JPH04157942A - Generator for fault notice cell - Google Patents

Abstract

PURPOSE:To inform a fault of a transmission line quickly by sending a fault notice cell in response to the speed or the number to a destination equipment of a virtual pulse of the failed transmission line in the case of occurrence of the fault of the transmission line. CONSTITUTION:A fault notice cell generator 30 is provided to each transmission line of an ATM transmitter and fault detection is inputted to a routing switch section 402 via a signal changeover device 15 by using a fault notice signal 17. When a fault is found out, a fault cell is composed by a fault cell composing device 14 via a generating series storage memory 13 from a counter 11 of a cell processing period and the result is inputted to the section 402 via the signal changeover device 15 selecting the output from the transmission line. Thus, a fault cell is sent similarly to the information cell to the destination equipment. Moreover, when the content of the memory 13 is rewritten, the method of generating the fault notice cell is revised.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention performs multiplexing of cell signals, cross-connection of Hirch cell paths, exchange of virtual channels, etc., in which transferred data is a cell consisting of a header and an information field. A TM (85ynch-ronous T
Transfer mode, abbreviation for asynchronous transfer mode, is hereinafter referred to as ATM. ) A failure notification generation cell device provided in a transmission device.

In particular, regarding the technology for notifying the destination device of a failure by replacing the corresponding cell with a failure notification cell that notifies the failure when a transmission path failure is discovered, a circuit that generates this failure notification cell is provided for each transmission path. This invention relates to notification of a failure notification cell to a destination device.

[Conventional technology]

ATM communication networks are being researched that divide information to be transmitted into fixed-length blocks with headers called "cells" and asynchronously transfer signals in units of cells.

In this ATM communication network, information to be transmitted is transmitted in the form of cells, so if a transmission line failure occurs,
The information cells to be transmitted are no longer transmitted to the receiving device of the user who is the destination of the virtual path or virtual channel accommodated in the transmission path. In this case, if the device within the communication network does not notify the destination receiving device of the failure, the receiving device may not be able to recognize the failure, or the failure may have occurred within the ATM communication network. It may not be possible to recognize whether the problem occurred on the receiving device side. Therefore, it is necessary to have a configuration in which a device within the ATM communication network notifies the destination device of a virtual path or virtual channel accommodated in a transmission path where a failure has occurred from a failure.

Conventionally, as a method of notifying the failure when such a transmission line failure occurs, the failure of the transmission line is detected by periodically monitoring incoming cells in ATM transmission equipment that performs cross-connection. In this case, the applicant has previously proposed a method for creating a failure notification cell indicating the numbers and failures of all virtual paths accommodated in that transmission line and outputting it to the transmission line in which each virtual path is accommodated. (Patent application No. 1-130059).

This failure notification method will be explained below.

FIG. 5 shows a block diagram of an ATM transmission device using the failed cell notification method proposed in this application.

This ATM transmission device 40 is equipped with human input interfaces 401a, . This captured signal is given to the routing switch section 402, which reads the virtual path number of the cell and stores it in the virtual path number management table (hereinafter referred to as VPI).
403 (referred to as a management table). The VPI management table 403 searches the table and sends the outgoing line number corresponding to the virtual path number to the routing switch unit 402.
Notify.

As a result, the routing switch section 402 outputs each cell to each outgoing line according to the virtual path number via the output interfaces 404a...404b.

Further, in FIG. 5, reference numeral 405 is a transmission line failure detection unit 405 that detects a failure in the transmission line, and accommodates all outputs of the human power interfaces 401a to 401b. The detection output of the transmission line failure detection unit 405 is input to a VPI search unit 406 that searches the VPI management table 403 for all virtual paths accommodated in the input transmission line. The output of this VPI search section 406 is input to a failure notification cell creation section 407 that creates an alarm cell, and the failure notification cell output from the failure notification cell creation section 407 is input to the routing switch section 402.

When the transmission line failure detection unit 405 detects a failure in the input transmission line, it notifies the VPI search unit 406 of the failed transmission line number. This failure is detected, for example, when cells that should arrive periodically do not arrive, or when cells become out of synchronization due to a CRC check. VPI search section 4
06 searches the management table 403 for the virtual path numbers of all virtual paths accommodated in the transmission path of the notified number, and notifies the failure notification cell creation unit 407 of the obtained virtual path numbers. The failure notification cell creation unit 407 creates a failure notification cell from the virtual path number and the information indicating the failure, and sends the failure notification cell to the routing switch unit 40.
Output to 2. The routing switch unit 402 outputs the input failure notification cell to the outgoing line corresponding to the path indicated by the virtual path number via the output ink face 404. This process is then repeated for all target virtual paths.

