JPH1168800A - Traffic controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely recover a congestion state by suppressing transmission of a data frame so as not to increase the scale of congestion even on the occurrence of congestion. SOLUTION: A network management system 5 monitors each port of a hub 3 and outputs information denoting a congestion state such as the number of communication packets for each port, the number of occurrence of collisions of packet data, and the number of abandoned packets to a traffic controller 1 as a control signal (c). When the control signal (c) from the network management system 5 exceeds each threshold level such as a communication packet number for each preset port, number of occurrence of collisions of packet data, and the number of abandoned packets, a control section (CTL) 13 discriminates that a bus 2 of an Ethernet (registered trademark) reaches a high load state to decrease the amount of data packets among the hub 3 and terminal equipments 4A, 4B, 4C and 4D.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traffic control apparatus, and more particularly to a CSMA / CD (carriersens).
e multiple access / collis
In a local area network (LAN) bus of an ion detection type, the LAN is installed between an arbitrary port of a concentrator having no flow control function and a plurality of terminal devices having no flow control function under the port, and a LAN bus. The present invention relates to a traffic control device that controls traffic.

[0002]

2. Description of the Related Art As a first example of a technique for preventing re-collision of transmission data in a conventional CSMA / CD bus type network, "CSMA / CD" disclosed in Japanese Patent Laid-Open Publication No. 1-143536.
Data transmission method in bus-type LAN ".

FIG. 3 shows a conventional CDMA / CD bus type LAN.
4 is a time chart for explaining the data transmission method in FIG. 4, and FIG. 4 is a flowchart for explaining the data transmission operation in the LAN shown in FIG. 3, and both figures are equivalent to the drawings described in the above publication.

The operation of the conventional example will be described with reference to FIGS.

[0005] After the station A301 of the IEEE802.3 CSMA / CD bus type LAN starts transmitting the transmission data frame 304, the transmission data frame 304 is transmitted to the station C3.
If the station C303 starts transmission of the transmission data frame 309 before the transmission to the transmission data
8, a collision of the transmission data frame occurs (steps S401, 404 to 409).

Due to this collision, the stations A301 and C
303 generates collision detection signals 305 and 310, respectively, and sends jam signals 306 and 311 respectively (step S411).

Next, the station B302 is connected to the jam signal detection point 316.
To detect the jam signal 311 (yes in step S401)
s), the longest data transmission operation stop interval 317 is calculated by the back-off algorithm (step S402). During this retransmission interval, there is a data transmission request, and data transmission is not performed even if the channel is not in use (step S402). Step S4
13).

At this time, the transmission data frame 313 from the station B 302 does not collide with the transmission data frames 304 and 309 from the station A 301 and the station C 303 (steps S 404 to S 409). Data frames 307 and 3
12 are transmitted without collision (step S41).
2, S413, S406-S410).

[0009] The retransmission intervals of the data frames from the station A301 and the station C303 are 3 retransmission intervals, respectively.
Shown at 14 and 315.

Next, as a second conventional example, Japanese Patent Laid-Open Publication No.
No. 3710, “Traffic control method” is mentioned. This traffic control method aims at increasing the throughput even when the network has high traffic,
In a CSMA / CD communication control device, a timer is provided which counts down by a collision detector when a random number generated by a random number generator is loaded at a fixed period and a collision occurs in a transmission line, and the timer is used when the LAN bus has high traffic. When a timeout occurs, traffic is reduced by instructing the transmitter to suppress transmission for a certain period of time to suppress transmission, and a timer value is given as a random number to avoid simultaneous transmission suppression for all communication control devices. I have.

[0011]

The first prior art C
In the data transmission system in the DMA / CD bus type LAN, even if a congestion state occurs in a network constituted by communication devices having no flow control function, the congestion state cannot be controlled. There is a problem that a function for extending the retransmission interval must be built in.

The second conventional example has the object of the present invention,
All of the configurations and operations are significantly different.

An object of the present invention is to provide a traffic control apparatus capable of suppressing data frame transmission so that the scale does not become large even when congestion occurs, and thereby reliably recovering from a congestion state. It is in.

