JP3045879B2 - Transmission speed mismatch detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for converting an input continuous signal (CBR signal: Constant Bit Rate) into an ATM (Asynchr) signal.
onous Transfer Mode) After converting to a cell, the packet is transferred through a virtual path in the ATM network.
In a transmission method of a continuous signal through an ATM network, in which M cells are returned to an original continuous signal, the speed of an input continuous signal on a transmission side and the reception of an ATM cell format continuous signal on a reception side. The present invention relates to a transmission speed mismatch detecting device for determining on the receiving side whether or not the speed set in the transmission speed matches.

When a continuous signal (CBR signal) of various transmission speeds (transmission units) comes in, a continuous signal of a specific speed is selected and divided into ATM cells, which are transferred through a virtual path in an ATM communication network. On the receiving side, by connecting the received ATM cells to restore the original continuous signal, when transmitting the continuous signal through the ATM network, the transmission rate (transmission rate) at which the continuous signal is selected and converted into an ATM cell is selected. unit)
Setting (continuous signal of the set transmission rate is selected)
If the setting does not match the setting of the transmission rate (transmission unit) when returning from the ATM cell to the continuous signal, the reception will not be performed normally, and the match or mismatch will be detected.

[0003]

2. Description of the Related Art FIG. 17 is an explanatory diagram showing a transmission system for transmitting a continuous signal (CBR signal) using an ATM communication network. In the figure, reference numeral 201 denotes a C input from the outside.
A conversion device for converting a BR signal into an ATM cell.
This is an inverse conversion device for returning a TM cell to an original CBR signal. That is, the conversion device 201 divides the CBR signal into ATM cells, transmits the ATM cells through a virtual path in the ATM network, and the reverse conversion device 202 converts the received ATM cells back to the original CBR signal.

FIG. 18 is an explanatory diagram showing a mode of transmitting an SDH (Synchronous Digital Hierarchy) path signal, which is a kind of CBR signal, using an ATM communication network. FIG. 18A shows a case where a buffer overflow occurs, and FIG. 18B shows a case where a buffer underflow occurs, which will be described later.

In FIG. 1, reference numeral 201 denotes an input continuous signal (S
AU-3, TU-2, T belonging to the DH signal format
A converter for converting a signal in a standardized format such as U-12 or TU-11 or a transmission unit) into a cell, and an inverse converter 202 for converting an ATM cell into a transmission unit (original continuous signal) of an SDH path. .

[0006] The inverse converter 202 has a buffer 103 for absorbing delay fluctuations of cells in the ATM communication network. AT
The cell arriving from the M network is transmitted to the
The data is written into the buffer 103 and read at the speed of the transmission unit set from outside the apparatus. Usually, the converter 2
In step 01, the same transmission unit as the transmission unit to be cellized is set in the inverse converter 202, and an operation of returning to the original transmission unit is performed.

The conversion device 201 is set to convert a continuous signal (transmission unit) of TU-2 of SDH into a cell, and the inverse conversion device 202 converts a received cell from a received cell to a signal (transmission unit) of another speed of TU-11. It is assumed that the transmission unit is incorrectly set to return. At this time, the converter 201 sends cells to the ATM network at the speed of the set transmission unit TU-2, and the inverse converter 202 receives the cells at that speed, and the received transfer unit is at the speed of TU-2. The data is written to the buffer 103.

On the other hand, since the inverse converter 202 is set to another speed of TU-11, the transmission unit in the buffer 103 is read from the buffer 103 at the speed of TU-11. Since the speed of TU-2 is higher than the speed of TU-11, the buffer 103 is written at a high speed and read at a low speed, so as shown in FIG.
Overflow occurs.

When TU-11 is set as the transmission unit of the conversion device 201 and TU-2 is set as the transmission unit of the inverse conversion device 202, the buffer 1 is conversely set as shown in FIG.
03 is an underflow. It goes without saying that the occurrence of overflow or underflow is inconvenient.

[0010]

SUMMARY OF THE INVENTION The present invention seeks to overcome the disadvantages of the prior art.
That is, an object of the present invention is to prevent overflow and underflow of a receiving buffer that occurs when a maintenance person mistakenly sets different transmission speeds in a transmitting-side converting device and a receiving-side inverting device. It is an object of the present invention to provide a transmission rate mismatch detecting device for detecting a transmission rate mismatch so that a setting can be found.

