JP3036527B2 - ATM alarm masking method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for detecting the normality of a virtual path communication channel, which requires a self-healing (SH: Self Healing) processing time for a virtual path (VP) in an ATM switch. Continuity check (CC) The present invention relates to an ATM alarm masking method and apparatus for preventing occurrence of a VP / CC disconnection alarm on an ATM exchange side when a disconnection detection time is exceeded.

[0002]

2. Description of the Related Art Conventionally, an ATM network shown in FIG. 7 is composed of an ATM cross-connect device XC1, 2, 3, 4 and an ATM switch SW accommodated in the ATM cross-connect devices XC1, XC3 through an optical fiber transmission line through a reproducing device.
It has ATM nodes 1 and 3. This ATM
ATM accommodated in cross-connect devices XC1 and XC3
Each of the exchanges SW1 and SW3 accommodates a plurality of ATM terminals TE1 and a plurality of ATM terminals TE3 for performing data communication.

A virtual channel connection (V) is provided between ATM terminals TE1 and TE3 (end-to-end terminal).
A virtual path (VP) handler (VPH: Virtual Path Handler) that relays a CC: Virtual Channel Connection.
P) Connection (VPC: Virtual Path Connection)
Are exchanged by the ATM exchanges SW1 and SW3. Also, A
The ATM cross-connect devices XC1 and XC3 accommodating the TM exchanges SW1 and SW3 form a digital section together with a reproducing device for reproducing an optical signal from an optical fiber transmission line. As described above, the ATM network is configured in a hierarchical manner, so that it is possible to easily cope with a change in the processing mode at each hierarchical level, and further, when a failure occurs, the failure identification and recovery are facilitated.

For example, as shown in FIG. 7, a transmission line failure occurs, and the self-healing (SH) processing time is reduced by the virtual path communication channel in the maintenance information in the maintenance cell (OAM cell) transmission at the ATM terminal TE1. If the VP / CC disconnection detection time to confirm normality is exceeded, ATM
The cross-connect device XC1 performs a process of generating an alarm for the ATM switch SW1. The same applies to a case where a node failure occurs in the ATM cross-connect device XC2 as shown in FIG.

During the SH processing for each VP path, the ATM
ATM cross-connect devices XC1 and XC in nodes
3 performs alarm masking to the ATM switches SW1 and SW3. That is, during the SH processing, not the “failure period” but the “failure recovery period”, so that the alarm indicating the occurrence of the VP flow in the ATM switches SW1 and SW3 as the VP termination points is prevented from being generated. .

[0006] The normality of the virtual path communication channel is confirmed by the VP / CC in the OAM function. That is, in the ATM transmission, an arbitrary transfer rate can be set according to the number of transfer cells, variable speed communication is possible, and an OAM function is provided. In this OAM function, a maintenance cell (OA) having the same destination label is used.
M cell) to notify a failure or the like in the same communication channel, and to transfer maintenance information for evaluating performance.

As described above, the VP / CC in the OAM function
Has confirmed the normality of the virtual path communication channel, the ATM switch SW1 on the transmitting side in this case.
SW3 generates the minimum cell transmission regardless of the presence or absence of the user information, and receives the ATM switch SW1 on the receiving side.
At SW3, the normality of the virtual path communication channel is detected.

For example, in the conventional example of Japanese Patent Application Laid-Open No. H10-65685, "Continuity Check Cell Monitoring Circuit", the receiving side is in spite of the presence of an empty cell in the cell flow and the transmission of the CC cell. , The CC cell is monitored by monitoring an abnormal state in which a CC cell is not received, and determining whether the CC cell transmitting side has an abnormal response or insertion state.

[0009]

As described above, in the above conventional example, in the normality detection of the virtual path communication channel, the self-healing (SH) processing time exceeds the VP / CC disconnection detection time in the ATM exchange. In case, VP ・ C
A VP / CC disconnection alarm occurs in the ATM switch that detects the disconnection of the C cell. That is, when the SH processing succeeds after the occurrence of the VP / CC disconnection alarm, an alarm is generated on the ATM exchange side despite the fact that the failure can be remedied.