[0014]

According to the present invention, a CSM is provided.
A traffic control device installed between an arbitrary port of a concentrator having no flow control function and a plurality of terminal devices having no flow control function under this port in an A / CD LAN bus, There is provided a traffic control device comprising a traffic limiting means for limiting transmission of a new data packet from the terminal device when data on the LAN bus is congested.

[0015] Further, the traffic restriction means may be provided by the LA
There is provided a traffic control device characterized in that the data packet between the port and the terminal device is physically disconnected by a control signal from a network management system that monitors traffic on the N bus.

Further, when the network management system monitors each port of the concentrator and outputs information indicating a congestion state for each port as the control signal, the congestion information is stored in advance for each port. Compared with the threshold, when the threshold value is exceeded, the LA
A traffic control device is provided which includes a control unit that determines that the N bus is in a high load state and performs control to reduce the data packet amount between the concentrator and each of the terminal devices.

The control unit compares the number of communication packets for each port on the LAN bus, the number of occurrences of packet data collisions, or the number of discarded packets with the respective thresholds to determine the load status of the LAN bus. Is determined, and a traffic control device characterized by determining

Further, a traffic control device characterized in that the LAN bus is an Ethernet bus is obtained.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the operation of the present invention will be described.

In the LAN bus of the CSMA / CD system of the present invention, traffic control installed between an arbitrary port of a concentrator having no flow control function and a plurality of terminal apparatuses having no flow control function under this port. The equipment is
By monitoring traffic on the LAN bus and detecting a situation where congestion is likely to occur, transmission of new data to the bus is restricted so as not to increase the amount of data being processed. Quickly resolved depending on processing capacity.

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1A is a system block diagram showing an embodiment of the present invention, FIG. 1B is a block diagram showing an example of the internal configuration of the traffic control device in FIG.
3 is a flowchart showing the flow of processing in the system shown in FIG.

Referring to FIG. 1, the system according to the present embodiment includes a traffic control device 1 and a hub 3 having no flow control function and connected to a CSMA / CD type Ethernet bus 2. It comprises a plurality of terminal devices 4A, 4B, 4C and 4D which do not have a flow control function under an arbitrary port of the concentrator 3, and a network management system 5 which monitors traffic on the Ethernet bus 2.

The traffic controller 1 has a bus interface (BIF) 11 for interfacing with the Ethernet bus 2 and a terminal interface (TIF) for interfacing with each of the terminal devices 4A, 4B, 4C and 4D.
IF) 12 and the concentrator 3 and each of the terminal devices 4A, 4B, 4C according to a control signal c from the network management system 5.
And a control unit (CTL) 13 for controlling the amount of data packets between the control unit and the 4D.

Next, the operation of this embodiment will be described in detail with reference to FIGS.

The network management system 5 includes the concentrator 3
(Step S201), and outputs information indicating the congestion state such as the number of communication packets for each port, the number of occurrences of collision (collision) of packet data, and the number of discarded packets to the traffic control device 1 as a control signal c. (Step S202).

In the traffic control device 1, the CTL 13 converts the congestion information indicated by the control signal c from the network management system 5 into a predetermined number of communication packets for each port, the number of occurrences of packet data collisions, and the number of discarded packets. If the threshold value is exceeded and the threshold value is exceeded (yes in step S203), it is determined that the Ethernet bus 2 is in a high load state, and the concentrator 3 and the terminal devices 4A, 4B, 4C and 4D are determined. Is reduced (step S204).

For example, if the terminal devices 4A and 4B
2, the data communication is simultaneously performed on the Ethernet bus 2 through the CTL 13 and the BIF 11, and the network management system 5 monitors the Ethernet bus 2 and outputs information indicating the number of collisions to the CTL 13 as a control signal c. For example, when the number of occurrences of the collision exceeds a preset threshold value, the CTL 13 determines that a high-load state is likely to be caused in a congestion state, and at this time, attempts to transmit a transmission data frame to the Ethernet bus 2. Suppress transmission from the terminal device.

