JP4481231B2 - Emulation synchronization system and method - Google Patents

Description

  Emulation of different network networks and interconnection, especially in the network field that requires synchronous clocks or emulation that transmits synchronous clocks of transmission devices via network networks that do not require synchronous clocks The present invention relates to a synchronization system and a transmission method thereof.

  With the spread of the Internet in recent years, IEEE 802.3 standard LAN (Local Area Network) network services are increasing. In particular, services for wide area LAN networks are cheaper than services such as conventional ATM (Asynchronous Transfer Mode) networks, where the fee structure varies depending on the distance between bases. There are things, and cost merit is great. Furthermore, the equipment investment cost is often cheaper for the LAN-compatible equipment, which is more popular than the equipment for the ATM network.

In this way, while there are existing dedicated line services (such as ATM networks) of communication carriers, cheap LAN network services (such as wide-area LAN networks) are rapidly spreading, and LANs replace existing ATM networks. There is a need for a system using an emulation technology that uses a network in a pseudo manner.
However, a transmission apparatus connected to the ATM network needs to receive a synchronous clock from the network side and transmit / receive data in synchronization therewith. On the other hand, in the LAN network, burst communication or the like for placing data on the physical layer is performed only when information is sent, and it is not necessary to always transmit a synchronous clock.

  Such a conventional technique will be described with reference to FIG. FIG. 10A is a diagram showing a configuration of a general ATM network in which an ATM device is connected to the ATM network. 901 is an ATM network, 902 is an ATM device of node A, 903 is an ATM device of node B, and 904 is A network synchronization clock supplied from the ATM network 901 to the ATM apparatus 902, and a network synchronization clock 905 indicate the network synchronization clock supplied from the ATM network 901 to the ATM apparatus 903, respectively. In FIG. 10A, the ATM device 902 of the node A transmits and receives cell data in synchronization with the network synchronization clock 904 supplied from the ATM network 901, and the ATM device 903 of the node B is supplied from the ATM network 901. Since the cell data is transmitted and received in synchronization with the network synchronization clock 905, the cell data is always transmitted and received in synchronization with the network synchronization clock of the ATM network 901.

  FIG. 10B is a diagram showing a conventional technique for connecting ATM devices 902 and 903 to a LAN network. 906 is a LAN network, 907 and 908 are for connecting the ATM devices 902 and 903 to the LAN network. A conventional ATM emulation apparatus, 909 is a clock source supplied from another ATM network, 910 is a clock line for transmitting a synchronous clock, 911 is a synchronous clock sent from the clock line 910 by the ATM emulation apparatus The clocks supplied to the ATM device 902 based on the above are respectively shown.

  In FIG. 10B, when the ATM device 903 is connected to the LAN network 906 to communicate with the ATM device 902, a clock source 909 is used instead of the network synchronization clocks 904 and 905 shown in FIG. It is necessary to prepare a clock line 910 for transmitting a clock supplied from the terminal and transmit the clock 911 to the ATM device 902 as a communication destination.

“Synchronization of asynchronous network using synchronization symbol of medium access control (MAC layer)” described in Patent Document 1 describes a method and a structure for delivery and use of synchronization in an asynchronous network. Symbols are periodically inserted on the MAC layer to be distributed in the network. Also, a method of using the count and interval of received sync symbols and the count and interval of transmit sync symbols to generate an error correction signal for use in the process of frequency locking within the device by sync symbols received from other devices Is also described.
JP-T-2004-522329

  Since a transmission apparatus connected to an ATM network needs to receive a synchronous clock from the network side and transmit / receive data in synchronization therewith, in order to emulate an ATM network over a LAN network, a conventional technique is shown in FIG. As described in (b), the clock line 910 for clock transmission has to be prepared. On the contrary, there is a problem that the cost is increased and the application system is limited.

  On the other hand, even if the clock information can be transmitted, the ATM emulation apparatus 908 converts the ATM cell data output from the ATM apparatus 903 into LAN packet data and transmits it to the communication destination ATM emulation apparatus 907 via the LAN network 906. A delay occurs due to the routing status of the LAN network 906 during transmission, and the ATM cell data output interval that is reproduced by the ATM emulation device 907 and output to the ATM device 902 is output from the ATM device 903 to the ATM emulation device 908. It may be different from the output interval of the cell data to be performed.

