JPH0793630B2 - Network connection method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a packet communication method for dividing data into digitized blocks and transferring them, and in particular to an inter-network connection method between a main network with a switching function and a sub-network without a switching function.

For example, there is a public network as a main network, and a home network connected to this public network as a sub-network.

[Background technology]

Traditionally, data communication networks have developed based on telephone switching networks, but with the rapid expansion of the information processing field, many problems have been pointed out due to the insufficient functionality of communication networks. As a solution to these problems, the idea of Integrated Services Digital Network (ISDN) has been put forward. ISDN is a broadband ISDN that integrates various services such as data communication networks, facsimile networks, voice communication, various dedicated networks, and image communication networks into one digital communication network, instead of the conventional narrowband ISDN (64Kbps).
(150Gbps). Due to the rapid development of communication technologies such as ISDN mentioned above, and the rapid development of computer-based information processing technology, there is a demand for information and communication systems that can organically combine various terminals and information devices and make more effective use of information and resources. In particular, in order to respond to demands for broadband services, multimedia, and diversification of communication formats, not only main networks such as public networks, but also
When connecting a sub-network such as a home network to a main network such as a public network,
There is a need to develop a system that is more economical, scalable, and efficient.

Conventional subnetworks include PBs with switching functions.
A network connection method is known which includes an X and a call processing processor that controls it, and enables connection to a main network.

However, as will be described in detail later with reference to the drawings, this conventional method requires a call processing setting means within the subnetwork, and therefore, when the subnetwork is used as a home network, it is suitable for large companies, but is not economical for small companies or ordinary households.

Another conventional network connection method is to provide the switching functions required by a sub-network (for example, a residential network) in the switch of the main network.

In this conventional system, the subnetwork itself does not have a switching function, so the cost can be lower than in the first conventional system described above.

However, as will be described in detail later with reference to the drawings, in this conventional system, even when transferring information between terminals within a subnetwork, an actual communication path is provided on the subscriber line between the subnetwork and the main network, and the information is returned at an exchange within the main network, which increases the traffic volume at the exchange, necessitating an increase in the exchange's capacity.

Furthermore, when applying a subscriber network configuration in which a multiplexing concentrator is inserted between subscriber lines to efficiently accommodate multiple subscribers, it is necessary to increase the capacity of the feeder loop and to have a switching function (remote switching function) to appropriately distribute data from the feeder loop to each subscriber line.

DISCLOSURE OF THE INVENTION

In view of the problems in the prior art described above, the object of the present invention is to realize an inter-network connection system between a main network (for example, a large-scale network (backbone LAN) or a public network) with a switching function and a sub-network (for example, a branch LAN or a home network), by providing scalability so that various sub-network configurations can be realized, reducing initial costs so that the system can be introduced into ordinary homes, thereby making it economical, and by providing efficiency so that the impact of traffic within the sub-network on the main network can be minimized.

To achieve the above object, the present invention provides an inter-network connection system for a system comprising a main network having an exchange and a call setup processor controlling the exchange, and a subnetwork connected to the main network and having a plurality of terminals and a connection control section equipped with loopback means, wherein, in the case of extension communication within the subnetwork, the call setup processor provides a first specific signal to the calling terminal to operate the loopback means of the connection control section, thereby establishing an actual extension communication path between the terminals in the subnetwork, and in the case of outside communication between the main network and a terminal in the subnetwork, the call setup processor provides a second specific signal to the calling terminal to stop the loopback means of the connection control section, thereby establishing an actual outside communication path between the exchange of the main network and the terminal in the subnetwork. The first and second specific signals are sent by the call setup processor to the calling terminal, and the calling terminal adds the received first or second specific signal to transmission information and sends it out. The connection control section determines whether or not to operate the loopback means for each piece of information in response to the first specific signal or the second specific signal, and sets up an actual communication path for extension communication and/or outside communication.

The main network and the sub-networks preferably comprise an Integrated Services Digital Network (ISDN).

Preferably, the first specific signal and the second specific signal are each one or more fixed data groups.

the connection control unit includes a rewritable table, and the first specific signal and the second specific signal are each one or more data groups, and the rewritable table stores one or more data groups corresponding to the first specific signal and the second specific signal, respectively;
It is preferable that the connection control unit compares the first specific signal or the second specific signal added to the information with the contents of the table, thereby determining whether to operate the loopback function and setting up the actual communication path.

The call setup processor may be provided with means for rewriting the contents of the table in the connection control section.

The terminal may be provided with means for rewriting the contents of the table in the connection control unit.

It is preferable that the connection control unit has a means for monitoring the traffic of internal and external communication, and automatically changes the contents of the table according to the traffic volume so that when the traffic volume of internal communication becomes greater than the traffic volume of external communication, the data volume of the first specific signal is increased, and when the traffic volume of external communication becomes greater than the traffic volume of internal communication, the data volume of the second specific signal is increased.