[0011]

In order to achieve the above object, according to the present invention, a continuous signal input through a specific virtual path is selected from continuous signals input and converted into cells. A conversion device that receives the cells transferred from the conversion device, receives the cells transferred from the conversion device through a virtual path in the ATM network, and returns the cells to the original continuous signal. In a transmission method of a continuous signal through an ATM network,

In the above-mentioned conversion device, means for writing the speed of an incoming continuous signal is provided in a cell area, and in the above-mentioned inverse conversion device, the speed of a continuous signal written in the above-mentioned area in a cell is read. Means, and means for comparing the read speed with a speed set in advance in the inverse conversion device, and from the result of the comparison, a match between the speed of the input continuous signal and the set speed is detected so as to detect a mismatch. did.

[0013]

According to the present invention, it is possible to prevent overflow and underflow of the receiving buffer caused when a maintenance person mistakenly sets different transmission speeds in the transmitting-side converting device and the receiving-side inverting device, and to perform erroneous setting. Can be found.

[0014]

FIG. 1 is a block diagram showing a first embodiment of the present invention. In the figure, reference numeral 201 denotes a conversion device;
Is a VPI (virtual path identifier) externally set by a cell circuit for assembling cells from an input CBR signal (continuous signal), and sets a VPI set from among CBR signals coming from various VPs (virtual paths). (A circuit for selectively receiving a CBR signal having the following formula (1)) and inserting the VPI into the header of the assembled cell).

Reference numeral 302 denotes a circuit for inserting a VCI (virtual circuit identifier, an identifier for identifying a line in the virtual path VP) into a cell header.
Is inserted into the header (each predetermined value corresponding to the transmission unit, that is, the transmission rate).

[0016]

[Table 1]

Reference numeral 202 denotes an inverse conversion device; 203, a circuit for selecting a VPI cell set from the outside;
A circuit 305 for extracting the VCI value of the cell selected in 03 and recognizing the transmission rate (transmission unit) of the received cell. A circuit 306 for comparing the transmission speed (transmission unit) obtained by absorbing the delay fluctuation of the cell and the original CB
Circuit for returning to the R signal.

In this embodiment, the transmission unit cellized by the conversion device 201 is transmitted to the inverse conversion device 202 by using an area transparently transmitted from the conversion device 201 to the inverse conversion device 202 in the header of the cell. . For example, when cells are transmitted from the conversion device 201 to the inverse conversion device 202 using a virtual path, the VCI of the header is transmitted transparently on the virtual path. The conversion device 201 assigns, for example, the VCI shown in Table 1 to the cell for each transmission speed (transmission unit). The transmission rate (transmission unit) is recognized from the VCI value of the cell arriving at the inverter 202 via the virtual path, and the recognized transmission rate (transmission unit) and the transmission rate (transmission unit) set in the inverter 202 are recognized. If they do not match, the transmission speed mismatch is detected.

Next, the circuit operation of this embodiment will be described with reference to FIG. For example, when the converter 201 converts TU-11 (format standard) of the SDH path signal as a CBR signal into a cell, the circuit 302
A VCI value of 000 0000 00010000 is assigned. This cell is a virtual path and is used by the inverse transformation unit 202.
Is transmitted to In the inverse converter 202, the setting is made so that the circuit 303 selects the VPI cell of the virtual path.

At this time, 0000 is subtracted from the cell by the circuit 304.
A VCI value of 0000 0001 0000 is extracted, whereby it is recognized that the received signal is TU-11. If the transmission rate (transmission unit) externally set to the inverse converter 202 is other than TU-11, the circuit 30
The result of the comparison at 5 is inconsistent. If the transmission rate (transmission unit) externally set in the inverse converter 202 is TU-11, the comparison result of the circuit 305 matches. The above circuit detects transmission speed mismatch.

Next, the second embodiment of the present invention will be described. For the sake of understanding, first, CCITT (International Telegraph and Telephone Consultative Committee) recommendation I. 363 AALs (ATM
Adaptation Layer) type 1 using T
The format of a cell when transmitting U-11 / TU-2 / AU-3 will be described.