[0010] In this case, the AT
Switching virtual channel (SV
C) In the case of a line, there is a possibility that the line is disconnected. This line disconnection has a great effect in view of the fact that the number of virtual channels (VC) accommodated in the virtual path (VP) in the ATM exchange, that is, the number of users is large. Therefore, in the conventional ATM communication, a high quality AT
In order to perform the M transmission, it is a problem that an alarm is not generated in the ATM exchange even when the VP / CC disconnection is detected during the SH processing.

The present invention solves such a problem in the prior art. In detecting the normality of the virtual path communication channel, the self-healing processing time is longer than the VP / CC disconnection detection time in the ATM switch. , The occurrence of a VP / CC disconnection alarm on the ATM exchange side can be prevented.
It is an object of the present invention to provide an ATM alarm masking method and an apparatus thereof capable of preventing a disconnection of a line of a switched virtual channel performing an M switching service.

[0012]

In order to achieve the above-mentioned object, an ATM alarm masking method according to the present invention comprises an ATM cross-connect device disposed on a loop-shaped transmission path, and an ATM cross-connect device.
An ATM terminal is accommodated through an M exchange, and when a self-healing (SH) processing time exceeds a virtual path continuity check (VP / CC) disconnection detection time, an alarm is prevented from being generated. The ATM cross-connect devices on both sides of the road or node detect a fault occurrence alarm on the user network interface, and then, upon detecting this alarm, perform SH processing on the VP / CC.
Until the time (T1) exceeding the disconnection detection time (T), and from the alarm detection until the time (T1), a pseudo VP / CC cell is sent to the ATM exchange side to perform alarm masking. I have.

The SH processing time is the time required to secure a detour, and if the SH processing is successful, V
After the reception of the P / CC cell is completed, the user A
When a TM cell is transmitted and SH processing fails, VP
After the reception of the CC cell, alarm masking based on the next alarm is re-executed.

Further, in the ATM alarm masking device of the present invention, the ATM cross-connect device arranged on the loop transmission path accommodates the ATM terminal through the ATM exchange,
Self-healing (SH) processing time
This is to prevent the occurrence of an alarm when the continuity check (VP / CC) disconnection detection time is exceeded, and the ATM cross-connect devices on both sides of the transmission line or the node where the failure has occurred cause a failure alarm at the user network interface. When SH is detected, the SH processing is executed until the time (T1) exceeding the VP / CC disconnection detection time, and the VP / CC cell is used for alarm masking to the ATM exchange accommodating from the alarm detection until the time (T1). The ATM switch transmits the VP / CC cell and performs alarm masking to prevent the occurrence of an alarm during the reception time of the VP / CC cell.

The ATM cross-connect device includes at least a connection communication control unit for controlling connection communication with a network, a switching unit for switching a detour, and a detection unit for detecting an alarm when a failure occurs in a user network interface. An alarm mask unit for performing alarm masking on the ATM switch side, an SH processing unit for executing SH processing, a CC cell insertion unit for transmitting a VP / CC cell to the ATM switch side for alarm masking, and an ATM switch. And an interface unit for processing the line connection.

[0016] The ATM exchange comprises at least an ATM.
An exchange interface for processing connection with the cross-connect device, and a VP / CC from the exchange interface
The configuration includes an alarm masking processing unit that performs an alarm masking process based on a cell, and a terminal interface unit that processes a line connection with an ATM terminal.

The SH processing time is the time required to secure a detour, and if the SH processing is successful, the VP
-After the end of the CC cell reception, the user AT through the detour
When the M cell is transmitted and the SH processing has failed, after the reception of the VP / CC cell is completed, alarm masking based on the next alarm is re-executed. Further, the VP / CC cell transmitted to the ATM exchange is configured as a pseudo VP / CC cell.

According to the ATM alarm masking method and apparatus of the present invention, a pseudo VP / CC cell is inserted into the ATM cross-connect device accommodating the ATM exchange during the self-healing process and transmitted to the ATM exchange side. (Notice.

