JPH04355529A - Lan communication controller - Google Patents

Abstract

PURPOSE:To efficiently build up the LAN system by suppressing retransmission and collision on a LAN transmission line considerably so as to remarkably improve the deterioration in the throughput. CONSTITUTION:A LAN communication controller 3 uses a transmission reception section 104 to implement transmission reception with other node connecting to a LAN transmission line 1 via a transceiver cable 2. A carrier detection section 100 detects a carrier generated on the LAN transmission line 1 and a carrier production number count section 101 counts number of times of production of the detected carrier. When the count exceeds a prescribed value, a timer set signal/transmission inhibit signal output section 102 generates a timer set signal to start a timer 103 and also generates a transmission inhibit signal for transmission suppression of the transmission reception section 104. The production period of the transmission inhibit signal is set by the timer 103.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to a LAN communication control device, and in particular to CSMA (Carrier Sense).
Multiple Access)/CD(Coll
The present invention relates to a LAN communication control device that is connected to a LAN of the LAN system and performs transmission and reception.

0002

2. Description of the Related Art A conventional CSMA/CD type LAN communication control device constantly monitors carriers on a LAN line and does not transmit while a carrier is present on the line. It also monitors jam signals sent when a collision occurs, and does not transmit them for a certain period of time after a collision occurs.

0003

This conventional LAN communication control device allows transmission except when there is no carrier or jam signal on the LAN line.

[0004] For this reason, when the traffic on the line increases, collisions occur frequently, resulting in an increase in the number of retransmitted frames, and collisions are also more likely to occur. This inevitably reduces the throughput of data flowing on the line, and the LAN system It has the disadvantage of hindering efficient construction.

The aim of the present invention is to eliminate the above-mentioned drawbacks and to
It is an object of the present invention to provide a LAN communication control device that significantly suppresses retransmissions and collisions on an AN line, and significantly suppresses a decrease in throughput, thereby enabling efficient construction of a LAN system.

[0006]

[Means for Solving the Problems] A LAN communication control device of the present invention is connected to a CSMA/CD type LAN.
a carrier detection unit that detects a carrier on a transmission path; a carrier occurrence count unit that counts the number of carrier occurrences within a certain period of time detected by the carrier detection unit; and a carrier occurrence count unit that counts the number of carrier occurrences counted by the carrier occurrence count unit. a timer set signal/transmission prohibition signal output section that outputs a timer set signal and a transmission prohibition signal when a predetermined value is exceeded; a timer that is activated by the timer set signal and sets the sending time of the transmission prohibition signal; and a timer that sets the sending time of the transmission prohibition signal; and a transmitting/receiving unit that suppresses transmission on the LAN transmission path during the period when the signal is being received.

[0007] Furthermore, the LAN communication control device of the present invention
a collision detection unit that is connected to an SMA/CD type LAN and detects a collision on a transmission path of the LAN; a collision occurrence count unit that counts the number of collisions within a certain period of time detected by the collision detection unit; a timer set signal/transmission prohibition signal output section that outputs a timer set signal and a transmission prohibition signal when the number of collisions counted by the frequency counting section exceeds a predetermined value; and a timer set signal/transmission prohibition signal output section that is activated by the timer set signal and sends out the transmission prohibition signal. A timer that sets the time and a period L during which the transmission prohibition signal is received.
The transmitter/receiver section suppresses transmission on the AN transmission path.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

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

The configuration of the embodiment shown in FIG. 1 includes a LAN transmission line 1 using a coaxial cable, a transceiver cable 2 connected to the LAN transmission line 1 for communicating with other nodes, and a transceiver cable 2 connected to the transceiver cable 2. It consists of a LAN communication control device 3.

The LAN communication control device 3 also includes a carrier detection section 100 that detects carriers on the LAN transmission line 1 via the transceiver cable 3, a carrier occurrence count section 101 that counts the number of carrier occurrences,
A timer set signal/transmission prohibition signal output unit 102 generates a timer set signal and a transmission prohibition signal for a predetermined period when the number of carrier occurrences exceeds a predetermined constant number, and a timer set signal/transmission prohibition signal output unit 102 that generates a timer set signal and a transmission prohibition signal for a predetermined period; It comprises a timer 103 that clocks up and sets the generation period of the transmission prohibition signal, and a transmitting/receiving section 104 that suppresses transmission to other nodes on the LAN transmission line 1 by the transmission prohibition signal.