It is also preferable to provide a third signal that simultaneously sets up an actual communication path for both communication within the subnetwork and communication between the main network and terminals in the subnetwork, so that the third signal enables simultaneous setting of an actual communication path for both internal communication and external communication.

The information may include a destination identification label, and a first specific signal and a second specific signal may be logically provided within the destination identification label.

It is preferable to logically provide a third specific signal in the destination identification label.

It is preferable to apply error correction to the first specific signal, the second specific signal and the third specific signal.

The destination identification label may be subjected to error correction.

It is preferable to provide a buffer for storing information in the loopback means of the connection control section, and when a vacant line from the main network is found, to take out the information from the buffer and transfer it to the terminal.

A buffer for storing information may be provided on the line between the connection control unit and the main network, and when a vacant loopback line is found, the information may be taken out of the buffer and transferred to the terminal.

A first buffer and a second buffer for storing information may be provided in the loopback means of the connection control section and in the line between the connection control section and the main network, respectively, and information may be alternately taken out from the first buffer and the second buffer and transferred to the terminal.

The connection control unit may include a buffer vacancy detection unit that detects whether either the first buffer or the second buffer is vacant, and when either buffer is vacant, information is transferred to the terminal sequentially from the other buffer.

The connection control unit may be provided with a loopback means in the connection control unit and a buffer common to the line from the main network of the connection control unit, and a write means for writing the information to be looped back and the information from the main network into the buffer at high speed, and the information may be transferred to the terminal in the order written into the buffer.

Priority information may be added to the information to be looped back and the information from the main network, and the connection control section may transfer the information from the terminal and the information from the main network to the terminal in order of priority according to the priority information.

The priority information preferably indicates whether internal communication has priority over external communication.

The priority may indicate whether the content of the communication service is prioritized or not.

Preferably, the connection control unit includes a priority control unit that writes priority information together with the information into a buffer, and the priority control unit transfers the information to the terminal in accordance with the priority information read from the buffer.

It is preferable that the connection control unit has a plurality of buffers for storing different priority information, and that information is stored in each buffer based on the priority information, and that information is transferred from each buffer to the terminal in order of priority.

The terminals may form multiple sub-networks, and the multiple sub-networks may be connected to a main network.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a block diagram showing an example of a conventional network connection method; FIG. 2 is a block diagram showing another example of a conventional network connection method; FIG. 3 is a block diagram showing a network connection method according to a first embodiment of the present invention; FIG. 4 is a block diagram showing an example of the configuration of a connection control unit (CC) in FIG. 3; FIGS. 5A and 5B are block diagrams explaining an example of the operation of the connection control unit shown in FIG. 4; FIG. 6 is a diagram showing an example of the configuration of a table provided in the connection control unit according to another embodiment of the present invention; FIG. 7 is a diagram explaining an example of changing the contents of the table shown in FIG. 6 according to traffic volume; FIG. 8 is a block diagram explaining paths when actual communication paths are set simultaneously for extensions and outside lines according to yet another embodiment of the present invention; FIG. 9 is a diagram explaining an example in which a code for logically setting paths for extensions, outside lines, or both, is set in a destination identification label according to yet another embodiment of the present invention; FIG. 11 is a block diagram showing an example of a configuration in which a buffer is provided in the connection control unit according to yet another embodiment of the present invention; FIG. 12 is a block diagram showing another example of a configuration in which a buffer is provided in the connection control unit according to yet another embodiment of the present invention; FIG. 13 is a block diagram showing an example of a configuration in which two buffers are provided in the connection control unit according to yet another embodiment of the present invention; FIG. 14 is a block diagram showing another example of a configuration in which two buffers are provided in the connection control unit according to yet another embodiment of the present invention; FIG. 15 is a block diagram showing an example of a configuration in which a common buffer is provided in the connection control unit according to yet another embodiment of the present invention; FIG. 16A is a diagram explaining an example in which a priority signal is added to information according to yet another embodiment of the present invention; FIG. 16B is a diagram showing an example of the priority signal in FIG. 16A; Figure 19 is a block diagram showing a configuration in which a buffer is provided for each priority in the connection control unit according to yet another embodiment of the present invention; Figure 20 is a block diagram showing a configuration in which multiple subnetworks are connected to a main network according to yet another embodiment of the present invention; Figure 21 is a block diagram showing an example in which a ring LAN is used as a subnetwork according to yet another embodiment of the present invention; Figure 22 is a block diagram showing an example in which a subnetwork has multiple small subnetworks according to yet another embodiment of the present invention; and Figure 23 is a block diagram showing the configuration of the connection control unit in Figure 22.

BEST MODE FOR CARRYING OUT THE INVENTION

Throughout the specification, like reference numbers refer to like parts, and like numbers with the addition of letters refer to variations of the same parts.

