JPH0230248A - Communication control system - Google Patents

Abstract

PURPOSE:To improve the utilizing efficiency of a trunk by using not only a multiple address message but also a communication message between stations to recognize the existence of other station so as to reduce number of times of publication of the multiple address message. CONSTITUTION:A node of a LAN of the CSMA/CD system includes a microprocessor 11, a memory 12, a floppy disk device 13, a communication controller 14 with the LAN and a system bus 15. The said node recognizes the existence of other station by using not only the multiple address message but also a communication message between stations.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a communication control system, and in particular to C3MA/CD (
Carrier 5ense Multiple Ac
cess with Collision Detect
ion: carrier sensing multiple access/unexpected detection) system, it is possible to reduce the number of times broadcast messages are issued to notify other nodes of the existence of the own node, and to improve trunk utilization efficiency. It is related to the communication control force formula.

[Conventional technology]

Conventionally, in order to make other nodes recognize the own node, it has been common to issue broadcast messages at regular intervals.

Regarding the above-mentioned C3MA/CD type LAN, see 1, for example, the rO5I protocol picture book by Ono et al.
(published by Ohmsha).

[Problem to be solved by the invention]

When using the above method, a broadcast message is transmitted from each node, so when the number of nodes increases, collision with one broadcast message occurs during actual data transfer, and retransmission is often required. Needless to say, the transmission efficiency decreases due to collision occurrence. This will be explained in detail below.

The above-mentioned broadcast message has the message format shown in FIG.
s is all(FF)H, S source A ddr
The address of the own station is entered in ess and sent.6 Conventionally, when broadcast messages are sent at regular intervals T,
On the receiving side, the other station table within the local station is updated (see Figure 6), and when no broadcast message is received for at least 2T, the node is determined to be down.
It was configured to be deleted from the other station table.

L of C5MA/CD system configured as shown in Fig. 7
When an AN transmits a broadcast message in the manner described above, the trunk is occupied as shown in FIG. 8, for example.

When data is transmitted in this state, as shown in Figure 9, ? #A collision may occur.

In FIG. 9, it is shown that a collision occurs at times marked with 0. If a collision occurs, the colliding broadcast message and data must be retransmitted, thereby further reducing trunk utilization efficiency.

The present invention has been made in view of the above circumstances, and its purpose is to solve the above-mentioned problems in the conventional technology, reduce the number of times the above-mentioned broadcast message is issued, and improve trunk utilization efficiency. The purpose of the present invention is to provide a communication control method that makes it possible to

[Means to solve the problem]

The above object of the present invention is to
In N, this is achieved by a communication control method characterized in that not only broadcast messages but also communication messages between stations are used to recognize the presence of other stations. More specifically, the transmitting station turns on the destination flag in the other station table and transmits the message, and when the receiving station receives the message, it performs at least the same process as when receiving a broadcast message. This is achieved by a communication control method characterized in that communication messages between each station are also used to recognize the presence of other stations.

[Effect]

In the conventional system, each receiving station discards messages other than those addressed to itself or broadcast messages, whereas in the communication control system according to the present invention, messages addressed to other stations are also discarded without being discarded. , 5ourc in that packet
e Address, DestinationA dd
ress is used to recognize the existence of each node, so that both the sending and receiving sides do not send broadcast messages for a certain period of time after the last data is sent or received.

In other words, the data also has the role of a broadcast message, which reduces the number of broadcast messages sent, reduces the occurrence of collisions, and improves trunk usage efficiency. .

〔Example〕

Hereinafter, the configuration of the present invention will be explained in more detail based on examples.

L of C3MA/CD system configured as shown in Fig. 7
In the AN, take nodes A-D as an example. In addition,
For example, as shown in FIG. 2, the node includes a microprocessor (MCPU) 11. Memory 12. 70y7 video disk device (FHDC) 13. It is composed of a communication controller (LAN-CCU) 14 with the LAN, a system bus 15 connecting these, and the like.