[Problem to be solved by the invention]

In this way, the above-mentioned application proposes a method of notifying the virtual path destination device of a failure by sending a failure notification cell from the transmission device when a transmission line failure occurs.
The following problems remain.

First, there is no clear method as to the order and period in which failure notification cells are generated for each virtual path accommodated in a failure transmission line. Therefore, in a method in which the failure notification cell creation unit 407 repeatedly generates failure notification cells simply in the order found by the VPI search unit 406, the generation interval is insufficient for destination devices that require notification of failure status in short cycles. If the path is too long, or if the path is slow, the destination device or intermediate transmission device may experience a glitch due to excess reception capacity, and in the worst case, it may have a negative impact on traffic on other paths. .

In addition, a method of searching for a barge cell path number accommodated after a transmission line failure occurs is shown, but with this method, the search time increases when the number of virtual paths accommodated in the transmission device increases. As a result, it was expected that the generation of failure notification cells would be delayed.

In view of the above-mentioned problems, the present invention can generate failure notification cells according to the speed or number of virtual paths or virtual channels accommodated in a transmission path, and can generate failure notification cells quickly after a failure is detected. It is an object of the present invention to provide a failure notification cell generating device that can be implemented with a simplified configuration and small-scale hardware for being installed in an ATM transmission device that performs cell multiplexing or cross-connection.

[Means to solve the problem]

The present invention is provided in an ATM transmission device that performs multiplexing, virtual path cross-connect processing, or virtual channel exchange on cell signals that are composed of a header and an information field and that arrives via a transmission path, and outputs the cell signals that occur on the transmission path. detects a fault that occurred and generates a fault notification cell,
In a failure notification cell generation device that generates a failure notification cell to notify the destination of a cell signal, provided in each transmission line connected to the ATM transmission device,
means for detecting a transmission path failure; means for counting periodic pulses that are set by the failure detection signal of the detecting means and reset at the cell processing cycle to indicate the cell processing cycle; and the output of the counting means is inputted; occurrence series storage means for storing the occurrence series of virtual path numbers or virtual channel numbers for which failure notification is to be given, and outputting the stored virtual path numbers or virtual channel numbers by using the output of the counting means as an address; A means for assembling a failure notification cell based on the number outputted by the storage means, a failure notification cell generated by this means and a cell signal of the transmission line, and a cell signal of the transmission line by the failure detection output of the detection means. The present invention is characterized by comprising a switching means for switching the output and outputting the failure notification cell.

Further, the occurrence sequence storage means stores the virtual path number or virtual channel so that the cycle for generating failure notification cells is 2'' when the speed S of the virtual path or virtual channel is as follows with respect to the transmission line speed t. Store the virtual channel number and set a value of 2m as the reset period of the counting means, assuming that the period of the path or channel with the slowest speed of the virtual path or virtual channel accommodated in this transmission path is 2m. I can do it.

Further, the occurrence sequence storage means stores the virtual path number or virtual channel number with the number of virtual paths or Hirch cell channels accommodated in the transmission path as one cycle, and sets the reset cycle of the counting means to the occurrence sequence. The period may be the number of virtual paths or virtual channels stored in the storage means.

[Effect]

In an ATM communication network, the information cell of each virtual path is routed in accordance with the virtual path number assigned to the cell in the routing switch section of the transmission device that performs cross-connection, and is delivered to the intended destination device. . Similarly, information cells of each virtual channel are routed according to the virtual channel number assigned to the cell in the routing switch unit that exchanges virtual channels.
It is delivered to the intended destination device.

In the transmission equipment or switching equipment in an ATM communication network, if a cell is generated with the same virtual path number or the same virtual channel number as the virtual path accommodated in the transmission path, it can be treated in the same way as an information cell. It is delivered to the destination device. The present invention takes advantage of this property.

