DE69535088T2 - Connectionless communication system, test method and intra-station control system - Google Patents

Description

Background of the invention

Field of the invention

The The present invention relates to connectionless communication systems to transfer from Data at a high speed, a method for checking the Systems, and a station-internal control system of a switching station to transfer of data at a high speed.

description of the prior art

In Recently, high-performance information processing equipment, such as workstation systems or workstations, workstations etc. developed to perform a process flow in which a variety of information processing devices via a high speed local area network (high speed LAN) are connected. The network connection, such as local area networks (LANs), should also be provided with the performance, with high speed data processing.

one the services for realizing the high-speed data communications described above is the so-called switched multi-megabit data service (SMDS). SMDS is a connectionless data switching service that is at a transmission speed based on 1.5 Mbps and 45 Mbps.

One Asynchronous Transfer Mode (ATM) system is considered as a procedure well known for realizing a broadband ISDN, and SMDS can be over Be provided ATM network. In this case is for a particular ATM switch an SMDS processing server (SMDS message control program) provided, and a fixed virtual connection or a fixed virtual channel (PVC) connects an SMDS subscriber to the SMDS processing server, which supplies or supports the SMDS participant. The connectionless data output from the SMDS subscriber is transferred to the SMDS processing server to at the server to perform a routing process, etc.

The connectionless data (data transmitted without connection) usually on a variable packet (data frame). There though the aforementioned fixed virtual circuit (PVC) in one Network to be established transmission path is, the connectionless data, after being in an ATM cell format have been converted (disassembled) before going to the ATM switch entered. The cell is a 53-byte big one Structure consisting of a 48-byte payload and payload a 5-byte large Header exists.

The data in the ATM cell format will be as it is in 35 is structured in the SMDS processing server temporarily as Layer 3 protocol data units (L3-PDU) or in a higher-layer data format in order to operate according to a destination address DA stored in the L3-PDU, one in the L3-PDU. PDU stored source address SA etc. to analyze routing information etc. Then, the data is again decomposed into cells to route the data according to the analyzed information.

As previously stated, is the conventional SMDS limited in speed because of the typed Cells in a higher-layer data format (for example in L3 PDU) when the SMDS processing server a routing process by software of a microcomputer program, etc. performs. additionally were performed with software of microcomputers, etc. processes such as For example, a data copy process that is performed when a group address is specified as a destination address DA, a traffic smoothing process, an operation without a control character of a data block or a Cell for marking the end of a message or a transmission (end-of-message, EOM: a cell containing the last section of Data stores when an L3 PDU decomposes into a plurality of cells becomes).

From therefore, the conventional one SMDS limited in terms of its processing speed, because the processes in the SMDS processing server with different Software performed become. If therefore connectionless communication data under Transfer using an SMDS become, the operation speeds of the transmission line and the central office increases, at the same time as the processes performed by the SMDS processing server as a bottleneck disturbing act, thereby preventing an actual high-speed process successfully put into action. Additionally, if in the SMDS processing server the previously described structuring process is performed, have to all Cells that form each L3 PDU are temporarily cached. Therefore, the necessary buffering capacity becomes undesirable Way extremely high.

In the SMDS, when a service is offered, the protocol performance is monitored as follows. That is, the formats of under various parameters are checked in the data and it is counted those data that are discarded with the check (those data that can not be validated). A predetermined special type of check is followed by a count process performed on the discarded data based on a predetermined algorithm. If the resulting value exceeds a predetermined threshold, a Threshold Exceeding Warning (TCA) is output to indicate that the threshold has been exceeded. In addition, whenever data is discarded, an error log is generated.

• (1) Ziel-Adresse DA
• (2) Quell-Adresse SA
• (3) SNI-Nummer (Teilnehmer-Netzwerkschnittstellen-Nummer)
• (4) Fehlertyp

The following parameters are listed in the error log.

• (1) destination address DA
• (2) source address SA
• (3) SNI number (subscriber network interface number)
• (4) error type

at the fixed virtual connection (PVC) between the user (participant) and the SMDS processing server, as previously described, Data is transferred in the cell format (actually the data is transferred in the ATM cell format and in the SMDS processing server processed in L2-PDU). The ATM cell and L2-PDU are based on the 53-byte configuration and are simply referred to as "cells." That I however, the previously described error log compilation often refers to layer-3, the data is received in cell format and then placed again in L3 PDU in the SMDS processing server.

As previously described, cells input in the conventional SMDS become into the data format of the higher layer Order (for example, L3 PDU) rearranged. This prevents SMDS processes are running at high speed.

The previously described services are based on the high reliability the physical quality the transmission lines, who train the network. Therefore, it is important the quality of the transmission to check the network and to judge.

The verification and evaluation of the transmission lines are activated in the connectionless communication network by the OS central office (operation center for managing the network), and an in-station feedback check is made to confirm the normal state of any intra-station connection (transmission path between exchanges). The in-station feedback check will be described below with reference to 36 described. In this embodiment, the check is made to check the connection between the SW station 3 and the SW station 6 to check.

The check is started by a request message for checking the connectionless packet transmission (check-start request) from the OS center 1 to the SW station 3 is delivered. The request message contains an identification information ID which the terminal or terminal SW station 6 displays. The SW station 3 generates a test packet with the identification address of the terminal SW station 6 , which is defined as the destination address DA of the test packet, and with the identification address from its home station (SW station 3 ), which is set as the source address SA of the test packet. The test packet becomes the terminal SW station 6 output. In the SW stations 4 and 5 the test packets are processed as normal packets and to the terminal SW station 6 transferred. Upon receipt of the test packet, the terminal SW station indicates 6 the packet, with its destination address DA and its source address SA reversed. That is, the package is from the terminal SW station 6 to the SW station 3 sent back and when the packet arrives at the source SW station again 3 this becomes the OS central office 1 reported.

Hence, the OS Central checks 1 whether or not the packet is normally transmitted in the network, that is, the OS center 1 checks the normal state of the transmission line (in this embodiment, the connection between the SW station 3 and the terminal SW station 6 ). Because in the procedure the source SW station 3 and the terminal SW station 6 Setting the timestamp to the payload field or payload field of the package is the OS center 1 notified according to this information regarding the transmission time of the packets.

However, in the verification process described above, the information obtained from the verification of the OS central (operations center) must be provided and no procedure for the subscriber (in 36 Terminal unit 2 ) with which the subscriber is informed in an autonomous manner with regard to the transmission quality of the network (transmission time delay, etc.). Therefore, if a packet is not normally transmitted from a source subscriber to a destination subscriber, subscribers can not detect whether the error factor is at the subscriber terminal unit or the network transmission line. Therefore, the OS center is called to uncover the error, which takes a lot of time and expense.

37 shows an embodiment of the SMDS. In 37 The SMDS support module analyzes a destination address DA and performs various checks. An SMDS support module S supplies a plurality of source SMDS subscribers (a) and (b) to analyze a destination address DA and perform various checks. The SMDS support module R feeds a plurality of target SMDS participants (x) and (y) to perform different checks. The modules having these S and R correspond to the previously described SMDS processing server (SMDS message control program).

Each of the source SMDS subscribers (a) and (b) is PVC over the fixed virtual connections 1 and 2 connected to the SMDS support module S. The SMDS support module S is connected to the SMDS support module R via the fixed virtual connection 3 connected. The SMDS support module R is connected to each of the destination SMDS subscribers (x) and (y) via the fixed virtual circuit 4 and 5 connected.

When the in 37 SW station shown has an ATM switch, the connectionless data (SMDS messages) output from the source SMDS subscribers (a) and (b) in the 37 Not shown interface converted into the cell format. The cell is transferred to the SMDS support module S by assigning to the cell header a special VPI / VCI specifying the SMDS support module as its destination (VPI / VCI specify the fixed virtual connection 1 and 2 ). When transitioning between the SMDS support modules S and R, the VPI / VCI value is assigned and output representing the fixed virtual connection 3 displays. The cell used by the SMDS support module R to target SMDS subscribers (x) and (y) with a special VPI / VCI value representing the fixed virtual circuits 4 and 5 is transmitted from the SMDS support module R and arrives at the destination SMDS subscribers (x) and (y). Each of the fixed virtual connections is set up when the system is initialized.

Since the number of source and destination SMDS subscribers accommodated in the SMDS support modules S and R is limited, a plurality of SMDS support modules are provided when a single SW station more SMDS subscribers than the maximum number supplied. 38 shows an example of this. In this case, every connection is made with the fixed virtual connection. 900 shows an example where SMDS subscribers (a), (b), (x) and (y) in the SMDS support module 1 and where the SMDS participants (c), (d), (v), and (w) are in the SMDS support module 2 are housed. The fixed virtual connection also connects the SMDS support module 1 with the SMDS support module 2 ,

As stated previously, the data transfer path is set upon initialization of the system in the SMDS. When the source SMDS subscribers (a) and (b) issue SMDS messages, the messages are delivered over the fixed virtual circuits 1 and 2 directed to the SMDS support module S and over the fixed virtual circuits 3 . 4 and 5 transferred to the target SMDS participants (x) and (y). Therefore, it can not be verified that the SMDS messages output from the source SMDS subscribers (a) and (b) have arrived at the destination SMDS subscribers (x) and (y) via the fixed virtual circuits.

If the data will not be successfully transferred can, is received from the source SMDS participants (a) and (b) or from the target SMDS participants (x) and (y) expects an indication. The ad of the participant should with as possible low costs are verifiably verified.

The PVC review and are the transmission time verification previously described, and the SMDS must be the normal state of the transmitted Confirm SMDS data. The procedure of confirmation the normal state of the data indicates the verification of the BS size of the L3 protocol data unit, the length the L2 protocol data unit etc. on.

at the review of BA size is approved, whether or not the value for use in the review of payload length the L3 protocol data unit (CPCS-PDU) is correct. When checking the BE marking (initial marking and end marking), the normal state of the data of the L3 protocol data unit can be confirmed, by the match between the head and tail markings the L3 protocol data unit. When length-checking is approved, that the packetization and final packetization between the L3 protocol data unit and the L2 protocol data unit was done normally, by the relationship between the valid Payload length value of L2 protocol data unit and the BA size of the L3 protocol data unit is verified.