  Next, this situation will be described with reference to FIG. FIG. 11 is a diagram showing the interval of ATM cell data transmitted from the ATM device 903 to the ATM emulation device 908 and the state of cell data received by the ATM emulation device 907 in the ATM device 902. The ATM devices 903 to 801 and 802 are shown. , 803, and 804 are transmitted in this order, and the received data is output from the ATM emulation device 907 in the order of 801, 802, 803, and 804 after a certain delay time. The cell data with the same number indicates that the same cell data is received after a certain transmission delay time has elapsed since the transmission, and the same cell data does not exist at the same time.

  In FIG. 11, the ATM device 903 transmits cell data 801 and cell data 802 at a time interval 805 (T1), cell data 802 and cell data 803 transmit at a time interval 806 (T2), and cell data 803. Cell data 804 is transmitted at a time interval 807 (T3). These cell data are converted into LAN packet data by the ATM emulation device 908 and transmitted to the ATM emulation device 907 via the LAN network 906. The ATM emulation device 907 reproduces this into cell data, and outputs it to the ATM device 902 in the order of cell data 801, 802, 803 and 804.

  However, the transmission time fluctuates depending on the routing status of the LAN network 906, and the cell data 801 and the cell data 802 are received at the time interval 812 (T11), and the cell data 802 and the cell data 803 are received at the time interval 813 (T12). ) And cell data 803 and cell data 804 are received at time interval 814 (T13). In other words, there is a problem that data is reproduced differently from the interval of cell data output from the ATM device 903.

  In general, in ATM communication, the cell data interval has a cell delay variation allowable value defined by the ATM protocol, and in the ATM network, a shorting is performed to keep the cell transmission interval below a certain value. However, as described above, there is a problem that cell data intervals differ when transmitted via a LAN network, which may exceed the cell interval defined by the ATM protocol.

  The present invention provides an emulation synchronization system and method capable of transmitting clock information without preparing a special line for transmitting a synchronous clock. Further, the present invention provides an emulation synchronization system and method that realizes a shaping function that corrects a cell interval shift generated in a LAN network based on transmitted clock information and transmits the cell interval.

  An emulation synchronization system according to the present invention includes a first network that requires a synchronization clock, a transmission device connected to the first network, and a second network that does not require a synchronization clock. Synchronization information for extracting a synchronization clock from transmission data transmitted on the first network in an emulation synchronization system configured by an emulation apparatus that transmits and receives transmission data transmitted on the network to the transmission apparatus via the second network Extraction means, transmission / reception means for transmitting / receiving the synchronization clock extracted by the synchronization information extraction means as synchronization information via the second network, and reproducing the synchronization clock from the synchronization information received by the transmission / reception means. Synchronization information reproducing means for outputting to the transmission device; And wherein the digit.

In particular, the first network is an ATM network, the second network is a LAN network, and the synchronization clock is a network synchronization clock of the ATM network.
An emulation synchronization system according to the present invention includes a first network that requires a synchronization clock, a transmission device connected to the first network, and a second network that does not require a synchronization clock. In an emulation synchronization system including an emulation device that transmits and receives transmission data transmitted through one network to the transmission device via the second network, an input interval of transmission data input from the first network is measured. A data interval measuring unit; a transmitting / receiving unit that transmits / receives data interval information measured by the data interval measuring unit to / from the second network together with the transmission data; and a data interval indicated by the data interval information received by the transmitting / receiving unit. Data to output transmission data to the transmission device Characterized in that a means out.

In particular, the first network is an ATM network, the second network is a LAN network, and the transmission data is cell data of the ATM network.
Alternatively, the emulation synchronization method of the present invention comprises a first network that requires a synchronization clock, a transmission device connected to the first network, and a second network that does not require a synchronization clock. In an emulation synchronization method in an emulation apparatus for transmitting / receiving transmission data transmitted through one network to / from the transmission apparatus via the second network, synchronization information extraction for extracting a synchronization clock from the transmission data transmitted through the first network Means, transmission / reception means for transmitting / receiving the synchronization clock extracted by the synchronization information extraction means as synchronization information via the second network, and synchronization information for reproducing the synchronization clock from the synchronization information received by the transmission / reception means The synchronization information reproducing means It is and outputs the synchronous clock to the transmission device.