As described above, as the load increases, the amount of data packets not passing through the Ethernet bus 2 increases, so that the passage of data packets exceeding a predetermined value is prevented.

Thus, in this embodiment, even if congestion occurs due to too many data packets to be communicated,
High traffic conditions can be recovered without deteriorating.

When the control signal c falls below a certain threshold value, the traffic control device 1 does not limit the amount of data packets between the concentrator 3 and each of the terminal devices 4A, 4B, 4C and 4D. .

[0032]

As described above, the present invention provides a CSMA
A traffic control device installed between an arbitrary port of a concentrator having no flow control function and a plurality of terminal devices having no flow control function under this port in a / CD LAN bus, By providing traffic restriction means for restricting transmission of a new data packet from the terminal device when the above data is congested, the traffic restriction means is provided from a network management system for monitoring traffic on a LAN bus. By physically disconnecting the data packet between the port and the terminal device by the control signal, the network management system further monitors each port of the concentrator and transmits information indicating the congestion state of each port to the control signal. When this is output as a threshold value for each port, this congestion information is set in advance. When the threshold value is exceeded and the threshold value is exceeded, it is determined that the LAN bus is in a high load state, and a control unit for performing control to reduce the amount of data packets between the concentrator and each terminal device is provided. The control unit compares the number of communication packets for each port on the LAN bus or the number of occurrences of packet data collisions or the number of discarded packets with respective thresholds to determine the load state of the LAN bus, and Since the LAN bus is an Ethernet bus, even if congestion occurs in a high traffic state, traffic control can be performed by a control signal from the network management system, so that collision of packet data can be suppressed beforehand. Has an effect.

[Brief description of the drawings]

FIG. 1A is a system block diagram illustrating an embodiment of the present invention, and FIG. 1B is a block diagram illustrating an example of an internal configuration of a traffic control device in FIG.

FIG. 2 is a flowchart showing a processing flow in the system shown in FIG. 1;

FIG. 3 is a time chart for explaining a data transmission method in a conventional CDMA / CD bus type LAN.

FIG. 4 is a flowchart for explaining a data transmission operation in the LAN shown in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Traffic control device 2 Ethernet bus 3 Concentrator (hub) 4A, 4B, 4C, 4D terminal device 5 Network management system 11 Bus interface unit (BIF) 12 Terminal interface unit (TIF) 13 Control unit (CTL) 301 Station A 302 Station B 303 Station C 304, 309, 313 Transmission data frame 305, 310 Collision detection signal 306, 311 Jam signal 307, 312 Retransmission data frame 308 Transmission data collision point 314, 315 Retransmission interval 316 Jam signal detection point 317 Longest Data transmission operation stop interval c Control signal

Claims (5)

[Claims] 1. A traffic control device installed between an arbitrary port of a concentrator having no flow control function and a plurality of terminal devices having no flow control function under the port in a CSMA / CD LAN bus. And
A traffic control device, comprising: traffic restriction means for restricting transmission of a new data packet from the terminal device when data on the LAN bus is congested. 2. The data limiter according to claim 2, wherein said traffic restricting means physically disconnects said data packet between said port and said terminal device by a control signal from a network management system for monitoring traffic on said LAN bus. The traffic control device according to claim 1, wherein 3. When the network management system monitors each port of the concentrator and outputs information indicating a congestion state of each port as the control signal, the network management system stores the congestion information for each port set in advance. When the threshold value is exceeded and the threshold value is exceeded, a control unit that determines that the LAN bus is in a high load state and performs control to reduce the data packet amount between the line concentrator and each of the terminal devices is provided. The traffic control device according to claim 2, wherein the traffic control device is provided. 4. The load state of the LAN bus by comparing the number of communication packets for each port on the LAN bus, the number of occurrences of packet data collisions or the number of discarded packets with the respective thresholds. 4. The traffic control device according to claim 3, wherein: 5. The traffic control device according to claim 1, wherein said LAN bus is an Ethernet bus.