When the normal state of the L3 protocol data is confirmed in the final packetized L2 protocol data, the size of the circuit becomes undesirably large. Since the BA size and the BE tag of the L3 protocol data unit and the length of the L2 protocol data unit are checked to be closely related, it is difficult for each cell (for each L2 cell) to be checked. protocol data unit) to carry out a process. When the data in the format of the cell (L2 protocol data unit) input to the SMDS processing server is processed after it has been packetized into the L3 protocol data unit, a high-speed process due to the software process involved is prevented, as described above has been.

When the connectionless communication service is implemented in the ATM-switched network, a connectionless data processing server (SMDS processing server in SMDS) is provided to prompt the server to check the routing process on the connectionless data received from the subscriber terminal unit be issued and perform different checks. 39 shows an example of the method for realizing such connectionless communication services. In the 39 configuration shown is the same as those in 37 is shown. That is, a fixed virtual connection 11 is between the source SMDS subscriber (a) and the connectionless data processing server CLS 2 set up. A fixed virtual connection 13 is between the destination SMDS subscriber (x) and the connectionless data processing server CLS 6 set up. These fixed virtual circuits are CPRs using a call processor 3 and 7 established.

In the in 39 The configuration shown is the connectionless data processing server CLS 2 serving the source subscriber (a) and the connectionless data processing server CLS 6 providing the destination subscriber (x) provided in different switching stations. That is, the connectionless data processing server CLS 2 is in the SW station 1 provided during the connectionless data processing server CLS 6 in the SW station 5 is provided. This connectionless data processing server CLS 2 and 6 are connected to each other via the fixed virtual connection 12 connected. A relay switch 4 of large dimensions, in which the fixed virtual connection 12 is provided has the configuration of forwarding agents, such as the configuration of SW 1 or SW 5 , or it is an ATM connection switch (AISW).

When connectionless data is transferred from the source SMDS party (a) to the destination SMDS party (x) having the configuration described above, the data output from the source SMDS party (a) becomes the fixed virtual connection 11 in the connectionless data processing server CLS 2 entered and then over the fixed virtual connection 12 to the connectionless data processing server CLS 6 transferred. Then they are from the connectionless data processing server CLS 6 over the fixed virtual connection 13 transferred to the destination SMDS participant (x). The data is transferred in cell units through the fixed virtual circuits and with the connectionless data processing servers CLS 2 and 6 1eitweggelenkt.

In the conventional connectionless communication service, the connectionless data processing server is CLS 2 containing the source SMDS participant ( 8th ), via the fixed virtual connection 12 with the connectionless data processing server CLS 6 which supplies the destination SMDS subscriber (x) as described in 39 is shown if these servers are different from each other. The fixed virtual connection 12 is set by the SW stations 1 and 2 and by the large-scale relay switch 4 passes. Therefore, the band resources for connectionless services must be reserved in advance in the exchanges to manage the services.

In the conventional one Systems, the band resources are used for each switch, even if the data of the connectionless service are not transferred, and the management of tape resources is complicated.

in the In contrast, the exchanges require switching of cells, such as a B-ISDN switch (broadband ISDN switch) for providing broadband services, for example ATM services (Asynchronous Transfer Mode) services, an SMDS switch to provide SMDS services (Switched Megabit Data Service) services, etc. much higher Line characteristics and functions in comparison with conventional ones Telephone exchanges or N-ISDN exchanges (narrowband ISDN exchanges). Therefore, set these exchanges for a station-internal control a uniform technology ahead.

The technology known in the art and the related art Problems will become closer below described.

following describes the problems that are related to the station internal Control of the communication technology for transmitting the control information between in-station devices, such as different transmission line interface devices (Trunk) etc., and the central office processor.

In the control of the station internal Vor directions in the conventional switching system is each of the station internal devices 6 and 7 via an input control device 4 for operation with an ATM switch 5 connected to a system bus 3, on which, as it is in 40 shown is a central office processor (CC) 1 connected to the control information between the in-station device and a main memory (MM) 2 via the direct memory access (DMA) system to the central office processor 1 connected is.

However, in this system, all in-station devices must 6 and 7 be connected to the system bus 3, and the cable should be mounted to the station-internal devices 6 and 7 to connect to the system bus 3. Therefore, the farther the station-internal devices, the longer the cable has to be 6 and 7 away from the system bus 3, which causes the problem of the complicated connection.

The connection of all in-station devices 6 and 7 with the system bus 3 causes a conflict in obtaining an access permission required to access the bus, resulting in an overload of the bus access.

In addition, the expansion of the system bus 3 to each of the in-station devices weakens 6 and 7 the transmission quality and may generate a transmission error, such as a data error and a parity error in the DMA procedure, which does not have an error control procedure.

When next the problem is described, which is related to the technology to transfer of control information such as call setting information etc., between a terminal unit and a control device, such as a central office processor.

The Control of a terminal interface device in the ATM exchange system, etc. sets the transmission of control information with a control system device, such as with a central office processor, etc.

The conventional technology for transmitting control information may be that system in which a physical interface with a terminal unit (TERM) is provided. 4 connected by the control system device (MPR1 and PRIF2) to the central office (SW). 3 connected as it is for a in 40 shown case in 41 is shown.

Because in this system a physical interface for each terminal 4 is required, the entire system configuration becomes complicated and the problem arises that the terminal units 4 can not be added in a simple way.

following describes the object that is related to the technology the review of a Exchange, such as an internal taxation system.

In the ATM exchange, etc., a check is made to see if or not a cell transmission data path is erroneous by performing a test on a data path for sending cells and for recovering and collecting receiving cells is connected. In this case, a test cell is transferred, after passing through the tester the destination information VPI (Virtual Transfer Path Identifier), the VCI (Virtual Channel Identifier), a cell feedback in the test facility and other LSIs have been set.

Indeed Such a system sets a complicated configuration of a test equipment and requires a relatively long time in setting up a test device.

following will the feedback check in the technology of reviewing Exchanges described.

With the increasing use of ATM switches and ATM-switched Networks in which the information of different traffic characteristics, such as language, data, animations etc. combined and mediated can, is a review of confirmation the normal state of a station-internal transmission path required. If an error occurs between two stations that have many stations, which between the two stations in an actual Operation, it is necessary that at the earliest possible Level errors are detected and corrected. The feedback verification process of an ATM-switched Network is an effective testing method to quickly detect an error between the stations.

The ATM switch has just been launched in the market, and the ATM switch has never been checked between stations. Indeed the subsequent test procedure is called an effective in-station ATM-switched network test procedure viewed on the conventional test methods based on electronic exchanges.

If according to this Process a number of stations in the ATM-switched network must have a testing device for every Station be provided.

If not enough test equipment must be a test facility for the review of shared between several stations.

Furthermore some stations are not constantly serviced by operators, and the operators must go to the stations to do the test.

From Therefore, in the method described above, it is assumed that it causes the operators inconvenience, a station-internal test perform.

When next describes the subject, which is based on the technology for Measuring the power characteristic in an exchange according to the station-internal Tax system refers.

The Conciliation procedure for Self-Rotating Module (SRM), which connects ATM, is the state for structuring a broadband ISDN system. However, it was Measuring the performance characteristics in the SRM becomes a difficult one Task.

Finally will hereinafter as an object of the in-house tax system the subject described, focusing on the control of a trailer in PLCP relates what for wireless networks a protocol coupled in DS3 format Physical Layer is, that is the digital signal level 3 format.

In The B-ISDN or SMDS service uses the DS3 format (Digital Signal Level 3 format) used to implement the service at 44.736 MHz.

The 42 and 43 show examples of system configurations according to the present invention.

42 shows the configuration in which the B-ISDN terminal unit is connected to the B-ISDN switch.

43 shows the configuration in which the SMDS terminal unit is connected to the SMDS exchange. The present invention relates to the transmission units in the B-ISDN terminal unit and B-ISDN exchange or in the SMDS terminal unit and the SMDS exchange.

44 shows the configuration of the DS-3 multiframe. The DS-3 frame has 85-bit base frames. The base frame has a 1-bit DS-3 header and an 84-bit DS3 payload. A subframe is formed by 8 basic frames, and 7 subframes form a single multiframe. That is, a multiframe consists of 56 (8x7) base frames.

The ATM cell of B-ISDN is a 53 octet cell and the L2 protocol data unit (level 2 protocol data unit cell) of SMDS is a 53 byte cell. That is, they are similar in their basic configuration, but different in terms of header content and payload, and in terms of the value of HEC and HCS. 45 (a) and (b) show the configurations of the ATM cell and the L2 PDU cell.

A ATM cell or L2-PDU cell is not directly in the payload stored in the DS3 reference frame, and they are transmitted over the Transmitted under the PLCP (Physical Layer Convergence Protocol).

46 shows the configuration of the PLCP multiframe coupled in the DS3 format.

The ATM cell or the L2 PDU cell is stored in a 53 octet PLCP, which is carried in the PLCP frame as a payload. The PLCP multiframe is big in 84-bit Segments are divided, and each segment is in one in the DS3 frame 84 octet DS3 payload is stored and then transmitted.

Of the PLCP frame is a multiframe that contains 12 pairs of a 4-byte PLCP header and a 53-byte big one PLCP payload and a trailer. The PLCP header is pointing A1 and A2 bytes on, viz POHI and POH. The trailer length is 13 or Half-bytes (Nibble). A nibble is 4 bits and is written as half Byte (nibble). The trailer data is 13 or 14 4-bit large pattern "1100." A PLCP multiframe will transmitted on average every 125 μsec (8 KHz cycle). A variable trailer length defines an average value.

following the trailer is described. Because the DS3 frame at a speed transmitted from 44.736 MHz will be lasting in the 125 μsec Time period 5592 bits according to the following Transfer equation.