For a better understanding of the present invention, a conventional network connection method will be described with reference to FIGS.

FIG. 1 is a block diagram showing an example of a conventional network connection system. In the figure, a main network (for example, a backbone LAN) includes a switch (S
A private branch exchange (PBX) 1 is provided in the sub-network (for example, a branch line or a residential network), and a call setup processor (CP S ) 4 is provided in the sub-network (for example, a branch line or a residential network), and a private branch exchange (PBX) 3 is provided in the sub-network, and a call setup processor (CP S ) 4 is provided in the sub-network (for example, a branch line or a residential network), ...3 is provided in the sub-network (for example, a branch line or a residential network), and a call setup processor (CP S ) 4 is provided in the sub-network (for example, a branch line or a residential network), and a call setup processor (CP S ) 4 is provided in the sub-network (for example, a branch line or a residential network), and a call setup processor (CP _{S ) 4 is provided in the sub-network (for example, a branch line or a residential network), and a call setup processor (CP S ) 4 is provided in the sub-network (for example, a branch line or a residential network), and a call setup processor (CP S} ) 4 is

When each terminal (TE) 5 accommodated in the PBX 3 wishes to communicate, it directly requests the PBX 3 for the destination terminal number, regardless of whether the destination terminal is within or outside the subnetwork.
The call setup processor (CP _S ) 4 that accepted this request
gives a communication logical identification number (LCN) or a destination identification label (VCI) to the calling terminal and the destination terminal, which differ depending on whether the destination terminal is in a sub-network or in the main network, and the destination terminal (TE) 5 receives this, the call setup process is completed, and then an actual communication path is set up between the terminals.

For example, if the request from terminal 5 is for data communication with another terminal in the subnetwork, as shown in the figure, CP _S 4 of PBX 3 that receives this request will provide the logical identification number LCN in the header of the received packet to the other terminal, perform the call setup process shown by the dotted line in the figure, and then set up the actual communication path P between the terminals.

If the request from the terminal 5 in the sub-network is for data communication with a terminal in the main network, as shown in the figure,
The CP _S 4 connected to the PBX 3 gives the received logical identification number LCN' of the remote terminal to the CP 2 of the main network, and after the call setup process between the terminal 5 and the PBX 3, sets up the actual communication path _PM , and the C in the main network that received the logical identification number LCN'
P2 provides the logical identification number LCN'' of the calling terminal to CP _S4 of the subnetwork, and sets up an actual communication path _P'M between the main network and the subnetwork.

Such a connection request from a terminal can be made in three ways: by directly specifying the destination terminal number; by distributing the connection request from the terminal to all terminals in the subnetwork in a broadcast format and using the compatibility check function in each terminal to specify the terminal that responds; or by a combination of the two.

The conventional method shown in Fig. 1 is flexible, but requires expensive call setup processors (CPs) in sub-networks such as residential networks.
_S ) 4, which is suitable for large companies, but is not economical for small companies or ordinary households.

Figure 2 is a block diagram showing another example of a conventional network connection system. This figure shows an example in which a subnetwork (such as a residential network) in ISDN is connected to a main network such as a public network. The main network includes a switch (SW) 21 and a call design processor (CP) 22.

The subnetwork comprises a network terminal (NT) 23 having no switching function, a plurality of nodes ( _N1 to _Nn ) 24, and terminals (TE) 25 connected to these nodes, respectively.

In this case, the switching function of the subnetwork is provided in the exchange SW of the main network, and in the transfer between a terminal of the subnetwork and the main network, as shown in the figure, an actual communication path _PM is provided on the subscriber line between the subnetwork and the main network, but even in the case of transfer between terminals within the subnetwork, an actual communication path _PS is provided on the subscriber line between the subnetwork and the main network, and is looped back at the exchange (SW) 21.

In this way, when communication between terminals in a sub-network (in-home equipment) is realized using the switching function of the main network (public network), the traffic volume in the switch (SW) 21 increases, which poses a problem that it is necessary to increase the capacity of the switch (SW) 21. Also, when a subscriber network configuration is applied in which a multiplexing concentrator is inserted between subscriber lines to efficiently accommodate multiple subscribers, it is necessary to increase the capacity of the feeder loop and to use a switching function (remote switching function) to appropriately distribute data from the feeder loop to each subscriber line.
There is a problem that it is necessary.

Next, examples of the present invention will be described.

3 is a block diagram showing a network connection system according to a first embodiment of the present invention. In the figure, a main network 30 has a switch (SW) 32 and a call setup processor (CP) 33 that controls it, and a subnetwork 31 has a plurality of terminals (or devices, hereinafter simply referred to as terminals) (TE
1 to TEn) 35 and a connection control unit (CC) 34 having a loopback function.