  The emulation synchronization method of the present invention comprises a first network that requires a synchronization clock, a transmission device connected to the first network, and a second network that does not require a synchronization clock. A data interval measurement for measuring an input interval of transmission data input from the first network in an emulation synchronization method in an emulation device for transmitting and receiving transmission data transmitted through one network to the transmission device via the second network Means, transmission / reception means for transmitting / receiving data interval information measured by the data interval measurement means together with the transmission data to the second network, and data transmission means for outputting the transmission data received by the transmission / reception means to the transmission device The data transmission means is the transmission / reception unit. Means and outputs the transmission data to the transmission device in the data interval indicated by the data interval information received.

  In the emulation synchronization system and method of the present invention, clock information for synchronization can be transmitted on the same line as the data, so that it is not necessary to transmit the clock information using another line. In addition, the cell data interval can be measured by the cell interval measurement means and transmitted to the receiving side, and output to the receiving side at the same cell data interval as before transmission, thus correcting fluctuations in the cell data interval caused by emulation transmission. In addition, it is possible to realize transmission between cell intervals.

Embodiments of the emulation synchronization system and method of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of an ATM emulation device, 101 is an ATM emulation device, 102 and 103 are ATM termination units for connection to an ATM network or ATM device, and 104 and 105 are connections to a LAN network or LAN device. LAN termination unit 106, a clock processing unit 106 that processes a clock handled by the ATM emulation apparatus 101, 107 a received cell interval measurement processing unit that measures a cell interval of cell data output from the ATM termination unit 102, and 108 a received cell A capsule unit that encapsulates cell data and cell interval data output from the interval measurement processing unit to generate a LAN packet, and 109 is a clock data in the LAN packet output from the encapsulation unit and the clock data output from the clock processing unit 106. With a flag to indicate A packet processing unit that converts a LAN packet sent from a communication destination ATM emulation device having the same configuration as the ATM emulation device 101 into clock information and encapsulation data; 111 is a clock data decomposing unit that analyzes the clock information output from the received packet processing unit 110, 112 is a capsule decomposing unit that decomposes the encapsulation data output from the received packet processing unit 110 into received cell data and interval data of the received cells, 113 is a transmission cell interval control unit that adjusts the cell interval according to the reception cell interval data, and 119 and 120 are reception cell data that is input to the ATM termination unit 102. ATM termination Transmitting cell data output from the 103, 123 shows transmission LAN packets output from the LAN terminating unit 104, 124 a reception LAN packet input to the LAN terminal portion 105, respectively.

In FIG. 1, transmission cell data 119 and 120 sent as physical layer signals in synchronization with the network clock on the ATM line are returned to cell data on the ATM layer by the ATM termination unit 102, and the received cell interval is measured. The data is output to the processing unit 107.
Next, the configuration of the clock processing unit 106 will be described in detail with reference to FIG. In FIG. 2, 201 is a selector for selecting either the clock from the clock source 909 or the clock extracted from the ATM terminal unit 102, 202 is a VCO oscillator whose oscillation frequency can be varied by voltage, and 203 is a frequency divider for the VCO oscillator 202. A PLL (Phase Locked Loop) circuit that controls and synchronizes the VCO oscillator 202 with an error voltage as a phase shift between the frequency thus selected and the clock output from the selector 201, and 204 compares the output of the VCO oscillator 202 with the output of the selector 201. The clock data conversion unit 205 converts the clock data into a clock data, the selector 205 selects either the clock component output from the selector 201 or the clock component output from the clock data decomposition unit 111, and the clock 206 sets the selection of the selector 201 in advance. Source setting switch, 207 is a selector 05 select the preset to a master / slave setting switch respectively show.

  Now, either the network clock component of the physical layer extracted from the ATM terminal unit 102 by the selector 201 or the clock component of the same clock source 909 as the external clock used by the ATM device connected to the ATM terminal unit 102 is clocked in advance. The source setting switch 206 selects the clock component output by the selector 201 or the clock data output from the clock data decomposing unit 111 by the master / slave setting switch 207 in advance. The PLL is synchronized with the VCO oscillator 202 having a frequency sufficiently higher than that of the clock component. Further, the local clock that is the output of the synchronized VCO oscillator 202 is output to the clock data conversion unit 204, and the clock is supplied to the reception cell interval measurement processing unit 107, the transmission cell interval control unit 113, and the ATM termination unit 103 in the apparatus. To do. The clock data conversion unit 204 counts the period of the network clock or clock source 909 output by the selector 201 with the local clock having a frequency sufficiently higher than that of the network clock output from the VCO oscillator 202 or the clock source 909, and calculates the count value. The data is output to the transmission packet processing unit 109 as clock data.

