JPH08149131A - Failure notification method and node device in multipoint ATM network - Google Patents

Abstract

(57) [Summary] [Objective] An object of the present invention is to provide a failure notification method and node device for correctly detecting a failure of a transmission connection in a multipoint ATM network. [Configuration] The connecting point C2 that has detected a lower layer failure is a branch point (connection confluence point)
If not, the first failure notification signal: AIS100 is sent downstream. When the connecting point B1 that has received the AIS cell terminates the AIS cell when it is a branch point, that is, a confluence point of the connection, the connecting point B1 sends a pseudo failure notification signal: MAIS cell, which is an alternative to the AIS cell, to the downstream side. , The second failure notification signal: FERF200 is returned to the reverse connection. Each of the connecting points C2, B2 on the downstream side transfers the received MAIS cell to the downstream without processing, and the endpoint (leaf) L1,
Terminate at L2. As a result, the leaves L1 and L2 detect the failure of the transmission connection. [Effect] There is no possibility that a FERF cell is transferred to the leaves L3 and L4 and a transmission connection failure is erroneously detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a multipoint ATM.
The present invention relates to a failure notification method and node device in a network.

[0002]

ITU-T (International Telecommunication Union-Telecommunication Standardization Sector) Recommendation I.T., which was approved by the WTSC (World Telecommunication Standardization Conference) in March 1993. 610 "Broadband ISDN Operation and Maintenance Principles and Functions" (hereinafter referred to as ITU-T
I. 610)), "Point point A
Although the failure notification method in "TM connection" is specified, "multipoint ATM connection"
It does not stipulate the failure notification method in.

In the point-to-point ATM connection (hereinafter, VP: virtual path will be described as an example) failure detection notification method, a transmission line failure (or A
A device that has detected a failure in the lower layer as seen from the TM layer) is placed in the downstream direction of the ATM connection multiplexed in the failure transmission line, and the VP-AIS (VP-Alarm Indication Si
gnal) Send a cell. The VP-AIS cell is an AT
It is recognized / terminated by the first device which is the end point of the M connection, and it is recognized that the ATM connection is in failure.

In response to the reception of the VP-AIS cell, the first device responds to the ATM connection in the opposite direction which is paired with the failed ATM connection by using the VP-FERF.
(VP-Far End Receive Failure) Cell is transmitted. This VP-FERF cell is terminated and detected by the second device which is the end point of the backward ATM connection. As a result, the second device can recognize that a failure point exists in the middle of the ATM connection which is the transmission side for this device.

However, the ITU-T I.S. In the present situation where there is no regulation by 610, the failure notification method in the point-to-point ATM connection described above is extended to the multi-point ATM connection as it is.

FIG. 8 shows a conventional point-to-point ATM.
The flow of the notification signal when the failure notification method in the connection is applied to the multipoint connection as shown in FIG. 6 is shown. The multipoint ATM connection shown in FIG. 6 has one receiving end point (hereinafter referred to as “route”) and a plurality of transmitting end points (hereinafter referred to as “leaf”) when viewed in the upstream direction, which is the direction in which the connections join. ), One or more connecting points with branching, and a connecting point without branching, and a multipoint ATM connection (VPC: virtual path connection, or VPC).
This is an example in which the generality of (CC: virtual channel connection) is not lost.

In the example of FIG. 6, the root R and the leaf L are the end points of the multipoint connection.
1, L2, L3, L4, and as connecting points, there are branch points B1, B2, B3,
There are points C1 and C2 with no branch. The route R is, for example, an exchange included in the network,
The leaves L1 to L4 are terminals or exchanges, and the connecting points B1 to C2 are exchanges or transmission devices.