To briefly explain the operation, in the case of communication between terminals within the subnetwork 31, the connection control unit (CC) 34 loops back within the subnetwork without setting up an actual communication path in the main network, so that the actual communication path connecting the main network 30 and the subnetwork 31 is set only for communication between terminals within the subnetwork 31 and terminals (not shown) accommodated in the main network.

That is, in the call setup process, the call setup processor (CP) 33, based on a request from the calling terminal 35, sends a destination identification label VCI and a signal specifying whether or not to loop back within the subnetwork to the calling terminal and the other terminal, respectively.
The calling terminal assigns the LB or TH. The calling terminal sends this destination identification label VCI, information (INFO), and the loopback LB and through TH.
The packet contains a specific signal (LB/TH) that identifies the type of the packet.

When the specific signal in the packet sent from the calling terminal 5 to the connection control unit (CC) 34 is a loopback signal LB, the loopback function of the connection control unit (CC) 34 operates, and as a result, the actual communication path becomes an internal actual communication path P _S looped back within the subnetwork, and the switch (SW) 32 of the main network 30
It does not pass through.

If the specific signal in the packet sent from the calling terminal 5 to the connection control unit (CC) 34 is a through signal TH, the loopback function of the connection control unit (CC) 34 is stopped, and the external line actual communication path P _M is connected to the called terminal via the switch (SW) 32.

The loopback signal LB and the through signal TH are added to packets sent to the calling terminal by the call setup processor (CP) 33 during call setup processing. Upon receiving the loopback signal LB and the through signal TH, the calling terminal includes the loopback signal LB and the through signal TH in a communication packet or cell and sends it to the connection control unit (CC) 34.

3, in response to all communication requests from terminals (TE1 to TEn) 35, the call setup processor (CP) 33 of the main network 30 determines the connection destination and communication type of the terminals (TE1 to TEn) 35 and assigns a specific destination identification label (VCI) to the calling terminal. For example, the VCI used for communication within a subnetwork and the VCI used for communication from a subnetwork via the main network are defined as follows:

Communication within the subnetwork: VCI#1 = (1XXXXXX) Communication via the main network: VCI#0 = (0XXXXXX) where X is arbitrary (0 or 1) A terminal, for example (TE1) 35, receives a destination identification label (VCI#1) by communication with the call setup processor (CP) 33 of the main network 30.
The VCI is received from the call setup processor (CP) 33, and is transferred by adding it to the beginning of the blocked transmission information. The connection control unit (CC) 34 identifies the specific bit in the destination identification label VCI and performs connection control. For example, VCI=VCI#
If VCI=VCI#1, the connection control unit (CC) 34 returns the packet belonging to VCI#1 from the T line to the R line (see FIG. 4). Also, if VCI=VCI#0, the connection control unit (CC) 34 returns the packet belonging to VCI#1 from the T line to the R line (see FIG. 4).
0 to the main network 30.

With this configuration, the call setup process required for communication between terminals in the subnetwork is performed using the call setup processor in the main network, so that devices (such as PBXs) involved in the call setup process other than the terminals in the subnetwork are not required.
In addition, traffic due to communication within the subnetwork is returned by the connection control unit (CC) 34, so that the traffic is not transmitted to the main network.
This prevents the call from flowing into the switch (SW) 32 in the network 30, allowing for efficient operation of the main network.

Call setup processing is performed by a call setup processor (CP) 33 connected to the switch (SW) 32, but the call setup processing traffic is very small compared to the actual communication traffic, and the call setup processing traffic that increases due to communication within the subnetwork is negligible as it is only the amount of setting signals LB and TH that group destination identification labels VCI into or out of the subnetwork.

The main network and the sub-networks preferably comprise an Integrated Services Digital Network (ISDN).

FIG. 4 is a block diagram showing an example of the configuration of the connection control unit (CC) 34 shown in FIG. 3, which includes two selectors 41 and 42,
The loopback control unit 43 receives a specific signal LB or TH from the terminals (TE1 to TEn) 35.

The loopback control unit 43 receives a specific signal LB/TH from the calling terminal (TE1 to TEn) 35 via the tip line T, and controls the selectors 41 and 42 in response to this signal.

The selector 41 selects between information from the switch (SW) 32 and information from the selector 42 according to the output of the loopback control unit 43. The selector 42 outputs information from the terminals (TE1 to TEn) 35 to either the selector 41 or the tip line T which outputs to the switch (SW) 32 according to the output of the loopback control unit 43.

As an example, the specific signal LB may be set to loop back when it is "1" and to pass through when it is "0." Similarly, the specific signal TH may be set to pass through when it is "1" and to loop back when it is "0."