  In this embodiment, the count value is used as clock data. However, if clock data is information that can reproduce the local clock by the PLL on the receiving side, such as an error value during PLL operation, the same effect can be obtained. can get. The master / slave setting switch 207 acts on the selector 205, selects a clock component decomposed and output by the clock data decomposing unit 111 from the clock data received from the transmission source ATM emulation device when the slave is set, and is input to the PLL 203. When the master is set, a clock signal from the clock source 909 or an extracted clock signal from the ATM terminal unit 102 as a master clock is selected by the selector 201, and a clock component is input to the PLL 203 via the selector 205.

  Next, the configuration of the reception cell interval measurement processing unit 107 will be described in detail with reference to FIG. In FIG. 3, 301 is a reception cell buffer for accumulating reception cell data output from the ATM termination unit 102, 302 is a cell interval measurement unit for measuring cell intervals when accumulating in the reception cell buffer 301, and 303 is a cell interval measurement unit 302. Shows the cell interval T4 between the received cell data 119 and 120 measured by.

  Now, the cell interval measurement unit 302 of the reception cell interval measurement processing unit 107 measures the cell interval of the reception cell data when accumulating in the reception cell buffer 301 by a constant interval pulse based on the clock output from the clock processing unit 106, The cell interval information is output to the encapsulation unit 108. For example, the cell interval measuring unit 302 measures the cell interval when the received cell data 119 and 120 are continuously input from the ATM terminating unit 102 to the received cell buffer 301, and the cell interval 303 (T4) is obtained. At the timing when the received cell data 120 is output to the encapsulation unit 108, the encapsulation unit 108 is informed that the cell interval is T4.

  Next, the operation of the encapsulation unit 108 will be described in detail with reference to FIG. FIG. 4A is a diagram showing a state in which received cell data and cell intervals output from the received cell interval measurement processing unit 107 are grouped into LAN packets one by one, and FIG. It is the figure which showed other embodiment which puts together a cell space | interval and makes it a LAN packet. In FIG. 4, reference numeral 403 denotes reception cell data input to the ATM terminal 102 following reception cell data 119 and 120, reference numeral 405 denotes a cell interval (T5) between the reception cell data 120 and 403, reference numerals 406, 407 and 412 denote LANs. 408 is a header of the LAN packet 406, 409 is a data field of the LAN packet 406, 410 is an FCS (Frame Check Sequence) for checking an error of the LAN packet 406, 412 is a LAN packet, 413 is a header of the LAN packet 412, 414 Indicates the data field of the LAN packet 412, and 415 indicates the FCS of the LAN packet 412.

  In FIG. 4A, the cell interval (T4) 303 between the received cell data 119 and the received cell data 120 output from the received cell interval measurement processing unit 107 is placed in the data field 409 of the LAN packet 406 together with the received cell data 120. And packetized. Similarly, the cell interval (T5) 405 between the received cell data 120 and the received cell data 403 is put together with the received cell data 403 in a data field (not shown in the figure) of the LAN packet 407 to be packetized. The received cell data 119 is packetized before the LAN packet 406 together with the cell interval with the previous received cell data (not shown in the figure). As described above, all the received cell data are packetized together with the cell interval from the previous received cell data, and are output to the transmission packet processing unit 109 in FIG.

  The case of FIG. 4B shows another embodiment in which two packets generated in succession in FIG. 4A described above are combined into one packet, and the LAN packet 412 The received cell data 120, its cell interval (T4) 303, the received cell data 403, and its cell interval (T5) 405 are put together in the data field 414 and packetized. In this way, by combining a plurality of received cell data and a plurality of cell interval information into one packet, the redundant portions such as the header 413 and the FCS 415 can be shared, and thus there is an advantage that communication efficiency is increased.

  Next, the operation of the transmission packet processing unit 109 in FIG. 1 will be described in detail with reference to FIG. FIG. 5A shows an example in which clock data output from the clock processing unit 106 is converted into LAN packets using clock information, and FIG. 5B shows another embodiment of LAN packetization. In FIG. 5, 501 and 506 are LAN packets, 502 and 507 are the headers of the LAN packets 501 and 506, 503 and 508 are the data fields of the LAN packets 501 and 506, and 504 and 509 are the LAN packets 501 and 506. Each FCS, 505 indicates clock data output from the clock processing unit 106, and 510 indicates a flag indicating that the clock data 505 is clock information.

