JPH04273736A - Packet communication system and packet re-transmission equipment - Google Patents

Abstract

PURPOSE:To eliminate burden on the re-transmission of data by communication terminal equipment which fails the transmission of packetized data. CONSTITUTION:When a data packet transmitted from the communication terminal equipment 12-1 to the communication terminal equipment 12-4 is received normally, an affirmative response packet is transmitted to a transmission source. Meanwhile, when no affirmative response packet is transmitted within regulation time, or when a negative response packet is transmitted, the communication terminal equipment 12-1 transfers the data packet for which transmission fails to a re-transmission device 13. The re-transmission device 13 performs the re-transmission to the communication terminal equipment 12-4 instead of the communication terminal equipment 12-1. Such re-transmission processing is performed until the affirmative response packet can be obtained from the communication terminal equipment 12-4, however, it is judged that the re-transmission is impossible when the number of times of re-transmission exceeds the prescribed number of times, and the negative response packet is transmitted to the communication terminal equipment 12-2. When the re-transmission succeeds, the affirmative response packet is transmitted to the communication terminal equipment 12-1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to data transfer in a packet communication network, and more particularly to a packet communication system and a packet retransmission device that perform retransmission control when a destination communication device temporarily becomes unable to receive data.

0002

2. Description of the Related Art As one method of data communication, so-called packet communication, in which data is transmitted in the form of packets, is popular. In this packet communication system, each communication terminal device connected to the packet communication network is assigned a unique address.
This is incorporated into the packet as destination address information and then transmitted. On the receiving side, when the reception is performed normally, an acknowledgment packet is generated to notify that fact and is sent back to the transmission source. On the sending side,
When this acknowledgment packet is returned within a predetermined time, it is determined that the transmission has been successful, and the series of transmission processing ends. However, if the acknowledgment packet is not received normally at the destination, that is, an acknowledgment packet is returned within a predetermined time. If there is no return,
A so-called retransmission process is performed to transmit the data packet again.

[0003] Hereinafter, such retransmission processing is performed a predetermined number of times, and if an acknowledgment packet can be received from the destination terminal device during this time, the process ends normally, and if an acknowledgment packet cannot be received after retransmission a predetermined number of times. At times, it was determined that there was an abnormality and the process was interrupted.

0004

[Problems to be Solved by the Invention] As described above, in conventional packet communication systems, retransmission processing when transmission is not performed normally is performed by the communication terminal device that is the transmission source. The communication terminal device cannot perform other processing during that time, and has the drawback that its processing capabilities are significantly degraded.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a packet communication system and a packet communication system that can reliably perform communication without burdening the transmitting terminal device with this processing even if it becomes necessary to retransmit a data packet. An object of the present invention is to provide a packet retransmission device.

[0006]

[Means for Solving the Problems] The invention according to claim 1 provides: (i) a packet communication network that transmits data in a packet format; (ii) a plurality of communication terminal devices connected to this packet communication network; (iii) a retransmission device that retransmits the data packet on behalf of the communication terminal device when the data packet sent from one communication terminal device to another communication terminal device via the packet communication network is not received normally; A packet communication system is equipped with this.

[0007] In the invention described in claim 1, a packet retransmission device is provided in the packet communication network, and the data packet is retransmitted to the other party communication terminal device in place of the communication terminal device that has failed to transmit the packet data. .

In the invention as claimed in claim 2, (i) a data packet sent from one of a plurality of communication terminal devices connected to a packet communication network to another communication terminal device and not received normally is received; (ii) extracting means for extracting the destination communication terminal address from the retrieved data packet; (iii)
) sending means for sending a data packet to the communication terminal device having the communication terminal address extracted by the extraction means; and (iv) indicating normal reception within a predetermined time after sending the data packet from the sending means. (v) an acknowledgment packet sending means for sending an acknowledgment packet indicating successful retransmission to the communication terminal device of the transmission source when the acknowledgment packet is returned; and (v) within a predetermined time after sending the data packet from the sending means. (vi) when the number of retransmissions of the data packet reaches a certain number; , and a negative response packet sending means for sending a negative response packet indicating that retransmission is not possible to the communication terminal device of the transmission source.

[0009] In the invention as claimed in claim 2, when there is no notification of normal reception within a predetermined period of time after sending the data packet received from the communication terminal that failed to send it to the destination communication terminal, the data packet is re-transmitted. resend the data packet,
This will be repeated a certain number of times.

0010

EXAMPLES The present invention will be explained in detail with reference to Examples below.

FIG. 1 shows a packet communication system in one embodiment of the present invention. This system is
A plurality of communication terminal devices 1 connected to a packet communication network 11
2-1 to 12-4, etc., and a retransmission device 13. Each communication terminal device is provided with receive buffers 14-1 to 14-4, etc., for temporarily storing received data packets. The retransmission device 13 includes a receiving section 16 that receives data packets transferred via the packet communication network 11, a receiving buffer 17 that temporarily stores the received data packets, a transmitting section 18 that transmits the data packets to be retransmitted, and A retransmission control section 19 is provided to control each of these sections.

The operation of the packet communication system configured as above will be explained. Here, it is assumed that data is transferred from the communication terminal device 12-1 to the communication terminal device 12-4.

First, the transmission processing operation of the communication terminal device 12-1 on the transmission side will be explained with reference to FIG. Communication terminal device 12
A transmission control unit (not shown) of -1 adds the address and other information of the destination communication terminal device 12-4 to the data to be transmitted, creates a data packet in a predetermined format, and sends it to the packet communication network 11. (Step S101). At the same time, the transmission control unit starts monitoring a timer (not shown),
When an acknowledgment packet indicating normal reception from the communication terminal device 12-4 is received within the specified time T1 (step S102; N, step S103; Y), it is determined that the transmission has been completed normally and the transmission process is performed. end.

