
The cell in the C device is input to the header conversion unit 12, and is guided to the line corresponding units 5A, 6A according to the all-line corresponding units 5A, 6A, 3B or the like or the standby system routing tag information.

In the line handling unit 5A, the cell (VP3 / VC1) in the outgoing VC device is extracted by the OAM cell receiving unit 16, and the connection information corresponding to the fault VC1 in the header conversion table 13 is currently used. "VP5 /
VC1 ”→“ VP3 / VC1 ”to spare“ VP5 / V
C1 "→" VP4 / VC1 ". After that, the extracted cell in the VC device (VP3 / VC1)
Is returned to the incoming side by the in-device cell transmitting unit 17, further provided with standby routing tag information by the header converting unit 12, and guided to the line corresponding unit 4B.

In the line handling unit 6A, the cell (VP3 / VC3) in the outgoing VC device is extracted by the OAM cell receiving unit 16, and the connection information corresponding to the fault VC3 in the header conversion table 13 is currently used. "VP6 /
VC3 ”→“ VP6 / V ”from“ VP3 / VC3 ”
C3 "→" VP4 / VC3 ". Then, the extracted cell in the VC apparatus (VP3 / VC3)
Is returned to the incoming side by the in-device cell transmitting unit 17, further provided with standby routing tag information by the header converting unit 12, and guided to the line corresponding unit 4B.

Although not shown in the figure, the line handling unit 4C also has a VP (VP1) for accommodating the fault VCs 11 and 13.
The same processing as described above is performed for the VP switching response cell of 3). As described above, the uplink connection information is switched from the working system to the protection system. In the line corresponding unit 3B, the cell (VP3 / VC1, VP3)
3 / VC3) is extracted by the OAM cell receiving unit 16, and triggered by this, the fault VC1, 3
The working connection information corresponding to (VP3) is closed. After that, the cells (VP3
/ VC1, VP3 / VC3) are returned to the ingress side by the internal cell transmission unit 17, and further guided to the line corresponding unit 4B by the backup system routing tag information via the header conversion unit 12, or discarded.

In the line corresponding unit 4B, the cells (VP3 / VC1, VP3 / VC3) in the outgoing VC device are extracted by the OAM cell receiving unit 16, and triggered by this, the active connection information of the header conversion table 13 is extracted. VC1 and VC
"VP4" of the standby system as connection information corresponding to
/ VC1 "→" VP5 / VC1 "and" VP4 / VC
3 ”→“ VP6 / VC3 ”.

Although not shown in the figure, the line handling unit 4C also stores the VPs (VP1
The same processing as described above is performed for the VP switching response cell of 3). As described above, the downlink connection information is also switched from the working system to the protection system. The switching node 10B may switch the connection information of its own node from the active system to the standby system before transmitting the VP switching request cell to the switching node 10A (when returning the cell in each VC device). This speeds up processing.

Also, instead of distributing the cells in the VC device to all the lines corresponding units or the lines corresponding to the failures, a certain V
It is also conceivable to circulate the cells in the C apparatus to the all-circuit corresponding unit or the line-corresponding unit for failure by a method of sequentially changing the routing tag information. Further, the control function of the ATM protection may be performed by the call control units 22A and 22B.

According to the fourth embodiment, ATM protection processing is mechanically performed by executing the above-described simple processing algorithm even if a VC (or group VP) fault occurs in any complicated manner. Also, the fault VP
Even when there are a plurality of backup VPs corresponding to VCs accommodated in the server, there is no need to perform special management. FIGS. 8 and 9 are diagrams (1) and (2) for explaining the ATM layer protection method according to the fifth embodiment. Each of the VPs accommodating one or more VCs, or one or more VPs This shows another case in which ATM layer protection control for each group VP accommodating is efficiently performed. Although the former case will be described here, the latter case can be similarly considered.