The connection corresponds to VPC or VCC, and is divided into several sections (links) by the above-mentioned end point and connecting point. In this example, the links are S1 (between R and C1), S2.
(Between C1 and B1), S3 (between B1 and C2), S4 (C2
-B2), S5 (B2-L1), S6 (B2-L2)
Interval), S7 (between B1 and B3), S8 (between B3 and L3),
S9 (between B3 and L4). Each connection is composed of an upstream connection from the leaf to the root and a downstream connection from the root to the leaf. FIG. 7A shows the upstream connection of FIG. (B) of each indicates a downlink connection. In this specification, the section Si
The connection in (i = 1 to 9) is S in the upstream direction.
ui (i = 1 to 9), Sdi (i = 1 to 9) in the down direction
Will be written as.

[0009]

The inventor of the present invention has proposed in Japanese Patent Application No. P06-43527 the problem and its solution when a failure occurs in the downstream direction. In the above-mentioned prior invention, it is assumed that the user cell is transferred in the downlink direction. The present invention proposes a problem and a solution when a failure occurs in a connection in the upstream direction when user cells are transferred in the upstream direction.

According to the conventional failure notification method, as shown in FIG. 8A, for example, when a lower layer failure occurs in the section Su5, the connecting point B2 adjacent to the downstream side of the failure point is A for upstream connection
The route R that inserts the IS cell and receives the IS cell, as shown in (b) of FIG.
The FERF cell will be returned.

In this case, since the VP-FERF cell is transferred to all the leaves L1 to L4, even though the end point which should recognize the transmission connection as a failure is only the leaf L1, the transmission is performed on all the leaves L1 to L4. There is a problem that the connection is recognized as a failure.

An object of the present invention is to provide a failure notification method and a node device for correctly detecting a failure of a transmission connection in a multipoint ATM network.

[0013]

In order to achieve the above object, the fault notification method of the present invention uses a multipoint ATM.
In the network, a node that has detected a failure in the first connection in the upstream direction transmits a first failure notification signal (eg, VP-AIS cell) in the downstream direction of the connection,
When the first branch node in the middle of the first connection (connecting point where upstream connections join) receives the first failure notification signal, the first failure among the first connections In the downstream direction of the branch path portion of the second connection in the downward direction that forms a pair with the branch path portion of the connection that has received the notification signal, the second
Failure notification signal (for example, VP-FERF cell) of each node, and each node on the second connection transmits the second signal.
The failure notification signal is sequentially relayed to the end point.

The branch node that first receives the first failure notification signal in the first connection is a pseudo failure notification that replaces the first failure notification cell in the downstream direction of the first connection. Signal, eg VP-AI
A VP-MAIS cell in which the S cell is simulated for multipoint is transmitted. When each node on the first connection receives the pseudo failure notification signal, it sequentially relays it to the connection end point.

The node device of the present invention is a node device that forms a plurality of multipoint ATM connections each of which has a pair of first and second connections with opposite transmission directions on an ATM network. Means for setting the state of the node to a predetermined state for each call, and a first means for indicating a failure on the first connection when the state of the node is in the predetermined state. When a failure notification signal is received or when a failure on the first connection is detected, a second failure notification signal is transmitted in the downstream direction of the second connection, and the second failure notification signal is transmitted in the downstream direction of the first connection. And means for sending a third failure notification signal.

[0016]

According to the present invention, the first failure notification signal (VP-AIS cell) sent from the node that has detected the failure is
Terminated at the first branch node in the middle of the first connection, this branch node is on the second connection toward the branch path to which the first failure notification signal of the first connection is transferred, Second failure notification signal (VP-
Since the FERF cell is sent back, there is no possibility that the second failure notification signal will be transferred to the leaf that is not affected by the failure.

The first failure notification signal (VP-AIS)
The branch node terminating the cell) causes a pseudo failure notification signal (VP-MAIS cell) instead of the first failure notification signal to flow downstream of the first connection, and the endpoint (route) is The second failure notification signal is generated as a response operation in response to the first failure notification signal of the above, but the second failure notification signal is relayed only to the pseudo failure notification signal. If the occurrence of the unnecessary second failure notification signal is suppressed, the pseudo failure notification signal can be used to notify each node on the second connection of the occurrence of the unnecessary second failure notification signal.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the flow of a failure notification signal according to the present invention when a lower layer failure occurs in the section Su1 of the first connection in the network shown in FIG. Each node that constitutes the network stores in advance configuration information indicating whether or not it is a branch node (connections merge in the upstream direction), and receives a failure notification signal. Then, a response operation is performed according to the type of the received signal and the state of the own node based on the above configuration information.