As a result, in the detection of the normality of the virtual path communication channel, if the SH processing time exceeds the VP / CC disconnection detection time in the ATM exchange, a VP / CC disconnection alarm is generated on the ATM exchange side. Can be stopped. In other words, when self-healing succeeds after the occurrence of the VP / CC disconnection alarm,
The generation of the P · CC disconnection alarm is prevented. This allows, among other things, a large number of users at any
It is possible to prevent line disconnection in a switched virtual channel for performing ATM communication by the TM switching service.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of an ATM alarm masking method and apparatus according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an ATM network configuration in an embodiment to which the ATM alarm masking method and apparatus of the present invention are applied. In the following text and figures, the same components as those in the conventional example of FIG.
The same reference numerals are given.

In the ATM network of this embodiment, ATM cross-connect devices XC1, X2, X3, and XC4 are connected by a transmission line such as an optical fiber. The ATM switches S21 and S21 are connected to the ATM cross-connect devices XC1 and XC3, respectively.
W3 is accommodated. Further, ATM exchanges SW1, S
Each of W3 accommodates a large number of ATM terminals TE1 and a large number of ATM terminals TE3 such as personal computers. The ATM cross-connect devices XC1 to XC1
The illustration of the reproducing apparatus in the digital section (optical fiber transmission) between the XCs 4 is omitted.

FIG. 2 is a functional block diagram of the ATM cross-connect devices XC1 to XC4 according to the present invention. FIG.
ATM cross-connect devices XC1 to XC4 shown in FIG.
e Interface), a connection communication control unit 10 for executing connection communication control (interface / communication protocol), a detour switching unit 11 for switching a detour under the control of the connection communication control unit 10, and a physical layer (user layer interface). PHY) and an alarm detection unit 12 for monitoring and detecting an alarm 41 of the ATM layer.

Further, the ATM cross-connect device XC
1 to XC4 include an alarm mask unit 13 that performs alarm masking for the ATM switches SW1 and SW3, and a self-healing (S) that performs a self-healing (SH) process.
H) Insert a virtual path continuity check (CC) cell 51 with the processing unit 14 and
An XC interface (I / I / O) for processing the interface of the line connection between the CC cell insertion unit 15 transmitting (notifying) to the terminals TE1 and TE3 and the ATM exchanges SW1 and SW3.
F) A configuration including a unit 16 and a CPU 17 that controls each unit.

FIG. 2 omits illustration of a flow processing system related to other ATM cell delay processing (buffer / FIFO) and the like.

FIG. 3 shows an ATM switch SW corresponding to the present invention.
1 is a functional block diagram of SW3. ATM shown in FIG.
The exchanges SW1 and SW3 are ATM cross-connect devices X
An exchange interface unit 20 for processing connection with the C1 and XC3; an alarm masking processing unit 21 for performing an alarm masking process based on the VP / CC cell 51 received through the exchange interface unit 20;
A terminal interface (I / F) unit 22 for processing an interface for line connection with E1 and TE3;

FIG. 3 omits illustration of other flow processing systems relating to delay processing (buffer / FIFO) of ATM cells.

Each of the ATM terminals TE1 and TE3 has, for example, a configuration in which a general-purpose small computer is provided with a connection interface device with the ATM exchanges SW1 and SW3 and a communication control device for executing a communication protocol with an ATM network.

The ATM network shown in FIG. 1 transfers ATM cells by a virtual channel (VC) and a virtual path (VP), but is set up between end terminals between the ATM terminals TE1 and TE3. The ATM exchanges SW1 and SW3 relay the VC communication channel (VCC). ATM exchanges SW1, SW3 and ATM cross-connect device XC1
XC4 is a VC handler (V
CH). ATM cross-connect devices XC1 to XC4 relay a virtual path communication channel (virtual path connection, VPC) between the VC handlers.

The ATM cross connect device XC here
1, XC3 has an alarm masking function. That is, the maintenance cell (OA) in virtual path (VP) units
M cell) and accommodated ATM exchanges (SW1, SW
For 3), an alarm during self-healing (SH) is masked for each virtual path (VP). Also, A
The TM exchanges SW1 and SW3 have a VP / CC function.

