JPH07143181A - Inter-network connector - Google Patents

Abstract

PURPOSE:To provide an inter-network connector in which a broad range network capable of large capacity multiple address communication is built up by using a digital communication satellite and a digital ground line and a logically 2-way communication channel making possible error retransmission control is realized. CONSTITUTION:The inter-network connector interposed among a digital communication satellite and a digital ground line being digital transmission line connecting in premises networks and the in-premises network is provided with a sender side connector 1 and receiver side connectors 2, 2... selecting either of the digital communication satellite and the digital ground line as digital transmission line according to a predetermined condition based on the information quality of data to be sent, the type of multiple address communication or 1:1 communication and the utilizing state of lines.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention establishes a private wide area network by connecting a plurality of local networks by using a digital communication satellite capable of large-capacity broadcast communication and a bidirectional digital ground line. The present invention relates to an inter-network connection device suitable for use in.

[0002]

2. Description of the Related Art As is well known, a digital ground line is widely used as a digital communication path for connecting local networks. In general, this digital terrestrial line is suitable for one-to-one bidirectional communication between local networks.
On the other hand, connecting the sending terminal and the receiving terminal directly via satellite,
Digital satellite communication is known in which all terminals directly communicate with communication satellites. This digital satellite communication is an advantageous method for economically performing digital transmission of broadcast information between one or a small number of transmitting terminals and a large number of receiving terminals.

[0003]

By the way, in the above-mentioned digital terrestrial line, the construction cost and the communication cost are increased in a usage mode in which large-scale broadcast communication frequently occurs such as broadcast type image transmission. It has a drawback that it is not suitable for such usage. On the other hand, in the digital satellite communication, as described above, since all terminals directly communicate with the communication satellite, another device is required to perform communication on the premises, which is economically problematic. Was becoming.
In addition, one-way communication, such as broadcast communication using a digital satellite, which cannot perform communication in the ascending direction (that is, the direction from the receiving side to the transmitting side) can be applied, such as interactive application is not possible. There was a problem that the application was limited. Further, considering that the digital communication satellite is used as an economical broadcast communication medium and the digital land line is used as the communication medium in the ascending direction, these two transmission media are treated as logically different communication paths. Therefore, there is a problem that communication control such as error resending control cannot be performed.

The present invention has been made under such a background, and a wide-area network capable of large-capacity broadcast communication is constructed by using a digital communication satellite and a digital ground line.
Moreover, it is an object of the present invention to provide an inter-network connection device that can realize a logically bidirectional communication path that enables error resending control and the like.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a connection between a digital communication satellite and a digital terrestrial circuit, each of which is a digital transmission line connecting between private networks, and the private network. In the inter-network connection device installed in the network, the digital communication as the digital transmission line is performed according to a predetermined condition based on the information amount of data to be transmitted, the type of broadcast or one-to-one communication, and the use status of the line. It is characterized by having a switching means for selecting either the satellite or the digital ground line.

[0006]

According to the present invention, the switching means performs digital communication as a digital transmission line in accordance with predetermined conditions based on the information amount of data to be transmitted, the type of broadcast or one-to-one communication, and the use status of the line. Select either satellite or digital ground line. As a result, the digital communication satellite and the digital terrestrial line can be optimally used according to the mode of communication without being logically treated as separate communication paths, so that large-capacity broadcast transmission can be performed efficiently. In addition to this, bidirectional communication such as error resending control can be performed.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention. In the figure, the transmission side connection device (central office GW) 1 is connected to a local network (central office LAN) connected to a large capacity information source such as a digital video server. On the other hand, each receiving side connection device (branch GW)
2, 2, ... Are each connected to a local network (branch LAN) to which a plurality of video terminals are connected. Then, from the transmission side connection device 1 to each reception side connection device 2, 2, ..., Broadcast communication of video information is performed via a digital communication satellite. Further, the transmitting side connecting device 1 and the receiving side connecting devices 2, 2, ...
SDN), and two-way communication of control information and the like is performed.

Further, as shown in FIG. 2, each connection device 1,
Since 2, 2, ... Operate as IP routers (information path selection devices) between the internal networks, the transport layer is aware of whether the transmission path is a digital communication satellite or a digital ground line. It can be used without being used.

Further, a general structure of a packet handled as a communication unit in this embodiment is as shown in FIG. That is, the packet includes a packet header portion P1 and a data portion P2, and the packet header portion P1 further includes information such as a source address P1a, a destination address P1b, and a packet length P1c.

Next, the operation of this embodiment will be described in detail with reference to the detailed diagram shown in FIG. First, packets from the digital terrestrial line and the ditch network are input to the transmission side connection device 1. These packets are input to the packet switch 13 via the private network interface 11 and the land line interface 12, respectively. When the destination address of the input packet indicates the private network, the packet switch 13 sends the packet to the private network buffer 1
Send to 9. If the destination address of the input packet indicates a broadcast over a plurality of private networks including the receiving side, the packet is copied and sent to the private network buffer 19 and the order storage signal adding unit 14. send. In addition, in the case other than the above, that is, when the destination address simply indicates the receiving side private network, the input packet is sent to the order preservation signal adding unit 14.