[Equation 1]

• Number of bits = 4.736 × 10 6  (Bit / sec) × 125 × 10 -6  (Sec) = 5592 bits

Indeed For example, the data forming the DS3 frame has 1-bit frame bit data and an 84-bit big one DS3 payload, where the number of bits in the DS3 payload for the time period of 125 μsec a total of 5592 × 84/85 = 5526,211 ..., which is not divisible.

The number of bits in the PLCP multiframe is 57x12x8 + 13x4 = 5524 bits when the trailer length 13 Is half-bytes, and 57x12x8 + 14x4 = 5528 bits if the trailer length 14 Is half-bytes. That is, during the 125 μsec long time period, a remainder remains in the DS3 payload when the trailer length 13 Is one-half byte, and in the DS3 payload, there is a deficit in the 125 μsec long time period when the trailer length 13 Is half-bytes.

In order to transmit PLCP multiframes at a mean speed of 125 μsec (at an 8 KHz cycle), the PLCP multiframes are transmitted while their trailer length is between 13 and 14 Nibbles is changed.

A C1 byte cycle staff counter is used to indicate the trailer length (cf. 46 ). 47 shows the definition in relation to the cycle staff counter.

As in 46 As shown, the C1 byte is cyclically changed on three multiframe cycles. In the first multiframe, C1 refers to FF _H , and the trailer length is 13 Nibbles. In the second multiframe C1 refers to OO _H and the trailer length is 14 nibbles. In the third multiframe itself refers to C1 66 _H or 99 _H and the trailer length is 13 Nibbles for C1 = 66 _H and 14 Nibbles for C1 = 99 _H. The trailer length of 13 or 14 One-half byte is determined such that the PLCP multiframes are transmitted at a mean speed of 125 μsec (8 KHz cycle).

Then a problem arises regarding the question of which value C1 of The third multi-frame should have, that is, how to control the trailer is. Hereinafter, the conventional Method for controlling the trailer described.

Assume that the pattern p is on 13 Nibbles for the third multiframe, and that the pattern Q is on 14 For the third multiframe, where the number of nibbles for the trailer for the pattern p is in order 13 . 14 . 13 changes, and wherein the number of nibbles for the pattern Q in the order 13 . 14 . 14 changes.

In the 125 μsec long time period, the number of bits from the DS3 payload is 5592 × 84/85 = 5526,211 ... The number of bits in the PLCP multiframe is 5524 if the trailer length 13 Is half-bytes, and 5528 if the trailer length 14 Is half-bytes. Therefore, the cycle of the PLCP multiframe on the cycle of 125 μsec is fast when the PLCP multiframe pattern is p, and is behind the cycle of 125 μsec when the PLCP multiframe pattern is Q.

Usually is the cycle of a transferred PLCP frame monitors, and the phase of the extracted clock becomes the phase of the 8 KHz clock which is achieved by dividing 44.736 MHz. If the phase of the transfer Precedes PLCP multiframe, the trailer pattern is switched to P. If the phase lags behind, the trailer pattern is switched to Q. Therefore, the transmission cycle becomes of the PLCP multiframe set appropriately.

In the 48 and 49 time charts showing the circuit configuration and the operation for realizing the aforementioned functions are shown.

A PLCP frame cycle monitor 7 monitors the transmission cycle of the PLCP frames sent by a selector unit 3 must be transmitted to output a phase comparison pulse S for every third PLCP frame. A divider unit 6 generates an 8 KHz clock by using a clock generation unit 5 44,736 MHz clock is divided by 5592. A phase comparison unit 8th compares the phase comparison pulse S with the phase of the 8 KHz clock and outputs a pattern switching signal C having a value of "1" when the phase comparison pulse S lags behind and a value of "0" when it leads.

The selector unit 3 selects inputs A1 and A2 according to the pattern switching signal C. That is, the selector unit 3 selects the pattern P when the pattern switching signal C indicates "0", and selects the pattern Q when the pattern switching signal C indicates "1".

The PLCP frame generation units 1 and 2 for the patterns P and Q store an ATM cell or an L2 PDU cell in the PLCP payload and add a PLCP header and a trailer to packetize a PLCP frame.

The PLCP frame generation unit 1 to generate the pattern P adds a trailer to the number of nibbles 13 . 14 and 13 to display on three cycles. The PLCP frame generation unit 2 for the pattern Q adds a trailer to the number of nibbles 13 . 14 and 14 at three Zy klen.

The DS3 interface unit 4 inserts a PLCP frame into the DS3 payload and adds a DS3 header to package and transmit a DS3 frame.

Indeed becomes a trailer pattern in the conventional technology described above according to the phase comparison result selected, and the transmission order the pattern P and Q is not fixed.

When a result of this arises a problem in that the complicated operations require a complicated circuit.

In addition there it is a problem regarding a large deviation of temporal Coordination of the transfer.

• 1. Kopieren einer Zelle
• 2. Erneutes Zuordnen von VPI/VCI

The following functions are required to implement the multicasting capability (point-to-multipoint connection) in the ATM switch.

• 1. Copy a cell
• 2. Reassign VPI / VCI

The Efficiency regarding the use of resources, if any Exchange higher This is when cells are copied at a point closer to that Output of the switching station are. The copied cells become distributed to each participant. The cells leading to each participant have different VPIs / VCIs. That is, the Value of VPI / VCI depends from the target participant from. The number of bits of VPI / VCI is equal to or greater than 22 bits. Simply converting the large number of bits results in an undesirable manner to a large-scale Hardware.

The ATM switch exchanges cells in a self-routing System off. If a system big capacity Conducting a self-routing process is the efficiency of Exchange higher, if the multicasting capabilities be kept in the exchange. Therefore, the whole System smaller in size be made, the costs are reduced.

The supported in B-ISDN Services must be one size Number of point-to-multipoint connection services and multicasting capacity included. To reduce the size of the entire exchange, have to the multicasting capabilities that added were the point-to-multipoint connection to realize, for less Dimensions and costs are minimized. Furthermore, the possibility should be a future extension the multicasting capabilities considered be.

at the point-to-multipoint connection requires such information which is the number of copied cells and the destination of each of the copied ones Cells specified. The information is usually indicative information (Tag information) added to the cell, when it is input to the switching station. There though the amount of information described above is not small, occupies the tag information in about 10 bytes. By such a Label information is added to a cell becomes the entire cell length longer than in the switching station. That is, if the tag information is longer, will the ratio the actual Data for the entire length lower, which reduces throughput.

50 shows the configuration of the shape of the conventional multicasting capacities. In 50 transfers a source terminal 1 in the multicasting method via an ATM exchange 2 Data to destination terminals 4-1 to 4-5 ,

The administration 3 connects the source terminal 1 with the ATM exchange 2 , The administration 3 can multiplex and transmit a variety of calls (transmission paths). The ATM exchange 2 is also via a subscriber line with the destination terminals 4-1 to 4-5 connected, which is designed to multiplex and transmit data. In the ATM exchange 2 a virtual transmission path is set according to the destination information that is in the source terminal 1 transmitted cell is inscribed. In the in 50 The examples shown are the virtual transmission paths 5-1 to 5-5 as transmission paths for transmitting cells to the destination terminals 4-1 to 4-5 established.

In the multicasting transmission described above, cells for the destination terminals in the source terminal 1 copied and over the between the source terminal 1 and the destination terminals 4-1 to 4-5 transmitted transmission paths. Then there are five channels in the line 3 multiplexed to cells to the destination terminals 4-1 to 4-5 transferred to. That is, the bands of five channels are occupied.

Since, therefore, N transmission paths are established between the source terminal and the destination terminal when a 1: N multicasting transmission according to the in 50 As shown in the conventional method, the resources for the line 3 and the ATM switch 2 more used than necessary, and the load on the source terminal 1 is extremely high.

It It is expected that the need for dynamic images in great Increase in size becomes. For example, employees have far-off Companies many ways Things with conference calls using dynamic pictures to discuss. These services are not just for individual subscribers, they also help to keep business running smoothly, regardless of geographical disadvantages.

Nevertheless So far, these services have not been offered in a sufficient manner. This means, the 1: 1 communications are much more prevalent than the private line services in the broadband communication networks, and the method of control the multi-terminal connection, for example a 3-subscriber communication, has not been used in practice.

following the problem is described which in connection with the process in case of a fault in a device in the switching station accomplished which is a transmission line processed.

With the ATM switch processes a communication line system device in the switching station, a number of virtual circuits (which will be referred to simply as "pipes" hereinafter), which are specified with individual VPI / VCIs. If a mistake in a communication line system device occurs, the question is how the processed with the device Cables are extremely important to handle the quality to maintain the communications.

If an error occurs in a communication line system device in the switching station, will be a call over the line processed with the device is forcibly connected with a forced release process which ended with the error-monitoring process for the entire system is activated. Therefore, the participants have the Problem that the communications can be stopped suddenly.

The usual Systems have no mechanism for managing the communication line system equipment processed line provided.

following describes the problem that affects the process that carried out when a fault in the line is detected.

If a line fault on a simple-structured, not duplex-configured one ATM switch is detected in a conventional manner the transmission information, such as subscriber information, billing information, traffic information, Performance information, etc., with a circuit mediation process in physical line units using a spare line etc. performed.

In practice, when a physical line fault is detected, as in 51 is shown, a remote concentrator unit 1 and an ATM switch 2 are connected via a plurality of physical lines that do not use error band or unused band for other lines, but the state of the failed line is assigned to a new alternative line such as a spare line, etc.