5A is a diagram showing the connection state of the selectors when the specific signal LB received by the loopback control unit 43 in FIG. 4 is "1". In this case, the loopback control unit 43 provides a loopback signal to the selectors 41 and 42.
In response to this loopback signal, selector 42 supplies the packet received from the calling terminal via tip line T to the input of selector 41. In response to this loopback signal, selector 41 does not select the information on ring line R from exchange SW, but instead selects and outputs the information from selector 42. As a result, an actual communication path within the subnetwork is set, and communication is performed via exchange SW.
This can be achieved without going through

5B is a diagram showing the connection state of the selectors when the specific signal LB received by the loopback control unit 43 in FIG. 4 is "0". In this case, the loopback control unit 43 provides a through signal to the selectors 41 and 42. The selector 42
In response to this through signal, the packet from the calling terminal received from the tip line T is supplied to the ring line R on the exchange SW side.
The information on the ring line R from SW is selected and output, but the information from the selector 42 is not selected. As a result, an actual communication path _PM between the sub-network and the main network is set, enabling communication.

According to another embodiment of the present invention, the loopback signal and the through signal may be logically allocated within the destination identification label, instead of being represented by one bit added to the outside of the destination identification label as described above. This embodiment is shown in Figure 6.

FIG. 6 shows a connection control unit (CC) according to another embodiment of the present invention.
1 shows the contents of the tables provided in the call setup processor (CP) 33 and the call setup processor (LB) 34. In the figure, a plurality of loopback signals LB are shown, each of which has a value of 0 to 20 (decimal number).
are stored in the table 60. For example, LB=0 to LB=5 are signals to be looped back, LB=6 to LB
=20 is defined as a signal that is passed through.
In this embodiment, the loopback signals 0 to 20 are the destination identification labels themselves. Therefore, when the destination identification label in a packet sent from a calling terminal in the subnetwork is 0 to 5, the signal is looped back to perform internal communication, and when the destination identification label is 6 to 20, the signal is passed through to perform external communication.

The contents of the table 60 can be rewritten under the control of the call setup processor (CP) 33, under the control of a terminal having a function for monitoring traffic, or under the control of the connection control unit (CC) .

In Fig. 6, the destination identification label to be looped back and the destination identification label to be passed through are fixed, but instead, in another embodiment of the present invention, the destination identification label to be looped back may be changed depending on the traffic, as shown in Fig. 7.

In the left diagram of Figure 7, in order to reduce the number of loopback calls when external line traffic (number of channels) increases, only LB = 0, LB = 1 and LB = 3 are used as destination identification labels for loopback, and LB = 4 to LB = 20 are all used for external lines and are used as through destination identification labels.

In the right diagram of Figure 7, in order to increase the number of loopback calls when internal line traffic (number of channels) increases, LB = 0 to LB = 7 are used as destination identification labels for loopback, and only LB = 8 to LB20 are used as through destination identification labels for external lines.

8 is a block diagram showing the configuration of a connection control unit (CC) according to yet another embodiment of the present invention. In this embodiment, in addition to the above-mentioned LB and TH signals, a bidirectional signal BT is used to simultaneously set up an actual communication path for both an internal line and an external line. A loopback control unit 43a controls the bidirectional signal BT.
When the selector 42a receives a signal 0x0 ...
The selector 41a receives the loopback signal and selectively sends the output signal of the selector 42a to the ring line R on the sub-network side.
It is also possible to simultaneously set up an actual communication path to a terminal in a sub-network and a terminal in a main network and transmit the same information in a broadcast format.

9 is a diagram showing a data format according to an embodiment of the present invention. In the figure, a packet has a VC in the header.
It consists of the destination identification label VCI and the data section information.
consists of 7 bits, and when the first bit is "1", it is a loopback signal LB, and the connection control unit (CC)
In addition, when the first bit of the destination identification label VCI is "0", it is a through signal TH, and the connection control unit (CC) sends the information belonging to LB to the TE side via the T line.
It controls the through of information belonging to TH to the exchange SW side.

10 is a diagram showing a data format according to another embodiment of the present invention. In this figure, the loopback signal LB is not logically included in the destination identification label VCI, but is provided separately from the destination identification label VCI.
A CRC code is added to the loopback signal LB for error correction.

The CRC code may be applied to the through signal TH or the destination identification label VCI.

11 is a block diagram showing the configuration of a connection control unit (CC) according to a further embodiment of the present invention.
In addition to selectors 41b and 42b and a loopback control unit 43b, the connection control unit (CC) 34b also includes a buffer 44 and an empty space detection unit 45. The buffer 44 is provided on the loopback path between selector 42b and selector 41b, and stores packets output for loopback from selector 41b. When the empty space detection unit 45 detects an empty space on the line from the main network, it controls selector 41b to selectively output the output of the buffer 44 to the R line on the subnetwork side.

In this way, loopback is performed only when a line from the main network becomes available, thereby enabling the line to be used efficiently, which is effective when there is a lot of traffic on the outside line.