In the figure, 35 is a VC switching request cell generation unit (KCG), 36 is a VC switching cell receiving unit (KCR),
37 is a VC switching cell transmission unit (KCT). In the line corresponding unit 3B of FIG. 9, each VC switching request cell (VP3 / VC1, VP3 / VC3) generated by the VC switching request cell generating unit 35 by detecting a failure of the link PL3 (VP3).
Are supplied to the standby line corresponding unit 4B in the same manner as described above, but these are sent to the opposite switching node 10A as they are or only by necessary format conversion.

In FIG. 8, each VC switching request cell input to the line corresponding unit 4B is stored in all the line corresponding units 1B, 2B, 3A.
It is distributed (or circulated) to the line corresponding units 1B and 2B corresponding to the equal or fault VCs 1 and 3, activates the switching of necessary connection information, and finally returns to the line corresponding unit 4B. At that time, each VC switching request cell is converted into a VC switching response cell at the time of loopback in the line corresponding units 1B and 2B, respectively.
Returned to the opposite switching node 10B.

Returning to FIG. 9, each VC switching response cell returned to the line corresponding unit 4B is distributed (or circulated) to all the line corresponding units 5A, 6A, 3B, etc. or to the line corresponding units 5A, 6A corresponding to the fault VCs 1,3. ), And activates switching of necessary connection information, and finally returns to the line corresponding unit 4B. Then, each VC switching response cell is extracted (captured) by the VC switching cell receiving unit 36 and finally discarded.

The switching node 10B may switch the connection information of its own node from the active system to the standby system before transmitting the VC switching request cell to the switching node 10A (when returning each VC switching request cell). . This speeds up processing. According to the fifth embodiment, in addition to the effects of the fourth embodiment, the function of collecting VC switching request / response cells can be reduced, and the amount of hardware can be reduced. FIG. 10 shows the sixth
FIG. 4 is a diagram for explaining an ATM layer protection method according to the embodiment of the present invention, in which an in-section alarm transfer cell (VP trigger cell) and an out-of-section alarm transfer cell (VP-AIS cell, VP-FERF cell, etc.) of this ATM layer protection are A case is shown in which distinctive processing is performed to avoid duplicate transfer of alarm transfer cells.

The line corresponding section 11 (for example, 3
The structure of B) is shown. In the figure, 31 is an out-of-section alarm transfer cell detection unit (ODT), 32 is an out-of-section alarm transfer state determination unit (OMT), and 33 is an out-of-section alarm transfer cell generation unit (OC).
G). The out-of-section alarm transfer cell input to the end point of the protection section is transferred to the downstream node according to normal alarm transfer control. Normally, the out-of-section alarm transfer cell is sent at regular time intervals while the fault continues. The out-of-section alarm state determination unit 32 includes an out-of-section alarm transfer cell detection unit 31.
Detects an out-of-section alarm transfer cell by detecting a predetermined number of out-of-section alarm transfer cells continuously, and detects no out-of-section alarm transfer cell by continuously detecting the out-of-section alarm transfer cell for a predetermined number of times or for a predetermined period. It is determined that it is not in the state. Therefore,
The state of the out-of-section alarm can be determined, and the out-of-section alarm transfer cell can be transferred.

The alarm transfer (VP trigger) cell within the section input to the end point of the protection section is extracted (captured) by the failure detection unit 14. Preferably, the alarm transfer cell in the section is also transmitted at regular time intervals while the failure continues. The fault detecting unit 14 determines that the in-section alarm transfer cell has been detected by continuously extracting the in-section alarm transfer cell once or a predetermined number of times, and detects the in-section alarm transfer cell continuously for a predetermined number of times or for a predetermined period. If not, it is determined that it is not in the section alarm state. Then, when the failure detection unit 14 determines that the alarm state is within the section, the OAM cell generation unit 15 and the out-of-section alarm transfer cell generation unit 33 are activated.