Then, the packet sent to the private network buffer 19 is sent to the private network of the transmitting side via the private network interface 16. On the other hand, a serial number for ordering each packet is added to the packets sent to the order storage signal adding unit 14. For example, as shown in FIG. 5, this serial number is added in the form of expanding the packet header P1 (P1d in the figure). The serial number is, for example, 8-bit natural binary data, and is a number that is incremented by 1 each time a packet is input to the order storage signal adding unit 14. When the serial number exceeds the number that can be expressed by 8 bits, the value is returned to "0". If it is not necessary to order the packets, the order storage signal adding unit 14 and the order reproducing unit 33 (described later) output the packets without processing them. In the following description, it is assumed that a serial number is added to order the packets.

The packet to which the sequence number is added by the order preservation signal adding section 14 is sent to the transmission path switch 15 which selects the transmission path through which the packet should be transmitted. Here, the operation of the transmission line switch 15 will be described with reference to the flowchart shown in FIG. First, the transmission path switch 15 first inputs one packet (step S1), and then judges from the destination address of the packet whether or not the packet is a broadcast (step S2). Here, if it is the same country, the packet is output to the ground line (step S
6). On the other hand, if the person is not a sibling, the following calculation is performed in step S3.

That is, the amount of untransmitted data in the digital satellite side buffer is Bs, the amount of untransmitted data in the terrestrial line side buffer is Bi, the transmission capacity and transmission delay in the digital satellite are Rs and Ts, respectively, and the transmission capacity in the terrestrial line. , And the transmission delays Ri and Ti, and the data amount of the input packet P, the transmission time Ss, Si to the receiving side when the input packet is transmitted using the digital satellite and the ground line, respectively. Is the following formula (1),
Given by (2). When using a digital satellite: Ss = (P + Bs) / Rs + Ts (1) When using a land line: Si = (P + Bi) / Ri + Ti (2)

In step S3, the calculation using the above equations (1) and (2) is performed to calculate the transmission time for each of the digital satellite and the ground line.

Then, in step S4, it is determined whether or not Ss <Si. Here, this judgment result is "Ye
s ”, that is, when it is determined that the transmission time Ss by the digital satellite is shorter than the transmission time by the ground line Si, the packet is selected to be transmitted by the digital satellite. On the other hand, if the determination result in step S4 is “No”, that is, if it is determined that the transmission time Ss by the digital satellite is longer than the transmission time by the ground line Si, the packet is selected to be transmitted by the ground line. . Thus, the transmission line switch 15
Selects unconditionally a digital satellite in the case of broadcast, but also in cases other than the broadcast, it is possible to perform optimal routing by selecting a digital satellite or a terrestrial line according to the transmission time. it can.

The packet sent to either the digital satellite or the digital terrestrial line is sent to the order reproducing unit 33 via the receiving side digital satellite interface 31 or the terrestrial line interface 32.
The sequence reproducing unit 33 sends the plurality of input packets to the packet switch 34 in the order of the sequence numbers. At this time, the order reproducing unit 33 deletes the serial number from each packet and restores the original packet format.

Then, the packet switch 34 takes in the packet sent from the order reproducing unit 33 and the packet input from the receiving side private network via the private network interface 36, and based on these destination addresses,
The packet is sent to the ground line buffer 35 or the private network buffer 37. These packets are sent to their respective destinations via the terrestrial line interface 36 or the private network interface 38.

As described above, according to this embodiment, the digital communication satellite or the digital communication satellite is used depending on whether or not the broadcast communication is used, the data amount of the packet, the transmission capacity of each transmission line, the transmission delay, and the like. One of the terrestrial lines is optimally selected, and efficient bidirectional communication of control information such as large-capacity broadcast transmission and error resending control is performed.

[0019]

As described above, according to the present invention, a digital communication satellite, which is a one-way broadcast type digital transmission line, and a digital terrestrial line, which is a bidirectional one-to-one type digital transmission line, are combined. Can be optimally used according to the mode of communication, so that large-capacity broadcast transmission can be efficiently performed, and bidirectional communication such as error resending control can also be performed. In addition, in a wide area network to which the present invention is applied, since each terminal connected to the network can perform terminal-to-terminal communication with other terminals in the same manner as a normal private network, it is created for the private network. Existing applications can be used as they are.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a network of the embodiment as seen from a transport layer.

FIG. 3 is a diagram showing a general configuration of a packet handled as a communication unit in the embodiment.

FIG. 4 is a block diagram showing a detailed configuration of the embodiment.

FIG. 5 is a diagram showing a configuration example of a packet to which a serial number is added in the embodiment.

FIG. 6 is a flowchart showing an operation of the transmission line switch according to the embodiment.

[Explanation of symbols]

 1 connection device on transmission side 2 connection device on reception side 11, 16, 36, 38 private network interface 12, 18, 32 terrestrial line interface 13, 34 packet switch 14 sequence preservation signal addition unit 15 transmission line switch 17, 31 digital satellite interface 19 , 37 Private network buffer 20 Digital satellite buffer 21, 35 Terrestrial line buffer 33 Sequence playback unit

Claims (1)

[Claims] 1. Information on data to be transmitted in an inter-network connection device interposed between a digital communication satellite and a digital terrestrial line, each of which serves as a digital transmission line connecting between private networks, and the private network. A switching means for selecting either the digital communication satellite or the digital ground line as the digital transmission line in accordance with a predetermined condition based on the amount, the broadcast or the type of one-to-one communication, and the use condition of the line. An inter-network connection device characterized by.