Also if big unused bands therefore, they do not exist in one another used effectively, thereby reducing the useful rate of the lines becomes.

Around a line switching process in physical line units perform, it is necessary to reserve either sufficient reserve lines or duplex each of the physical lines. As a result Of these, the cost of communications is high.

As well it is necessary to use the station internal device, such as a Communication system device, etc., in the switching station to duplicate in order to maintain the functional reliability of the communications. When on the station internal device of the active system Error occurs, will be different communication control data transmitted to the station internal device of a standby system, to stop the operation of that in-station device, which is a device in the active system and the operation to start those station-internal device, which a station-internal device of the standby system is.

In This case will be common different communication control data in the station internal Device of the active system are set, with a processor transferred to the station-internal device of a standby system, the controls the station-internal device. However, since the scope the different communication control data for the ATM switch etc. is great, need the processor takes a long time to get the data from the station's internal Device of an active system to the station internal device of a standby system, causing disadvantageously the reliability of the switching station is negatively affected when an error at the switching station occurs.

In the document WO 93/06674 A is a discloses a self-routing, non-blocking, multicast network that routes input messages to selected addresses by checking a routing tag combined in each message. The routing tag has a plurality of sections, each section associated with a level of a tree hierarchy that refers to the outputs of the switched network. The network sorts the messages by checking only a portion of each routing tag, and routs the sorted messages to the selected addresses based on the bits contained in the routing tags.

SUMMARY THE INVENTION

According to the present The invention provides a switching system which is an exchange which automatically routes in a network a cell is provided, which data and data control information according to the control information contains to a point-to-multipoint connection service to provide, wherein the switching system characterized is that the switching system is designed to handle the point-to-multipoint Connection using a bit map by internal To create functions of the intermediary, and wherein the switching system is adapted to a bit map information over a transmission path from an input cell to the input cell.

SHORT DESCRIPTION THE DRAWINGS

1 shows the switch configuration for realizing the point-to-multipoint function;

1 (a) shows a communication line system (trunk system);

1 (b) shows an input copy system; and

1 (c) shows an internal copy system;

2 is a table showing the characteristics of the three in 1 represents shown systems.

3 shows the configuration for realizing the point-to-multipoint connection using the internal copy system.

4 Figure 4 shows the system for implementing the previously described bitmap without extending the cell length.

5 shows the VPI / VCI decoder circuit.

6 shows the configuration of a point-to-multipoint connection.

7 shows the configuration of the buffer and the output unit VCCT, which is provided for each output line.

8th is a table with the contents of the output unit VCCT, which are set with the firmware according to the software settings.

9 shows an example of a table in which an output VPI / VCI is set.

10 Fig. 10 is a flowchart explaining the process of the VCCT of the output unit.

11 shows the configuration of the switching system, the switch is equipped at its entry point with a VCCT.

12 shows the configuration of the switching system according to the present invention.

13 shows the format of a cell in the central office.

14 shows the configuration of the switching station according to the present embodiment.

15 shows an example of the configuration of the control information for a point-to-multipoint connection.

16A shows the configuration of the cache of a central office.

16B shows an example of the switching of bit maps and the switching of bit assignments in the point-to-multipoint connection control information.

17 shows another characteristic configuration of the present invention.

18 Fig. 15 shows an example in which the multicast function of the present embodiment is applied to the video distribution service.

19 shows the configuration of the multicast facility 130 ,

20 shows the configuration of the system for communications between a plurality of communication sites via a multi-communication link established in the switching station.

21 shows the configuration of the system for multi-user communications using a multi-terminal unit in the subscriber line.

22 FIG. 3 is a flowchart showing the process described in FIG 851 shown system shown 3-subscriber communication service.

23 FIG. 10 is a flow chart illustrating the process of the multi-party communication service in the in 20 shown system represents.

24 Fig. 10 is a flowchart illustrating the process of the multi-party communication service using a group identification number.

25 shows the flow of the process in the 3-subscriber communication service in the in 21 shown system.

26 FIG. 10 is a flow chart illustrating the multi-party communication service in the in-game 21 shown system represents.

27 is a flowchart of the call waiting service in the in 20 shown system.

28 is a flowchart (1) of a call transfer service in the in 20 shown system.

29 is a flowchart (2) of a call transfer service in the in 20 shown system.

30 FIG. 10 is a flowchart illustrating the point-to-multipoint connection service in the in 851 shown system represents.

31 is a flowchart of the call waiting service associated with the in 21 shown system is provided.

32 is a flow chart (1) of the call transfer service, which with the in 21 shown system is provided.

33 FIG. 3 is a flow chart (2) of the call transfer service associated with the in 21 shown system is provided.

34 FIG. 10 is a flowchart of the point-to-multipoint connection service associated with the in 21 shown system is provided.

35 shows the relationship between the L3 protocol data unit and a cell.

36 shows the conventional in-station feedback test method.

37 shows the configuration (1) of a general SMDS system.

38 shows the configuration (2) of a general SMDB system.

39 shows the method for implementing the conventional connectionless services.

40 shows another conventional technology.

41 shows another conventional technology.

42 shows the configuration in which the B-ISDN terminal unit is connected to the B-ISDN switch.

43 shows the configuration in which the SMDS terminal unit is connected to the SMDS exchange.

44 shows the configuration of the DS3 multiframe.

45 shows the configuration of the ATM cell and L2 PDU cell.

46 shows the configuration of the PLCP frame adapted to the DS3 format.

47 shows the restrictions that are related to the cycle staff counter.

48 shows the conventional circuit for transmitting a PLCP multiframe.

49 Fig. 15 is a time chart showing the operation of the conventional PLCP multiframe transmission circuit.

50 shows the configuration of a conventional multicast connection.

51 shows the problems of the conventional technology in which lines in physical switching units are switched when a fault occurs on the line itself.

DESCRIPTION THE PREFERRED EMBODIMENTS

Subsequently, the exchange be be which has multicasting capabilities.

• 1. Kopieren einer Zelle
• 2. Erneutes Zuordnen einer VPI/VCI

The switch according to the present embodiment is based on the ATM switch for switching an ATM cell. In the ATM switch, the following functions are required to realize the multicasting capabilities:

• 1. Copy a cell
• 2. Reassign a VPI / VCI

• 1. Kopieren in einer Vermittlungsstelle
• 2. Kopieren auf der gleichen Verbindungsleitung.

When a cell is copied, the following two processes are required:

• 1. Copy in an exchange
• 2. Copy on the same connection line.

• (1) Kommunikationsleitungssystem bzw. Trunk-System: eine Punkt-zu-Mehrpunkt-Verbindungszelle, welche die Ausgabe von einem Quell-Terminal ist, und welche zu einer Vielzahl von Teilnehmern verteilt wird, wird vorübergehend über eine Vermittlungsstelle in eine Kommunikationsleitung (beispielsweise in einen Nachrichten-Handler in der SMDS) eingegeben. Nach dem Kopieren von Zellen und dem erneuten Zuordnen ihrer VPI/VCIs in der Kommunikationsleitung werden die Zellen erneut zu der Vermittlungsstelle überführt und zu einer Vielzahl von Ziel-Teilnehmern verteilt.
• (2) Eingabe-Einheits-Kopiersystem: ein Block wird bereitgestellt, bevor eine Vermittlungsstelle Zellen hierzu kopiert. Eine Punkt-zu-Mehrpunkt Zelle wird zu dem Block kopiert. Die Vermittlungsstelle weist lediglich die Funktion des Vermittelns (Verbindens) einer kopierten Zelle auf.
• (3) Internes Kopiersystem: eine Zelle wird in die mehrstufige, sich selbst leitweglenkende Konfiguration (MSSR-Konfiguration) kopiert.

1 shows the switch configuration for realizing the point-to-multipoint function. 1 (a) shows a communication line system; 1 (b) shows an input unit copying system; and 1 (c) shows an internal copy system.

• (1) Trunk system: a point-to-multipoint connection cell, which is the output from a source terminal and which is distributed to a plurality of subscribers, is temporarily switched to a communication line (e.g. entered a message handler in the SMDS). After copying cells and reassigning their VPI / VCIs in the communication line, the cells are again transferred to the central office and distributed to a plurality of destination subscribers.
• (2) Input Unit Copy System: a block is provided before an exchange copies cells for it. A point-to-multipoint cell is copied to the block. The switch has only the function of switching (linking) a copied cell.
• (3) Internal copy system: a cell is copied into the multi-level self-routing configuration (MSSR configuration).

In the point-to-multipoint connection cell, information is set indicating that the cell is a point-to-multipoint connection cell. The Point-to-multipoint connection cell For example, with the VPI / VCI of the cell, a plurality of Target participants.

In 2 a table is presented in which the features of in 1 shown are three systems.

If a small number (10 to 100) of point-to-multipoint connections that is supported in the system or

provided be the communication line system is preferred. When a size Number (100 or more) of point-to-multipoint There is connections that are supported in the system the input unit copy system or the internal copy system preferred. If the number of sources, the point-to-multipoint transmission request, almost equal to the number of lines (channels) of Cell destination subscriber, then the input unit copy system is preferred. If these numbers are significantly different, then the internal copy system is preferred.

Even if a mediated network has a small difference in the number of channels of the lines between the source and destination users, there may be a case in which the internal copy system is preferable. That is, when a point-to-multipoint connection is provided, a source device does not need to provide a variety of sources. However, considering the available bands, the same band is used as a point-to-multipoint connection. As a result, the input unit copying system as a switched network has no advantageous aspects. If there are large differences between the sources and the subscriber lines in a central office, the internal copy system is preferred because it does not require the addition of blocks (which are included in FIG 1 shown copy function) requires. Therefore, an internal copy system is particularly advantageous in a large-scale system.

3 shows the configuration for realizing the point-to-multipoint connection using the internal copy system.