As shown in FIG. 1A, the route R that has detected the failure of the first connection is ITU-TI. 6
According to the rule of No. 10, as shown in FIG. 1B, the second failure notification signal: FERF cell (VP-FERF cell or VC-FERF cell) 200 is transmitted in the downstream direction of the second connection.

The connecting point B1 having received the FERF cell is transferred in the downstream direction of each branch without processing. Similarly, the connecting points B2 and B3 transfer the received FERF cells in the downstream direction of each branch without processing. The above-mentioned FERF on leaves L1, L2, L3, and L4
By detecting the cell, it is possible to know that the first connection on the transmitting side has a failure.

FIG. 2 shows the flow of a failure notification signal when a lower layer failure occurs in the section Su2 of the first connection. In FIG. 2A, the connecting point C1 that has detected the failure of the first connection is ITU-TI. According to the regulations of 610, the first failure notification signal: AIS cell (VP-AIS cell or VC-AIS cell) 100 is transmitted in the downstream direction of the first connection. The route R that has detected the AIS cell is ITU-TI. According to the regulations of 610, as shown in FIG. 1B, the second failure notification signal: FERF
The cell 200 is transmitted in the downstream direction of the second connection.

The connecting point B1 having received the FERF cell is transferred in the downstream direction of each branch without processing. Similarly, the connecting points B2 and B3 transfer the received FERF cells in the downstream direction of each branch without processing. The above-mentioned FERF on leaves L1, L2, L3, and L4
By detecting the cell, it is possible to know that the first connection on the transmitting side has a failure.

FIG. 3 shows the flow of a failure notification signal when a lower layer failure occurs in the section Su3 between the branch connections B1 and B2. As shown in (a) of FIG. 3, since the connecting point B1 that has detected the failure is a branch point, the pseudo failure detection signal MA
The IS (VP-MAIS cell or VC-MAIS cell) 101 is sent to the downstream of the first connection, and the FERF 200 is generated as shown in (b),
This is sent to the branch path where the lower layer failure of the second connection in the reverse direction has occurred. The connecting point B2 that has received the FERF cell is transferred in the downstream direction of each branch without processing. FE on the leaves L1 and L2
By detecting the RF cell, it is possible to know that the first connection on the transmitting side has a failure.

FIG. 4 shows the flow of a failure notification signal when a lower layer failure occurs in the section Su4 between the branch connections B1 and B2. As shown in (a) of FIG. 4, when a failure occurs in the section Su4, the connecting point C2 that has detected the failure outputs the first failure detection signal AIS100, which is generated because it is not a branch point, in the downstream direction. Send out. The connecting point B1 that has received the AIS cell is a branch point,
The payload of the received AIS cell is rewritten to generate the MAIS cell 101, which is sent downstream, and (b)
As shown in, the second failure detection signal: FER is sent to the branch path to which the AIS cell of the reverse connection is transferred.
Return F200. The connecting point B2 that has received the FERF cell is transferred in the downstream direction of each branch without processing. By detecting the FERF cell in the leaves L1 and L2, it is possible to know that the first connection on the transmission side has a failure.

FIG. 5 shows a branch connection B2 and a leaf L.
In the section Su5 between 1 and 1, a flow of a failure detection signal when a lower layer failure occurs is shown. As shown in (a) of FIG. 5, when a failure occurs in the section Su5, the connecting point B2 on the downstream side detects the failure, and since it is a branch point, the connecting point B1 in the example of FIG. According to a similar operation procedure, the first failure detection signal: MAIS cell 101 is generated and sent to the downstream side, and as shown in (b), the second detection signal: FERF200 is sent to the reverse connection. To do. By detecting the FERF cell in the leaf L1, it is possible to know that the first connection on the transmitting side has a failure.

