JP3252833B2 - ATM communication device and its failure notification method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM communication apparatus for detecting and notifying a failure in an ATM network and a failure notification method thereof.

[0002]

2. Description of the Related Art ATs commonly used in ATM communication devices
Operation and maintenance (hereinafter referred to as O
AM) The processing and flow specifications are in ITU-T ReC.I610
“B-ISDN Operation and Maintenance Principals and
Function ”.

A transmission network of the ATM layer will be described.
FIG. 8 is a configuration diagram of a transmission network of the ATM layer. ATM
The layer transmission network exists in the transmission path of the physical layer,
The transmission function of the ATM layer is a virtual path (hereinafter referred to as V
P) level and a virtual channel (hereinafter referred to as VC) level. When a failure occurs in the transmission path in the ATM network, each VP multiplexed on the transmission path is notified to notify the failure at the connecting point of the VPC multiplexed on the transmission path.
VP-AIS is transmitted to C in the downstream direction. In addition, at the terminal point of the VPC, the VC-AIS is transmitted in the downstream direction with respect to each VCC multiplexed in the VPC.
Is sent. Here, the downstream direction is the direction in which a cell flows when transmitting a cell to a connecting point opposite to the connecting point that has transmitted the received cell, along the flow of the cell transfer path. The upstream direction is the opposite, and indicates the direction in which a cell flows when transmitting a cell to a connecting point that has transmitted the cell. In the case of FIG. 8, when a failure occurs in the transmission path 701, the VP-AIS 711 is transmitted to the VPC-1 (702) and VPC-2 (703) multiplexed on the transmission path 701. Also, V
At the termination points of PC-1 (702) and VPC-2 (703), the multiplexed VCC-1-1 (704)
VC-AIS713 for C-2-1 (705)
Is sent. Also, VPC-1 (702), VPC-
2 (703), the VP-AIS 711 is terminated, and the VP-AIS 711 is transmitted to the opposite VPC end point.
RDI 712 is sent. Similarly, VCC-1-1
(704), Vcc at the termination point of VCC-2-1 (705)
The C-AIS 713 is terminated, and the VC-RDI 714 is sent to the end point of the opposite VCC.

As described above, the OAM flows of the ATM layer include the VP level F4 flow relating to the VP connection and the VC level F5 flow relating to the VC connection. Further, the F4 and F5 flows have two flows, an end-end flow and a segment flow.

Next, an end-to-end flow and a segment flow will be described. FIG. 9 shows VPC and VC
FIG. 6 is a diagram showing a relationship between a connection and a segment related to C. The end and end points of the connection
Between the points (810, 820, 830, 840), connecting points (811, 81) which are connection points.
2, 813, 814, and 831, 832, 833, 83
4) exists. An end-to-end flow is performed for a VP connection 850 and a VC connection 860 sandwiched between two end points at the VP and VC levels. On the other hand, the segment flow is executed for a segment sandwiched between any two connecting points at the VP level and the VC level. Multiple VPs on a VP connection
A C segment can be defined, and a plurality of VCC segments can be defined on a VC connection, but each segment must not overlap. In FIG. 9, the VPC segments are 851, 852 on the VP connection 850.
, The VCC segment is a VC connection 860
It can be set as above, such as 861 and 862. When defining a VP connection and a VC connection, or a VPC segment and a VCC segment, it is necessary to define that each node (device) on the network is an end point or a connecting point, respectively. It depends on the type of ATM connection to be made.

[0006] As described above, the OAM flow of the ATM layer includes end-to-end transmissions for the F4 and F5 flows.
There are two flows, flow and segment flow. However, segment flow alarm notification (AIS /
RDI) is likely to be recommended in the future,
It is not yet recommended in ITU-T Rec. I610.

[0007]

However, when a failure alarm notification for a VPC segment is implemented with the conventional device specifications, two flows, an end-end flow and a segment flow, are placed on the same connection. There is a problem that a failure alarm notification (AIS / RDI) cell is duplicated.

[0008] Here, the alarm transfer operation between devices in the ATM access network will be described. FIG.
FIG. 3 is a diagram showing the position of an access network. The access network 930 is an ATM SW9
20 and subscriber terminals CPE1 (941) to CPEN (9
42) shows the network between. The access network 930 includes an ATM concentrator 931 and a VP multiplexer / demultiplexer 932. VP level AT
When the M connection is confirmed, CPE1 (94
1) to CPEN (942) are devices for terminating the ATM, and therefore are the end points of the VPC. Also,
Since the VP multiplexing / demultiplexing device 932 only changes the VPI value of the ATM cell to be transmitted / received, it becomes a connecting point of the VPC. Further, the ATM concentrator 931
Is the end point of the VPC because the VPI value and the VCI value of the ATM cell to be transmitted and received are changed. Therefore, for the VP level ATM connection, the CPE
FIG. 11 shows an example of 1 (941). CP
VPC between E1 (941) and ATM concentrator 931
1 (1010), ATM concentrator 931 and AT
VPC2 (1020) is set up between MSWs 920.