FIG. 2 is an explanatory diagram showing the format of a cell in a case where a cell having an even SC (sequence count) has a leading byte of a TU / AU signal. Also, FIG.
TU / A for odd-numbered cells with SC (sequence count)
FIG. 9 is an explanatory diagram showing a cell format when there is a first byte of a U signal.

Here, the SC (sequence count) is a serial number assigned to each cell.
That is, when 0 is given as SC to the first cell, 1 is given to the next cell, 2 is given to the next cell, and so on.
After the serial number is assigned, return to the original and return to 0 again
And so on. In the cell format, bytes are sent from 1 and the bits in each byte are sent from 8 onwards. The first transmitted bit in each field is the MSB.

As described above, in the cell format for transmitting the TU-11 / TU-2 / AU-3 of the SDH path signal using the AAL type 1, the SC (Sequence) is set at the sixth byte of each cell. Count), and serial numbers 0 to 7 are inserted for each cell.

As shown in FIG. 2, TU-11 / TU-2
If the first byte of / AU-3 or the like is in an even-numbered SC cell, the CS pointer area is set to the seventh byte of the cell and the CS pointer bit is set to 1 to confirm that the CS pointer area is set. indicate. The offset value of the CS pointer is equal to the TU-11 / TU- in the information area of the cell.
2 / Indicates the first byte of AU-3.

As shown in FIG. 3, TU-11 / TU-2
If the first byte such as / AU-3 is in an odd-numbered SC cell, the CS pointer area is set to the seventh byte of the preceding even-numbered SC cell, and the CSI bit is set to 1 to set
This indicates that the S pointer area has been set. CS
The pointer offset value indicates the TU-11 / TU-2 / AU-3 first byte in the information area of the odd-numbered SC cell.

The first byte such as TU-11 / TU-2 / AU-3 has CCITT recommendation G. shown in FIG. There is a V1 byte of the TU pointer or an H1 pointer of the AU pointer defined in 709, and the SS bit is extracted from the V1 byte. FIG. 4 is an explanatory diagram showing the configuration of the TU / AU pointer.

The SS bit of the TU / AU pointer is CCI
TT Recommendation G. 709 indicates the transmission unit as shown in Table 2 below. Therefore, by extracting the SS bits by the inverse converter 202, the TU-1
It becomes clear which of 1 / TU-2 / AU-3 has been made into a cell. Therefore, if the setting of the transmission unit (transmission speed) of the converter 201 and the inverse converter 202 does not match, it can be detected.

[0029]

[Table 2]

Next, a second embodiment of the present invention will be described based on the above. FIG. 5 is a block diagram showing a circuit configuration of the second embodiment of the present invention. In this embodiment, the input continuous signal is
It is limited to a signal of any one of TU-11 / TU-2 / AU-3. In the figure, reference numeral 201 denotes a conversion device;
Reference numeral 01 denotes a circuit for assembling cells by storing the signals of TU-11 / TU-2 / AU-3 including the TU / AU pointer in the cell information area, and inserting a VPI set from outside into the header. is there. Reference numeral 202 denotes an inverse conversion device.

Reference numeral 602 denotes a circuit for selecting a cell of a VPI set from outside, reference numeral 603 denotes a circuit for identifying the first byte of the TU-11 / TU-2 / AU-3 signal from the CSI and CS pointer of the cell, and reference numeral 604 denotes identification. A circuit for identifying a transmission unit of a received signal from the SS bit of the converted byte,
5 is a circuit for comparing the recognized transmission unit with the transmission unit set in the device 202, and 606 is a circuit for absorbing the delay fluctuation of the cell and returning it to the original TU-11 / TU-2 / AU-3 signal. .

Next, the circuit operation of this embodiment will be described with reference to FIG. For example, when the TU-11 of the SDH path signal is converted into a cell by the conversion device 201, the SS bit of the TU pointer is 11, and the V1 byte of the TU pointer is specified by the CSI and the CS pointer to be converted into a cell. The cell is communicated to device 202 via a virtual path. The device 202 is set so that the circuit 602 selects the VPI cell of the virtual path.

At this time, the first byte of the TU / AU signal is identified by the circuit 603 using the CSI and the CS pointer.
In step 4, 11 is extracted as the SS bit from the first byte, and it is recognized that the transmission unit of the received signal is TU-11. The transmission unit set externally to the device 202 is T
If U-2 / AU-3, the comparison result in the circuit 605 does not match. If the transmission unit set externally to the device 202 is TU-11, the comparison result of the circuit 605 matches.