A node configuration for performing the above-described failure detection signal generation and transmission / reception processing will be described by taking the connecting point B1 in the network of FIG. 4 as a typical example.

FIG. 9A shows the configuration of the failure notification cell processing unit of the node, FIG. 9B shows the overall configuration of the node, and FIG. 10 shows the structure of the table used for controlling the transfer of the failure notification cell. At the connecting point B1, FIG. 9 (a)
As shown in FIG. 7, the cell extraction copy unit 303 extracts a failure notification cell (first failure notification cell: VP-AIS cell) 306 from the cells received from the upstream transmission path 300A and notifies it of the failure. It is supplied to the cell control unit 301.
The failure notification cell control unit 301 includes a VP table 400 shown in FIG. 10, and the VP table 400 is a V
A field 402 indicating whether or not a VP connection is being set up, and a field 40 indicating the presence or absence of branching, that is, the presence or absence of connection merging in the upstream direction, corresponding to PI.
It has a record consisting of 3. Upon receiving the VP-AIS cell, the failure notification cell control unit 301 refers to the VP table 400 using the VPI attached to the cell header as an address, and determines at the branch point, that is, the confluence point of the connection in the upstream direction. Determine if there is.

For example, the VP of the received VP-AIS cell
When I is “12”, in the record corresponding to VPI (= 12), the valid bit “1” indicating that the VP connection is being set is set in the valid display field 402, and the merge presence / absence display field 403 is set. Since the bit “1” indicating that there is merging is set, the failure notification cell control unit 301 may find that the VP connection indicated by the VP-AIS cell is a branch node, that is, a merging connection. I understand. In this case, the failure notification cell control unit 301 rewrites the payload of the received AIS cell to generate a pseudo failure notification cell: V
A P-MAIS is generated and passed to the cell insertion unit 304-1, a second failure notification cell (VP-FERF cell) is generated, and this is inserted into the cell insertion unit 304 provided in the downlink transmission path 300B. -Pass to -2.

The cell insertion units 304-1 and 304-2 receive the VP- received from the failure notification cell control unit 301, respectively.
The transmission line 3 on the downstream side of the MAIS cell and the VP-FERF cell
It is sent to 00A 'and 300B'.

Next, referring to FIG. 4B, the FERF cell is returned to the branch path between the branch nodes B1 and B2 to which the AIS cell is transferred, and is not returned to the branch path between the branch nodes B1 and B3. Will be described with reference to FIG. Figure 9
In (b), the cells of the upstream connection are merged by the cell merging unit 308, and the cells of the downstream connection are branched by the cell branching unit 309. Control of the merging and branching (for example, designation of a branching route) is performed by the cell merging unit 308 and the cell branching unit 3 of the line individual interface 311, respectively.
This is performed by the merging / branching control unit 310 of the portion connected to 09. The control information is set from the central controller 312.

Failure notification cell processing unit 3 shown in FIG. 9 (a)
07 are provided in the individual line interfaces 311. Here, the uplink connection at the connecting point B1 in FIG.
b, 311-2b, 308, 311-1a, and the downlink connections are 311-1a, 309, 31.
1-1b and 311-2b.

Therefore, the connecting point B in FIG.
The failure notification cell transfer control in No. 1 is performed by the failure notification cell processing unit 307-1b. As a result, the FERF cell is returned to the branch path (contained in 311-1b) between the branch nodes B1 and B2 to which the AIS cell has been transferred, and the branch path (311-between the branch nodes B1 and B3). 2b) is not returned.

Next, the processing operation executed by each connecting point and end point will be described. FIG. 11 shows a processing flow of an upstream connection performed at the connecting point. When an event occurs, the content of the event is analyzed, and if an AIS cell is received, the AIS reception process 10 (FIG. 12) is detected. If an MAIS cell is received, the MAIS reception process 11 (FIG. 13) is detected. In the case of failure detection processing 12 (see FIG.
Execute 4) respectively.