12 is a block diagram showing the configuration of a connection control unit (CC) according to a further embodiment of the present invention. In this figure, a buffer 44 is connected to an R line from the main network and a selector
When a vacancy detector 45 detects a vacancy in the loopback output of selector 42b, it controls selector 41b to selectively output the packet in buffer 44 to the R line on the subnetwork side.

In this way, packets from the main network can be transferred to the subnetwork only when there is free space in the loopback, which is effective when there is a lot of traffic on the extension lines.

13 is a block diagram showing the configuration of a connection control unit (CC) according to a further embodiment of the present invention. In this figure, two buffers 44a and 44b are provided.
is placed between the R line from the main network and the input of the selector 41d, and the buffer 44b is placed between the loopback output of the selector 42d and the loopback input of the selector 41d. The selector control unit 45 controls the selector 41d so that the output of the buffer 44a and the output of the buffer 44b are alternately selected and taken into the selector 41d. The loopback control unit 43d and the selector 42d are shown in Figs. 4 and 5A.
The operation is the same as that of the corresponding loopback control unit and selector in Fig. 5B or 8. In this embodiment, it is preferable to target packets with a fixed frame length.

Fig. 14 is a block diagram showing the configuration of a connection control unit (CC) according to yet another embodiment of the present invention. In this figure, a buffer empty detection unit 46 is provided instead of the selector control unit 45 shown in Fig. 13. The buffer empty detection unit 46 controls the selector 41e so that when either buffer 44a or 44b becomes empty, the selector 41e takes in a packet from the other buffer. As a result, the output of the empty buffer, either buffer 44a or 44b, is not selected by the selector 41e, allowing for efficient packet transfer.

15 is a block diagram showing the configuration of a connection control unit (CC) according to still another embodiment of the present invention. In this figure, a first speed conversion unit 47a is provided between the R line on the main network side and the first input of selector 41f, and a second speed conversion unit 47b is provided between the loopback output of selector 42f and the second input of selector 41f.
A buffer 44f is provided between the output of the selector 41f and the R line on the sub-network side, and therefore serves as a buffer common to the loopback function and the line from the main network.

In FIG. 15, the loopback control unit 43f controls the selector 42 in response to a specific signal LB from the T line on the subnetwork side.
It controls only the speed converter 47a and 47b, and in the case of loopback, it sends packets from the T line on the sub-network side to the speed converter 47b, and in the case of through, it sends them to the T line on the main network side. Packets from the main network are converted into high-speed data by the speed converter 47a, selected by the selector 41f, and written at high speed into the buffer 44f. Packets for loopback output from the selector 42f are also converted into high-speed data by the speed converter 47b, selected by the selector 41f, and written at high speed into the buffer 44f. The packets are transferred to the terminals in the sub-network in the order they were written into the buffer 44f. The selector control unit 45f controls the speed converters 47a and 47b.
The selector 41f is controlled so as to alternately select the outputs of b and c. In this way, the packets are converted into high-speed data by speed conversion, stored in a buffer, and transferred in the order of storage, thereby enabling high-speed information transfer.

16A to 16C are diagrams showing packet formats when a priority signal is added to a packet according to an embodiment of the present invention.

In Fig. 16A, the packet contains information, destination identification, label VCI, and a specific signal LB indicating whether it is a loopback, as well as a priority signal PR. As shown in Fig. 1B, for example, when PR = "1", the outside line is given priority,
When PR="0", the extension line is given priority. Also, as shown in FIG. 16C, the priority may be determined according to the content of the service as a priority signal. For example, PR
When PR = "2", it is signaling for call setup and has the highest priority, when PR = "1", it is audio or video information and has the second highest priority, and when PR = "0", it is data and has the lowest priority.

FIG. 17 shows a priority control unit according to an embodiment of the present invention.
1. In this case, the loopback control unit 43g controls only the selector 42g in response to the specific signal LB from the T line on the subnetwork side, as in FIG. 1, and in the case of loopback, the packet from the T line on the subnetwork side is sent to the buffer 44.
g, and in the case of through, it is sent to the T line on the main network side.

The priority control unit 48 reads the priority signals in the packets input to the buffer 44g and outputs the packets from the buffer 44g in descending order of priority.

Fig. 18 shows an example of the contents of the buffer 44g shown in Fig. 17. As shown in the figure, the buffer 44g stores information and a priority signal PR for each packet. In this case, the information includes the information shown in Fig. 9 and a destination identification label, or the information shown in Fig. 10, a destination identification label VCI, a specific signal LB, and a CRC code, etc.