• 1. Erste Stufe in dem MSSR: Punkt-zu-Mehrpunkt-Verbindung
• 2. Zweite Stufe in dem MSSR: Bit-Kennfeld bzw. Bit-Zuordnung für eine Punkt-zu-Mehrpunkt-Verbindung
• 3. Dritte Stufe in der MSSR: Bit-Kennfeld bzw. Bit-Zuordnung für Punkt-zu-Mehrpunkt-Verbindung
• 4. DMUX-Einheit: Bit-Zuordnung durch Dekodierung der VPI/VCI

When the point-to-multipoint connection is realized with the internal copy system, a bit map is used. Assuming that there are 64 output transmission paths, and that the concentration ratio in the MSSR is 4: 1, the output transmission paths to the 16 × 4 × 64 × 64 = individual lines are much more than the number associated with the Bit map display is displayed. Therefore, the multicast connection system according to the present embodiment is configured as follows:

• 1. First Stage in the MSSR: Point-to-Multipoint Connection
• 2. Second stage in the MSSR: bit map for a point-to-multipoint connection
• 3. Third stage in the MSSR: bit map or bit assignment for point-to-multipoint connection
• 4. DMUX unit: Bit assignment by decode the VPI / VCI

• 1. Erste Stufe in der MSSR: 3 Bits (beispielsweise für eine 8 × 8-Vermittlungsstelle)
• 2. Zweite Stufe in der MSSR: 8 Bits
• 3. Dritte Stufe in der MSSR: 8 × 8 Bits

The number of bits used in the bit allocation in the point-to-multipoint connection is defined as follows:

• 1st stage in the MSSR: 3 bits (for example for an 8x8 switch)
• 2nd stage in MSSR: 8 bits
• Third level in the MSSR: 8x8 bits

each Bit in the previously described bit allocation or in the previously described Bit map is inscribed in a tag area, which is added in the exchange to each cell. In the above case are for a labeling area 9 octets required. However, the size of a label area can be in the exchange for each switch will optionally be set, and the previously described bit allocation can be realized with the identification information be that for 9 octets is set, and with the length of each cell being 64 octets is fixed. When the cell length at a higher level Value is set should when performing processes in the central office the clock increases become. For example, when normally processing 54 octet cells should the clock be increased to 64/54 times.

4 Figure 12 shows the system for implementing the previously described bit allocation, which does not extend the cell length.

In this case, the bit map associated with the third stage of the MSSR with the in 4 configuration has been processed with the external communication line 2 processed. That is, to the exchange 1 transmitted point-to-multipoint connection cell becomes the communication line 2 entered, and in the exchange 1 the number of connections for the third stage of the MSSR is copied. A VCCT 3 is at the output unit of the communication line 2 to add an 8-bit bit map to each of the copied cells and then to the switch 1 to convict. Therefore, the bit allocation for the point-to-multipoint bit map can be realized without expanding the cell length.

5 shows the VPI / VCI decoder circuit. In the 5 For example, the VPI / VCI decoder circuit shown in FIG 3 provided DMUX unit provided.

The table provided in the VPI / VCI decoder circuit 11 is searched by using VPI / VCI of an input cell as an address. The found data is a bit map of 16 × 4 = 64 bits.

The C-bit test unit 12 searches for the bits (C bits) set at a predetermined position in the designation information of an inputted cell. If the value is "1", it is determined that the input cell is a point-to-multipoint connection cell. The result of the determination by the C-bit test unit 12 is addressed to the processor and used when the table 11 is searched.

• 1. Die VPI/VCI-Dekodierfunktion als Kopierfunktion auf der gleichen Leitung
• 2. Die VPI/VCI-Neuzuordnungsfunktion bei einem Ausgangsterminal.

The point-to-multipoint connection on the same line will be described below. The process on the same line requires the following two functions.

• 1. The VPI / VCI decoding function as a copy function on the same line
• 2. The VPI / VCI remapping function at an output terminal.

The reassignment of VPI / VCI to an output terminal requires a VPI / VCI Conversion Table (VCCT). The VCCT is needed for a point-to-point connection and for a point-to-multipoint connection. The VCCT is a table from which information is requested (output VPI / VCI, etc.) from a cell using a VPI / VCI. When information is to be assigned to all VPI / VCI, a memory having a capacity of 2 to ²⁴ information units is required when the number of bits of VPI / VCI is 24 bits, for example. The provision of such a memory is impractical, and the exchange according to the present embodiment is configured as follows.

at The input terminal will be a process of reassigning a VPI / VCI of an input cell and a process of assignment carried out by labeling information. At the same time, the transmission path must be from a reassigned VPI / VCI only one transmission path identify on an output line or on each line, and does not have all VPI / VCI identify. Therefore, an address value becomes essential is less than the number of bits of VPI / VCI, as VPI / VCI at Input terminal used. The actual VPI / VCI is being used the address value as a key visited. Therefore, in the central office using a regressed VPI / VCI achieved a smaller memory size.

6 shows the configuration of a point-to-multipoint connection.

In the description given below, the VPI / VCI of a cell which is input to the central office will be referred to as "I-VPI / VCI" The VPI / VCI used in the central office is referred to as "S-VPI / VCI", and the VPI / VCI specified for the cell issued by the central office is referred to as "O-VPI / VCI". VPI / VCI ".

The VPI / VCI for which a point-to-point connection is set displays the settings below. That is, an S-VPI / VCI, flag information and the information (the C-bit is set to "0") indicating a point-to-point connection are in the input unit VCCT (IVCC). 21 for each I-VPI / VCI set as a transmission path set for the I-VPI / VCI of an input cell. At the output unit VCCT (OVCC) 22 the O-VPI / VCI is set for each S-VPI / VCI. The decoding table 23 has no specifications.

In a point-to-multipoint connection, an S-VPI / VCI, a tag information, and the information (the C bit is set to "1") indicating the point-to-multipoint connection are for every I-VPI / VCI in the input unit VCCT (IVCC) 21 established. The decoding table 23 indicates a bit allocation in the DMUX unit 24 for each S-VPI / VCI. The bit map or the bit map can contain one or more output units VCCT (OVCC) 22 from the plurality of output units VCCT. In the output unit VCCT (OVCC) 22 For example, the number of copies for each line and the O-VPI / VCI are set for each S-VPI / VCI.

7 shows the configuration of the buffer memory and the output unit VCCT provided for each output line.

With the in 7 As shown, the copying process for point-to-multipoint cells is performed using a buffer, and the VPI / VCI remapping process is performed using a table provided for a point-to-point connection. With the configuration, the hardware can be greatly reduced.

When receiving one from the DMUX unit 24 The output cell is referenced to the C-bit which is set at a predetermined position of the label information of a cell. When the C bit takes the value "0", it designates a point-to-point connection. When the line number specified in the label information relates to the number of the VCCT of the output unit, the cell becomes a particular class (for example, 0) in the buffer 31 written.

When the C bit takes the value "1", it designates a point-to-point connection. In this case, reference is made to the bit map which is in the in 6 shown decoding table is set. When the number of the VCCT of the output unit (line number) is specified, the cell is put in the buffer 31 written. Then, the cell is written to more than one class in the classes 0 to 3 according to the class identification information set in the label information in the cell.

• 1. Das Band, welches zu jeder Klasse zugeordnet ist (Inhalte des Schedulers der DMUX-Steuerung)
• 2. Inhalte der Tabelle der VCCT der Ausgabeeinheit (in einem Fall einer Punkt-zu-Punkt-Verbindung, 0-VPI/VCI für S-VPI/VCI: im Falle einer Punkt-zu-Mehrpunkt-Verbindung, die Anzahl von Kopien, einen Wert von S-VPI/VCI zum Reservieren eines Übertragungspfades, und 0-VPI/VCI).

The cell read process from the cache 31 is performed in accordance with the information set with the software for managing the exchange when a transmission path is established. The software determines the information given below.

• 1. The band associated with each class (contents of the scheduler of the DMUX controller)
• 2. Contents of the VCCT table of the output unit (in a case of a point-to-point connection, 0-VPI / VCI for S-VPI / VCI: in the case of a point-to-multipoint connection, the number of copies, a value of S-VPI / VCI for reserving a transmission path, and 0-VPI / VCI).

In 8th Fig. 12 is a table showing the contents of the output unit VCCT set with the firmware according to the software settings.

In In the case of the point-to-point connection, the E-F bit is set to "1". In the case of the point-to-multipoint connection is one of the 0-VPI / VCIs according to the goals established. Then the values of S-VPI / VCI become reserved the transmission paths of O-VPI / VCI is sequentially set to Q-ADD, and an O-VPI / VCI is included the address for set the S-VPI / VCI. The last address is the E-F bit set to "1". Otherwise the E-F bit is set to "0".

9 shows an example of a table in which an output VPI / VCI is set.

In the in 9 shown example is a multicast transmission for 4 transmission paths (to the destinations 1 to 4 ) performed on the same line. The value of S-VPI / VCI is "a"; the value of O-VPI / VCI is "b0" to "b3"; and the band assigned to each transmission path is "c0" to "c3".

10 Fig. 10 is a flowchart explaining the process of the VCCT of the output unit. The VCCT of the output unit extracts the label information and VPI / VCI etc. added to each cell copies the cell by referring to the in 9 and writes the output VPI / VCI for each of the copied cells.

A Class number (i) for use in identifying a class, its cells next to be read is determined. The Q address and the E-F bit, which are identified by the given class number are from read from the class process store, and the cells are taken from the Class i read into the QCP cache (steps S1 to S3).

If the E-F bit takes the value "0" is the S-VPI / VCI read in the aforementioned method step S3 Set the cell as the Q address of the class process store is read out (method steps S4 and S5).

The O-VPI / VCI, the Q-address and the EF-bit are read out as an address from the output unit VCCT using the S-VPI / VCI. For example, if a cell in the in 840 example shown to the target 2 is addressed, B1, C1 and 0 are visited according to the address c0 (step S6).