Therefore, a case where a failure occurs in the ATM connection will be considered. FIG. 12 is a diagram showing a conventional failure alarm notification procedure. ATM Concentrator 931 to C
Regarding the direction in which data flows to the PE1 (941), if a failure occurs at the mark 950, an end-end VP-AIS (hereinafter, referred to as VP-AIS) from the VP multiplexer / demultiplexer 932 which is the nearest connecting point downstream of the failed VPC
EE-VP-AIS) 1110 is sent. EE
The VP-AIS 1110 terminates at CPE1 (941), which is the end point of VPC1 (1010). The CPE1 (941) performs the end-end VP-RDI11 for the connection in the reverse direction of the failed VPC.
20 (hereinafter, E-E VP-RDI) is transmitted upstream. The EE VP-RDI 1120 is terminated at the other end point, the ATM concentrator 931.

Next, consider the case where a VPC segment is set. The VPC segment is generally set from a network management system. The management area of the network management system that manages the access network is shown in FIG.
2, only the ATM concentrator 931 and the VP multiplexer / demultiplexer 932 are provided. Therefore, the VPC segment that can be set is between the ATM concentrator 931 and the VP multiplexer / demultiplexer 932 on the VPC1 (1010). FIG.
FIG. 1 is a diagram showing a conventional fault alarm procedure including a segment level. That is, the ATM concentrator 931 and the VP
A VPC segment 1200 is provided between the multiplexing / demultiplexing devices 932, and the ATM concentrator 931 and the VP multiplexing / demultiplexing device 9
32 are segments of the VPC segment 1200, respectively.
Become an end point.

The ATM concentrators 931 to CPE1 (94
Regarding the direction of data flow to 1), if a failure occurs at the mark 950, the nearest connecting point downstream of the failed VPC, the VP multiplexer / demultiplexer 932
Sends the EE VP-AIS 1110. Also, the VP multiplexing / demultiplexing device 932 outputs the VPC segment 1
Since there are 200 end points, the segment VP-
RDI 1210 (hereinafter Seg VP-RDI) must be sent. EE VP-AIS1110
Is the end point of VPC1 (1010)
It is terminated at PE1 (941). CPE1 (94
1) is EE for the connection of the failed VPC pair.
The VP-RDI (1120) is sent upstream. The EE VP-RDI (1120) is terminated at the other end point, the ATM concentrator 931. Also, Seg VP-RDI (1210) is A
It is terminated in the TM concentrator 931. That is, V
Between the P multiplexer / demultiplexer 932 and the ATM concentrator 931, Seg VP-RDI (1210) and E-E VP
-RDI (1120) has been transmitted redundantly.

As described above, when a failure alarm notification for a VPC segment is implemented without changing the conventional device specifications, a failure alarm is issued on the same connection for two flows, an end-end flow and a segment flow. Notification (AIS / RDI) cells may be duplicated, which will cause an additional increase in communication traffic due to the duplication. The present invention has been made in view of such a point, and a plurality of similar alarm monitors OA are provided.
An object of the present invention is to provide an ATM communication device for controlling transmission of an M cell and a failure notification method thereof.

[0013]

In order to achieve the above object, according to the present invention, there is provided an ATM communication apparatus constituting an ATM network for transmitting and receiving ATM cells. Detecting the state of the ATM connection in response to the failure notification from the failure detecting means, and detecting the first connection and the second connection.
OAM management means for controlling transmission of an alarm monitoring OAM cell to the connection of the first connection, and sending the OAM cell to a connecting point opposite to the connection point detected by the failure detection means of the first connection in accordance with the OAM management means. Cell transmitting means for relaying the OAM cell transmitted from the end point to which the OAM cell of the first connection is transmitted, and the second cell in response to the OAM cell transmitted from the end point. Cell multiplexing processing means for controlling whether or not to insert the OAM cell of the connection in the transmission direction of the OAM cell transmitted from the end point. And

[0014] The ATM communication device having such a configuration is the first type.
The OAM cell for notifying the failure alarm is transmitted in the downstream direction for transmitting the cell to the connecting point opposite to the connecting point where the failure is detected, and the OAM cell transferred from the end point is transmitted.
Receive a cell. Then, it controls whether or not to insert the OAM cell of the second connection in order to transmit the received OAM cell in the upstream direction which is the transmission direction of the OAM cell transmitted from the end point. As described above, since the transmission control of the OAM cell to the second connection is performed, the transmission of the similar OAM cell for failure alarm notification can be prevented.

