JPS63302640A - Packet transmission control system - Google Patents

Abstract

PURPOSE:To prevent the deterioration of throughput of a whole network by obtaining a transmission right of a data packet only for a communication node which is decided to be able to receive a data packet by means of reception propriety display information. CONSTITUTION:If a prescribed condition is satisfied, a transmission reception control part 111 updates the number of idle reception buffers of a self communication node in the storage part of the number of idle reception buffers of the control packets, which is stored in a control packet storage part 1111 to a real value. Next, the data packet stored in a transmission buffer 112 is transmitted on a transmission line 2. If transmission completes, the number of the idle reception buffers of destination communication node of the transmission data packet in the storage part for the number of the reception buffers within the storage part 1111 is subtracted by one and the control packet is transmitted on the transmission line 2. On the other hand, the transmission reception control part fetches the data packet, stores it in a reception buffer 113 or 114 and erases the data packet from the transmission line 2 if the content of the destination address part in the data packet agrees with the address of the self communication node.

Description

DETAILED DESCRIPTION OF THE INVENTION 15.1 The present invention relates to a packet transmission control system, and in particular, to a method that includes a ring-shaped transmission path and a plurality of communication nodes connected to the transmission path, and that controls data transmission between the communication nodes. This invention relates to a packet transmission control method in a data transmission system in which data packets are used to perform data packets.

1. Local area networks are cited as an example of the data transmission system mentioned above (Nikkei Electronics, March 14, 1983 issue, pages 143 to 174) local
network). Such a data transmission system requires bucket transmission control to allocate data packet transmission rights to each communication unit.

Conventionally, in the token passing method used to control packet transmission in a ring-shaped local area network, a communication node captures a transmission right packet circulating on a ring-shaped transmission path and deletes it from the transmission path. However, the right to transmit data packets to any other communication node is granted.

In the conventional packet transmission 1 control method described above, when one communication node in the network obtains the transmission right, there is no guarantee that the destination communication node of the communication node that has obtained the transmission right is ready to receive the data packet. There isn't. for that,
There is a possibility that the transmitted data packet will be rejected by the destination communication node, and if reception is rejected, the source communication node should retry the transmission of the data packet in order to prevent the transmission data packet from being lost. There is a need.

As a result, when the network is under high load and data packets are concentrated on one communication node from multiple communication nodes, the above-mentioned data packet transmission retries occur frequently and the overall network throughput decreases. be.

OBJECT OF THE INVENTION Therefore, the present invention has been made to solve the drawbacks of the conventional methods, and its purpose is to prevent transmitted data packets from being rejected at the destination node and to retransmit them. Packet transmission 11Jt that prevented the decrease in overall network throughput due to trials
The objective is to provide a ll method.

■m circumferences According to the present invention, there is provided a packet transmission control method in a data transmission system in which data transmission between a plurality of communication nodes connected to a ring-shaped transmission path is performed using data packets, wherein the data packets between the communication nodes are Transmission IIJ
A packet for 1lJIj for tllll is circulated through the ring-shaped transmission path, and each of the communication nodes determines in the control packet whether or not its own communication node is in a state in which it can receive the data packet. means for writing reception permission display information to be displayed; and means for updating the reception permission display information corresponding to the destination communication node of the data packet in the control packet when the data packet is transmitted; One communication node that has received the Mtll packet transmits the data packet only to the remaining communication nodes that are determined to be able to receive the data packet based on the reception availability display information. A packet transmission control system is obtained which is characterized in that the transmission right is obtained.

K Yutaka J Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an overall diagram of a local area network which is a data transmission system according to an embodiment of the present invention. In the figure, this local area network includes a plurality of (n) communication nodes 1-1 connected to a ring-shaped transmission path 2.
．． 1-2.1-3. −・・Axis・.

1-n. Also, communication node 1-1. ...
....

1-n contains an address A1.1-n for uniquely identifying each communication node within the network. . . . , An are respectively assigned.

