JPH07107099A - Lan system - Google Patents

Abstract

PURPOSE:To prevent the decline of throughput due to the frequent occurance of collision at the time of high traffic and to communicate sound and pictures, etc., requiring to be in real time on a LAN relating to a CSMA/CD system which is one of the access control systems of the LAN. CONSTITUTION:A LAN controller 1 and plural hub devices 2 are connected to two buses #0 and #1 and plural terminal equipments 4 connected to the plural hub devices 2 mutually perform communication by the CSMA/CD system under the control of the LAN controller 1. In this LAN system, the LAN controller 1 divides the hub devices 2 into plural groups and allocates the time for using one bus #0 to the respective groups in a time-division manner. Then, transmission through the bus #0 is performed by time group within the allocated time and data transmitted from the allocated group are transmitted through the other bus #1 to the remaining groups after a pseudo collision state is attained and the transmission 15 stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carrier detection multiple access system with a collision detection function (CSMA / CD system) which is one of LAN access control systems. CSMA / CD (Ca
rrier SenseMultiple Access With Collision Detectio
n) method is a LAN transmission medium access control (MAC) method for sharing communication with a plurality of stations for communication,
Standardized by the American Institute of Electronics Engineers.

Recently, with the spread of personal computer communication in Japan, personal computers communicate with each other using dedicated lines, and a specific personal computer (file server, printer server, etc.) is shared by a plurality of personal computers. In many cases, the terminals are connected to each other via a coaxial cable, a pair wire, or the like to improve the efficiency of work.

[0003]

2. Description of the Related Art FIG. 5 shows an example of a LAN network configuration. In the figure, 31 is a terminator (T), 32 is a transceiver (TR), 33 is a terminal device, 34 is a hub device, 35 is a LAN connection device (repeater, bridge, router, etc.), 36 is a coaxial cable, and 37 is a pair. Shows a line. Coaxial cable 36 is 10BASE
2/5 interface (length of 185m / 500m at 10Mbps speed
), The pair line 37 has a 10BASE-T interface (twin pair line 100 m in length at a speed of 10 Mbps).

LAN of 10BASE2 / 5 is terminator (T)
Transceiver on coaxial cable 36 terminated at both ends by
A plurality of terminal devices 33, a hub device 34, an inter-LAN connecting device 35, etc. are connected by 32. The hap device 34 connects the plurality of terminal devices 33 in a star state by a pair line,
The LAN-to-LAN connection device 35 is a bridge or router that reproduces / relays signals and identifies a repeater that extends the transmission distance, identifies the destination of transmission data, and does not propagate data that does not need to be relayed to improve the utilization efficiency of the transmission path. Etc.

[0005]

Specifically, a station or a terminal that is going to transmit data by LAN-to-LAN connection is
Before transmitting the data signal, confirm that the transmission line is idle and transmit it. At this time, if a data signal is already being transmitted from another station or terminal, the data signal is transmitted after waiting until there are no carriers on the transmission path. Further, if a collision is detected during transmission, a collision signal is transmitted to all stations or terminals.

The station or terminal which has detected this collision signal retransmits after a lapse of random time. Further, when collisions are repeated, because the transmission line is congested, access control is performed to extend the retransmission time in order to reduce the load. Due to this control method, the average transmission delay time increases as the amount of traffic increases, and the average transmission delay time increases rapidly with a certain traffic, resulting in a problem that the response is significantly deteriorated.

In a network where such a problem frequently occurs, a network connecting device such as a bridge or a router is used to divide the network into a plurality of segments, and the segments other than the destination of the transmission data are not relayed. It is common to increase the efficiency of use of transmission lines,
These devices are very expensive.

Further, in the CSMA / CD system, the delay time randomly changes due to the traffic, and it is impossible to keep the transmission interval constant. Therefore, the voice / image requiring real-time property is the same as the data. There is also a problem that communication is not possible on the LAN. An object of the present invention is to solve the above problems and provide an economical LAN network.

[0009]

FIG. 1 is a block diagram showing the principle of the present invention. In the figure, 1 is a LAN control device (LAN
C), 2 is a hub device (HUB), 3 _1, 3 _2, ... 3 _n is a group of hub devices, 4 is a terminal device, 5 is a bus (# 0,
# 1) is shown.