As shown in FIG. 12, AIS reception processing 10
Then, the ITU-TI. After performing the prescribed state transition (step 13) in 610, referring to the management information table as shown in FIG. 10, the connection corresponding to the reception cell (VPC specified by the VPI of the VP-AIS cell, or VC specified by VPI-VCI of VC-AIS cell
C) determines whether or not the vehicle joins at the connecting point (step 14).

If they are merged, the payload of the received AIS cell is rewritten to generate a MAIS cell, which is transmitted to the downstream side (step 15), and then a FERF cell is generated, which is used for reverse connection. (Step 16). In addition, the transmission of the FERF cell is performed by the IT.
U-I. 610 at the frequency specified. If the connection corresponding to the reception cell has not merged at the connecting point, the received AIS cell is directly transferred to the downstream direction without any processing (step 17).

As shown in FIG. 13, in the MAIS cell reception processing 11, the ITU-TI. The MAI received after the state transition (step 18) conforming to the regulations of 610 is performed.
The S cell is directly transferred to the downstream direction without any processing (step 19).

As shown in FIG. 14, in the lower layer failure detection processing 12, the ITU-TI. After performing the state transition (step 20) according to the regulations of 610, it is determined whether or not the active connections multiplexed in the connection (transmission path) of the faulty lower layer are merging at the connecting point. (Step 21). if,
If the connections are merged, a MAIS cell, which is a pseudo failure detection signal, is generated and transmitted in the downstream direction (step 22), and at the same time, a FERF cell is generated. -TI. 6
10 is transmitted at a prescribed frequency (step 23). If the connections have not joined, an AIS cell, which is the first failure detection signal, is generated and transmitted in the downstream direction (step 24).

FIG. 15 shows a processing flow of the downlink connection performed at the connecting point. When the FERF cell is received (step 25), the ITU-TI. 610
After performing the state transition (step 26) in accordance with the regulation (1), the received FERF cell is transferred to the downstream direction without processing (step 27).

FIG. 16 shows a processing flow of the upstream connection performed at the endpoint. The endpoint is
When the AIS cell is received, the AIS reception process 50 (see FIG. 1)
7), the MAIS cell reception process 51 (FIG. 18) is executed when the MAIS cell is received, and the lower layer failure detection process 52 (FIG. 19) is executed when the lower layer failure is detected.

In the AIS receiving process 50, as shown in FIG. 17, the ITU-TI. After performing the state transition (step 53) according to the regulations of 610, a FERF cell is generated,
This is used as a reverse connection by ITU-T I.D. It is transmitted to 610 at a prescribed frequency (step 54).

In the MAIS cell reception process 51, as shown in FIG. 18, the ITU-TI. A state transition (step 55) conforming to the regulations of 610 is performed.

In the lower layer failure detection processing 52, FIG.
As shown in FIG. After performing the state transition (step 56) according to the regulations of 610, a FERF cell is generated, and the FER-T I.S. It is transmitted to 610 at a prescribed frequency (step 57).

FIG. 20 shows a processing flow of downlink connection executed at the endpoint. When the FERF cell is received (step 58), the ITU-TI. A state transition (step 59) conforming to 610 is performed.

FIG. 21 shows the ITU-TI. The format 500-1 of the AIS cell defined in 610 is shown. A
The IS cell includes a header section 501 and a payload section 502, and the header section 501 is a 4-bit GFC (Gen).
eric Flow Control / VPI, 24
Bit VPI and 3-bit PTI (Payload)
Type Identifier) and 8-bit HE
Including C and. The payload section 502 also includes a function type, a failure type code, data indicating a failure point, and an error check code (CRC). Function type "0001000" indicates that the cell is an AIS cell.

FIG. 22 shows the ITU-TI. 610 shows the format 500-2 of the FERF cell defined in 610.
The function type of the FERF cell is FERF
It has the same content as the AIS cell except that it is changed to "00010001" indicating that it is a cell.