According to a second aspect of the present invention, there is provided an ATM communication apparatus in which the first connection is an end-to-end flow of an ATM layer and the second connection is a segment flow. It is characterized by being. The ATM communication device having such a configuration monitors an OAM cell for failure alarm and controls transmission when OAM is performed in a condition where a segment is set in an access network. O
AM cells are not transmitted separately for end-to-end flows and segment flows.

[0016] In the invention according to claim 3 of the present invention, the cell multiplexing processing means according to claims 1 and 2 is characterized in that:
Receiving means for receiving an OAM cell from the end point to which the OAM cell of the connection has been transmitted, and monitoring whether the OAM cell received by the receiving means is an RDI cell. A cell monitoring unit for extracting a VPI, an RDI cell generation unit for controlling generation of an RDI cell of the second connection according to the VPI extracted by the cell monitoring unit, and an RDI cell of the first connection. When generated by the RDI cell generating means, the RD of the second connection
An ATM communication device comprising: a cell insertion unit for multiplexing and transmitting an I cell. The ATM communication device having such a configuration, when the RDI cell received corresponding to the first connection is the same failure notification information as the RDI cell to be generated corresponding to the second connection, RDI of the second connection
Cancel cell generation. As a result, transmission of the same RDI cell for failure alarm notification can be prevented.

According to a fourth aspect of the present invention, the RDI cell generating means according to the third aspect is arranged such that the RDI cell generating means and the VPI of the RDI cell of the second connection which generate the VPI are generated by the cell monitoring means. When the second
Characterized in that it is an ATM communication device that stops RDI cell generation for the connection. ATM with such a configuration
By checking the VPI of the RDI cell of the first connection and the second connection, the communication device can prevent transmission of the failure alarm notification RDI cell having the same VPI value.

According to a fifth aspect of the present invention, the OAM management means according to the first, second, third and fourth aspects further comprises an OAM cell to be terminated in advance according to the state of the ATM connection. The cell communication means is an ATM communication apparatus further comprising a cell terminating means for monitoring the set OAM cell to be terminated and terminating the detected OAM cell when it is detected. The ATM communication device having such a configuration further terminates one of the OAM cell of the first connection and the OAM cell of the second connection, which must be transmitted in the same direction, so that a similar OAM cell is transmitted. To prevent

The invention according to claim 6 of the present invention provides an AT for transmitting and receiving an asynchronous transfer mode (ATM) cell.
In a failure notification method for an ATM communication device constituting an M network, a failure on an ATM connection is detected, and when the failure is detected, the state of the ATM connection is confirmed.
A request for transmission of an alarm monitoring OAM cell for the first connection and the second connection is made in accordance with the state of the TM connection, and a connection point detected by the failure detection means of the first connection in accordance with the OAM cell transmission request. Connecting facing
Transmitting an OAM cell to a point; receiving an OAM cell transmitted from an end point to which the OAM cell of the first connection is transmitted; receiving a VPI of the received predetermined OAM cell and transmitting the OAM cell; VPI of OAM cell of second connection generated according to request
ATM communication apparatus having a procedure for not inserting an OAM cell of the second connection into a multiplex cell transmitted in the transmission direction of the OAM cell transmitted from the end point when the VPIs match. The failure notification method is characterized in that:

The failure notification method of the ATM communication apparatus having such a procedure is described in the following.
It sends out M cells in the downstream direction and receives OAM cells transferred from the terminal. And the received OA
OA of the second connection to be transmitted by comparing the VPI of the M cell with the VPI of the generated OAM cell
It controls whether the M cell is inserted into the multiplex cell transmitted in the transmission direction of the OAM cell transmitted from the end point. Thus, the OAM for the second connection
In order to perform cell transmission control, a similar O
AM cell transmission can be prevented.

[0021]

Embodiments of the present invention will be described with reference to the drawings. Here, it is assumed that the configuration of the ATM network is the same as the conventional configuration described above. FIG.
FIG. 1 is a block diagram showing a configuration of an ATM communication apparatus constituting an ATM access network according to an embodiment of the present invention. Here, a functional block configuration of the VP multiplexer / demultiplexer is shown. This VP multiplexer / demultiplexer has N
× M (N and M are arbitrary integers) subscriber lines (230-1
-1,..., 230-NM, 240-1-1,.
0-NM). The VP multiplexing / demultiplexing device has a distribution interface 110, A serving as an interface with the ATM concentrator.
An OAM management unit 120 that manages TM level alarm monitoring;
And N drop interface units 130-1 to 130-N serving as interfaces with the subscriber terminals.