In this embodiment, to control the transmission of data packets containing user data, a control packet 3 having information on the number of free reception buffers of each communication node and circulating uniquely on the transmission path 2 is used. The format of this control packet 3 is shown in FIG. In the figure, control packet 3 includes a start flag section indicating the start of the packet and indicating that this packet is an IIJtIl packet, and the number of free receive buffers that stores the number of free receive buffers of each communication node in the network. It consists of a storage section and a termination flag section indicating the end of the packet. For the communication node that took in this IJ official packet 3 and deleted it from the transmission path 2, there is a communication in which the number of free receive buffers stored in the free receive buffer number storage section of the taken control packet is not 0. It is assumed that a group of nodes is given the right to transmit data packets.

FIG. 3 shows the format of data packets transferred in this network. In the figure, the data packet is
A start flag section that indicates the start of the packet and indicates that this packet is a data packet, a destination address section that stores the address of the destination communication node of this data packet, and an address that stores the address of the source communication node of this data packet. The packet is composed of a source address field, a data field that stores data to be transferred, and a termination flag field that indicates the end of the packet.

FIG. 4 is a diagram showing the internal configuration of each communication node. In the figure, a communication node 1 includes a network interface section 11 having a packet transmission/reception function, and a data processing section 12 that processes transmitted and received data packets. The network interface section 11 includes a transmission/reception control section 111 that controls transmission of packets onto the transmission path 2 and reception of packets from the transmission path 2, and a transmission buffer 112 for storing data packets to be transmitted. It has two receive buffers 113 and 114 for storing received data packets.

The data processing unit 12 has a function of generating a data packet to be transmitted and storing it in the transmission buffer 112, and a function of processing data stored in the data portion of the data packet stored in the reception buffer 113 or 114. . When the data processing unit 12 completes the received data processing, the reception buffer becomes empty and can store the next data packet.

The transmission/reception control unit 111 has a control packet storage unit 1111 for storing control packets, and has a control packet storage unit 1111 for storing control packets.
The packet is detected by examining the above signal, and the following operations are performed depending on the type and content of the detected packet and the state of the own communication node.

First, the operation of the transmission/reception control section 111 when a control packet is detected will be described. The transmission/reception control unit 111
If the following conditions (1) or (2) are satisfied,
The detected @regular packet is stored in the capture control packet storage section 1111 and deleted from the transmission path 2.

If neither of the following conditions (1) and (2) are satisfied, the transmission/reception control unit 111 allows the detected control packet to pass through as it is and sends it out onto the transmission path 2.

Condition (1): The value of the number of free receive buffers of the self-communicating node stored in the free receive buffer count storage section of the detected control packet matches the actual number of free receive buffers of the self-communicating node. do not have.

Condition (2): A data packet to be transmitted is stored in the transmission buffer 112, and the number of free reception buffers for control packets detected is that the number of free reception buffers of the destination communication node of this data packet is not 0. Indicated by the value in the storage.

The transmission/reception control unit 111 satisfies the above condition (1) or condition (2).
) is satisfied, the tiAIIl packet is stored in the control packet storage unit 111, and the control packet is deleted from the transmission path 2, and then the following operations are performed. First, if the above-mentioned condition (1) is satisfied, the transmission/reception control unit 111 selects the free reception buffer of the own communication node in the storage unit for the number of free reception buffers for l1lIlI packets stored in the control packet storage unit 1111. Update the number to the actual value. If the above condition (1) is not satisfied, this update is not performed.

Subsequently, if the above-mentioned condition (2) is satisfied, the transmission/reception control section 111 transmits the data packet stored in the transmission buffer 112 onto the transmission path 2. After sending is completed,
After updating the number of free reception buffers of the destination communication node of the sending data packet stored in the control packet free reception buffer number storage section 1111 stored in the control packet storage section 1111 to a value obtained by subtracting 1, the control The packet is sent out onto the transmission line 2 again. If the above condition (2) is not satisfied, the transmission/reception control section 111 simply sends out the control packet stored in the control packet storage section 1111 onto the transmission path 2 again.

Second, the operation of the transmission/reception control section 111 when a data packet is detected will be described. The transmission/reception control unit compares the contents of the destination address section of the detected data packet with the address of its own communication node, and if the two match,
The detected data packet is taken in and sent to the reception buffer 11.
3 or 114, whichever is vacant, and erases this data packet from the transmission path 2. This packet transmission control system guarantees that at least one of the receive buffers is empty. Further, if the destination address of the data packet and the own address do not match, the transmission/reception control unit 111 allows the detected data packet to pass through as is and sends it out onto the transmission path 2.