The failure notification cell generating device of the present invention is provided for each transmission path of an ATM transmission device, and when a transmission path failure is detected,
The output of the device is switched to output the failure notification cell generated from the cell output of the transmission line, and the output is manually input to the routing switch section. A counting means for counting cell processing cycles is provided, and when a failure is detected, the output of this counting means is given as an address to a memory that stores the generation sequence of the path or channel number for which failure notification is to be made. A failure notification cell is manually assembled using the path or channel number of the output of this memory, and the output is manually input to the routing switch section using a switching circuit that switches the output from the transmission line side. As a result, a failure notification cell is sent to the destination device in the same way as an information cell.

Furthermore, by rewriting the contents of the generation sequence storage memory, the method of generating failure notification cells can be easily changed.

〔Example〕

The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a block diagram of an ATM transmission device equipped with a failure notification cell generating device according to an embodiment of the present invention.

This ATM transmission device has input interfaces 401a to 401a.
401b, the routing switch unit 402 outputs a cell signal manually inputted to the cell to a target outgoing line via output interfaces 404a to 404b in accordance with the virtual path number or virtual channel number assigned to the cell.

The difference between this ATM transmission device 40 and the conventional ATM transmission device shown in FIG. 5 is that a failure notification cell generating section 30 of the present invention is provided for each manual transmission path, and a failure of the corresponding input transmission path is detected. It is configured to generate a failure notification cell and output it to the routing switch section 402 when a failure occurs. Further, the VP management table 403 is a table indicating to which outgoing line the cell is to be output for each virtual path number (or virtual channel number) of the cell input from each manual transmission line, and the routing switch unit 402 Information cells or failure notification cells are routed according to the contents of this VPI management table 403.

FIG. 2 is a block diagram showing the configuration of the failure notification cell generating section 30 according to an embodiment of the present invention.

Cell signals input from each input interface 401 are input to the signal switch 15 and are also input to the failure detector 16.
is input. Failure detection signal 17 of this failure detector 16
is input as a switching control signal to the signal switch 15, and is also input to the counter 11 that counts the cell cycle pulses 18. The counter output I9 of this counter 11 is
A cell sequence length value 20 is input to a comparator 12, and a sequence of bird cell path numbers (or virtual channel numbers) is output as an address to a generation sequence storage memory 13. The output of the comparator 12 is input as a counter reset signal 21 for the counter 11.

The virtual path number (or virtual channel number) signal 22 outputted from the occurrence sequence storage memory 13 is manually inputted to the failure notification cell assembler 14 .
The failure notification cell signal 23 outputted from the signal switch 15 is manually inputted to one side of the signal switch 15. The output of the signal switch 15 is manually input to the routing switch unit 402 .

Next, the operation of this failure notification cell generating section 30 will be explained.

The fault detector 16 examines the cell signal 24 manually input from the transmission line, and outputs a fault detection signal 17 when a fault is detected.

The failure detection signal 17 is sent to the counter 11 and the signal switch 15.
is output to. When the failure detection signal 17 is input manually, the counter 11 starts counting the cell processing cycle pulses 18 from an initial value, for example, 0, and outputs the counter output 19 to the comparator 12 and the generation sequence storage memory 13.Comparator 12 compares the counter output 19 with a sequence length value 20 indicating the length of a sequence of failure notification cells given in advance, and outputs a counter reset signal 21 if they match.

When the counter reset signal 2I is inputted manually, the counter 11 performs the counting operation again from the initial value. Therefore, the values from the initial value to the sequence length are repeatedly output to the counter output 19 in order.

Occurrence series memory memo January 3 stores in advance a series of virtual path numbers (or virtual channel numbers) to which failure notification cells are sent, and using the counter output 19 as an address manual, the barge cell path number (or virtual channel number) signal 22 Output as .

The failure notification cell assembler 14 assembles a failure detection cell using a predetermined failure indication button and virtual path number (or virtual channel number), and outputs a failure notification cell signal 23. The signal switch 15 switches the signal output to the routing switch unit 402 from the cell signal 24 from the transmission line to the failure notification cell signal 23 in response to the failure detection signal 17 . Routing switch section 40
The failure notification cell sent to 2 is distributed to the target output transmission line according to the virtual path number (or virtual channel number) assigned to the cell.

With the above configuration, when a transmission path failure occurs, a failure notification cell is generated to the destination device of the virtual path number (or virtual channel number) stored in the occurrence sequence storage memory 13.