FIG. 23 shows the format 5 of the MAIS cell.
00-3 shows an example. The MAIS cell may have a configuration in which the malt point display bit 503 is provided in a specific field in the payload in the AIS cell format shown in FIG. Currently, ITU-T
I. In 610, only “0000”, “0001”, “0100”, and “1000” are determined as values set in the lower 4 bits of the function type field of the OAM cell for failure management, and “0010” is It is unused. Therefore, as the malt point display bit 503, for example, as shown in FIG. 24, the position 504 of the lower second bit of the function type field in the first octet of the payload 502 may be used.

If the bit 504 is a malt point display bit, the conversion from the AIS cell to the MAIS cell in step 15 in the AIS cell reception process shown in FIG. 12 is performed by changing the display bit 504 from "0" to "1". , And recalculate the EDC.

In the embodiment, as shown in FIG. 9, the failure notification cell 306 once extracted from the main signal flow (user cell flow 305) is converted into the MAIS cell by the failure notification cell control unit 301, and this is converted again. Although the format is such that it is inserted into the main signal flow, the bit rewriting for conversion into the MAIS cell may be performed while the AIS cell is in the main signal flow.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, in the network of FIG. 6, connecting points B1, B2, and B3, which are branch points, are designated in advance as “segment end points”, so that the multipoint connection between the route R and the leaves L1 to L4 is segmented as “S1 + S2”. , "S3 + S4",
When the segment is divided into “S5”, “S6”, “S7”, “S8”, and “S9”, all of these segments are point-to-point connections. 6
The failure detection notification method defined in 10 can be applied.

In this case, instead of terminating the AIS cell / FERF cell at the connection endpoint, the operation of each node is defined so that the AIS cell / FERF cell is terminated at the segment endpoint or the connection endpoint. , The AIS cell can be terminated at the branch node without notifying the connection endpoint and the FERF cell can be returned at the branch node. Therefore, as in the case of the above-described embodiment, the fault notification signal is unnecessary. It is possible to transfer to a required node without transmitting to a route.

[0051]

As is apparent from the above description, according to the present invention, the first failure notification signal (for example, VP-AIS).
Cell) is terminated at a branch node, and a second failure notification signal (for example, VP-FERF cell) is returned there, so that the second end is sent to the endpoint that can transmit the user cell without being affected by the failure. The inconvenience of the failure notification signal being returned is eliminated.

Further, the branch node terminating the first failure notification signal transmits a pseudo failure notification cell (for example, VP-MAIS cell) instead of the first failure notification signal to the downstream side of the connection, By sequentially relaying this to the nodes on the way, it is possible to notify the connection end point (root node) of the connection failure by the pseudo failure notification cell.

Further, the root node is caused to issue the second failure notification signal when the first failure notification signal is received, and the issuance of the second failure notification signal is suppressed when the pseudo failure notification signal is received. By doing so, it is possible to prevent the second failure notification signal from being returned to the endpoint that can transmit the user cell without being affected by the failure.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a first example of failure notification according to the present invention.

FIG. 2 is a diagram for explaining a second example of failure notification according to the present invention.

FIG. 3 is a diagram for explaining a third example of failure notification according to the present invention.

FIG. 4 is a diagram for explaining a fourth example of failure notification according to the present invention.

FIG. 5 is a diagram for explaining a fifth example of failure notification according to the present invention.

FIG. 6 is a diagram showing an example of a configuration of a multipoint connection.

FIG. 7 is a diagram showing the multipoint connection shown in FIG. 6 divided into upstream and downstream connections.

FIG. 8 is a diagram for explaining the problems of the conventional technique applied to the multipoint connection of FIG.

FIG. 9 is a diagram showing an example of a node configuration for implementing the present invention.

FIG. 10 is a diagram showing a structure of a table included in the node.

FIG. 11 is a flowchart of an upstream connection process executed at a connecting point.