The above circuit detects the mismatch of the transmission units. In this embodiment, since the VCI is not used for transmitting information between the device 201 and the device 202, the connection between the device 201 and the device 202 can be made by a virtual channel instead of a virtual path. At this time, the circuit 601 uses the VPI corresponding to the virtual channel.
And VCI are inserted into the cell, and the set V
The PI and VCI cells are selected.

Next, a third embodiment of the present invention will be described. In the third embodiment, the mismatch of the transmission unit is detected by counting the frame length of the SDH signal as the CBR signal extracted from the information area of the ATM cell by the inverse converter 202. The frame head position information of the SDH signal is described in CCITT Recommendation I. Assume that the operation is performed using the CSI and CS pointer of H.363.

For example, the TU-11 / T of the SDH path signal
When transmitting U-12 / TU-2 / AU-3 / AU-4, CSI and CS pointer are used. TU-
11 / TU-12 / TU-2 / AU-3 / AU-4 starts with CCITT Recommendation I.11. 363 is indicated by the CS pointer defined in the cell as shown in FIG. By counting the number of bytes in the cell information area from the byte designated by the CS pointer to the byte designated by the next CS pointer, the frame length of the signal can be determined.

TU-11 / TU-12 / TU-2 / AU
-3 / AU-4 frame length is based on CCITT Recommendation G. 70
9 as defined in Table 3 below. Therefore,
If the inverse transform unit 202 extracts the frame length, the transform unit 201 extracts TU-11 / TU-12 / TU-2 / AU-3.
/ AU-4 is made into a cell. Therefore, if the settings of the transmission units of the conversion device 201 and the inverse conversion device 202 do not match, it can be detected.

[0038]

[Table 3]

Based on the above, a third embodiment of the present invention will be specifically described below. FIG. 6 is a block diagram showing a circuit configuration of the third embodiment of the present invention. In the figure, 2
01 is a conversion device, 701 is TU-11 / TU-12 / T
A circuit that accommodates U-2 / AU-3 / AU-4 signals in a cell information area to assemble a cell and inserts an externally set VPI into a header.

Reference numeral 202 denotes an inverse converter, 702 a circuit for selecting a VPI cell set from outside, and 703 a TU-11 / TU-12 based on the CSI and CS pointer of the cell.
A circuit for identifying the first byte position of the / TU-2 / AU-3 / AU-4 signal, 704 counts the number of bytes between the two first byte positions identified in 703, and determines the reception transmission unit from the length. A circuit for recognizing 705 is a circuit for comparing the transmission unit identified in 704 with the transmission unit set in the device 202, and 706 is a circuit for absorbing the delay fluctuation of the cell to obtain the original TU
A circuit 706 for returning the signal to a -11 / TU-12 / TU-2 / AU-3 / AU-4 signal.

Next, the circuit operation of this embodiment will be described with reference to FIG. For example, the TU of the SDH path signal is
When -11 is cellized, the frame length of TU-11 is 1
08 bytes, the head of which is indicated by the CSI and CS pointers, and is cellized. The cell is communicated to device 202 via a virtual path. The device 202 is set so that the circuit 702 selects the VPI cell of the virtual path.

The circuit 703 uses the CSI and CS shown in FIG.
The start position of the frame in the information area of the cell is identified using the pointer. The number of bytes from the head position to the head position of the next frame is counted by the circuit 704 to be 108 bytes. Therefore, the circuit 704 recognizes that the transmission unit of the received signal is TU-11.

The transmission unit recognized by the circuit 704 and the device 20
The transmission unit set externally to 2 is compared by the circuit 705. If the setting of the transmission unit of the device 202 is other than TU-11, the comparison result in the circuit 705 becomes inconsistent. Device 2
If the transmission unit externally set to 02 is TU-11, the comparison result of the circuit 705 matches. The above-described circuit detects the mismatch of transmission units.

In this embodiment, since the VCI is not used for transmitting information between the device 201 and the device 202, the device 20
It is also possible to connect the device 1 and the device 202 by a virtual channel instead of a virtual path. At this time,
In the circuit 701, the VP corresponding to the virtual channel
I and VCI are inserted into the cell, and the circuit 702 selects the cell of the set VPI and VCI.