Next, the operation of the first embodiment shown in FIG. 1 will be explained.

During transmission and reception, the carrier detection unit 100 always detects carriers on the LAN transmission line 1 through the transceiver cable 2.
The carrier occurrence count section 101 counts the number of times detected by the carrier detection section 100 at regular intervals. When the count value exceeds a predetermined value, the timer set signal/transmission prohibition signal output section 102 sets timer 1 according to the output signal from the carrier generation number counting section 101.
At the same time as outputting a timer set signal to 03, a transmission prohibition signal is output to transmitting/receiving section 104.

The transmitting/receiving section 4 is inhibited from transmitting while the transmission prohibition signal is provided. A transmission prohibition signal is provided to the timer 103 for a preset time, and after the set time has elapsed, the state returns to a state in which transmission and reception are possible.

FIG. 2 is a block diagram showing the configuration of a second embodiment of the present invention.

The embodiment shown in FIG. 2 has a LAN transmission line 1,
It consists of a transceiver cable 2 and a LAN communication control device 4.

The LAN communication control device 4 also includes a collision detection section 105, a collision occurrence count section 106, a timer set signal 102, a timer 103, and a transmitting/receiving section 104.
It consists of:

Among these configurations, a collision detection section 105 and a collision occurrence count section 106 are different from those of the first embodiment shown in FIG.
In the first embodiment, the presence of a carrier on the LAN transmission line 1 is detected, whereas in the second embodiment, collisions on the LAN transmission line 1 are detected, and when the number of collisions exceeds a predetermined value, A timer set signal and a transmission prohibition signal are generated.

[0019] In this way, frequent occurrence of retransmissions or collisions is suppressed, and a drop in throughput of the LAN line is significantly suppressed, making it possible to construct an efficient LAN system.

[0020]

Effects of the Invention As explained above, the present invention monitors carrier occurrence or collision occurrence on a LAN line, and when the number of occurrences within a certain period of time exceeds a predetermined value, transmission of subsequent frames is controlled to a certain level. By stopping time,
This has the effect of significantly suppressing the frequent occurrence of retransmissions and collisions due to high LAN loads, significantly suppressing the decline in LAN line throughput, and making it possible to construct an efficient LAN system.

[Brief explanation of the drawing]

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

FIG. 2 is a block diagram showing the configuration of a second embodiment of the present invention.

[Explanation of symbols]

1 LAN transmission path 2 Transceiver cables 3, 4 LAN communication control device 100 Carrier detection section 101 Carrier generation number counting section 102
Timer set signal/transmission prohibition signal output section 103
Timer 104 Transmitter/receiver 105 Collision detector

Claims (2)

[Claims] 1. A carrier detection section that is connected to a CSMA/CD type LAN and detects a carrier on a transmission path of the LAN, and a carrier occurrence count section that counts the number of carrier occurrences within a certain period of time detected by the carrier detection section. a timer set signal/transmission prohibition signal output section that outputs a timer set signal and a transmission prohibition signal when the number of carrier occurrences counted by the carrier occurrence count section exceeds a predetermined value; A timer that sets the sending time of the transmission prohibition signal and a LAN during which the transmission prohibition signal is received.
A LAN communication control device comprising: a transmitting/receiving unit that suppresses transmission over a transmission path. 2. A collision detection unit that is connected to a CSMA/CD type LAN and detects a collision on a transmission path of the LAN, and a collision occurrence count unit that counts the number of collisions detected by the collision detection unit within a certain period of time. a timer set signal/transmission prohibition signal output unit that outputs a timer set signal and a transmission prohibition signal when the number of collision occurrences counted by the collision occurrence count unit exceeds a predetermined value;
A LAN characterized by comprising: a timer that is activated by the timer set signal and sets the transmission time of the transmission prohibition signal; and a transmitter/receiver unit that inhibits transmission on a transmission path of the LAN while receiving the transmission prohibition signal. Communication control device.