19 is a block diagram showing the configuration of a connection control unit (CC) according to yet another embodiment of the present invention. In this figure, a buffer is provided for each priority, and packet information is stored in each buffer based on the priority. That is, information with PR="1" is stored in buffer 44h, and information with PR="0" is stored in buffer 441h. Priority control unit 48h selects selector 41h based on the priority signal stored in the buffer.
In this case, the loopback control unit 43h controls the T
In response to a specific signal LB from the line, only the selector 42h is controlled, and in the case of loopback, the packet from the T line on the sub-network side is sent to the buffers 44h and 441h, and in the case of through, the packet is sent to the T line on the main network side.

20 is a block diagram showing yet another embodiment of the present invention. In the figure, a subnetwork 201 is made up of a parent subnetwork 202 and a plurality of small subnetworks #1 to #m, and each small subnetwork has a connection control unit (CC
2) 230 and multiple nodes #1 to #n. Terminals (not shown) are connected to each node. Each small subnetwork can be considered to replace each terminal in Figure 3. The parent subnetwork 202 is equipped with a connection control unit (CC1) 220 with switching functions and a call setup processor (CP) 221. A PBX is used as the call setup processor (CC1) 220. In this case, the parent subnetwork (PBX) plays the same role as the main network (public network) in the embodiment shown in Figure 3. Even a large-scale residential network may have multiple subnetworks like this. The configuration of the main network 200 is the same as the main network 30 in Figure 3.

In this way, even if the terminals in Figure 3 are replaced with small subnetworks and the network is made hierarchical, all of the above-mentioned embodiments of the present invention can be applied. That is, when a call is made from each small subnetwork, it requests a destination identification label VCI from the parent subnetwork 202, and if the destination is within the subnetwork, the call setup processor (CP) 221 in the parent subnetwork assigns the destination identification label VCI to the calling terminal and the called terminal. The destination identification label VCI is either added with the above-mentioned specific signal LB, TH, or BT, or added outside the VCI. Only when the destination is an outside line is the call setup process performed between the call setup processor (CP) 211 in the main network by signaling. The connection control unit (CC2) 230 in each small subnetwork performs a loopback or through operation in response to the specific signal from the terminal, as in the above-mentioned embodiment.

FIG. 21 is a block diagram showing yet another embodiment of the present invention.

In FIG. 21, the subnetwork 31a is configured as a ring LAN, and 36 is a network terminal (NT).
In this case, the call setup process for communication within the subnetwork and communication between the subnetwork and the main network is performed by the call setup process processor (C
When the specific signal LB given to the calling terminal is "1", the ring LAN
When the specific signal LB is "0", an actual communication path is established between the main network 30 and the subnetwork 31a, as in the previous embodiment. Furthermore, since communication within the subnetwork and communication via the main network are performed by the same call setup processor, the same protocol is possible, and therefore a gateway for protocol conversion is not required between the subnetwork 31a and the main network 30.

22 is a block diagram showing yet another embodiment of the present invention, which is expanded to a multiple subnetwork configuration. That is, even when subnetwork 31b is configured from multiple small subnetworks 31-1 and 31-2, the same operations as in all the above-mentioned embodiments are possible.

Fig. 23 is a block diagram showing the configuration of the connection control unit (CC) 34b in Fig. 22.
C) 34b includes a multiplexer (MUX) 231 and a distributor (DIS) for switching small sub-networks.
T) 232 is added to the components of FIG.

In the following embodiments, the special signal for connection control is provided in another location of the packet apart from the destination identification label VCI, or is logically included in the destination identification label, but the present invention is not limited to this. For example, the special signal may be the first bit of the logical identification number LCN in the header of the packet.
It may also be placed anywhere else in the packet.

[Industrial Applicability]

As explained above, according to the present invention, various types of flexible multipoint communications can be realized using only the physical path setting function within the subnetwork, making it possible to build a highly scalable network. Also, since there is no need to provide a call setting processing function within the subnetwork, an economical network can be built. Furthermore, traffic due to intra-subnetwork communications does not flow into the exchanges of the main network, making it possible to efficiently operate the exchanges in the main network. Furthermore, call setting processing is performed between terminals in the subnetwork and exchanges of the main network,
Since other devices within the subnetwork are not involved in the call setup process, it is possible to significantly reduce the size of each device (NT, CC, etc.). In addition, each terminal can communicate using the same protocol regardless of the communication format, such as communication within a subnetwork, communication between subnetworks, or communication via the main network.