The distribution interface 110 includes a cell receiving unit 111 for receiving a cell from the transmission line 210, a failure detecting unit 112 for detecting a failure of a connection through which the received ATM cell is transmitted, and drop interfaces 130-1 to 130. -ATM transferred from -N
Cell multiplexing unit 113 for multiplexing cells, AT
It comprises a cell transmission section 114 for transmitting M cells. The cell receiving unit 111 receives a cell input via the transmission line 210, and receives each of the drop interface units 130-1 to 130-1.
Distribute cells to 130-N. The failure detection unit 112 is a failure detection unit, and detects a failure on the ATM connection by monitoring cells received by the cell reception unit 111. The cell multiplexing unit 113 multiplexes the cells transferred from each of the drop interface units 130-1 to 130-N, and sends the multiplexed cells to the cell transmitting unit 114. Cell transmitting section 114
Transmits the multiplexed cell to the transmission path 220.

The OAM management unit 120 is an OAM management unit and includes a storage unit (not shown) for storing a connection table indicating the state of the ATM connection. The connection table will be described. FIG.
FIG. 1 is a configuration diagram of a connection table according to an embodiment of the present invention. The connection table 121 is
Indicates the input VPI value and whether it is a connection level end point or a connecting point of the VPC, and indicates whether it is a segment level end point of the VPC, a connecting point, or a VPC segment. Also indicates whether or not is set. More specifically, the connection 12 of the input VP value 20
1a indicates that it is a connecting point at the connection level of the VPC and an end point at the segment level of the VPC. Also,
The connection 121b of the input VPI value 32 is a connecting point at the connection level of the VPC, and indicates that the segment level of the VPC is not set.

Returning to FIG. OAM management unit 12
0, when a failure notification is received from the failure detection unit 112, the AT is determined using the connection table described above.
The state of the M connection is checked, and an OAM cell transmission command is issued to the drop interface units 130-1 to 130-N as appropriate. Assuming that L is an arbitrary natural number greater than or equal to 1 and less than or equal to N, the cell separation unit 131-L of each drop interface unit 130-L is connected to the signal line 161-L, and the cell multiplexing unit 132-L is connected to the signal line 162-L. Connected.

N drop interface units 130
In the case of -1 to 130-N, assuming that 130-N is an example, ATM cells transferred from the distribution interface 110 are M lines 230-N-1 to 230-N.
−M, and the cell separation unit 131-N that distributes the signals to the M lines 240-N-1 to 240-NM.
And a cell multiplexing unit 132-N for multiplexing TM cells.

The operation of the VP multiplexer / demultiplexer having such a configuration and a method of notifying a failure will be described. Normally, when no failure occurs, the ATM cell transmitted from the ATM concentrator is received by the cell receiving unit 111 of the distribution interface 110 via the transmission line 210, and the cell separation of each of the drop interfaces 130-1 to 130-N is performed. It is distributed to the units 131-1 to 131-N. Each of the cell separation units 131-1 to 131-N filters the ATM cell only for the corresponding connection to be transmitted, and
It is transmitted to the subscriber terminal from the corresponding line of 0-1-1 to 230-NM. In addition, A transmitted from the subscriber terminal
The TM cells are stored in each of the lines 240-1-1 to 240-N-M.
The cell multiplexing unit 132- of each drop interface
1-131-N and multiplexed. Then, the signal is multiplexed again by the cell multiplexing unit 113 of the distribution interface 110 via the signal lines 152-1 to 152-N, and is transferred to the cell transmitting unit 114. The transferred ATM cell is transmitted to the ATM concentrator via the transmission line 220.

Next, a case where a failure occurs will be described. FIG. 3 is a diagram showing a segment according to an embodiment of the present invention.
9 shows a failure alarm notification procedure including a level. In the event that a failure of the mark 290 occurs on an ATM connection in which ATM cells are transmitted from the ATM concentrator 320 to the subscriber terminal CPE1 (330), the failure detection unit 11
2 (FIG. 1) detects a failure on the ATM connection,
Notify the OAM management unit 120 (FIG. 1). Upon receiving the notification, the OAM management unit 120 checks the state of the ATM connection from its own connection table. VP
The multiplexer / demultiplexer 100 is a connecting point of the VPC1 (430), and the VPC segment (4
10) is the end point. Therefore, as an ATM-level failure alarm notification, E-E-downstream from the ATM concentrator 320 toward the subscriber terminal CPE1 (330) is performed.
The EVP-AIS cell (510) must be sent. Further, in the conventional case, the VP multiplexer / demultiplexer 100
Seg from upstream to ATM concentrator 320
A VP-RDI cell must be sent.

Here, it is assumed that a failed connection exists at the drop interface 130-N (FIG. 1). First, the OAM management unit 120 grasps the connection state from the connection table, and immediately transmits and receives the ATM cell of the corresponding connection.
EE VP-AI to 30-N cell separation unit 131-N
Generate an S cell (510) and instruct it to transmit downstream. Also, Seg VP is sent to the cell multiplexing unit 132-N.
Generate RDI cells and instruct them to transmit upstream.