The O-VPI / VCI read in step S6 is written to the cell and output, and then the Q address and the E-F bit in the class process memory inscribed (method steps S7 and S8).

The processes in steps S1 to S8 are repeatedly performed until the EF bit indicates "1". When the EF bit indicates "1", the buffer address, etc., relating to the class i are released. In the in 9 In the example shown, the processes in steps S1 to S8 are repeatedly performed until the cell which reaches the target 4 addressed is output (method steps S9 and S10).

The self-employed Routing Module (SRM), which is part of the MSSR of the central office forms, identifies a transmission path according to the VPI / VCI a cell that is entered with the central office. The Routing in the switch becomes transmission path units according to the added to a cell Labeling Information carried out. Therefore, at the entry point of the cell, the information which indicates the routing in the central office of the cell, according to the VPI / VCI queried, which is set in the cell. The function of the adding the requested routing information to the cell as label information is required. In The mediation process is also the function of reassignment the VPI / VCI required, which in the entered cell as issued VPI / VCI is set.

For the exchange the MSSR configuration can perform the previously described function (VCCT) be provided in each SRM. However, the number of bits is from a VPI / VCI "28" for the network-to-network interface and "24" for the user-to-network interface. The provision of a plurality of large tables (memories) in which Identification information and output VPI / VCI for all VPI / VCIs are undesirably required large-scale hardware.

From therefore, at the entry point of the switch, a VCI Conversion Table (VCCT) for use in the realization of the functions described above provided. According to the VCCT the tag is added and the VPI / VCI rewritten.

11 shows the configuration of the switching system, the switch is equipped at its entry point with a VCCT.

Assume that the table is searched using the VPI / VCI with the VCCT. As previously described, the VPI / VCI is 28 or 24 bits in size. Setting the tag information and the output VPI / VCI for all VPI / VCI requires a memory (a VCC table) having 2 ²⁸ or ²⁴ addresses. Such a large memory is undesirable because it occupies a large-scale hardware configuration. Similarly, the usage amount parameter control / network parameter control (UPC / NPC) is searched using a VPI / VCI. In this case, the table search system using the VPI / VCI requires an undesirably large memory.

The Switching system according to the present embodiment has the function of transforming (rebuilding) a VPI / VCI into a memory polling address with a small number of bits on. In the point-to-multipoint connection, cells become one Exchange office copied and for each Output line is a VCCT required.

12 shows the configuration of the switching system according to the present embodiment.

As in 12 is shown at the entrance of the switching station, an I-VPI / VCI conversion unit 41 provided (UPC before the identification allocation unit). The I-VPI / VCI conversion unit 41 At the switching station, the VPI / VCI (I-VPI / VCI) of an input cell is converted to the VPI / VCI (F-VPI / VCI) which must be used as the memory polling address. An S-VPI / VCI conversion unit 42 to convert the S-VPI / VCI in an output VPI / VCI (O-VPI / VCI) is provided at the output unit of the switching station.

In The ATM communication service is a VP service and a VC service intended. In the VP service, data becomes in the unit of virtual transmission paths VP transferred, which occupy a plurality of virtual channels VC. From therefore can a communication line with only one VPI without use VCI in the VP service. This helps the size of the VCCT to reduce.

First, the service identification information is set to the issue flag information of each cell indicating the VP service or the VC service. The switching station provides a table for use in the VP service and a table for use in the VC service. An output VPI is set for an input VPI on the table for the VP service. An output VPI / VCI is set for an input VPI / VCI on the table for the VC service. When a cell enters the switching station, the service identification information of the cell recognizes the service type and performs VPI / VCI conversion according to one of these tables. The process comes with the I-VPI / VCI conversion unit 41 carried out.

The cell which has passed through the exchange recognizes the service type according to the service identification information in the S-VPI / VCI conversion unit 42 , The O-VPI / VCI table 43 to which with the S-VPI / VCI conversion unit 42 Has a table for the VPI service and a table for the VC service. Depending on the service type, one of these tables is accessed.

If, as in the configuration described above, the tables for the VP service and the VC service can be deployed individually, the size of the hardware because the table is relatively small for the VP service is.

From therefore, there are different methods of regressing the VPI / VCI. The procedure for limiting the number of bits used for A VPI / VCI can be a problem in terms of the Cause system operations. Therefore, the memory can be reduced in size be by the number of transmission paths limited will be set at the same time.

As previously stated, a point-to-multipoint connection can be used without one external device according to the switching station the present embodiment will be realized.

following becomes the embodiment a system for transferring for the Point-to-multipoint connection of necessary information in parallel with the cell in the switching station described.

As previously stated, the functions of copying a cell and reassigning the VPI / VCI of the copied cell, to realize the point-to-multipoint connection. These functions are performed in units of cells.

13 shows the format of a cell in the central office. As in 13 As shown, a cell in an exchange has tag information, a header and a payload, and is processed in the 8-bit parallel format. The tag information includes routing information in the switching station, etc., and is added according to the VPI / VCI of each cell at the entrance of the switching station. In the central office, the cell is controlled only with the flag information (routing control, copy instructions, etc.). According to the system of the present embodiment, the control information necessary for the point-to-multipoint connection is transferred in parallel with the cell in the switching station and processed in the 9-bit parallel format.

14 shows the configuration of the switching station according to the present embodiment.

The cell transferred via the user-to-network interface or via the network-to-network interface (UNI / NNI) is connected to the line interface unit 51 terminated, which is provided for each line. The VPI / VCI conversion unit (VCCT) 52 re-writes the VPI / VCI from an input cell. The multiplex unit MUX 53 performs a multiplex function on a cell which is input over a plurality of lines. The exchange 54 is an exchange of an 8x8 cache type. The demultiplex unit DMUX 5 Distributes one from the central office 54 output cell to a particular line interface unit 51 ,

15 shows an example of the configuration of the control information for a point-to-multipoint connection.

The point-to-multipoint connection control information comprises a switch bit map, a DMUX bit map, and a subscriber ID. In the switch bit map, the switch has an 8x8 configuration and refers to 8-bit information. In the DMUX bit map, the number of demultiplexing units is DMUX 55 supplied wires 16 , and it's assigned to 16 bits. The subscriber ID identifies a destination subscriber and is assigned to 8 bits.

The point-to-multipoint connection control information in the configuration described above is in the VPI / VCI conversion unit (VCCT) 52 which corresponds to the VPI / VCI stored in the header of the input cell. The information is set when a call is established. It is not set for a point-to-point connection. The VPI / VCI conversion unit (VCCT) 52 transfers the point-to-multipoint connection control information in parallel with an inputted cell when the cell with added identification information is transferred to a central office. The synchronization is established between a cell and the point-to-multipoint connection control information, and both are transferred in the 9-bit-large parallel format.

• 1. Das Kopieren in der Vermittlungseinheit und der DMUX-Einheit
• 2. Das Kopieren und das erneute Zuordnen von VPI/VCI in der Leitungs-Schnittstelleneinheit

The point-to-multipoint connection according to the present embodiment has the following two important functions:

• 1. The copying in the exchange unit and the DMUX unit
• 2. Copy and reassign VPI / VCI in the line interface unit

First, the copy capacities in a switching unit will be described. When a cell enters the switching station, the VPI / VCI conversion unit (VCCT) 52 Added tag information to the cell it is in 14 is shown. In the flag information, the information indicating that the cell is a point-to-point connection cell or a point-to-multipoint connection cell is set as C-bit information. When the C-bit information takes the value "0", it designates a point-to-point connection and the cell is processed according to the routing information set in the tag information added to the cell in the switching station.

16A shows the configuration of the cache (buffer memory) of a central office. 16B shows an example of the switching bit map in the point-to-multipoint connection control information.

When the C-bit information takes the value "1", it means a point-to-multipoint connection, and reference is made to the point-to-multipoint connection control information transferred in parallel with the cell in the switching station. In the switch, reference is made to the switch bit map. In this stage, a cell whose C-bit information is set to "1" enters from the input bus line 61 into the central office, and the switch bit map is in 16B shown. In this case, the cell is written to the latches 12 ¹ , 13 ¹ , 15 ¹ and 16 ¹ . Accordingly, that of the input bus line 61 input cell to the output bus line 2 . 3 . 5 and 6 output. therefore, the function of copying cells in the exchange unit can be realized. The cells can be similarly copied in the DMUX unit.

following the copy function and the VPI / VCI remapping function are described.

Upon receipt of a cell whose C bit becomes "1", the line interface unit determines 51 in that there is a point-to-multipoint connection and polls a subscriber ID in the point-to-multipoint connection control information. The line interface unit 51 is provided with a table which is searched using a subscriber ID as a key. The table contains the number of copies and a VPI / VCI associated with each cell created with a copy process. The line interface unit 51 accesses the table with the requested subscriber ID, copies a cell, and reassigns the VPI / VCI.

The process of switching station software relating to the point-to-multipoint connection will be described below. Upon receiving a point-to-multipoint connection request in response to a transmission path set request (call setup request), the software of the switching station sets the C bit to the value "1" corresponding to the VPI / VCI sent to the transmission path must be assigned. In specifying the transmission path, the destination subscriber ID is specified, and the software of the switching station writes in the in the line interface unit 51 provided table according to the specification of the number of copies and the VPI / VCI, which are set for each cell generated with the copying process.

If a cell enters the switching station, the leads previously described hardware a point-to-multipoint connection according to the the software of the switching station information specified by.

With The configuration described above may be a point-to-multipoint connection be realized in the central office, without having to be outside the exchange a device for copying a cell is provided. Because the point-to-multipoint control information is not as identification information, but is transferred in parallel with the cell in the switching station is the throughput does not deteriorate.

17 shows another characteristic configuration of the present invention. 17 shows an example in which a source terminal 61 Data in a multicast method via a switching station 62 to destination terminals 64-1 to 64-5 transferred.