Next, a method of obtaining the frame length in this embodiment will be described. FIG. 7 shows two CS pointers (P
FIG. 3 is a diagram illustrating a method for obtaining a frame length from (1, P2). The first method is to count the number of bytes in the information area from the byte indicated by P1 to the byte indicated by P2. FIG. 8 shows an example of a circuit for realizing the first method.

In FIG. 8, P1 is first loaded into the counter 1, and is decremented by one each time a byte in the information area is received. When the counter 1 becomes zero, the counter 2 is reset. Thereafter, the counter 2 starts counting bytes in the information area following the byte indicated by P1.
Meanwhile, P1 is loaded into the counter 1 and is decremented by 1 in the byte of the information area. When the counter 1 becomes zero again, the contents of the counter 2 are stored in the latch, and the counter 2
Is then reset. The value stored in the latch becomes the frame length.

The second method is a method of obtaining a frame length from the values of P1 and P2 and the number of cells received between them. FIG. 9 shows a circuit for realizing the second method. The counter is CS
It is reset when the pointer is received, and counts the number of cells received until the next CS pointer is received. The counted cell number is stored in the latch. An adder adds P2 to the number obtained by multiplying the number of cells stored in the latch by 47, and subtracts P1 and P2 to obtain the frame length.

Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, the conversion apparatus 201 generates a transmission rate identification OAM cell having a different identifier for each transmission rate, and
The same VPI as that of the cell that converted the signal is applied to
Send M cells. Cell for transmitting CBR signal and OAM
Cells are identified by assigning different VCIs.

Further, in the OAM type area of the OAM cell, the OAM cell for identifying the transmission rate (transmission unit) and another OA
Identify M cells. OAM for transmission speed (transmission unit) identification
FIG. 10 shows an example of a cell format. Table 4 below shows examples of identifiers indicating transmission speeds (transmission units).

[0050]

[Table 4]

The OAM cell arrives at the inverse transformer 202 via the same virtual path as the cell carrying the CBR signal. The OAM cell is identified from the VCI value of the cell header by the inverse converter 202. Further, an OAM cell for identifying a transmission rate (transmission unit) is identified from the OAMtype area. This O
From the transmission rate (transmission unit) identifier in the AM cell,
Recognizing the transmission rate (transmission unit) set to 01 and comparing the transmission rate (transmission unit) set to the inverse converter 202, if they are different, the transmission between the converter 201 and the inverse converter 202 It detects that the speeds (transmission units) do not match.

Hereinafter, a fourth embodiment will be specifically described.
FIG. 11 is a block diagram showing a circuit configuration of the fourth embodiment of the present invention. In the figure, reference numeral 201 denotes a conversion device;
Reference numeral 01 denotes a circuit for accommodating a CBR signal in a cell information area to assemble a cell and insert a VPI set from the outside into a header. Reference numeral 1202 denotes an OAM having an identifier of a transmission rate (transmission unit) of the cellized CBR signal. Circuit for generating cells.

Reference numeral 202 denotes an inverse converter; 1203, a circuit for selecting a VPI cell set from outside; 1204, a circuit for separating a transmission rate (transmission unit) identification OAM cell from other cells; 1205, a separated OAM cell; From the transmission rate (transmission unit) identifier in the cell, the transmission rate (transmission unit)
1206 is a circuit for comparing the transmission rate (transmission unit) identified by the circuit 1205 with the transmission rate (transmission unit) set from the outside of the device 202, and 1207 absorbs the delay fluctuation of the cell and restores the original. Circuit for returning to a CBR signal.

Next, the circuit operation of this embodiment will be described with reference to FIG. For example, when the device 201 converts the TU-11 of the SDH path signal as the CBR signal into a cell, the transmission unit identifier is 0000 0 in the circuit 1202 based on Table 4.
001 OAM cells are generated. This OAM cell is
It is transmitted to the device 202 on the same virtual path as the cell transmitting the CBR signal.

In the device 202, the V of the virtual path
The cell of the PI is set to be selected by the circuit 1203.
At this time, the cell transmitting the CBR signal and the transmission unit identification OAM cell are separated from the VCI and OAM type of the cell in the circuit 1204, the transmission unit identifier of 0001 0000 is extracted in the circuit 1205, and the transmission unit of the received signal is TU- 1
1 is recognized.