The cell separation section 131-N is provided with an E-E VP-
An AIS cell (510) is generated and a downstream line 230 is generated.
-N-1 to 230-NM are transmitted to the corresponding connection. On the other hand, the cell multiplexing unit 132-N
1 (330) and the E-E VP-RDI cell (52) for the E-E VP-AIS cell (510).
0) is received. This EE VP-RDI cell (52
0) and a Seg VP-RDI cell, and
If it is determined that the cell is an AM cell, the Seg VP-RDI
Suspend cell generation. EE VP-RDI cell (5
20) Distribution interface 1
The data is transferred to the cell multiplexing unit 113 and multiplexed with another ATM cell. In this way, only the EE VP-RDI cell (520) is transmitted from the cell transmission unit 114 to the transmission path 22.
0 is transmitted to the ATM concentrator 320.

Drop interface units 130-1 to 130-1
130-N will be described in detail. FIG. 4 is a functional block diagram of the drop interface unit. Here, the drop interface unit 130-N will be described. The drop interface unit 130-N includes a cell separation unit 131-N and a cell multiplexing unit 132-N.

The cell separation unit 131-N is an end-end VP-A which is one of ATM-level failure alarm notification cells.
E (hereinafter referred to as E-E VP-AIS) cell
-EAIS cell generator 1311-N and EE VP-
E-E AI to insert AIS cell into corresponding connection
The S cell insertion unit 1312-N and the AT of the connection
Cell filter section 13 for filtering only M cells
13-N-1 to 1313-NM, ATM to subscriber terminal
Cell transmitters 1314-N-1 to 1314 for transmitting cells
-N-M. The cell multiplexing unit 132-N
Cell receiver 1321-N-1 for receiving ATM cells transmitted from M lines 240-N-1 to 240-NM
To 1321-N-M, cell receiving section 1321-N-1 to 1-1
VP-replacement units 1322-N-1 to 1322-replace VP values of ATM cells transferred from the 321 -NM.
NM, an EE RDI cell monitoring unit 1323-N-1 that monitors and extracts the received EE VP-RDI cell
1323-NM, a segment VP-RDI (hereinafter referred to as Seg V), which is one of ATM-level failure alarm notification cells.
A Seg RDI cell generation unit 1324-N that generates a P-RDI) cell, and a Seg RDI cell insertion unit 1325 that inserts a Seg VP-RDI cell into a corresponding connection.
N, and a cell multiplexing unit 1326-N for multiplexing ATM cells.

The cell separation section 131-N and the cell multiplexing section 132
A detailed operation of −N and a failure notification method will be described.
Normally, when no failure occurs, the ATM cell transmitted from the distribution interface 110 via the signal line 151 is transmitted to the cell separation unit 131-N by the EE.
The signal passes through the AIS cell insertion unit 1312-N and is distributed to each line. However, the cell filter 1313-N-1
１３１ 1313 -N−M to filter to be sent to the corresponding connection. The filtered ATM cells are transmitted to the corresponding cell transmitting unit 131.
The data is transmitted to the subscriber terminal from the line 230-N-1 to 230-NM by any one of 4-N-1 to 1314-NM.

On the other hand, the ATM cell transmitted from the subscriber terminal is transmitted to the cell receiving section 1321-N- in the cell multiplexing section 132-N via the lines 240-N-1 to 240-NM.
1 to 1321-NM. The received ATM cell is stored in the VPI replacement unit 1322-N-1.
１３２1322-NM, it is replaced with the VPI value to be transmitted to the ATM concentrator. The ATM cell whose VPI value has been changed is sent to the E-E RDI cell monitoring unit 13.
The signal passes through 23-N-1 to 1323-NM and is multiplexed by the cell multiplexing unit 1326-N. The multiplexed ATM cells are:
The signal passes through the Seg RDI cell insertion unit 1325-N and is transmitted to the distribution interface 110 via the signal line 152-N.

Referring to FIG. When a failure of the mark 290 occurs on the ATM connection in which ATM cells are transmitted from the ATM concentrator 320 to the subscriber terminal CPE1 (330), the EE AIS cell generator 131
1-N is transmitted from the ATM concentrator 320 to the subscriber terminal CPE.
The EAM VP-A is sent from the OAM management unit 120 to notify the failure alarm in the downstream direction which is the 1 (330) direction.
Commanded to generate IS cell (510). On the other hand, the Seg RDI cell generation unit 1324-N generates a Seg VP-RDI cell from the OAM management unit 120 to notify a failure alarm from the VP multiplexing / demultiplexing device 100 to the upstream direction which is the direction of the ATM concentrator 320. Ordered to do so.