LAN control device 1 and a plurality of hub devices 2
Are connected to two buses # 0 and # 1, and under the control of the LAN control device 1, a plurality of terminal devices 4 connected to the plurality of hub devices 2 communicate with each other by the CSMA / CD method. In the LAN system to be used, the LAN control device 1
Is configured to connect the hub device 2 to a plurality of groups 3 _1, 3 _2, ... 3 _n.
The time to use one bus # 0 is allocated to each group in a time division manner, and the group is allowed to perform transmission via the one bus # 0 within the allocated time. For the remaining groups, the pseudo-collision state is set to stop the transmission, or the waiting state is set, and then the data transmitted from the assigned group is transmitted via the other bus # 1.

Further, the LAN control device 1 is further configured to monitor traffic via a bus and determine the number of group divisions according to the traffic.

[0012]

According to the present invention, means for forcibly transmitting / stopping a collision signal to a specific station or group to bring about a pseudo collision state (waiting and data transmission is not possible) or cancellation (data transmission possible state). Together with
A means for sequentially switching the other party of the collision signal is provided.

According to the above-mentioned means, the LAN is used, and particularly in a situation where collisions occur frequently with high traffic,
By prioritizing the use of the transmission path in terms of time, it is possible to avoid collisions between specific stations or groups, and to prevent the response from significantly deteriorating due to repeated collisions and retransmissions.

[0014]

FIG. 2 shows an embodiment of the connection configuration of the LAN control device and the hub device of the present invention. In the figure, 11 is a LAN control device (LANC), 12 is a plurality of hub devices (HUB # 0 to #n), and 13 is
10BASE2 / 5 LAN connection device (AUI), 14 is multiple terminal device
(PC # 0 to (PC # m), 15 is a transmitter / receiver (DV / RV), 16 is a HUB controller (HCTL), 17 is a buffer (BUF), 18 is a data bus #
0 and 19 are data buses # 1 and 20 are pseudo collisions, switching signal lines,
21 is a collision control unit (# 0 to #n, # n + 1), 22 is a data relay unit,
23 is a traffic monitoring unit, 24 is a control unit, 25 is a timing unit, 26 is a 10BASE2 or 10BASE5 transceiver unit (DV / RV)
Indicates.

The hub device 12 includes a transmission / reception unit (driver / receiver) 15 of a 10BASE-T interface, a control unit 16 required to operate in conformity with the IEEE802.3 repeater specification,
It comprises a buffer 17 for transmitting and receiving signals to and from the LAN control device 11 and other hub devices 12. The 10BASE2 / 5 LAN connection device 13 has the same configuration as the plurality of hub devices 12, and is connected to the coaxial cable by the transceiver 26 of the 10BASE2 / 5 interface via the transceiver.

The LAN control device 11 transmits / receives a control signal for setting the hub device 12 and the terminal device 14 to a pseudo collision state or a normal state, and data to be relayed using either of the data buses # 0 and # 1. The collision control unit 21 outputs a signal for switching between the two, and the data relay unit 22 receives the data from the transmission source that passes through the hub device 12, and transmits the data to another hub device 12. The traffic monitoring unit 23 monitors the LAN traffic, and the control unit 24 divides the traffic into groups according to the traffic. Timing required for these is generated from the timing unit 25.

FIGS. 3 and 4 are diagrams showing the principle of operation in the above configuration example. In the figure, (a) shows the operation principle in the case of low traffic (same as the conventional example), and (b) and (c) show the operation principle in the case of high traffic. Hub devices are # 0, # 1, # 2, #
n indicates the state, A, B, C, D and E indicate transmitted / received packet data, X indicates collision data, and a shaded portion indicates a pseudo collision state. t0, t1, and t2 indicate the movable time (act) of each packet.

The operation at low traffic of (a) is, for example, when data is transmitted from the terminal (PC # 0),
The data is received via the 0 port transmitter / receiver 15 of the hub device # 0 and is relayed to another port in the same hub device # 0 in the controller 16 and, at the same time, a clock etc. using the buffer 17 and the data bus 18. It is relayed to another hub device 12 together with a necessary signal. Further, it is sent to all terminals connected to the hub device 12. The LAN control device 11 only monitors traffic in the low traffic state and does not perform any traffic priority control.

The operation at the time of high traffic is divided into groups according to the traffic monitoring result and temporally prioritized control is performed.
In the high traffic of (b), a case where the hub device # 0, 1 is divided into a group A and the hub device # 2, n is divided into a group B will be described. When the control unit 24 of the LAN control device 11 determines that the traffic is in a high traffic state, the collision control unit 21 transmits to the hub devices # 0 and 1 using the data bus 18 in accordance with an instruction from the control unit 24 during the time period t0. It issues a buffer switching signal to relay the original data. Also, other hub devices # 2
For n, a buffer switching signal is issued to use the data bus 19 for receiving the relay data from the LAN control device 11, and a collision signal is issued to the terminal in a pseudo collision state so that data cannot be transmitted.

