JPH01120929A - Packet information miss preventing system - Google Patents

Abstract

PURPOSE:To prevent missing of packet information by resending a packet whose transmission is finished just before the reception of a link resetting signal when the link resetting signal sent to an opposite packet terminal is received by the opposite packet terminal at the changeover of a receiver. CONSTITUTION:If a fault takes place in a receiver 10 at an opposite packet terminal equipment 9 and the receiver is switched into a receiver 11, a link resetting signal is sent. A communication control section 4 sends a link resetting signal to reset the link and gives it to a retransmission processing section 2'. The retransmission processing section 2' commands the transmission of a preceding packet to a data transmission processing section 3, then the data transmission processing section 3 retransmits a packet whose transmission is finished just before the reception of the link resetting signal. Thus, the missing of packet information at the changeover is prevented.

Description

[Detailed Description of the Invention] [Summary] Regarding a packet information loss prevention method for a packet terminal that transmits information via a packet switching network, the present invention relates to a packet information loss prevention method that can prevent packet information loss in an inexpensive manner when switching receivers. In order to provide a dropout prevention method, the sending device of the other party's packet terminal is provided with a retransmission processing means that retransmits the previously transmitted packet when receiving a link resetting signal.

[Industrial application field]

The present invention relates to an improvement in a packet information loss prevention method for packet terminals that transmit information via a packet switching network in a packet switching system.

For packet terminals that have a working and a backup receiving device, and when the current device fails, it switches to the backup device and sends a link reconfiguration signal to the other packet terminal. What can be done at low cost to prevent packet information loss during switching? is desirable.

[Conventional technology]

Using an example of a packet switching system, we will explain how when switching the receiving device of a packet terminal from active to standby, the receiving device takes time to process and output packets, causing packet information to be lost. do.

Figure 5 is a block diagram of an example packet switching system, Figure 6 is a sequence diagram of signals during switching/link resetting in Figure 5, and Figure 7 is the packet transmission sequence when switching the receiving device in Figure 5. It is a diagram.

A packet as shown in FIG. 7(A) transmitted from the transmitting device 1' of the packet terminal 5 in FIG. The data is sent as shown in FIG. 7(B), and is processed and outputted as shown in FIG. 7(C) with a delay corresponding to the amount of processing.

For example, when a failure occurs in the receiving device 10 at the time of completion of the B transmission in FIG. 7(A), the control unit 12 in FIG.
1 to receive it.

When this switching is performed, as shown in FIG. 6, the receiving device 11 sends a disconnection signal to the packet switch 8, and when a reception response is returned from the packet switch 8, it sends a restart request signal.

Then, the packet switch 8 tells the packet switch 7,
By sending a reset request signal, the packet switch 7 instructs the transmitter 1' to reset.

Then, the transmitter 1' resets and sends a reset confirmation signal to the packet switch 7, and the packet switch 7 sends a reset confirmation signal to the packet switch 8.

Then, the packet switch 8 sends a restart confirmation signal to the receiving device 11, which means that the link has been re-established.

Therefore, the transmitter 1' transmits the next packet C in FIG.
) as shown below.

At the time of this failure, the output of the receiving device IO is delayed by the processing time, so the information of packet B is not output as shown in FIG. 7(C), but the information of packet C is not output as shown in FIG. 7(D).
As shown in FIG.
It is output as shown in E).

Therefore, the output from the receiving device 10.11 is shown in Fig. 7 (F).
The information in packet B is lost as shown in FIG.

In order to prevent this omission, conventionally, as shown in FIG.
) The packets from the transmitting device 1° shown in (B) (D)
The signals are received simultaneously by the receiving devices 10' and 11' as shown in FIG. I am trying to output it.

In this case, when transmitting device 1' outputs packet B and receiving device 10 processes packet B and has not yet output it, a failure occurs, and the switch is switched to receiving device 11', and transmitting device 10 Even if packet C is sent from ', packet C is
-B is output from the receiving device 11'', so the output from the receiving devices 10' and 11' is (F
), packet B with no missing information is output.

[Problem that the invention seeks to solve]

However, in the conventional method, the data link connection part 1
4.15 and the data link 13 to perform synchronization and simultaneous reception, there is a problem in that it is expensive.

An object of the present invention is to provide a packet information loss prevention method that can prevent packet information loss using an inexpensive method when switching receivers.

[Means for solving problems]

FIG. 1 is a block diagram of the principle of the present invention.

The present invention focuses on sending a link resetting signal to the other packet terminal when switching the receiving device, and as shown in FIG. The configuration includes a retransmission processing means 2 for retransmitting the received packet.

[For production]

According to the present invention, when the other packet terminal receives the link resetting signal sent to the other packet terminal when switching the receiving device, the transmitting device 1 completes the transmission immediately before receiving the link resetting signal based on the instruction from the retransmission processing means 2. retransmit the packet.