In FIG. 5A, the clock data 505 output from the clock processing unit 106 is added with a flag 510 indicating that it is clock information, and is put on the data field 503 of the LAN packet 501 to be packetized. In the case of the figure, an example in which a header 502 and an FCS 504 are added to one clock data to form one LAN packet 501 is shown.
In the case of FIG. 5B showing another embodiment of LAN packetization, the clock data 505 to which the flag 510 of FIG. 5A described above is added and the received cell data 120 output by the encapsulation unit 108. And the cell interval (T4) 303 are integrated into one LAN packet 506. By combining the clock data, the received cell data, and the cell interval information into a single packet, redundant portions such as the header 507 and the FCS 509 can be shared, which has an advantage that communication efficiency is increased. Of course, in order to further improve the communication efficiency, the clock data 505 may be placed together with the LAN packet 412 of FIG.

As described above, in FIG. 1, the received cell data such as ATM received cell data 119 and 120 input from the ATM network to the ATM terminating unit 102 includes ATM network clock data, cell data, and cell interval information. Packetized and output from the LAN termination unit 104 to the LAN network as a transmission LAN packet 123.
In the present embodiment, the block is divided into the encapsulation unit 108 and the transmission packet processing unit 109 for easy understanding. However, since both are processes for converting information into LAN packets, the blocks are processed together. However, the effect of the present invention is not changed. The ATM terminal units 102 and 103 may be connected to an ATM network or an ATM device. However, when an ATM device is connected to the ATM terminal unit 102, it is necessary to supply a clock to the ATM device from the outside. This will be described later with reference to FIG.

  On the other hand, the received LAN packet 124 input from the LAN network to the LAN termination unit 105 is output to the received packet processing unit 110. The reception packet processing unit 110 performs the reverse operation of the transmission packet processing unit 109 described above. If the reception LAN packet 124 is, for example, the LAN packet 501 shown in FIG. 5A, the clock data 505 is extracted. If the received LAN packet 124 is the LAN packet 406 shown in FIG. 4A, for example, the LAN packet 406 is output to the capsule decomposition unit 112.

  Here, the clock data decomposing unit 111 receives the clock data 505 from the received packet processing unit 110, converts the clock data 505 into a count value obtained by counting the network clock on the master side or the cycle of the clock source, and transmits it to the clock processing unit 106. Based on these values, the clock processing unit 106 divides a sufficiently high frequency local clock by the PLL circuit in the clock processing unit 106 as described in FIG. 2, and generates a network clock or clock source on the master side. To do. The operation in this case corresponds to the operation in the slave described above.

Next, the capsule disassembling unit 112 performs the reverse operation of the encapsulation unit 108. For example, when receiving the LAN packet 406 of FIG. 4A from the received packet processing unit 110, the cell data 120 and the cell interval (T4) 303 The data is decomposed and output to the transmission cell interval control unit 113.
Here, the configuration of transmission cell interval control section 113 will be described in detail with reference to FIG. In FIG. 6, reference numeral 601 denotes a cell transmission control unit, and 602 denotes a transmission cell buffer. In addition, since the thing of the same code | symbol as what was demonstrated previously is the same, description is abbreviate | omitted.

  Now, the cell transmission control unit 601 controls the interval of cells transmitted from the transmission cell buffer 602 by pulses at regular intervals based on the clock output from the clock processing unit 106, and the interval according to the cell interval input from the capsule decomposing unit 112. The ATM terminal unit 103 converts the cell data received from the transmission cell buffer 602 into transmission data of the physical layer of the ATM network and outputs the clock signal output from the clock processing unit 106. Synchronously sent to the ATM network or ATM device.

  For example, if the transmission cell interval control unit 113 receives the reception cell data 119, 120, and 403 described with reference to FIG. 4A from the capsule decomposition unit 112, the capsule decomposition unit 112 sends the received cell data to the cell transmission control unit 601. Since the cell transmission control unit 601 sends the cell data 119 to the transmission cell buffer 602 to the ATM termination unit 103 and delays it by the cell interval (T4) 303 since the cell interval between the cells 119 and 120 is T4. Control is performed so that the cell data 120 is transmitted.