Next, the operation of this embodiment will be described. Here, a VC communication channel (VC connection / VC) is connected between the ATM switch SW1-ATM cross-connect device XC1-XC2-XC3-ATM switch SW3 in FIG.
CC) to perform the ATM communication. Also, AT
A detour for the transmission order of the M cross-connect devices XC1-XC2-XC3 is the ATM cross-connect device XC1.
-The transmission order is XC4-XC3.

FIG. 4 is a diagram for explaining the operation when a failure occurs in the transmission line in the ATM network of FIG. FIG. 4 shows an ATM cross-connect device XC
This figure shows the operation state of the ATM network when the self-healing (SH) processing time for the transmission line failure between the X1 and XC2 exceeds the VP / CC disconnection detection time on the side of the ATM switches SW1 and SW3.

In FIGS. 1 to 4, when a failure occurs in the transmission line between the ATM cross-connect devices XC1 and XC2, the nodes of the ATM cross-connect devices XC1 and XC3 on both sides use the physical layer (PHY) and the ATM layer. Is detected by the monitor in the connection communication control unit 10 and the alarm detection unit 12. By this detection, the alarm masking (transmission of the alarm mask 42) for the ATM switches SW1 and SW3 is performed by the alarm mask units 13 and C.
The C cell insertion unit 15 executes. In this case, arbitrary switching 31 by the connection communication control unit 10 and the detour switching unit 11
Executes the ATM cross-connect device XC1-X
A detour is set in the transmission order of C4-XC3. As a result, communication between the ATM switches SW1-SW3 is continued, and the ATM communication is maintained.

The operation of the main part of the alarm masking will be described in detail. FIG. 5 shows the ATM cross-connect device X shown in FIG.
ATM cross-connect devices XC1 and XC3 and ATM switch SW when a transmission line failure occurs between C1 and XC2
1 is a timing chart of the operation of SW3. This FIG.
When a transmission line failure occurs between the ATM cross-connect devices XC1 and XC2, self-healing (S
H) Processing time is VP in ATM switches SW1 and SW3
-ATM cross-connect devices XC1 and XC3 and ATM switch SW when CC disconnection detection timeout time is exceeded
1, SW3 operation timing.

4 and 5, when a transmission path failure occurs between the ATM cross-connect devices XC1 and XC2, the ATM cross-connect devices XC1 and XC2 on both sides of the ATM cross-connect devices XC1 and XC2.
3, the alarm 41 in the physical layer (PHY) and the ATM layer in the user network interface (UNI) as shown in FIG.
The alarm detection unit 12 monitors and detects through 0.

Upon detection of the alarm 41, the self-healing (SH) processing unit 14 executes the self-healing (SH) processing until time T1 at time t. The time T1 is set to A by the arbitrary switching 31 performed by the connection communication control unit 10 and the detour switching unit 11.
This is the time until the detour is set (switched) in the transmission order of the TM cross-connect devices XC1-XC4-XC3.

Connection communication control unit 10 and alarm detection unit 1
2 and the ATM cross-connect devices XC1 and XC3 receive the
The alarm masking unit 13 and the CC cell inserting unit 15 execute alarm masking (transmission of the alarm mask 42) for the M exchanges SW1 and SW3. In performing this alarm masking,
As shown in FIG. 5 (b), the ATM cross-connect device XC
1, XC3 to ATM exchange SW1, SW3,
During the SH processing, the CC cell insertion unit 15 inserts the pseudo VP / CC cell 51, and the XC interface unit 16
It is sent to the TM exchanges SW1 and SW3.

In the ATM exchanges SW1 and SW3, the ATM
The VP / CC cells 51 from the cross-connect devices XC1 and XC3 are received through the exchange interface unit 20 and transmitted to the alarm masking processing unit 21. When the alarm masking processing section 21 exceeds the VP / CC disconnection detection time T, the time T1 of the end of the self-healing (SH) processing.
Until the VP / CC cell 51 is received.