If the transmission unit set externally to the device 202 is other than TU-11, the comparison result in the circuit 1206 will be inconsistent. If the transmission unit externally set to the device 202 is TU-11, the comparison result of the circuit 1206 matches. The above circuit detects the mismatch of the transmission speed (transmission unit).

Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, a transmission speed (transmission unit) is used in the conversion device 201.
A transmission rate (transmission unit) identifier having a different code every time is put in a specific position of the information area of the cell. Figure 1 shows how to put the transmission rate (transmission unit) identifier in the last byte of every cell
It is shown in FIG. In FIG. 12, SC is even and CSI = 1.
In this case, a CS pointer area is provided.

FIG. 13 shows an example in which a transmission rate (transmission unit) identifier is placed in the seventh byte of an odd-numbered SC cell in which the CS pointer is not set. There is also a method of placing a transmission rate (transmission unit) identifier only in the cell of SC = 1. As described above, various methods can be considered for the position where the transmission rate (transmission unit) identifier is placed. The inverse conversion device 202 extracts a transmission rate (transmission unit) identifier at a specific position in the information area of the cell, and transmits the transmission rate (transmission unit) represented by the identifier to the inverse conversion device 20.
The transmission rates (transmission units) set in step 2 are compared, and if they are different, the conversion device 201 and the inverse conversion device 202
Are detected as having different transmission speeds (transmission units).

Based on the above, the fifth embodiment will be specifically described below. FIG. 14 is a block diagram showing a circuit configuration of the fifth embodiment of the present invention. In the figure, 201 is a conversion device, 1501 is a circuit for generating an identifier of the transmission rate (transmission unit) of a CBR signal to be converted into cells, and 1502 is a CB
This is a circuit that accommodates the R signal and the identifier generated by the circuit 1501 in the information area of the cell, assembles the cell, and inserts an externally set VPI into the header.

Reference numeral 202 denotes an inverse converter, 1503 a circuit for selecting a VPI cell set from the outside, 1504 a transmission rate (transmission unit) identifier extracted from the information area of the cell selected by the circuit 1503, and a transmission rate A circuit for identifying the (transmission unit) 1505 is a circuit for comparing the transmission rate (transmission unit) identified by the circuit 1504 with the transmission rate (transmission unit) set externally to the device 202, and 1506 absorbs the cell delay fluctuation To restore the original CBR signal by disassembling the cell.

Next, the circuit operation will be described with reference to FIG. For example, when the device 201 converts the TU-11 of the SDH path signal as a CBR signal into a cell, the circuit 1501 generates a transmission rate (transmission unit) identifier of 0000 0001 in the cell, and the circuit 1502 generates the transmission speed (transmission unit) identifier in FIG. The transmission speed (transmission unit) identifier is inserted into the location shown in FIG. This cell is communicated to the device 202 via a virtual path.

In the device 202, the V of the virtual path
The setting is made so that the cell of the PI is selected by the circuit 1503.
At this time, 0001 0000 is subtracted from the cell in the circuit 1504.
The transmission rate (transmission unit) identifier of the device 201 is extracted.
It can be identified that the transmission speed (transmission unit) formed into cells is TU-11.

If the transmission rate (transmission unit) set externally to the device 202 is other than TU-11, the circuit 1505
Results in a mismatch. If the transmission rate (transmission unit) externally set to the device 202 is TU-11,
The comparison result of the circuit 1505 matches. The above circuit detects the mismatch of the transmission speed (transmission unit).

In this embodiment, since the VCI is not used for transmitting information between the device 201 and the device 202, the device 201
It is also possible to connect the device 202 with the device 202 using a virtual channel instead of a virtual path. At this time, the circuit 1502 uses the VPI corresponding to the virtual channel.
And VCI are inserted into the cell, and the circuit 1503 selects the cell of the set VPI and VCI.

In the first to fifth embodiments described above, if a bit error occurs in the area indicating the transmission speed (transmission unit) while the cell is transmitted from the device 201 to the device 202, the transmission speed is erroneously set. There is a problem that mismatch of (transmission unit) is detected.

To avoid erroneous determination due to a bit error,
In the first to fifth embodiments, when a mismatch is detected N times, it is determined that the transmission speed is mismatched, and when it matches M times, it is determined that the transmission speed is matched. Here, N and M are each a positive integer of 2 or more.