  Next, the effect of the emulation synchronization system and method of the present invention will be described with reference to FIG. In FIG. 7, reference numerals 701, 704 and 705 denote clock information transmitted via the LAN network 906 according to the technology of the present invention, and reference numerals 702, 706 and 707 denote ATM emulation apparatuses having the same configuration as the ATM emulation apparatus 101 of FIG. ing. FIG. 7A is a comparison with FIG. 10B described in the prior art. In the present invention, the clock of the clock source 909 is transferred from the ATM emulation device 707 to the LAN of the clock information 701 via the LAN network 906. Since it can be transmitted to the ATM emulation device 706 as a packet, the clock line 910 is not required as shown in FIG. 10B, the clock 911 can be supplied to the ATM device 902, and the ATM device can be used at low cost. It becomes.

  In this embodiment, the ratio is 1: 1, but as shown in FIG. 7B, even if the ATM device 703 of the node C is connected via the ATM emulation device 702 via the LAN network 906, For example, the ATM emulation device 702 can be a master to send clock information 704 to the ATM emulation device 706 to maintain synchronization, and the ATM emulation device 707 can be a master to transmit the clock information 705 to the ATM emulation device 702. can do. In FIG. 7B, the clock source corresponding to the clock source 909 is omitted.

  Next, the relationship between the master and the slave will be described with reference to FIG. FIG. 8 is a diagram showing a flow of clock information when the clock component of the ATM device 903 operating in synchronization with the clock source 909 is considered as a master. When viewed from the system, the ATM emulation device 707 is supplied with the clock component from the ATM device 903 and thus corresponds to the slave. However, when viewed from the relationship between the devices, the ATM emulation device 707 sends the clock component to the ATM emulation device 706 via the LAN network 906. In this case, the selector 205 described in FIG. 2 selects the selector 201 side, and the selector 201 selects the ATM terminal unit 102 side.

  In the ATM emulation device 706, the clock component is sent from the ATM emulation device 707 via the LAN network 906, so that it becomes a slave. In this case, the selector 205 described in FIG. 2 selects the clock data decomposing unit 111 side. become. Further, when viewed between the ATM emulation device 706 and the ATM device 902, the ATM emulation device 706 serves as a master and supplies a clock component to the ATM device 902.

In this way, by maintaining the relationship between the master and the slave, clock components can be supplied from a single master clock source using each device in the system as a slave at the system level, and synchronization can be achieved.
Next, another effect of the emulation synchronization system and method of the present invention will be described with reference to FIG. FIG. 9 is compared with FIG. 11 described in the related art, and the same reference numerals as those described in the related art and the embodiment of the present invention indicate the same components. In FIG. 9, since the ATM emulation device 706 can send ATM cell data to the ATM device 902 at the same cell interval as the ATM cell data output from the ATM device 903, the ATM device 902 appears to the ATM device 903. ATM cell data of the same quality as that directly connected can be received.

  For example, when the ATM device 903 sends the cell data 801 to 804 at the cell intervals 805 to 807, the received cell interval measurement processing unit 107 of the ATM emulation device 707 has the cell interval 805 between the cell data 801 and 802 as T1. This is measured, converted into a LAN packet, and sent to the ATM emulation device 706 via the LAN network 906 together with the cell data 802. Similarly, the reception cell interval measurement processing unit 107 measures that the cell interval 806 of the cell data 802 and 803 is T2, and that the cell interval 807 of the cell data 803 and 804 is T3, and is converted into a LAN packet. The cell data 803 or 804 is sent to the ATM emulation device 706 via the LAN network 906.

  In response to this, the transmission cell interval control unit 113 of the ATM emulation device 706 stores the cell data 801 to 804 in the transmission cell buffer 602, sends the cell data 801, waits for the cell interval (T1) 805, and then waits for the cell data. Similarly, the cell data 803 is sent after waiting for the cell interval (T2) 806, and the cell data 804 is sent after waiting for the cell interval (T3) 807.

  As described above, the conventional technique of FIG. 11 has a problem that the cell interval is changed by transmitting ATM cell data via the LAN network, and in an extreme case, the ATM cell interval is not within the regulation. However, in the present invention, as shown in FIG. 9, the ATM emulation device 706 connected via the LAN network 906 has the same cell interval as the ATM cell data output from the ATM device 903. The ATM cell data can be transmitted to the ATM device 902, and ATM cell data can be transmitted through the LAN network without degrading the quality of the ATM.