As a result, the OAM cell generation unit 15 generates a VP switching request cell used in the protection section or a series of cells in the VC device used in the switching node 10B. However, these cells are generated only once.
On the other hand, the out-of-section alarm transfer cell generating unit 33 generates out-of-section alarm transfer cells at regular time intervals on condition that the out-of-section alarm state determination unit 32 determines that the out-of-section alarm state is not set. These out-of-section alarm transfer cells are transferred to downstream nodes according to normal alarm transfer control. Therefore, a fault occurring in the protection section can be reported to another section by the out-of-section alarm transfer cell. The out-of-section alarm transfer cell generation unit 33 does not generate an out-of-section alarm transfer cell when the out-of-section alarm state determination unit 32 determines that the out-of-section alarm state is present. Therefore, it is possible to prevent the out-of-section alarm transfer cell from being transferred to another section in an overlapping manner, and to prevent the possibility of pressure on the link band.

Instead of using the out-of-section alarm state as the determination condition, the in-section alarm state is used as the determination condition to control the flow of the out-of-section alarm transfer cell input to the end point of the protection section. Is also good. Further, the flow control function of the out-of-section alarm transfer cell may be provided on the output side (source point side) of the line corresponding unit. Although the above embodiments have been described mainly with respect to the example of the VP protection, the present invention provides the VC protection and the switching node having the VP protection.
The present invention can also be applied to a switch (cross-connect device or the like).

In each of the above embodiments, the case where the faulty connection is switched from the working system to the protection system has been described. However, the case where the protection system is switched back from the protection system to the working system can be similarly considered. In addition, although a plurality of embodiments suitable for the present invention have been described, it is needless to say that various changes can be made in the configuration, control, and combination of these components without departing from the spirit of the present invention.

[0092]

As described above, according to the present invention, each node mutually holds the connection information of the working system and the protection system for the protection section, and the connection switching request specifying the failed connection from the failure detecting node 10B. Due to the configuration for transmitting cells to the opposing node 10A, even in the case of generally complicated ATM layer protection, independent (by distributed control) for each protection section
Highly reliable ATM layer protection can be efficiently performed with a simple configuration and control.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a diagram (1) illustrating an ATM layer protection scheme according to the first embodiment;

FIG. 3 is a diagram (2) illustrating an ATM layer protection scheme according to the first embodiment.

FIG. 4 is a diagram illustrating an ATM layer protection scheme according to a second embodiment.

FIG. 5 is a diagram illustrating an ATM layer protection scheme according to a third embodiment.

FIG. 6 is a diagram (1) illustrating an ATM layer protection scheme according to a fourth embodiment.

FIG. 7 is a diagram (2) illustrating an ATM layer protection scheme according to a fourth embodiment.

FIG. 8 is a diagram (1) illustrating an ATM layer protection scheme according to a fifth embodiment;

FIG. 9 is a diagram (2) illustrating an ATM layer protection scheme according to a fifth embodiment.

FIG. 10 is a diagram illustrating an ATM layer protection scheme according to a sixth embodiment.

FIG. 11 is a diagram illustrating an AIS cell format.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Switching node (ATM switch, cross-connect device, etc.) 11 Line handling unit 12 Header conversion unit (HCV) 13 Header conversion table 14 Failure detection unit (EDT) 15 OAM cell generation unit (SCG) 16 OAM cell reception unit (SCR) Reference Signs List 17 OAM cell transmission unit (SCT) 18 Cell collection unit in VC device (SCG) 19 VP switching request cell generation unit (KCG) 21 ATM switch (ASW) 22 Call control unit 23 Switching control unit 24 Control unit 25 OAM cell receiving unit (CRV) 26 OAM cell transmission unit (CXT) 27 Line switching table 28 Header conversion table 31 Out-of-section alarm transfer cell detection unit (ODT) 32 Out-of-section alarm state determination unit (OMT) 33 Out-of-section alarm transfer cell generation unit (OCG) ) 35 VP switching request cell generator (KCG) 36 VP switching cell receiver (K R) 37 VP switching cell transmission section (KCT) 40 relay nodes 50 switch management node