FIG. 12 is a flowchart of AIS cell reception processing executed at a connecting point.

FIG. 13: MAIS executed at the connecting point
The flowchart of a cell reception process.

FIG. 14 is a flowchart of a lower layer fault detection process executed at a connecting point.

FIG. 15 is a flowchart of downlink connection processing executed at a connecting point.

FIG. 16 is a flowchart of upstream connection processing executed at the endpoint.

FIG. 17 is a flowchart of an AIS cell reception process executed by an endpoint.

FIG. 18 is a flowchart of a MAIS cell reception process executed by the endpoint.

FIG. 19 is a flowchart of lower layer failure detection processing executed at an endpoint.

FIG. 20 is a flowchart of downlink connection processing executed at an endpoint.

FIG. 21 is a diagram showing a format of an AIS cell.

FIG. 22 is a diagram showing a format of a FERF cell.

FIG. 23 is a diagram showing an example of a format of a MAIS cell.

FIG. 24 is a diagram showing another example of a MAIS cell format.

[Explanation of symbols]

R ... Route, L1-L4 ... Leaf, C1, C2 ... Connecting point without branch, B1-B3 ... Connecting point with branch, S1-S9 ... Section (link), Su1-Su9 ... Upstream link, Sd1-Sd9 ...
Downstream link, 100 ... AIS cell, 101 ... MAIS cell, 200 ... FERF cell

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H04Q 3/00

Claims (20)