Returning to FIG. The generated EE
The VP-AIS cell is an EE AIS cell insertion unit 13
12-N is inserted into the connection corresponding to the failure. The inserted E-E VP-AIS cell is distributed to each line, but the cell / filter units 1313 -N-1 to 1313-
According to NM, it is transmitted to a line having only the relevant VPI value, and is discarded in a line having another VPI value. The filtered EE VP-AIS cell is transmitted to the subscriber terminal from the line 230-N-1 to 230-NM by one of the corresponding cell transmission units 1314-N-1 to 1314-NM. Sent in the direction. In addition, the generated Seg V
The P-RDI cell is a Seg RDI cell insertion unit 1325
-N is inserted into the connection corresponding to the failure. The inserted Seg VP-RDI cell is transferred to the distribution interface 110 via the signal line 152-N.

Meanwhile, the E-E VP-AIS cell transmitted from the cell separation unit 131-N is stored in the subscriber terminal CPE.
When it reaches 1 (330), it is terminated. Then, the subscriber terminal CPE1 (330) transmits the EE VP-RDI cell (520) in the reverse direction, that is, for the connection from the subscriber terminal 330 to the ATM concentrator 320. The EE VP-RDI cell is transmitted to the cell receiving units 1321-N-1 to 1321- of the cell multiplexing unit 132-N.
NM, and received by one of the VPI replacement units 1322-N-1 to 1322-NM.
You can change the value. EE with VPI value changed
The VP-RDI cell is a Seg VP-RDI already generated by the Seg RDI cell generator 1324-N.
It will have the same VPI value as the cell. That is, the EE VP-RDI cell transmitted from the subscriber terminal and the Seg VP-RDI cell already generated by the Seg RDI cell generation unit 1324-N have at least the fault alarm notification VP of the same property between VPC segments. -RDI
It becomes a cell. Therefore, the E-E RDI cell monitoring unit 1323-N is set so as not to overlap with the cell multiplexing unit 1326-N in the distribution interface 110.
EEVP-RDI in -1 to 1323-NM
The cell is monitored, and if an EE VP-RDI cell is received, the received V is transmitted to the SegRDI cell generation unit 1324-N.
Notify the PI value. The notified Seg RDI cell generation unit 1324-N outputs the generated Seg VP-RDI
Cell VPI Value and EE RDI Cell Monitoring Unit 1323-
If the VPI values notified by N-1 to 1323-NM are equal, the generation of the Seg VP-RDI cell is immediately stopped. EE RDI cell monitor 1323-N-1
EE-VP monitored at ~ 1323-NM
The RDI cell is transferred to the cell multiplexing unit 1326-N,
EG The signal passes through the RDI cell insertion unit 1325-N and is transmitted to the signal line 152-N.

Next, another embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a functional block diagram of a VP multiplexer / demultiplexer according to another embodiment of the present invention. Parts that are the same as or equivalent to those in FIG. 4 are given the same reference numerals, and descriptions thereof are omitted. In the present embodiment, the cell separation unit 131-
N is an E-E AIS cell insertion unit 1312-N-1 to 1
312-NM are distributed for each line, and Seg
RDI cell insertion units 1325-N-1 to 1325-NM
Is distributed to each line.

Since the basic operation is the same as that of FIG. 4, the difference between the operations will be described. Due to the failure described above,
When transmitting an EE VP-AIS cell from the VP multiplexer / demultiplexer 100 in the direction of the subscriber terminal 330, the OAM management unit 120 uses the EE AIS cell generation unit 1311-N.
To generate an E-E VP-AIS cell. The EE AIS cell generation unit 1311-N generates the EE VP-AIS cell generated in any of the EE AIS cell insertion units 1312-N-1 to 1312-NM of the line where the connection exists. Insert

Also, the VP multiplexing / demultiplexing apparatus 100
When transmitting a SegVP-RDI cell in the direction of the M concentrator 320, the OAM management unit 120 instructs the Seg RDI cell generation unit 1324-N to generate a SegVP-RDI cell. Seg RDI cell generator 13
24-N is the Seg of the line where the connection exists.
RDI cell insertion units 1325-N-1 to 1325-N-
Insert the generated Seg VP-RDI cell into any of M. Further, the EE VP-AIS cell transmitted from the cell separator 131-N is terminated by the subscriber terminal 330. The subscriber terminal 330 transmits an EE VP-RDI cell toward the ATM concentrator 320 for the connection in the reverse direction. E-E VP-R sent
The DI cells include cell receiving units 1321-N-1 to 1321-
NM. EE received
The VP-RDI cell is a VPI replacement unit 1322-N
-1 to 1322-NM, the VPI value is changed, and the EE RDI cell monitoring units 1323-N-1 to 13-13
23-N-M. This EE VP-RDI
The cell and the Seg VP-RDI cell already generated by the Seg RDI cell generation unit 1324-N are provided with a failure alarm notification V of the same property at least between VPC segments.
It becomes a P-RDI cell. Therefore, the E-E RDI cell monitoring units 1323-N-1 to 1323-N-M
-Seg RD when receiving an EVP-RDI cell
The received VPI value is notified to the I-cell generator 1324-N. Seg RDI cell generator 1324-N notified
Indicates the VPI value of the generated Seg VP-RDI cell and the E-E RDI cell monitoring units 1323-N-1 to 132-N.
If the VPI values notified by 3-NM are equal, the generation of Seg VP-RDI cells is immediately stopped. EE
RDI cell monitoring units 1323-N-1 to 1323-N-
The E-E VP-RDI cell monitored at M
eg, which passes through the RDI cell insertion unit 1325-NM, is multiplexed in the cell multiplexing unit 1326-N, and
-N.