 ──────────────────────────────────────────────────の Continuing from the front page (71) Applicant 000005108 Hitachi, Ltd. 4-6-1 Kanda Surugadai, Chiyoda-ku, Tokyo (72) Inventor Kenichi Kawai 4-1-1 1-1 Uedanaka, Nakahara-ku, Nakazaki-ku, Kawasaki-shi, Kanagawa Fujitsu Stock Inside the company (72) Inventor Kazuyuki Suzuki 4-1-1, Kamidadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Inside Fujitsu Limited (72) Inventor Koichi Minada 3-192-2 Nishishinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone (72) Inventor Yukihiro Doi 3-192-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Masami Hagio 1-7-112 Toranomon, Minato-ku, Tokyo Oki Electric Industrial Co., Ltd. Inside the company (72) Takaaki Higashi 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Norihiko Moriwaki Tokyo Kokubunji Koigakubo chome 280 address Co., Ltd., Hitachi Central Research Institute in (72) inventor Akio Makimoto Kanagawa Prefecture, Totsuka-ku, Yokohama-shi Totsuka-cho, 216 address Co., Ltd., Hitachi Information and Communications business unit

Claims (17)

[Claims] 1. A communication failure in a protection section is determined by an AT.
In an ATM layer protection method for protection in the M layer, a plurality of nodes mutually holding active and standby connection information for a protection section are provided, and a communication failure of a working connection is detected at an end point of the protection section. The failure detection node generates a connection switching request cell specifying the failed connection, transmits the cell to the opposing node, and, upon transmission and reception of the connection switching request cell, triggers the failure detection node and the opposing node respectively. A characterized by switching a failed connection to a standby connection
TM layer protection method. 2. The opposite node switches a failure connection of its own node to a connection of a standby system upon receiving a connection switching request cell, and transmits a connection switching response cell to a failure detection node. 2. The ATM layer protection method according to claim 1, wherein a failure connection of the own node is switched to a connection of a protection system upon reception of a cell. 3. A communication failure in a protection section is determined by an AT.
In a node device of an ATM communication system protected by an M layer, a connection information holding unit for mutually holding active and standby connection information on a protection section, and a communication failure in the protection section at an end point of the protection section. A failure detection unit to detect, and generates a connection switching request cell specifying a failed connection by the failure detection of the failure detection unit, transmits the cell to the opposite node, and receives a connection switching response cell from the opposite node. A switching control unit for switching a failed connection of the own node to a standby connection. 4. A communication failure in a protection section is determined by an AT.
In a node device of an ATM communication system protected by an M layer, a connection information holding unit for mutually holding connection information of a working system and a protection system for a protection section, and a connection switching request cell specifying a failed connection from a failure detecting node. A node device, comprising: a switching control unit configured to switch a corresponding failed connection of the own node to a connection of a standby system in response to the reception. 5. The switching control unit according to the failure detection unit, detects a failure of every VC or VP under the failed connection.
A connection switching request cell is generated for each VP or group VP for which a faulty connection has been specified for each backup VP or group VP accommodating these, and the cell is transmitted to the opposite node. 4. The method according to claim 3, wherein a failure connection corresponding to the own node is switched to a connection of a standby system when a connection switching response cell for each group VP is received.
2. The node device according to 1. 6. The switching control unit, for each VC or all VPs under the fault connection from the fault detection node, for each VP or group VP that specifies a fault connection for each backup VP or group VP that accommodates them. 5. The node device according to claim 4, wherein the failure connection corresponding to the own node is switched to the connection of the standby system by receiving the connection switching request cell. 7. The node device according to claim 3, wherein the switching control unit switches the failed connection of the own node to the connection of the standby system without waiting for the connection switching response cell from the opposite node. 8. The switching control unit according to claim 4, wherein the switching control unit switches the corresponding failed connection of the own node to the connection of the standby system, and transmits a connection switching response cell to the failure detecting node. Node device. 9. A communication failure in a protection section is determined by an AT.
In a node device of an ATM communication system protected by an M layer, a connection information holding unit for mutually holding active and standby connection information of a protection section, and a faulty connection by detecting a communication fault at an end point of the protection section. All VCs or all Vs under