Therefore, until this time T1, the ATM
The alarm 41 is no longer detected on the exchanges SW1 and SW3, and the alarm masking is executed on the ATM exchanges SW1 and SW3. Further, in the ATM exchanges SW1 and SW3, the terminal interface unit 22 has a large number of ATM terminals T.
It performs exchange connection processing with E1 and TE3, and performs ATM communication through the ATM cross-connect devices XC1 and XC3.

The self-healing (S) shown in FIG.
H) When the processing is successful, the ATM cross-connect device XC secured by switching after the reception of the VP / CC cell 51 is completed.
The user ATM cell is transmitted through the detour in the transmission order of 1-XC4-XC3. Also, when the self-healing (SH) process shown in FIG.
After the reception of the cell 51 is completed, alarm masking by the next alarm 43 is executed. That is, FIGS. 5A and 5B
The alarm masking at the timing of (c) is executed again.

As a result, it becomes possible to prevent the occurrence of an alarm on the ATM exchanges SW1 and SW3 side, and in particular, the virtual channel (V) accommodated in the virtual path (VP).
C) The number of users (the number of users) can prevent line disconnection in a large number of switched virtual channels (SVCs), and high-quality ATM transmission becomes possible.

FIG. 6 is a diagram for explaining the operation of the ATM cross-connect device XC2 in the ATM network of FIG. 1 when a node failure occurs. This FIG.
The self-healing (SH) processing time for the node failure of the ATM cross-connect device XC2 is shorter than that of the ATM switch S.
The operation state of the ATM network when the VP / CC disconnection detection time on the W1 and SW3 side is exceeded is shown.

The operation in this case is the same as the operation when a failure occurs in the transmission line in the above-described ATM network. That is, the ATM cross-connect device XC1,
The XC3 node monitors and detects the alarm 41 and
The alarm masking (transmission of the alarm mask 42) for the TM exchanges SW1 and SW3 is executed. In this case, a detour is formed by the execution of the arbitrary switching 31 and A
Communication between the TM exchanges SW1 to SW3 continues,
TM communication is maintained.

Further, when the alarm 41 is detected, the AT
The alarm masking (transmission of the alarm mask 42) from the M cross-connect devices XC1 and XC3 to the ATM exchanges SW1 and SW3 housed therein is executed. In this execution, during self-healing (SH) processing, pseudo VP
-Insert the CC cell 51 and switch the ATM switches SW1 and SW
3

In the ATM exchanges SW1 and SW3, VP
Self-healing when the CC disconnection detection time T is exceeded (S
H) Until the processing end time, the VP / CC cell 51 is received and the alarm 41 is not detected. FIG. 5 (b)
The operation at the time of success or failure of the self-healing (SH) process shown in (c) is the same as the operation at the time of occurrence of a failure in the transmission line in the above-described ATM network.

In this embodiment, the AT shown in FIG.
The alarm masking processing unit 21 provided in each of the M exchanges SW1 and SW3 performs alarm masking with the alarm mask 42 from the ATM cross-connect devices XC1 and XC3. This alarm masking is performed by the ATM terminals TE1 and TE3.
It may be performed in. In this case, the ATM switch SW
1, SW3 does not include the alarm masking processing unit 21. That is, the ATM switches SW1 and SW3 perform only the switching process for the plurality of ATM terminals TE1 and the plurality of ATM terminals TE3.

[0046]

As is apparent from the above description, according to the ATM alarm masking method and apparatus of the present invention, A
In an ATM cross-connect device accommodating a TM exchange, a pseudo VP / CC cell is inserted during self-healing processing and transmitted (notified) to the ATM exchange side.

As a result, in the detection of the normality of the virtual path communication channel, if the SH processing time exceeds the VP / CC disconnection detection time in the ATM exchange, a VP / CC disconnection alarm is generated on the ATM exchange side. Can be stopped.

That is, the occurrence of the VP / CC disconnection alarm when the failure can be remedied when the self-healing succeeds after the occurrence of the VP / CC disconnection alarm is prevented. It is possible to prevent line disconnection in the switched virtual channel.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an ATM network configuration according to an embodiment to which an ATM alarm masking method and apparatus according to the present invention are applied.

FIG. 2 is a functional block diagram of the ATM cross-connect device in the embodiment.