An example of the configuration of this failure notification cell is shown in FIG.

In FIG. 6, a failure notification cell 51 is composed of a header 52 and an information field 53 like other information cells. A virtual path number (or virtual channel number) 54 for notifying a failure is placed in the header 52, and a failure display pattern 55 is placed in the information field 53 as shown in FIG. 6(a), or in the information field 53 as shown in FIG. 6(b). It is placed on the header 52 as shown in FIG.

In the failure notification cell generation unit 30 of the embodiment of the present invention, the content to be written in advance to the occurrence series storage memo month 3 and the comparator 12
By setting the sequence length value 20 given to the transmission line according to the speed of the virtual path (or virtual channel) accommodated in the transmission path or the number of virtual paths (or virtual channels), the method of generating failure notification cells can be changed. I can do something.

An example of the failure notification cell generation method will be shown below.

(Embodiment 1 of Failure Notification Cell Generation Method) As an example of the first failure notification cell generation method, a method of generating failure notification cells at a period proportional to the speed of the virtual path will be described with reference to FIG.

When the speed S of a virtual path (or virtual channel) accommodated in a transmission path with a transmission speed t is , the period for generating failure notification cells is set to be 2 m''.

Next, the virtual path number (or virtual channel number) is set in the generation sequence memory 13 at a given period starting from the faster virtual path (or bird cell channel).

In the occurrence sequence storage memory 13 of FIG. 3, the occurrence period of virtual path number (or virtual channel number) a is set to "2", and the occurrence period of virtual path number (or virtual channel number) b is set to "4". This is an example. In addition, the sequence length value 20 of the comparator 12 is 2n- corresponding to addresses "0" to r2n-IJ of the generation sequence storage memo January 3 when the generation cycle for the slowest Hirch cell path (or virtual channel) is 2n. ] Set.

Here, to explain the relationship between m and n, m is a value given to each H'-Cell path (or H'Cell channel), and n indicates the maximum value of m. That is, since n is the period value of the slowest virtual path (or virtual channel), there is a relationship of ■≦m≦n, where n is the maximum value.

For example, if the speed of the slowest virtual path (or virtual channel) is 54 kb/s and the speed of this transmission line is 67 Mb/s, then n-10 is 102
This virtual path (or virtual channel) appears at a cycle of 4, the addresses of the generation sequence memory 13 are 0 to 1023, and 1023 is given as the sequence length value 20. In a virtual path (or virtual channel) with a speed of 33 Mb/s, m=l, which appears with a period of 2, and appears corresponding to the virtual path number (or virtual channel number) of a in FIG.

Note that the above relational expression between S and t is such that S is, for example, 80 kb/
s, it means that the period of this bird cell path (or virtual channel) is the same as that of the lowest speed, 54 kb/s.

This is because if the cycle is made faster, overflow will occur and the receiving device will not be able to receive the failure notification cell, so to prevent this, the cycle is set to be the same as the 54kb/s path, which is slower than 80kb/s. It is.

In this way, the occurrence sequence memory memo January 3 virtual path number (or virtual channel number) and sequence length value 2
By setting 0, when a transmission path fails, failure notification cells can be generated at a period proportional to the speed of each virtual path (or virtual channel).

(Example 2 of failure notification cell generation method) Next, as another example of failure notification cell generation method, a virtual path (or virtual channel) accommodated in a transmission path
A method of generating failure notification cells at regular intervals will be explained based on FIG.

When the number of virtual paths (or virtual channels) accommodated in the transmission path is k, the addresses "0" to "k-1" of the generated sequence storage memory 13 are used as the sequence length value of the comparator 12.
Set -1 in response to .

Further, the virtual path numbers (or virtual channel numbers) of the virtual paths (or virtual channels) accommodated in the occurrence sequence storage memory 13 are set one by one. With this setting, failure notification cells are generated at the shortest cycle relative to the number of virtual paths (or virtual channels) accommodated in the transmission path.

Note that the stored contents such as the virtual path number (or virtual channel number) and the sequence length value 20, which are written in advance in the occurrence sequence storage memory 13, are stored in the VP shown in FIG.
It can be easily created based on the contents of the I management table 403.