[Claims] 1. A plurality of nodes, which have first and second connections having opposite transmission directions and paired with each other, for receiving a signal from an upstream and transmitting a signal to a downstream, are arranged on these connections. In a multipoint ATM network in which at least one of the nodes is a branch node, one node that detects a failure on the first connection sends a first failure notification signal in the downstream direction of the first connection. , The branch node in the middle of the first connection is
When the first failure notification signal is received, in the downstream direction of the branch path portion of the second connection that is paired with the branch path portion of the connection that receives the first failure notification signal among the first connections. A second failure notification signal is transmitted, each node on the second connection sequentially relays the second failure notification signal, and transfers the second failure notification signal to the end point of the second connection. Failure notification method in multipoint ATM network. 2. The branch node, which has received the first failure notification signal, transmits a pseudo failure notification signal in place of the first failure notification signal in the downstream direction of the first connection, 2. The failure notification method in a multipoint ATM network according to claim 1, wherein each node on the first connection relays the pseudo failure notification signal in sequence to a connection end point. 3. The first failure notification signal is ITU-T
I. In the VP-AIS cell defined in 610, the second failure notification signal is ITU-TI. The fault notification method in the multipoint ATM network according to claim 1 or 2, wherein the fault notification method is a VP-FERF cell defined by 610. 4. The first failure notification signal is ITU-T
I. 610, the second failure notification signal is ITU-T I.600. The fault notification method in the multipoint ATM network according to claim 1 or 2, which is a VC-FERF cell defined by 610. 5. The pseudo failure notification signal is ITU-T.
I. The fault notification method in a multipoint ATM network according to claim 2, wherein the fault notification method is a cell simulating a VP-AIS cell defined by 610. 6. The pseudo failure notification signal is ITU-T.
I. The fault notification method in a multipoint ATM network according to claim 2, wherein the fault notification method is a cell simulating a VC-AIS cell defined by 610. 7. A format of the pseudo failure notification signal includes information described in the format of the first failure notification signal and information indicating that it is for multipoint. Multipoint ATM described in
Failure notification method in network. 8. The multipoint ATM according to claim 2, wherein the format of the pseudo failure notification signal has information indicating that it is for multipoint.
Failure notification method in network. 9. The fault notification method in a multipoint ATM network according to claim 7, wherein the information indicating that the multipoint is used is 1 bit. 10. The branch node extracts the first failure notification signal from a main signal flow on the first connection, and generates the pseudo failure notification signal based on information included in the notification signal. 3. A multipoint AT according to claim 2, characterized in that it is generated and inserted into the main signal stream.
Failure notification method in M network. 11. The branch node uses 1 of information included in a first failure notification signal flowing on the first connection.
The multipoint AT according to claim 2, wherein a rewritten part is used as the pseudo failure notification signal.
Failure notification method in M network. 12. A VCI pre-assign value of a failure notification cell simulating the VP-AIS cell is ITU-T.
I. The multipoint ATM network according to claim 5, wherein the value is "0004 (H)" indicating the end-to-end OAM flow defined by 361, or the value "0003 (H)" indicating the segment OAM flow. Failure notification method in. 13. A PTI pre-assign value of a failure notification cell simulating the VC-AIS cell is ITU-T.
I. 7. The multipoint ATM network according to claim 6, wherein the value is "101 (B)" indicating the end-to-end OAM flow defined by 361 or the value "100 (B)" indicating the segment OAM flow. Failure notification method in. 14. A VCI pre-assign value of a failure notification cell simulating the VP-AIS cell is ITU-T.
I. Is a preliminary pre-assignment value defined in 361,
The VCI pre-assignment value of the VP-FERF cell is ITU-TI. The fault notification method in a multipoint ATM network according to claim 3 or 5, wherein the preassignment value is a spare preassigned value defined by 361. 15. A first pair having opposite transmission directions and paired with each other.
One node that has a second connection and detects a failure on the first connection transmits a first failure notification signal in the downstream direction of the first connection, and in the downstream direction of the first connection In a multipoint ATM network in which a node terminating the first failure notification signal sends a second failure notification signal to the second connection, and a node on the way relays these failure notification signals, The connecting point of a branching node is designated in advance as the segment end point, and the node designated as the segment end point or the node that is the connection end point on the first and second connections is the first end point. A multipoint AT characterized in that a failure notification signal or a second failure notification signal is terminated. Failure notification method in the network. 16. The first failure notification signal is ITU-T.
I. VP-AIS cell defined by H.610, and the second failure notification signal is ITU-TI. The fault notification method in a multipoint ATM network according to claim 15, wherein the fault notification method is a VP-FERF cell defined by 610. 17. The first failure notification signal is ITU-T.
I. 610-VC-AIS cell, and the second failure notification signal is ITU-TI. The fault notification method in a multipoint ATM network according to claim 15, wherein the fault notification method is a VC-FER cell defined by 610. 18. The VP-AIS cell and VP-FE.
The VCI pre-assign value indicating the RF cell is IT
U-I. The failure notification method in a multipoint ATM network according to claim 16, wherein the failure notification method is a preliminary preassigned value according to the provisions of 361. 19. A node device for forming a plurality of multipoint ATM connections on an ATM network, each of which comprises a first connection and a second connection, the transmission directions of which are opposite to each other. Means for setting the state to the first, second or third state for each call, and a first failure notification indicating a failure on the first connection in the call in which the first state is set When a signal is received or when a failure on the first connection is detected, a second failure notification signal is sent in the downstream direction of the second connection and a third failure notification signal is sent in the downstream direction of the first connection. When a third failure notification signal is received from another node in a call in which the failure notification signal is transmitted and the second state is set, the third failure notification signal is sent to the first connection. In the downstream direction of the second connection, when the first failure notification signal is received from another node in the call in which the third state is set, the second failure notification signal is transmitted in the downstream direction of the second connection. To send
A node device comprising: means for suppressing transmission of the second failure notification signal when the third failure notification signal is received from another node. 20. In a node device forming a plurality of multipoint ATM connections each having a first connection and a second connection whose transmission directions are opposite to each other on an ATM network, the state of the node on the connection is set. Control means for setting a predetermined state for each call, and when the state of the node is in the predetermined state,
When a first failure notification signal indicating a failure on the first connection is received, or when a failure on the first connection is detected, a second failure notification signal is provided downstream of the second connection. And a means for sending a third failure notification signal in the downstream direction of the first connection.