If the source terminal 61 Establishes a multicast connection, the transmission data (hereinafter referred to as "cell") to a multicast device 66 transferred. That is, the source terminal 61 Transfers the cell using the destination address of the multicast facility 66 to the ATM exchange 62 , The ATM exchange 62 connects the transmission path 65 according to the destination address and transfers the cell to the multicast facility 66 , Then the transmission lines are between the source terminal 1 and the multicast facility 66 that is the line 63 and the transmission path 65 set in the communication state of the connection of 1: 1.

When receiving the with the source terminal 61 transferred cell transfers the multicast device 66 the cell to the destination terminal 64-1 , That is, the multicast facility 66 transfers the cell to the ATM switching station 62 with the destination terminal 64-1 , which is set as the destination address of the cell. The ATM exchange 62 switches the transmission path 67-1 according to the destination address and transfers the cell over the transmission path 67-1 to the destination 64-1 ,

Then convict the multicast facility 66 the one with the source terminal 61 transferred cell sequentially to the destination terminals 64-2 to 64-5 , Then the ATM switching station switches 2 the transmission paths 67-2 to 67-5 by.

The multicast facility 66 is provided in the switching station, and the destination information etc. is set for each multicast service request by the user. A variety of multicast services are being processed.

As previously mentioned, the multicast device 66 the power of copying cells. If the copied cells go to N destination terminals ( 5 Terminals in 17 ) distributes the multicast facility 66 the cells sequentially to each destination terminal. The amount of resources is the same as in the 1: 1 connection.

18 Fig. 10 shows an example in which the multicast function of the present invention is applied to the video distribution service. In 18 an example is shown in which the in the video server 111 stored video data to the subscriber terminals 120-1 to 120-3 be distributed.

The control 112 Controls video data and transfers a video signal to the B-ISDN adapter 113 , The B-ISDN adapter 113 transferred according to the protocol of the subscriber line interface 114 that from the controller 112 transmitted video signal to the network interface device 115 ,

The network interface device 115 converts the transmitted data containing the video signal into data in a format associated with the switching station 116 is processed. The switching station 116 is hereinafter referred to as "ATM switching station". In this case, the network interface device converts 115 the transferred data containing the video signal into an ATM cell. The network interface device 115 Put in each cell the VPI / VCI, which is the multicast facility 130 identified as the destination address, and transfers the cells to the switching station 116 , The VPI / VCI representing the multicast facility 130 is identified, as described later, with the controller 127 reported.

When receiving the cell, the switching station builds 116 the transmission path 117 for a connection to the network interface device 115 with the multicast facility 130 according to the VPI / VCI set in the cell to the cell via the transmission path 117 transferred to.

19 shows the configuration of the multicast facility 130 ,

The VPI / VCI conversion table 131 is written when a multicast connection request call is turned on. For example, if a call connection request is for multicast distributed video data stored in the video server 111 stored to the subscriber terminals 120-1 to 120-3 is output, then achieved the control 127 first a VPI / VCI (VPI / VCI 117 ) representing the transmission path (transmission path 117 ) for connecting the network interface device 115 with the multicast facility 130 specified. Then the controller reports 127 the VPI / VCI 117 to the network interface device 115 and reserves the area for the VPI / VCI 117 in the VPI / VCI conversion table 131 ,

Then the controller achieves 127 the VPI / VCIs (VPI / VCIs 1 to 3 ), which are the transmission paths (transmission paths 122-1 to 122-3 ) for connecting the multicast device 130 with the network interface devices 123-1 to 123-3 specify. Then the controller writes the VPI / VCIs 1 to 3 in the for the VPI / VCI 117 in the VPI / VCI conversion table 131 reserved area.

The following is the operation of the multicast facility 130 described when she receives a cell. The cell is powered by the network interface device 115 via the switching station 116 transmitted and temporarily in the receiving unit 132 saved. The control unit 133 searches in the VPI / VCI conversion table 131 according to the VPI / VCI set in the cell, which is in the receiving unit 132 is stored. Since the VPI / VCI specified in the entered cell is the VPI / VCI 117 is, the VPI / VCIs 1 to 3 queried as output VPI / VCIs. These output VPI / VCIs become the VPI / VCI allocation unit 134 directed. The control unit 133 Detects the number of destination participants from the requested VPI / VCIs.

Then copy the copy unit 135 in the receiving unit 132 stored cell according to the instruction of the control unit 133 and write them into the output buffer 136 , Then set the VPI / VCI allocation unit 134 "VPI / VCI 1 "for those with the copy unit 135 copied cell. The copy unit 135 copies two cells in the receiving unit 132 are stored and the cells become VPI / VCI 2 and VPI / VCI 3 assigned to the output buffer 136 written.

The control unit 133 first converts the cell, which is the VPI / VCI 1 is assigned to the switching station 121 , The switching station 121 is an ATM switching station having a self-routing module. Upon receiving the cell, the switching station connects 121 the transmission path 122-1 between the multicast facility 130 and the network interface device 123-1 , Therefore, those of the video server 111 read out video data via the transmission path 122-1 to the network interface device 123-1 transfer. Then those with the network interface device 123-1 received data via the controller 125 to the subscriber terminal 120-1 transfer.

Similarly, the control unit transmits 133 sequentially the cells to the switching station 121 that the VPI / VCI 2 and the VPI / VCI 3 assigned. Upon receipt of the cell, the switching center directs 121 the transmission paths 122-2 and 122-3 according to the VPI / VCI values. The VPI / VCI 2 and the VPI / VCI 3 associated cells become the transmission paths, respectively 122-2 and 122-3 transmit and reach the subscriber terminals 120-2 and 120-3 ,

The control 127 recognizes the application state of the switching stations via the connection access control function (CAC function) 116 and 121 , The control unit 133 receives from the controller 127 a notification regarding the application state of the switching stations 116 and 121 , When the switching station 121 is in the overload state, the control unit stops 133 the cell readout process from the output buffer 136 at. With the configuration, cells in the output buffer can 136 be discarded when the congestion state of the switching station 121 stops. However, the entire switching station can recover from the congestion condition.

As previously stated, the multicast connection system can handle the traffic load reduce on the source terminal and the switching station, and the operations of the switching station can be successfully reduced because the data sender has only the same amount of data as in the case of the one-to-one connection, regardless of the number of goals. Therefore, the hardware resources or hardware resources with the configuration in one pass over unused condition (the previously described transmission lines and switching stations) in a meaningful way to other services be assigned.

If a multicast connection service over the usual Switching stations is provided, this can only be realized be provided by providing the previously described multicast device. There the ATM switching station extraordinarily depends on the hardware configuration, it's a big achievement a multicast connection service without design changes with regard to the switching stations.

20 shows the configuration of the system for communication from a plurality of communication devices via a multiple communication line, which is constructed in the switching station. In this example, the subscriber A communicating in the concentrator unit communicates 71 is housed, with participants B and C, in the concentrator unit 72 are housed. The 3-subscriber communication is referred to as a TV conference call about voice and pictures. The concentrator units 71 and 72 are at the host switching station 73 connected. The host switching station 73 is an ATM switching station having a self routing switch, and a transmission path is fixed according to the VPI / VCI of each cell sets. The multi-party communication line 74 is with the host switching station 73 in e.g. a switching station, and it processes or synthesizes data for the cell associated with the VPI / VCI specifying a destination subscriber and transmits this data to the host switching station 73 , The multiple-user communication line 74 is intended for each multiple subscriber communication.

Subscriber A is over the bidirectional virtual transmission path 75 specified with the VPI / VCI = xa, with the multi-party communication line 74 connected. Subscribers B and C are over the bidirectional virtual transmission paths 76 and 77 , respectively specified with the VPI / VCI = xb and the VPI / VCI = xc, with the multi-party communication line 74 connected.

With the configuration described above, when the subscribers A, B and C start the 3-subscriber communication, the transmission data from each subscriber temporarily becomes the multi-subscriber communication line 74 and then transmit to the destination party after the transmission data with the multi-party communication line 74 were prepared. Therefore, the system with the above-described configuration provides multi-party communication services through the functions of the switching station.

21 shows the configuration of the system for multi-subscriber communications using a multi-terminal unit in the subscriber line.

This in 21 shown system uses the multi-terminal unit 211 when subscribers A, B and C record the 3-subscriber communication. The multi-terminal unit 211 is via a subscriber line in the concentrator unit 71 involved. The bidirectional virtual transmission path specified by VPI / VCI = yd 212 connects subscriber A to the multi-terminal unit 211 , The bidirectional virtual transmission paths specified by VPI / VCI = ye and VPI / VCI 0 yf 213 and 214 Subscribers B and C each connect to the multiple terminal unit 211 ,

The multi-terminal unit 211 can simultaneously process data transmitted over a plurality of virtual transmission paths specified with a plurality of VPI / VCIs, and adds the edited or synthesized data to the cell associated with the VPI / VCI, which has a Destination subscribers specify and then transmit the data to the host switching station 73 , Therefore, the system having the above-described configuration provides multiple subscriber communication via a terminal provided in the subscriber line.

Hereinafter, the procedure of providing a multi-party communication service in the in 20 or 21 described system described.

22 is a process flowchart illustrating the 3-subscriber communication service in the in 20 shown system represents. In this example, the subscriber C is called in the 2-subscriber communication state in which the subscribers A and B communicate with each other, and the 3-subscriber communication state is recorded.

A certain VPI / VCI (eg VPI / VCI = ab) connects the subscriber A with the subscriber B. In such a 2-subscriber communication state there one of the participants A and B, a 3-subscriber communication request from, by the participant C according to a particular procedure is specified.

Upon receiving the 3-subscriber communication request, the host switching station calls 73 the subscriber C and checks whether an unused multiple-subscriber communication line 74 is available (process steps S1 and S2).