〔Effect of the invention〕

As explained above, by using the failure notification cell generator of the present invention in a transmission device that performs cell multiplexing or cross-connection in a ΔTM communication network, when a failure occurs in a transmission line, Since failure notification cells can be sent to the destination device of each accommodated virtual path (or virtual channel) according to the speed or number of virtual paths (or Hirch cell channels),
It becomes possible to quickly report transmission line failures.

In addition, by providing a failure notification cell generator for each transmission path, the configuration for generating failure notification cells is simplified.
Moreover, the capacity required for the generation sequence storage memory is, for example, AT
A minimum of 54 Mb/s transmission lines with a transmission speed of 150 Mb/s in the M communication network
1 even when accommodating a virtual path with a speed of kb/s.
The size of the fault notification cell generation circuit is approximately 0.00 kbyte, and only a few memory chips are sufficient, so that the entire fault notification cell generation circuit can be realized with a small hardware scale.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an ATM transmission device equipped with a failure notification cell generating section of the present invention. FIG. 2 is a block diagram showing the configuration of a failure notification cell generating section according to an embodiment of the present invention. FIG. 3 and FIG. 4 are diagrams for explaining an embodiment in which a failure notification cell is generated. FIG. 5 is a block diagram of a conventional ATM transmission device configured to notify failures. FIG. 6 is a diagram showing an example of the format of a failure notification cell. 11... Counter, 12... Comparator, 13... Occurrence sequence storage memory, 14... Failure notification cell assembler, 1
5...Signal switcher, 16...Failure detector, 17...
・Failure detection signal, 18... Cell processing period pulse, 19
...Counter output, 20...Sequence length value, 21...
Counter reset signal, 22... Virtual path number (or virtual channel number) signal, 23... Failure notification cell signal, 24... Cell signal from transmission path, 3
0... Failure notification cell generation unit, 40... ATM transmission device, 51... Failure notification cell, 52... Header, 53
...Information field, 54...Virtual path number (or virtual channel number), 55...Failure display button, 401...Input interface, 402
... Routing switch section, 403 ... VPI management table, 404 ... Output ink face, 405 ...
...Transmission path failure detection section, 406...VPI search section, 4
07... Failure notification cell creation unit. Patent applicant: Nippon Telegraph and Telephone Corporation Representative Patent attorney: Naotaka Ide (and one other person)

Claims (1)

[Scope of Claims] 1. Provided in an ATM transmission device that performs multiplexing, virtual path cross-connect processing, or virtual channel exchange on cell signals that are composed of a header and an information field and that arrive via a transmission path, and outputs the resultant cell signals, In a failure notification cell generation device that detects a failure occurring in a transmission path, generates a failure notification cell, and generates a failure notification cell to notify the destination of the cell signal, a device installed in each transmission path connected to the ATM transmission device. means for detecting a transmission path failure; means for counting periodic pulses that are set by the failure detection signal of the detecting means and reset at the cell processing cycle to indicate the cell processing cycle; and an output of the counting means is input. occurrence series storage means for storing the occurrence series of virtual path numbers or virtual channel numbers for which failure notification is to be performed, and outputting the stored virtual path numbers or virtual channel numbers by using the output of the counting means as an address; means for assembling a failure notification cell based on the numbers output by the sequence storage means; and a failure notification cell generated by this means and the cell signal of the transmission line are input, and the cell of the transmission line is inputted by the failure detection output of the detection means. A failure notification cell generating device comprising: switching means for switching signal output and outputting the failure notification cell. 2. The occurrence sequence storage means generates a failure notification when the speed s of the virtual path or virtual channel is t/2^m^-^1<s≦t/2^m with respect to the transmission line speed t. The above-mentioned virtual path number or virtual channel number is stored so that the cell generation period is 2^m, and the speed of the virtual path or virtual channel accommodated in this transmission path is the slowest as the reset period of the above-mentioned counting means. When the period of a path or channel is 2^n, set the value of 2^n. However, m and n are 1≦m≦n
2. The failure notification cell generating device according to claim 1, wherein the cell is a natural number having the relationship: . 3. The occurrence sequence storage means stores the virtual path number or virtual channel number with the number of virtual paths or virtual channels accommodated in the transmission line as one cycle, and stores the reset period of the counting means as the occurrence sequence storage means. 2. The failure notification cell generating device according to claim 1, wherein the cycle is equal to the number of virtual paths or virtual channels stored in the means.