On the other hand, when a negative response packet indicating that the packet was not received normally is received (step S102;
Y) or the communication terminal device 12- within the specified time T1.
If an acknowledgment packet indicating normal reception cannot be received from No. 4 (step S102; N, step S10
3; N), the data packet whose transmission failed is transmitted to the retransmission device 13 (step S104). Then, it waits for an acknowledgment packet from the retransmission device 13 until the specified time T2 has elapsed. This specified time T2 is usually the time T
Set it longer than 1. During this time, communication terminal device 1
2-1 can perform other processing.

Thereafter, when a negative response packet is received from the retransmission device 13 (step S105; Y), or when an affirmative response packet cannot be received from the retransmission device 13 within the specified time T2 (step S105; N).
, step S106; N), and performs predetermined error processing (
In step S107), if the acknowledgment packet is received within the specified time T2 (step S106; Y), it is determined that the transmission has ended normally and the transmission process is ended.

Next, the operation of the retransmission device 13 will be explained with reference to FIG. The retransmission control unit 19 of the retransmission device 13 constantly inspects the reception buffer 17 (step S101), and if there is a data packet (step S102; Y), extracts the source address from this and stores it in a memory (not shown). (Step S103). Then, it adds its own address to this data packet and transmits it (step S104).
). In this case, if the data packet that the communication terminal device 12-1 failed to transmit is stored in the reception buffer 14-4, the retransmission control unit 19 extracts the address of the communication terminal device 12-1 from this data packet. , and then transmits the data packet to the communication terminal device 12-4.

Thereafter, when an acknowledgment packet is received from the communication terminal device 12-4 within the specified time T1 (step S105; Y), an acknowledgment packet is created (step S106), and the transmission source communication terminal device 12-1 (step S107). On the other hand, if an acknowledgment packet is not received from the communication terminal device 12-4 within the specified time T1 (step S105; N), the number of retransmissions performed so far is checked (step S108),
When this number is less than or equal to the predetermined number, steps S104 and S105 are repeated. When the number of retransmissions reaches a predetermined number (step S108; Y), it is determined that retransmission is impossible, and a negative response packet is created (step S108; Y).
109), and sends it to the source communication terminal device 12-1 (
Step S107).

Next, the operation of the communication terminal device 12-4 on the receiving side will be explained with reference to FIG. Communication terminal device 12-4
The transmission/reception control unit (not shown) uses its own reception buffer 14.
-4 (step S101), and if there is a data packet (step S102; Y), the data packet is taken over and the source address is extracted. Then, an acknowledgment packet is transmitted to the device at the extracted address (step S104). In this case, when the extracted source address is the communication terminal device 12-1, an acknowledgment packet is sent to this communication terminal device 12-1, and when the source address is the retransmission device 13, an acknowledgment packet is sent to the communication terminal device 12-1. is transmitted to this retransmission device 13.

[0019]

As explained above, according to the invention as set forth in claim 1, a packet retransmission device is provided in a packet communication network,
Since we decided to resend the data packet to the other communication terminal instead of the communication terminal device that failed to send the packet data, even if it is necessary to resend the data packet, this process can be performed by the sending terminal device. Communication can be performed reliably without burdening the users. Therefore, it is possible to suppress an increase in the load on each communication terminal device, and it is possible to prevent a decrease in processing efficiency.

Further, according to the invention as claimed in claim 2, since the data packet received from the communication terminal that failed in transmission is repeatedly retransmitted a certain number of times, the transmission source communication terminal device is not involved in the retransmission. This has the effect of not only eliminating the problem, but also increasing the probability of successful transmission since retransmission is attempted multiple times.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a packet communication system in one embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of a communication terminal device on the transmitting side.

FIG. 3 is a flowchart for explaining the operation of the retransmission device.

FIG. 4 is a flowchart for explaining the operation of a communication terminal device on the receiving side.

[Explanation of symbols]

11 Packet communication network 12-1 Sending side communication terminal device 12-4 Receiving side communication terminal device 13 Retransmission device 16 Receiving section 17 Receive buffer 18 Transmission section 19 Retransmission control unit

Claims (2)

[Claims] Claim 1: A packet communication network that transmits data in a packet format, a plurality of communication terminal devices connected to this packet communication network, and a communication terminal device that transmits data in a packet format from one communication terminal device to another communication terminal device via the packet communication network. 1. A packet communication system comprising: a retransmission device that retransmits a transmitted data packet in place of the one communication terminal device when the transmitted data packet is not properly received. 2. A reception buffer that receives and stores data packets sent from one communication terminal device to another communication terminal device out of a plurality of communication terminal devices connected to a packet communication network and not received normally. , an extraction means for extracting a destination communication terminal address from the retrieved data packet; a sending means for sending the data packet to a communication terminal device having a communication terminal address extracted by the extraction means; Acknowledgment packet sending means for sending an acknowledgment packet indicating successful retransmission to the one communication terminal device when an acknowledgment packet indicating normal reception is returned within a predetermined time after sending the data packet from the means; a retransmission instruction for instructing the sending means to retransmit the data packet in the reception buffer when an acknowledgment packet indicating normal reception is not returned within a predetermined time after the sending means sends the data packet; and negative response packet sending means for sending a negative response packet indicating that retransmission is impossible to the one communication terminal device when the number of retransmissions of the data packet reaches a certain number. Retransmission device.