FIG. 15 shows the state transition of this determination method.
FIG. 16 shows a circuit for realizing this state transition. In the comparison circuits of the first to fifth embodiments, 0 is input to the shift register 1701 if they match, and 1 if they do not match. A
The ND circuit 1702 detects N consecutive mismatches and sets the RS non-lip flop 1704. AND circuit 17
At 03, a match for M consecutive times is detected, and the RS non-lip flop 1704 is reset. RS non-lip flop 170
The output of No. 4 indicates the transmission speed match / mismatch state.

[0068]

As described above, according to the present invention,
A signal capable of identifying the transmission rate (transmission unit) in the conversion device 201 is accommodated in a cell, and a signal capable of identifying the transmission speed (transmission unit) is extracted from the cells transmitted by the inverse conversion device 202, thereby converting the conversion device. 201 and inverse converter 202
Can be detected that the transmission speed (transmission unit) is different, the maintenance personnel can immediately recognize the incorrect setting of the transmission speed (transmission unit), and correct the settings correctly,
Overflow and underflow of the delay fluctuation absorbing buffer can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a format of a cell in a case where a cell having an even SC (sequence count) has a leading byte of a TU / AU signal;

FIG. 3 is an explanatory diagram showing a cell format when a cell having an odd SC (sequence count) has a leading byte of a TU / AU signal;

FIG. 4 is an explanatory diagram showing a configuration of a TU / AU pointer.

FIG. 5 is a block diagram showing a circuit configuration of a second embodiment of the present invention.

FIG. 6 is a block diagram showing a circuit configuration according to a third embodiment of the present invention.

FIG. 7 is a diagram illustrating a method of obtaining a frame length from two CS pointers (P1, P2).

FIG. 8 is a block diagram showing an example of a circuit for counting a frame length.

FIG. 9 is a block diagram showing another example of a circuit for counting a frame length.

FIG. 10 is an explanatory diagram showing a format example of a transmission rate (transmission unit) identification OAM cell.

FIG. 11 is a block diagram showing a circuit configuration of a fourth embodiment of the present invention.

FIG. 12 is an explanatory diagram showing a format example of a cell used in a fifth embodiment of the present invention.

FIG. 13 is an explanatory diagram showing another format example of the cell used in the fifth embodiment of the present invention.

FIG. 14 is a block diagram illustrating a circuit configuration according to a fifth embodiment of the present invention.

FIG. 15 is an explanatory diagram showing a state transition between transmission speed (transmission unit) coincidence / mismatch.

FIG. 16 is a circuit diagram showing a transmission speed (transmission unit) match / mismatch state determination circuit.

FIG. 17 is an explanatory diagram showing a transmission system when transmitting a continuous signal (CBR signal) using an ATM communication network.

[FIG. 18] SDH (Synchronous Digital Hierarchy) which is a kind of CBR signal using an ATM communication network
FIG. 4 is an explanatory diagram illustrating a mode of transmitting a path signal.

[Explanation of symbols]

201: conversion device, 202: inverse conversion device, 301, 60
1, 701, 1201 ... cell conversion circuit, 302 ... VCI insertion circuit, 303, 602, 702, 1203, 1503
... VPI selection circuit, 304 ... VCI extraction circuit, 305,
605, 705, 1206, 1505 ... comparison circuit, 30
6, 1207, 1506... CBR signal reconstruction circuit, 60
3, 703... TU / AU first byte identification circuit, 604.
SS bit extraction circuit, 606, 706: TU / AU signal reconstruction circuit, 704: frame length count circuit, 120
2 OAM cell generation circuit, 1204 OAM cell selection circuit, 1205, 1504 Transmission unit identifier extraction circuit, 1
501: transmission unit identifier generation circuit, 1701: 3-bit shift register, 1702: AND circuit, 1703: NAND circuit, 1704: flip-flop

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 12/28 H04L 12/56 H04J 3/00 H04L 29/08

Claims (6)