During the time period of t1, a switching signal is output from the transmission source to the hub devices # 2, n using the data bus 18 to relay data, and the hub devices # 0, 1 are provided with a LAN control device. Data bus 19 for receiving relay data from 11
In order to use, the buffer switching signal is output, and a pseudo collision state is set to output a collision signal to the terminal so that data cannot be transmitted.

The data from the terminal connected to the hub device # 0 by the above control is the hub device # 1 and the LAN control device via the hub device # 0 and the data bus # 0 during the time t0. Entered in the central part of 11. This data is relayed to the hub devices # 2 and n using the data bus # 1 after releasing the pseudo collision state of the hub devices # 2 and n, and further transmitted to all the connected terminals.

The data from the terminal of the hub device #n is t1.
During the time zone of L, via hub device #n and data bus # 0,
It is input to the central part of the AN control device 11 and similarly transmitted to the terminal. As described above, since the group A and the group B have different transmittable time zones, collisions between groups are avoided, and it is possible to prevent the response from being significantly deteriorated due to repeated collisions and retransmissions.

When the traffic becomes higher,
Groups A, B, C as in (c) High Traffic
By increasing the number of groups, the collision between groups can be avoided. At this time, the time zones are t0 and t1.
The collision is prevented by dividing the movable band in three stages, i.e. and t2. Although the embodiment has been described above, this embodiment is merely an example, and the number of groups can be increased to avoid collision between groups.

In the configuration diagram of the embodiment shown in FIG. 2, the function of the LAN control device 11 may be built in the hub device 12 and the similar priority control may be performed for each port of the 10BASE-T interface. The transmitting / receiving unit 26 of the hub device
May be built into 12. In traffic monitoring, not only the usage rate of the transmission path per unit time but also the number of collision occurrences may be counted to monitor the traffic state.

Further, in FIGS. 4B and 4C, time zones grouped in a time division manner, for example, the time width and interval of t0 are periodically controlled to force the data length and the delay time due to traffic. By setting the constant, the voice that requires not only data but also real-time property and isochronism,
A moving image signal and the like can also be communicated via the LAN network.

[0026]

According to the present invention, it is possible to prevent a rapid increase in delay time due to frequent collisions, which is a drawback of the CSMA / CD system, and thus an economical LAN network is constructed without using an expensive LAN connecting device. it can. Also, not only data, but voice that requires real-time and isochronous
It is possible to communicate moving image signals and the like on the same LAN network.

[Brief description of drawings]

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

FIG. 2 is a connection configuration example of the present invention.

FIG. 3 is an explanatory diagram of the operation principle of the embodiment (No. 1)

FIG. 4 is an explanatory diagram of the operation principle of the embodiment (No. 2)

[Fig. 5] LAN network configuration example

[Explanation of symbols]

1,11 LAN control device 2,12,34 Hub device 3 _1, 3 _2, ... 3 _n Hub device group 4,14,33 Terminal device 5,37 Pair line 13 LAN connection device 15, 26 Transceiver unit 16 HUB control Part 17 Buffer 18 Data bus # 0 19 Data bus # 1 20 Pseudo collision, switching signal line 21 Collision control unit 22 Data relay unit, 23 Traffic monitoring unit 24 Control unit 25 Timing unit 31 Terminator 32 Transceiver 35 LAN connection device 36 Coaxial cable

Claims (4)

[Claims] 1. A LAN control device (1) and a plurality of hub devices (2) are connected to two buses # 0 and # 1, and the L
In a LAN system in which a plurality of terminal devices (4) connected to the plurality of hub devices (2) communicate with each other under the control of the AN control device (1) by the CSMA / CD system, the LAN control device ( 1) divides the hub device (2) into a plurality of groups (3 _1, 3 _2, ... 3 _n ) and time-divisionally allocates time to use one bus # 0 to each group. , Within the allotted time the group has one bus #
0 is transmitted, and for the remaining groups, the data transmitted from the assigned group is transmitted via the other bus # 1 after the transmission is stopped in the pseudo collision state. A LAN system having a function. 2. The hub device (2) has a built-in function (equivalent to a LAN control device) for temporally prioritizing control, and 10BASE
2. The LAN system according to claim 1, wherein the LAN system is controlled in units of ports of the -T interface. 3. The LAN according to claim 1, wherein the LAN control device (1) further monitors traffic via a bus and determines the number of group divisions according to the traffic. system. 4. The LAN control device (1) communicates voices, images, etc., with one or a plurality of time zones and intervals being constant in a temporally divided group. LAN system described in 1 and 2.