Therefore, as shown in FIG. 7(C) described earlier, even if the receiving device 10 is switched before completing the processing for the packet B, the switched receiver ε device 11 will receive the packet B. Since the packet information is received, processed, and output, no packet information is lost.

In this case, if the link reconfiguration signal is simply received, it is sufficient to provide a retransmission processing means 2 that retransmits the packet that was transmitted immediately before receiving the link reconfiguration signal. It can be made cheaper than the method using .

〔Example〕

An embodiment of the present invention will be described below with reference to the accompanying drawings.

Fig. 2 is a block diagram of the transmitting unit of the packet terminal according to the embodiment of the present invention, Fig. 3 is a sequence diagram of signals during switching/link resetting in Fig. 2, and Fig. 4 is the receiving device switching shown in Fig. 2. FIG. 3 is a packet transmission sequence diagram at

In the case of the present invention, a retransmission processing unit 2° as shown in FIG. 2 is provided in the transmitting device portion of the packet terminal 5 of the packet switching system shown in FIG.

To explain the operation of the transmitter shown in FIG.
The data processing unit 3 divides the input data into fixed lengths, adds header information to form packets, and transmits the packets via the communication control unit 4.

When a packet arrives at the destination packet terminal 9 in FIG.
As shown in FIG. 3, a packet reception signal is sent, and the communication control section 4 receives it and transmits the next packet.

When a failure occurs in the receiving device 10 at the destination packet terminal 9 in FIG. 5 and the device is switched to the receiving device 11, a link resetting signal (reset signal) is sent as shown in FIG. instructions) are sent.

Then, as shown in FIG. 3, the communication control unit 4 transmits a signal indicating that the link has been reset (reset confirmation), causes the link to be reset, and sends it to the retransmission processing unit 2°.

The retransmission processing unit 2° instructs the data transmission processing unit 3 to transmit the previous packet. Then, the data transmission processing unit 3 retransmits the packet that was transmitted immediately before receiving the link resetting signal.

This state is shown in FIG. 4. When the receiving device 10 becomes faulty and is switched to the receiving device 11 at the time when the transmission of packet B is completed, the received value flO is changed to the information of packet B as shown in FIG. 4(C). Although it has not been processed and output, when the link reconfiguration signal is sent to the transmitting device 1 and the link is reconfigured, the transmitting device 1 sends the retransmitted packet B of packet B as shown in FIG. 4(A). Send ゛.

Then, the receiving device 11 receives the packet B'' as shown in FIG. 4(D), and receives the packet L- as shown in FIG. 4(E).
B' is processed and output.

Therefore, the output from the receiving device 10.11 is shown in Fig. 4 (F).
As shown in the following, there will be no words that will be missing.

In this case, when the transmitter receives a signal from the communication control unit 4 indicating that the link has been reset (reset confirmation), the receiver can Since packet loss at the time of switching can be eliminated, packet loss can be prevented with a cheaper configuration than in conventional systems using data links and data link connections.

〔Effect of the invention〕

As explained in detail above, according to the present invention, the present invention is applicable to the present invention.

A packet terminal that has a backup receiving device, switches to the backup when a failure occurs in the current device, and sends a link resetting signal to the other packet terminal has the effect of preventing loss of packet information at the time of switching in an inexpensive manner.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a block diagram of a transmitter of a packet terminal according to an embodiment of the present invention, and FIG. 3 is a sequence diagram of signals during switching and link reconfiguration in FIG. 2. Figure 4 is a packet transmission sequence diagram when switching the receiving device in Figure 2. Figure 5 is a block diagram of an example of a packet switching system. Figure 6 is the signal sequence when switching and link reconfiguration in Figure 5. Figure 7 is a packet transmission sequence diagram when switching the receiving device in Figure 5, Figure 8 is a block diagram of the receiving section of a conventional packet terminal, and Figure 9 is a packet transmission sequence diagram when switching the receiving device in Figure 8. FIG. 3 is a transmission sequence diagram. In the figure, 1.1' is a transmitting device, 2 is a retransmission processing means, 2' is a retransmission processing section, 3 is a data transmission processing section, 4 is a communication control section, 5.9 is a packet terminal, 6 is a packet switching network, 7.8 is a packet switch, 10.11.10°, 11' is a receiving device, 12 is a control section, 13 is a data link, and 14.15 is a data link connection section. After Bathing Sun and Moon's Blade Layer Figure O.72 Diagram 1

Claims (1)

[Scope of Claims] In a packet terminal that has a working and a backup receiving device, and when the current device becomes a failure, it switches to the backup device and sends a link resetting signal to the destination packet terminal, which provides a link to the transmitting device (1) of the destination packet terminal. A method for preventing packet information loss, characterized in that a retransmission processing means (2) is provided for retransmitting a packet that has been transmitted immediately before when a reconfiguration signal is received.