Further, another embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a functional block diagram of a VP multiplexer / demultiplexer according to another embodiment of the present invention. Parts that are the same as or equivalent to those in FIG. 4 are given the same reference numerals, and descriptions thereof are omitted. The present embodiment is different in that the cell separation unit 131-N has a Seg RDI cell termination unit 1315-N. The Seg RDI cell termination unit 1315-N
The Seg VP-RDI cell in the failure alarm notification from the M concentrator 320 to the VP multiplexer / demultiplexer 100 is terminated.

The operation of the present embodiment will be described with reference to the drawings. FIG. 7 shows a fault alarm notification procedure including a segment level according to another embodiment of the present invention. The same components as those in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted. This is the same network configuration as FIG. 3, and the connection state is also the same. However, here, FIG.
And the connection in the opposite direction. That is, from the subscriber terminal CPE1 (330) to the ATM concentrator 320
When a failure indicated by a cross 295 occurs on the ATM connection in which the ATM cell is transmitted in the direction, the ATM concentrator 320 is the end point of the VPC1 (430) and the end point of the VPC segment 410. . Therefore, the ATM concentrator 320 sends the subscriber terminal CPE1 (33) as a failure alarm notification at the ATM level.
The E-E VP-RDI cell must be transmitted in the upstream direction, which is the 0) direction. The ATM concentrator 320
Must send a Seg VP-RDI cell (550) in the same direction. On the other hand, the VP multiplexer / demultiplexer 100
Is the E-E VP transmitted from the ATM concentrator 320.
-Receive the RDI cell (540), Seg VP-RDI cell (550). The VP multiplexing / demultiplexing device 100
Since it is the connecting point of VPC1 (430), it transfers the EE VP-RDI cell (540) to the subscriber terminal CPE (330). Further, the VP multiplexer / demultiplexer 100 controls the end / end of the VPC segment (410).
Since this is a point, the Seg VP-RDI cell (55
0) is terminated. Thus, the subscriber terminal CPE1 (3
30), the same OAM cell is prevented from being transmitted.

Returning to FIG. ATM concentrator 3
The E-E VP-RDI cell transmitted from the E-AIS cell insertion unit 131 is transferred from the signal line 151 to the E-E AIS cell insertion unit 131.
2-N, passing through the Seg RDI cell terminator 1315
N. Seg RDI cell termination unit 1315
In N, since the Seg VP-RDI cell to be terminated by the signal line 161-N from the OAM management unit 120 is set in advance with reference to the connection table, the transferred E-E VP-RDI cell is terminated. It is determined that the cell is not an OAM cell to be used, and the cell filter units 1313-N-1
1313-NM. The Seg VP-RDI cell transmitted from the ATM concentrator 320 is transferred from the signal line 151 and transmitted to the EE AIS cell insertion unit 13.
12-N, the Seg RDI cell terminating unit 1315
-N. Seg RDI cell termination unit 1315
-N determines that the Seg VP-RDI cell should be terminated, and terminates the transferred Seg VP-RDI cell.

[0043]

As described above, according to the present invention, the OAM cell for notifying the failure alarm is transmitted downstream in the first connection, and the OAM cell transferred from the terminal is received. Then, it controls whether or not to insert the OAM cell of the second connection into the upstream cell flow for transmitting the received OAM cell. As described above, in order to perform transmission control of the OAM cell for the second connection,
It is possible to prevent transmission of a similar OAM cell for failure alarm notification. Further, since the same OAM cell for failure alarm notification is not transmitted, an effective band can be used in communication.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an ATM communication device constituting an ATM access network according to an embodiment of the present invention.

FIG. 2 shows a connection according to an embodiment of the present invention;
It is a block diagram of a table.

FIG. 3 is a diagram showing a failure alarm notification procedure including a segment level according to an embodiment of the present invention.

FIG. 4 is a functional block configuration diagram of a drop interface unit.

FIG. 5 is a functional block configuration diagram of a VP multiplexer / demultiplexer according to another embodiment of the present invention.