Claims (25)

[Claims] [Claim 1] A system comprising: a main network having a switch (SW) and a call setup processor (CP) for controlling said switch; and a subnetwork connected to said main network and having a plurality of terminals and a connection control section (CC) equipped with loopback means, wherein in the case of internal line communication which is communication within said subnetwork, said call setup processor gives a first specific signal (LB) to a calling terminal to operate the loopback means of said connection control section, thereby setting up an internal line actual communication path (P _S ) between terminals in said subnetwork; in the case of external line communication which is communication between said main network and a terminal of said subnetwork, said call setup processor gives a second specific signal (TH) to a calling terminal to stop the loopback means of said connection control section, thereby setting up an external line actual communication path (P _M ) between said switch of said main network and a terminal of said subnetwork; The first specific signal and the second specific signal are sent by the call setup processor to the calling terminal, and the first or second specific signal received by the calling terminal is added to transmission information and sent out, and the connection control unit is configured to
a network connection system that determines whether or not to operate a loopback means for each piece of information in response to a specific signal from the network operator and sets an actual communication path for the extension communication and/or the outside communication. 2. The network interconnection system according to claim 1, wherein said main network and said sub-networks constitute an integrated services digital network (ISDN). 3. The network connection system according to claim 1, wherein said first specific signal and said second specific signal are each one or more fixed data groups. [Claim 4] The network connection method according to claim 1, wherein the connection control unit (CC) is provided with a rewritable table (60), the first specific signal and the second specific signal are each one or more data groups, the rewritable table stores one or more data groups corresponding to the first specific signal and the second specific signal, respectively, and the connection control unit compares the first specific signal or the second specific signal added to the information from the calling terminal with the contents of the table, thereby determining whether to operate a loopback function and setting up an actual communication path. 5. The network connection system according to claim 4, wherein said call setup processor comprises means for rewriting the contents of said table in said connection control section. 6. The network connection system according to claim 4, wherein said terminal comprises means for rewriting the contents of said table in said connection control section. [Claim 7] The connection control unit (CC) is provided with a means for monitoring the traffic between the internal line communication and the external line communication, and automatically changes the contents of the table (60) according to the traffic volume so that when the traffic volume of the internal line communication becomes greater than the traffic volume of the external line communication, the data volume of the first specific signal is increased, and when the traffic volume of the external line communication becomes greater than the traffic volume of the internal line communication, the data volume of the second specific signal is increased. 8. A third signal (B) for simultaneously setting up an actual communication path for both the intra-subnetwork communication and the communication between the main network and a terminal of the sub-network.
2. The network connection system according to claim 1, further comprising a third signal (3) for setting an actual communication path for both the internal line communication and the external line communication simultaneously. [Claim 9] A network connection method as described in claim 1, wherein the information has a destination identification label, and the first specific signal and the second specific signal are logically provided within the destination identification label. 10. The network connection system according to claim 8, wherein said third specific signal is logically provided within said destination identification label. 11. The network connection system according to claim 9, wherein error correction is performed on said first specific signal and said second specific signal. 12. The network connection system according to claim 10, wherein error correction is performed on said third specific signal. 13. The network connection system according to claim 10, wherein error correction is performed on the destination identification label. [Claim 14] The network connection method according to claim 1, wherein a buffer for storing information is provided in the loopback means of the connection control unit, and when an available line from the main network is found, the information is taken out of the buffer and transferred to the terminal. [Claim 15] A network connection method as described in claim 1, in which a buffer for storing information is provided on the line between the connection control unit and the main network, and when a vacant line is found on the loopback line, the information is taken out of the buffer and transferred to the terminal. 16. The network connection system according to claim 1, wherein a first buffer and a second buffer for storing information are provided in the loopback means of the connection control unit and in the line between the connection control unit and the main network, respectively. 17. The network connection system according to claim 16, wherein information is alternately taken out from said first buffer and said second buffer and transferred to said terminal. [Claim 18] The network connection method described in claim 16, wherein the connection control unit is provided with a buffer vacancy detection unit that detects whether the first buffer or the second buffer is vacant, and when either buffer is vacant, information is transferred to the terminal sequentially from the other buffer. [Claim 19] An inter-network connection method as described in claim 1, comprising a buffer common to the loopback means within the connection control unit and the line from the main network of the connection control unit, and a write means for writing loopback information and information from the main network into the buffer at high speed, and transferring information to the terminal in the order written into the buffer. [Claim 20] The network connection method described in claim 19, wherein priority information is added to the looped-back information and information from the main network, and the connection control unit transfers the information from the terminal and the information from the means network to the terminal in order of priority according to the priority information. 21. The network connection system according to claim 20, wherein said priority information indicates whether internal line communication has priority over external line communication. 22. The network connection system according to claim 20, wherein said priority indicates whether a communication service has priority or not depending on its contents. [Claim 23] The network connection method described in claim 22, wherein the connection control unit includes a priority control unit that writes the priority information along with the information into the buffer, and the priority control unit transfers the information to the terminal according to the priority information read from the buffer. [Claim 24] The network connection method described in claim 20, wherein the connection control unit is provided with multiple buffers for storing different priority information, the information is stored in each buffer based on the priority information, and information is transferred from each buffer to the terminal in order of priority. 25. The network connection system according to claim 1, wherein said terminals constitute a plurality of sub-networks, and said plurality of sub-networks are connected to said main network.