The data packet transmission operation in this embodiment will be explained with reference to FIG. Communication node 1-1.1-2 in FIG.
1-3 each sends one data packet to communication node 1-4.
Let's discuss the case of sending to . First, communication node 1-
It is assumed that the two receiving buffers No. 4 are both in an empty state, and the explanation will be given below in order according to the numbers in FIG.

(2) The communication node 1-1 takes in the i-control packet 31 circulating on the transmission path 2 and deletes it from the transmission path 2. It is assumed that the number of free reception buffers of the communication nodes 1-4 in the control packet 31 is two. Communication node 1-
1 subsequently transmits a data packet 32 addressed to the communication node 1-4, and then sends a control packet 33 with the number of free buffers of the communication node 1-4 changed to 1 onto the transmission path 2.

(2) Next, the communication node 1-2 takes in the control packet 33 and erases it from the transmission path. Next, communication node 1-
After transmitting the data packet 34 to the communication node 1-4, the control packet 35 with the number of free reception buffers 7 of the communication node 1-4 set to 0 is sent onto the transmission line 2.

■ Communication node 1-4 in l1lltl packet 35
Since the number of free reception buffers in communication node 1-
No. 3 cannot obtain the right to transmit data packets to the communication nodes 1-4, and the control packet 35 continues to circulate on the transmission path 2.

■ When the communication node 1-4 finishes processing the previously received data packet 32 and has one free reception buffer,
It takes in the 1IIID packet 35 circulating on the transmission path 2, erases it from the transmission path 2, and instead uses the free reception buffer of its own communication node, that is, the communication node 1-4. A control packet 36 with a number of 1 is sent onto the transmission path 2.

(2) Subsequently, the communication node 1-3 takes in the control packet 36 and erases it from the transmission path 2. Communication node 1-
3 sends the data packet 37 to the communication node 1-4, and then the free reception buffer of the communication node 1-4? A control packet 38 with a number of O is sent onto the transmission path 2. This means that all data packet transmission from each communication node has been completed. Thereafter, each time the communication node 1-4 completes the processing of the received data packets 34 and 37, it updates the number of free reception buffers 7 of its own communication node for control packets circulating on the transmission path in the same way as in the process (2). .

In this embodiment, the number of reception buffers that each communication node has is two, but the present invention can be similarly applied to a network in which each communication node has a different number of reception buffers.

■1st item and 1st item According to the present invention, data packets are configured to be transmitted only to communication nodes that are in a receivable state.
This has the effect that a transmitted data packet is not rejected by the destination communication node, and therefore a data transmission system can be realized in which the throughput of the entire network does not decrease due to transmission retries.

[Brief explanation of drawings]

FIG. 1 is an overall block diagram of a data transmission system according to an embodiment of the present invention, FIG. 2 is a diagram showing the format of a t111Ill packet used in an embodiment of the present invention, and FIG. 3 is a diagram showing a format of a t111Ill packet used in an embodiment of the present invention. FIG. 4 is a block diagram of a communication node used in the embodiment of the present invention, and FIG. 5 is a diagram illustrating the operation of the embodiment of the present invention. Explanation of symbols of main parts 1-1 to 1-4...Communication node 2...
Ring-shaped transmission line 3...Control packet 12...Data processing section

Claims (1)

[Claims] A packet transmission control method in a data transmission system in which data transmission between a plurality of communication nodes connected to a ring-shaped transmission path is performed using data packets, the method comprising a control packet for controlling data packet transmission between the communication nodes. The ring-shaped transmission path is circulated, and each of the communication nodes writes reception availability display information indicating whether or not the own communication node is in a state capable of receiving the data packet in the control packet. a means of entering,
means for updating the reception permission display information corresponding to the destination communication node of the data packet in the control packet when the data packet is transmitted; , among the remaining communication nodes, the right to transmit the data packet is obtained only for those communication nodes that are determined to be in a state capable of receiving the data packet based on the reception availability display information. Packet transmission control method.