(57) [Claims] 1. A conversion device for selecting a continuous signal input through a specific virtual path from input continuous signals, converting the selected signal into a cell, and outputting the cell. A continuous signal ATM network comprising: an ATM network which takes in and transfers the data through an ATM network via a virtual path; and an inverse conversion device which receives cells transferred through the ATM network and restores the original continuous signal. In the transmission method, when the VCI (virtual circuit identification) area in the header of the cell is empty, the conversion apparatus includes means for writing the speed of the input continuous signal in the area, The device includes means for reading the speed of the continuous signal written in the area in the cell, and means for comparing the read speed with a speed preset in the inverse conversion device. If the provided, from the comparison result, consistent speed and set speed consecutive input signals, the transmission rate mismatch detection apparatus being characterized in that to detect the mismatch. 2. A conversion device for selecting a continuous signal input through a specific virtual path from input continuous signals, converting the selected signal into cells, and outputting the cells. A continuous signal ATM network comprising: an ATM network which takes in and transfers the ATM cell via a virtual path through a virtual path; In a transmission method via a TU, the incoming continuous signal is a TU belonging to the SDH (Synchronous Digital Hierarchy) signal format.
-11, TU-2, or AU-3 signal,
When the signal is converted to a cell, the TU /
Means for finding the SS bit position in the AU pointer and reading the speed of the continuous signal previously written therein is provided in the inverse conversion device, and the read speed and the speed preset in the inverse conversion device are provided. Transmission speed mismatch detecting device, wherein means for comparing the speed of the input continuous signal with the set speed is detected from the result of the comparison. 3. A conversion device that selects a continuous signal input through a specific virtual path from input continuous signals, converts the selected signal into cells, and outputs the cells. A continuous signal ATM network comprising: an ATM network which takes in and transfers the data through an ATM network via a virtual path; and an inverse conversion device which receives cells transferred through the ATM network and restores the original continuous signal. In a transmission method via a multiplexed signal, an incoming continuous signal is transmitted by a TU belonging to an SDH (Synchronous Digital Hierarchy) signal format.
-11, TU-12, TU-2, AU-3, or AU-4 signal, the frame length when the signal is transferred as a continuous signal in a frame format is determined by the inverse conversion device. In the above, a means for determining and determining from the cells received one after another is provided, and from the determined frame length , the type of the transferred signal and thus the speed are known, and the speed and the speed preset in the inverse conversion device are determined. A transmission speed mismatch detecting device, wherein means for comparing is provided in the inverse conversion device, and a match or mismatch between the speed of the input continuous signal and the set speed is detected from the result of the comparison. 4. A conversion device for selecting a continuous signal input through a specific virtual path from input continuous signals, converting the selected signal into cells, and outputting the cells. A continuous signal ATM network comprising: an ATM network which takes in and transfers the data through an ATM network via a virtual path; and an inverse conversion device which receives cells transferred through the ATM network and restores the original continuous signal. In the transmission system through which, the means for generating a specific cell in which the speed of the input continuous signal is written is provided in the converter, and the specific cell is mixed and transferred to a cell obtained by converting the continuous signal. The inverting device detects the specific cell and reads the speed of the continuous signal written therein, and compares the read speed with a speed preset in the inverting device. And means, may be provided, from the comparison result, consistent speed and set speed consecutive input signals, the transmission rate mismatch detection apparatus being characterized in that to detect the mismatch. 5. A conversion device that selects a continuous signal input through a specific virtual path from input continuous signals, converts the selected signal into a cell, and outputs the cell. A continuous signal ATM network comprising: an ATM network which takes in and transfers the data through an ATM network via a virtual path; and an inverse conversion device which receives cells transferred through the ATM network and restores the original continuous signal. In the transmission method, the conversion device selects a specific cell from cells obtained by converting a continuous signal, and in a specific area of the cell, an identifier indicating a speed of the continuous signal input thereto. Means for writing, wherein the inverse conversion device determines a specific cell in which the identifier is written, reads the identifier from the cell to determine the speed, and calculates the speed and the determined speed and the inverse conversion device. Means for comparing the speed of the input continuous signal with the set speed based on the result of the comparison. Detection device. 6. The transmission speed mismatch detecting device according to claim 1, wherein the comparing means sets the speed of the input continuous signal when the comparison result is N times inconsecutive. A transmission speed mismatch detecting device provided with means for judging that the speeds do not match, and judging that the speed of the input continuous signal and the set speed match when the comparison result matches M times continuously. (However, N and M are positive integers, respectively).