It is a block diagram which shows embodiment of this invention. It is an auxiliary figure for explaining clock processing part 106 of an embodiment of the present invention. It is a block diagram which shows the receiving cell space | interval measurement process part 107 of embodiment of this invention. It is an auxiliary figure for explaining the capsule part 108 of an embodiment of the present invention. It is an auxiliary | assistant figure for demonstrating the transmission packet process part 109 of embodiment of this invention. It is a block diagram which shows the transmission cell space | interval control part 113 of embodiment of this invention. It is explanatory drawing which shows the whole structure of an emulation synchronous system. It is an auxiliary | assistant figure for demonstrating the relationship between a master and a slave. It is an auxiliary figure for explaining the effect of the present invention. It is explanatory drawing which shows the network connection of a prior art. It is an auxiliary | assistant figure for demonstrating the subject of a prior art.

Explanation of symbols

101 ... ATM emulation device 102, 103 ... ATM termination unit 104, 105 ... LAN termination unit 106 ... clock processing unit 107 ... received cell interval measurement processing unit 108 ... capsuling unit 109 ..Transmission packet processing unit 111... Clock data decomposition unit 112... Capsule decomposition unit 113... Transmission cell interval control unit 119.

Claims (6)

A first network that requires a synchronous clock;
A transmission device connected to the first network;
A second network that does not require a synchronous clock,
In an emulation synchronization system including an emulation device that transmits and receives transmission data transmitted through the first network to and from the transmission device via the second network,
Synchronization information extracting means for extracting a synchronization clock from transmission data transmitted in the first network;
Transmission / reception means for transmitting / receiving the synchronization clock extracted by the synchronization information extraction means via the second network as synchronization information;
Synchronization information reproducing means for reproducing the synchronization clock from the synchronization information received by the transmission / reception means and outputting the same to the transmission device;
An emulation synchronization system characterized by comprising: The emulation synchronization system according to claim 1,
The first network is an ATM network,
The second network is a LAN network,
An emulation synchronization system, wherein the synchronization clock is a network synchronization clock of the ATM network. A first network that requires a synchronous clock;
A transmission device connected to the first network;
A second network that does not require a synchronous clock,
In an emulation synchronization system including an emulation device that transmits / receives transmission data transmitted through the first network to / from the transmission device via the second network,
Data interval measuring means for measuring an input interval of transmission data input from the first network;
Transmission / reception means for transmitting / receiving data interval information measured by the data interval measurement means to the second network together with the transmission data;
Data transmission means for outputting the transmission data to the transmission device at a data interval indicated by the data interval information received by the transmission / reception means;
An emulation synchronization system characterized by comprising: The emulation synchronization system according to claim 3,
The first network is an ATM network,
The second network is a LAN network,
An emulation synchronization system, wherein the transmission data is cell data of the ATM network. A first network that requires a synchronous clock;
A transmission device connected to the first network;
A second network that does not require a synchronous clock,
In an emulation synchronization method in an emulation apparatus for transmitting / receiving transmission data transmitted through the first network to / from the transmission apparatus via the second network,
Synchronization information extracting means for extracting a synchronization clock from transmission data transmitted in the first network;
Transmission / reception means for transmitting / receiving the synchronization clock extracted by the synchronization information extraction means via the second network as synchronization information;
The synchronization information reproducing means for reproducing the synchronization clock from the synchronization information received by the transmission / reception means,
The synchronization information reproducing means outputs the synchronization clock to the transmission device. A first network that requires a synchronous clock;
A transmission device connected to the first network;
A second network that does not require a synchronous clock,
In an emulation synchronization method in an emulation apparatus for transmitting / receiving transmission data transmitted through the first network to / from the transmission apparatus via the second network,
Data interval measuring means for measuring an input interval of transmission data input from the first network;
Transmission / reception means for transmitting / receiving data interval information measured by the data interval measurement means to the second network together with the transmission data;
The data transmission means for outputting the transmission data received by the transmission / reception means to the transmission device;
The emulation synchronization method, wherein the data sending means outputs the transmission data to the transmission device at a data interval indicated by the data interval information received by the transmitting / receiving means.

Images