FIG. 3 is a functional block diagram of the ATM exchange in the embodiment.

FIG. 4 is a diagram illustrating an operation when a transmission line failure occurs in the embodiment.

FIG. 5 is a timing chart of the operation of the ATM cross-connect device and the ATM switch when a transmission line failure occurs in the embodiment.

FIG. 6 is a diagram illustrating an operation when a node failure occurs in the ATM network in the embodiment.

FIG. 7 is a block diagram for explaining the configuration and operation of a conventional ATM network.

[Explanation of symbols]

 SW1, SW3 ATM exchange TE1, TE3 ATM terminal XC1-XC4 ATM cross-connect device 10 Connection communication control unit 11 Detour switching unit 12 Alarm detection unit 13 Alarm mask unit 14 Self-healing processing unit 15 CC cell insertion unit 21 Alarm masking processing unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 12/28 H04M 3/00

Claims (9)

(57) [Claims] An ATM arranged on a loop-shaped transmission path
A cross-connect device accommodates an ATM terminal through an ATM switch, and a self-healing (SH) processing time is reduced by a virtual path continuity check (VP · C).
C) An ATM alarm masking method for preventing occurrence of an alarm when a disconnection detection time is exceeded, wherein an ATM cross-connect device on both sides of a transmission line or a node in which a failure has occurred detects a failure occurrence alarm in a user network interface. Next, when this alarm is detected, the SH processing is performed by the VP · C
Until the time (T1) that exceeds the C disconnection detection time (T), and from the alarm detection until the time (T1), a pseudo VP / CC cell is sent to the ATM exchange side to perform alarm masking. An ATM alarm masking method, comprising: 2. The SH processing time is a time required to secure a detour, and, when the SH processing is successful, transmission of a user ATM cell through the detour is performed after reception of the VP / CC cell is completed. 2. The ATM alarm masking method according to claim 1, wherein when SH processing fails, alarm masking based on the next alarm is re-executed after reception of the VP / CC cell is completed. 3. An ATM arranged on a loop transmission path
A cross-connect device accommodates an ATM terminal through an ATM switch, and a self-healing (SH) processing time is reduced by a virtual path continuity check (VP · C).
C) An ATM alarm masking device for preventing the occurrence of an alarm when the disconnection detection time is exceeded, wherein an ATM cross-connect device on both sides of the transmission line or node where the failure has occurred detects a failure alarm on the user network interface. The SH process is executed until the time (T1) exceeds the VP / CC disconnection detection time, and the VP / CC cell is sent out to the ATM exchange accommodating from the alarm detection until the time (T1) for alarm masking, The ATM alarm masking device, wherein the ATM switch executes alarm masking for preventing occurrence of an alarm during reception of a VP / CC cell. 4. The ATM cross-connect device includes at least a connection communication control unit that controls connection communication with a network, a switching unit that switches a detour, and a detection unit that detects an alarm when a failure occurs in a user network interface. An alarm mask unit for performing alarm masking on the ATM switch side; an SH processing unit for executing SH processing; a CC cell insertion unit for sending VP / CC cells to the ATM switch side for alarm masking; The ATM alarm masking device according to claim 3, further comprising: an interface unit that processes a line connection with the exchange. 5. The ATM switch, comprising: at least a switch interface unit for processing connection with an ATM cross-connect device; and a warning masking processing unit for performing a warning masking process based on a VP / CC cell from the switch interface unit. The ATM alarm masking device according to claim 3, further comprising: a terminal interface unit for processing a line connection with the ATM terminal. 6. The ATM alarm masking apparatus according to claim 3, wherein the SH processing time is a time until a detour is secured. 7. The ATM alarm masking apparatus according to claim 3, wherein, when the SH processing is successful, the transmission of the user ATM cell through the bypass is performed after the reception of the VP / CC cell is completed. 8. The ATM alarm masking apparatus according to claim 3, wherein when the SH processing has failed, alarm masking based on the next alarm is re-executed after the reception of the VP / CC cell is completed. 9. VP / CC to be sent to the ATM exchange
The ATM alarm masking device according to claim 3, wherein the cell is a pseudo VP / CC cell.