FIG. 6 is a functional block configuration diagram of a VP multiplexer / demultiplexer according to another embodiment of the present invention.

FIG. 7 shows a segment according to another embodiment of the present invention.
It is a figure showing a failure alarm notification procedure including a level.

FIG. 8 is a configuration diagram of a transmission network of an ATM layer.

FIG. 9 is a diagram illustrating a relationship between a connection and a segment regarding VPC and VCC.

FIG. 10 is a diagram showing the positioning of an access network.

FIG. 11 is a diagram showing a VP level ATM connection;

FIG. 12 is a diagram showing a conventional failure alarm notification procedure.

FIG. 13 illustrates a conventional fault alarm procedure including a segment level.

[Explanation of symbols]

Reference Signs List 110 distribution interface 111 cell receiving unit 112 failure detecting unit 113 cell multiplexing unit 114 cell transmitting unit 120 OAM management unit 130-N drop interface 131-N cell separating unit 132-N cell multiplexing unit

Continuation of the front page (56) References JP-A-7-307744 (JP, A) JP-A-10-13421 (JP, A) JP-A-11-98140 (JP, A) JP-A-6-338898 (JP) , A) JP-A-10-65696 (JP, A) JP-B-6-71260 (JP, B2) 1998 IEICE General Conference B-10-101 (58) Fields surveyed (Int. Cl. ⁷ , DB name ) H04L 12/56

Claims (6)

(57) [Claims] 1. An ATM communication device constituting an ATM network for transmitting and receiving cells in an asynchronous transfer mode (hereinafter referred to as ATM), a failure detecting means for detecting a failure on an ATM connection, and a failure notification of the failure detecting means. OAM management means for confirming the state of the ATM connection according to the above, and controlling transmission of an alarm monitoring OAM cell for the first connection and the second connection; and the failure detection means for the first connection according to the OAM management means. Cell transmitting means for transmitting an OAM cell to a connecting point opposite to the connecting point where a failure is detected, and relaying the OAM cell transmitted from the end point to which the OAM cell of the first connection has transmitted the OAM cell. And the OA sent from the end point
Cell multiplexing processing means for controlling whether or not to insert an OAM cell of the second connection into a multiplexed cell transmitted in the transmission direction of the OAM cell transmitted from the end point according to an M cell; An ATM communication device characterized by the above-mentioned. 2. The ATM communication apparatus according to claim 1, wherein said first connection is an end-to-end flow of an ATM layer, and said second connection is a segment flow. 3. The cell multiplexing processing means includes: a receiving means for receiving an OAM cell transmitted from an end point to which the OAM cell of the first connection has been transmitted; and an OAM cell received by the receiving means. A cell monitoring means for monitoring whether the RDI cell is an RDI (far end reception failure) cell and extracting the VPI if the cell is an RDI cell; and RDI of the second connection according to the VPI extracted by the cell monitoring means. An RDI cell generating means for controlling generation of a cell; an RDI cell of the first connection;
ATM according to claim 1 or claim 2 when it is generated by the I cell generating means, characterized in that it is composed of a cell inserting means for delivering to the RDI cell of the second connection to multiple Communication device. 4. The RDI cell generation means, when the VPI extracted by the cell monitoring means matches the VPI of the RDI cell of the second connection to be generated, generates the RDI cell of the second connection. 4. The ATM communication device according to claim 3, wherein the operation is stopped. 5. The OAM management means further comprises an ATM.
OAM cells to be terminated are set in advance according to the state of the connection, and the cell transmitting means further comprises cell terminating means for monitoring the set OAM cells to be terminated and terminating when detecting the detected OAM cells. The ATM communication device according to any one of claims 1, 2 , 3 , and 4 , wherein: 6. A failure notification method for an ATM communication device constituting an ATM network for transmitting and receiving asynchronous transfer mode (ATM) cells, comprising: detecting a failure in an ATM connection; and detecting a state of the ATM connection when the failure is detected. Requesting transmission of an alarm monitoring OAM cell for the first connection and the second connection in accordance with the state of the ATM connection. Failure is detected by the failure detection means of the first connection in accordance with the OAM cell transmission request. OA at the connecting point opposite to the connecting point
Transmitting an M cell, receiving an OAM cell transmitted from an end point to which the OAM cell of the first connection is transmitted, and receiving a VPI of the received predetermined OAM cell;
Comparing the OAM cell of the second connection generated in accordance with the cell transmission request with the VPI of the OAM cell of the second connection, and if the VPIs match, the OAM cell of the second connection is transmitted to the OAM cell transmitted from the end point;
A method of notifying a failure of an ATM communication apparatus, comprising a procedure of not inserting the cell into a multiplex cell transmitted in the transmission direction of an AM cell.