The host switching station 73 receives the response from the subscriber C and reports it to the multi-party communication line 74 (Step S3).

The VPI / VCIs of a certain number become the multi-party communication line 74 associated with each of the subscribers A, B and C with the multi-subscriber communication line 74 connect to. The host switching station 73 selects VPI / VCI = xa, xb and xc as those VPI / VCI representing the transmission path between the subscribers A, B and C and the multi-subscriber communication line 74 specified. Then, the value "3" is set as the number of the participants connected to each other (process steps S4 and S5).

Upon receiving the response of the subscriber C in the aforementioned step S3, the host switching station disconnects 73 the transmission path between subscribers A and B and directs the transmission paths 75 . 76 and 77 between the multi-party communication line 74 and each of the subscribers A, B and C (steps S6 and S7).

Then, the cells transmitted from each of the subscribers A, B and C first become the multi-subscriber communication line 74 transferred, processed there and then forwarded to the destination subscriber. Therefore, the 2-subscriber communication state is switched to the 3-subscriber communication state. When image and sound data from the multi-party communication line 74 may be included in the band associated with a subscriber, there is no need for a band check when transitioning to the 3-subscriber communication state.

23 FIG. 10 is a flow chart illustrating the process of the multi-party communication service in the in 20 shown system represents. The following describes the procedure of calling a number of subscribers in a 3-party or multi-party communication state.

In the multi-subscriber communication state, one of the communication subscribers requests to add the nth subscriber (subscriber N) to the multi-subscriber communication. Upon receiving the request, the host switching station checks 73 whether the value n is smaller than the number of users who at the same time the multi-subscriber communication line 74 can use. That is, the multi-party communication line 74 determines whether or not the number of communication units exceeds the maximum value for the multi-party communication (steps S11 and S12).

If the maximum value for the number of communication units is exceeded, the process becomes discarding the request (step S13).

If the number of communication units is less than the maximum value, the host switching station calls 3 subscriber N and selects the VPI / VCI representing the transmission path between each of the subscribers N and the multi-subscriber communication line 74 specified. Then the number of already connected participants is updated. That is, the number is set to "n". Then, the transmission path between each subscriber N and the multi-subscriber communication line becomes 74 configured to transition to an n-subscriber communication state (steps S14 to S18).

24 Fig. 10 is a flowchart showing the process of the multi-party communication service using a group identification number. The following shows the case where any subscriber (subscriber D) issues a request for multi-party communication. The multi-party communication service is given for a group of previously selected subscribers, and a group identification number is assigned to each group. The multi-party communication line 74 is associated with the multi-party communications from each group.

If the host switching station 73 receives a specific number of the multi-party communication service request and a group identification number from a subscriber, determines whether or not the multi-subscriber communication is performed in a group which is designated with the group identification number (process steps S21 and S22) ,

When the multicast communications are performed in a group, the host switch recognizes station 73 the multi-party communication line 74 , which provides the multi-party communication service, and checks whether or not the number of the communication devices the maximum value for the multi-party communication line 74 exceeds when a communication device is added to the currently communicating party (step S23).

If the maximum value is not exceeded, the controller proceeds to step S26. If he passed though is carried out, the process of rejecting the request (method step S24).

If it is determined in step S22 that the multi-subscriber communications are not performed in the group, the multi-party communication line becomes 74 in an unused state, and the control goes to step S26 (step S25).

The host switching station 73 selects the VPI / VCI which specifies the transmission path between the subscriber D requesting the multi-subscriber communications in step S21 and the multi-subscriber communication line 74 specified. Then the number of participants connected is updated. Then, a transmission path between the subscriber B and the multi-subscriber communication line becomes 74 set up. Therefore, any participant in the multi-party communications can participate in a specific group (process steps S26 to S28).

25 shows the flow of the process in the 3-subscriber communication service at the in 21 shown system. In this system, a transmission path between the multi-terminal unit 211 set up in the subscriber circuit and each subscriber. In essence, the process order is the same as those in 22 is shown.

26 FIG. 5 is a flowchart illustrating the multi-party communication service at the in-game 21 shown system represents. In this system, a transmission path between the multi-terminal unit 11 set up in the subscriber circuit and the called subscriber again. The process order is essentially the same as those in 23 is shown.

27 is a flowchart of the call waiting service in the in 20 shown system. In this example, the subscriber C (the third party) issues a connection request to the subscriber A while the 2-subscriber communications between the subscribers A and B are carried out.

Upon receiving a connection request from the subscriber C to the subscriber A in the 2-subscriber communication state between the subscribers A and B, the host switching station selects 73 the VPI / VCIs in the area where the multi-party communication line 74 is available and sets new virtual transmission paths between the multi-party communication line 4 and each of the users A and C (process steps S31 to S33).

The host switching station 73 notifies subscriber A of the fact that the call request was received from the third party. In response, the subscriber A determines whether or not he / she requests to re-communicate with the subscriber B after communicating with the third party (subscriber C).

If the host switching station 73 receives a request to communicate with the subscriber B again after the communications with the third party sets the host switching station 73 the subscriber B in a standby state and connects the subscriber A to the subscriber C via the multi-subscriber communication line 74 (Process steps S34 to S38).

If the host switching station 73 receives a request from the subscriber A or C to terminate the communications between the subscribers A and C, gives the host switching station 73 free the virtual transmission paths that exist between the multi-party communication line 74 and the subscribers A and C, and again connects the subscriber A to the subscriber B (steps S39 to S41).

If the host switching station 73 receives a request to stop the communications with the subscriber B after the communications with the third party, this disconnects the subscriber B. Then, the host switching station issues 73 between the multiple-party communication line 74 and the subscribers A and C fixed virtual transmission paths and connects directly the subscriber A with the subscriber C (steps S34, S42 and S43).

28 is a flowchart ( 1 ) of a call transfer service in the in 20 shown system. Hereinafter, the connection made with the subscriber A between the subscriber B and the subscriber C (third party) while the subscribers A and B are in the 2-subscriber communication will be described.

If the host switching station 73 from the subscriber A receives a call transfer request and a call transfer destination information indicating the subscriber C, it selects the VPI / VCI which identifies the area in which the multi-user communication line 74 is available and establishes new virtual transmission paths between the multi-party communication line 74 and subscribers B and C (steps S51 to S54).

The host switching station 73 calls subscriber C When the subscriber C returns an answer, the host switching station connects 73 the subscriber B to the subscriber C via the multi-subscriber communication line 74 (Process steps S55 and S56).

29 Figure 2 is a flow chart (2) of a call transfer service in the in 20 shown system.

If the host switching station 73 from the participant A, who after the in the 28 shown steps S51 to S55 hands the call, the host switching station gives the between the multi-party communication line 74 and the participants B and C defined virtual transmission paths to directly connect the subscriber B to the subscriber C (steps S61 to S63).

According to the in 28 or 29 gezeig th system, a call from the subscriber B to the subscriber A to the subscriber C can be transferred.

30 FIG. 10 is a flowchart illustrating the point-to-multipoint connection service in the in 20 shown system represents. The following describes the case in which the subscribers B and C access the subscriber A (subscriber providing information).

If the host switching station 73 receives a point-to-multipoint connection request from subscriber A, it selects the VPI / VCI in the area in which the multi-party communication line 74 is available and sets a virtual transmission path between the subscriber A and the multi-subscriber communication line 74 fixed (method steps S71 and S72).

If the host switching station 73 receives a connection request from subscribers B and C to subscriber A, it issues two VPI / VCIs in the area in which the multi-party communication line 74 is available and establishes virtual transmission paths between the multi-party communication line 74 and participants B and C. Thereafter, the point-to-multipoint communications may be over the multi-party communication line 74 to be set up (method steps S73 to S75).

A Multicast transfer can be performed by the subscriber A to the participants B and C. In this case, the subscriber A specifies the subscribers B and C as connection-to-information in step S73.

The 31 to 34 show flowcharts of different services provided with the system, each in 21 and accordingly in the 27 to 30 is shown. In the in the 31 to 34 The system shown processes the multiple terminal unit 211 virtual transmission paths.

According to the before described embodiment provides the multi-party communication line necessary for the switching station or for the provided in the subscriber line multiple terminal unit services, such as multi-user communication services, Call Waiting Services, Transfer Services Etc.

Claims (7)

Switching system, which is an intermediary ( 1 ) provided in a network for autonomously routing a cell containing data and data control information according to the control information to provide a point-to-multipoint connection service, characterized in that the switching system is adapted to to establish the point-to-multipoint connection using a bit map by internal functions of the switch, and adapted to add a bit map information about a path from an input cell of the input cell. A switching system according to claim 1, wherein the Switching system is adapted to the point-to-multipoint connection using a small bit map to create, and is adapted to decode a routing information which in the control information is set, and subsequently the small one Bit map to update information. A switching system according to claim 1, wherein the Switching system is adapted to the point-to-multipoint connection on the same line, and a table for use when reforming a routing information, which in the control information is set, both at the input and output terminals of the switch contains. A switching system according to claim 1, wherein the Switching system is adapted to the point-to-multipoint connection on the same line using multiplexing / demultiplexing functions to create which at an output port of the intermediary are provided. A switching system according to claim 1, comprising: a first forming means ( 41 ) provided at an input terminal of the mediator to convert a routing information set in the control information from an input cell into an intra-switching routing information; and a second forming means ( 42 ) provided at an output port of the switch to transform the intra-switch routing information into routing information for an output cell. Switching system according to Claim 5, in which the first conversion means ( 41 ) is adapted to set the intra-switch routing information based on a number of paths which are connectable simultaneously. A switching system according to claim 1, which includes: setting means for setting a point-to-multipoint control information in response to the control information from an inputted cell; transmission means for transmitting the cell in parallel and the point-to-multipoint control information; and a control means for controlling the point-to-multipoint connection in accordance with the point-to-multipoint control information.