A first line-corresponding unit for generating predetermined internal cells for each P and outputting them downstream in accordance with the active connection information; and capturing the internal equipment cells on the outgoing side and connecting the cells to the standby connection. One or two or more second line corresponding units that are turned back into the device according to the information, and the faulty connection is specified for each backup VP or group VP that collects the turned-back cells in the device and accommodates them. A node device comprising: one or more third line corresponding units for generating a connection switching request cell for each VP or for each group VP and transmitting the cell to an opposite node. 10. A communication failure in a protection section is set to A.
In a node device of an ATM communication system protected by a TM layer, a connection information holding unit for mutually holding active and standby connection information for a protection section, and a fault connection for each VP or each group VP from a fault detection node. Upon receiving the connection switching request cell for each specified VP or each group VP, a predetermined device cell is generated for each of all the VCs or VPs of the corresponding failed connection, and these cells are transferred upstream according to the connection information of the standby system. One or more first line corresponding units to be output, and a cell in the device on the outgoing side which is captured and the corresponding faulty connection is switched from the working system to the standby system, and the captured cell is connected to the standby system. One or more second line pairs that loop back into the device according to the information Node device, characterized in that it comprises a part. 11. A communication failure in a protection section is designated as A.
In a node device of an ATM communication system that is protected by a TM layer, a connection information holding unit that mutually holds connection information of a working system and a protection system with respect to a protection section, and a failure connection by detecting a communication failure at an endpoint of the protection section. All VCs or all Vs under
A first line-corresponding unit for generating predetermined connection switching request cells for each P and outputting them downstream in accordance with the connection information of the active system; One or more second line corresponding units that return to the device according to the connection information of the above, and one or more third line corresponding units that transmit the returned connection switching request cell to the opposite node. A node device characterized by the above-mentioned. 12. A communication failure in a protection section is defined as A
In a node device of an ATM communication system protected by a TM layer, a connection information holding unit for mutually holding active and standby connection information for a protection section, and all VCs under a fault connection from a fault detection node.
Or one or more first line-corresponding units that output connection switching request cells transmitted upstream for all VPs in accordance with standby connection information, respectively, and a connection switching request cell on the outgoing side. And switching one or more second line corresponding units to return the captured cell to the apparatus according to the connection information of the standby system while switching its corresponding connection information from the active system to the standby system. Characteristic node device. 13. The system according to claim 9, wherein the second and third line corresponding units switch each corresponding failed connection from the active system to the standby system after receiving the connection switching response cell from the opposite node. 12. The node device according to 11. 14. The system according to claim 9, wherein the second and third line corresponding units switch each corresponding failed connection from the active system to the standby system without waiting for a connection switching response cell from the opposite node. 12. The node device according to 11. 15. The first line responding unit switches its own connection from the active system to the standby system when receiving a connection switching request cell from the failure detecting node or when collecting one or more return cells in the own node. The node device according to claim 10, wherein the switching is performed. 16. The system according to claim 10, wherein the first line-corresponding unit transmits a connection switching response cell to the failure detecting node after collecting one or more return cells in the own node. The described node device. 17. A communication failure in a protection section is designated as A.
A node device of an ATM communication system that protects at a TM layer, comprising: an alarm cell identification unit for identifying an alarm transfer cell outside a section generated outside a section of protection and an alarm transfer cell within a section generated within a section; Based on the identification result of the section, while the out-of-section alarm transfer cell is input from the upstream, the out-of-section alarm transfer cell is transferred to the downstream, and the out-of-section alarm transfer cell is not input, and the in-section alarm transfer cell And a warning cell transfer control unit that converts the in-section alarm transfer cell into an out-of-section alarm transfer cell and transfers the cell to the downstream when the alarm occurs.