When the above-mentioned nodes A and B transmit a broadcast message, in the conventional system, nodes C and D subsequently transmit a broadcast message as well. However, in this embodiment, if data is transmitted from node C to node D before the transmission cycle, transmitting node C resets T, and nodes A and B receive broadcast messages from nodes C and D. Perform the same processing as when received.

That is, as shown in FIGS. 1(a) and 1(b), the node C transmitting the packet sets the partner (destination) flag in the other station table to "ON" (step 51), and then sets the last packet time. Update the time in the table (step 52)
) transmit the packet (step 53).

On the other hand, when nodes A and B receive the packet (step 61), they search the tables of other stations and check whether the corresponding node exists in the table (steps 62 and 63). Add to table step 64)
and set the reception flag to roNJ (step 65).
. In addition, if it is on the table.

Directly set the reception flag to "○N" (step 65).

FIG. 3 shows an example of the contents of the other station table. As shown in the figure, the other station table is composed of a node name and a reception flag, and the reception flag corresponding to the received node name is "○NJ(1)."

Nodes A and B check whether the packet received above is addressed to their own station (step 66), and if it is addressed to their own station, they update the time in the final packet time table (step 67).
. If it is not addressed to your station, the call ends immediately.

In addition, when there is no data to be sent and a broadcast message is to be sent at a predetermined period, the difference between the time in the final packet time table and the current time is determined by the predetermined period (as shown in FIG. 4).
When it is detected that T) has been exceeded (step 71),
A circular packet for Machiki-dori is transmitted (Step 72), and the time in the final packet time table is updated (Step 73).

In the above embodiment, the case where data is transmitted from node C to node D has been described as an example, but the same applies to transmission between other nodes. For example, from node B to node A
When the data is sent to node B, the time in the last packet time table of node B is updated, and nodes C and D perform the same processing as when receiving a broadcast message from nodes A and B.

According to the above embodiment, in order to make other nodes recognize the own node, the number of broadcast messages issued at regular intervals is reduced, the number of packets flowing through the trunk within a unit time is reduced, and the occurrence of collisions is also reduced. It has the effect of An example is shown in FIG. In FIG. 10, as data is transmitted from node C to node D, nodes C and D
This example shows an example in which the transmission of broadcast messages from the network is suppressed.

It should be noted that the above-mentioned embodiment is shown as an example, and it goes without saying that the present invention should not be limited thereto.

〔Effect of the invention〕

As described above, according to the present invention, in a LAN using the C3MAlCD system, not only broadcast messages but also communication messages between each station are used to recognize the existence of other stations. It has the remarkable effect of realizing a communication flow control method that reduces the number of times broadcast messages are issued to notify other nodes of the existence of its own node, and improves trunk usage efficiency. It is.

[Brief explanation of the drawing]

1(a) and 1(b) are processing flowcharts showing the characteristic operations of the present invention, FIG. 2 is a configuration diagram of a node, FIG. 3 is a diagram showing an example of the contents of the other station table, and FIG. 4 is a diagram showing a predetermined Figure 5 is a diagram showing the format of broadcast messages; Figure 6 is a flowchart showing operations using only conventional broadcast messages; Figure 7 is C5MA/ FIG. 2 is a diagram showing an example of the configuration of a CD-based LAN. FIG. 8 is a diagram showing a general trunk occupancy state, FIG. 9 is a diagram showing the possibility of a collision occurring, and FIG. 10 is a diagram showing the effects of an embodiment of the present invention. A-E: Node, 11: Microprocessor, 12: Memory, 13: Floppy disk device, 14: Communication controller with LAN, 15 System bus, 21-23.31-35.41-43.51-53.
61-67: Processing steps. Patent applicant Rico Co., Ltd. - Figure (a) Receiving side (b) Sending side Figure (b) Receiving side (b) Sending side bacteria

Claims (2)

[Claims] (1) In a LAN using the CSMA/CD system, a communication control system characterized in that not only broadcast messages but also communication messages between stations are used to recognize the presence of other stations. (2) The transmitting station turns on the destination flag in the other station table and transmits the message, and when the receiving station receives the message, it performs at least the same process as when receiving a broadcast message. A communication control method according to claim 1, characterized in that: