RU2200344C2 - Method for delaying message block transmission to computer network data bus - Google Patents

Abstract

FIELD: automatic control and computer engineering. SUBSTANCE: method that may be used for data transmission systems including those of networks employing common bus for connecting several subscribers involves generation of signal in adapter that simulates busy bus. EFFECT: reduced number of conflict situations in access to common bus, enhanced carrying capacity of the latter. 4 dwg

Description

FIELD OF THE INVENTION
The invention relates to automation and computer technology, more specifically, to information transmission systems, and in particular to methods of transmitting a message block to a computer network bus, and can be used in computer networks in devices using a bus common to several subscribers.

State of the art
The use of increasingly widespread local area network Ethernet networks is associated with the difficulty determined by the subscriber’s access to the bus that forms the basis for building networks.

 The basis of the international standard ICO 8802-3, or the American standard IEEE 802.3, in accordance with the requirements of which the adapters connecting the subscribers of the local area network to the bus are manufactured and operate, is the multiple access method with carrier control and CSMA / CD collision detection (Carrier Sense Multiple Access with Collision Detected). In accordance with this method, all subscribers of a computer network that have message blocks ready for transmission monitor the status of the bus, and when the bus is released (one of the subscribers finishes transferring the next data packet), the subscribers wait each and every same specific time called IFG (Inter Frame Gap), start transmitting their message block on the bus. If the transmissions of the message blocks of different subscribers overlap each other, the subscribers interrupt the transmission and repeat it after a time selected randomly from the interval, which is doubled after each unsuccessful attempt to start the transmission of the message block. After the tenth consecutive unsuccessful attempt, the interval doubling stops, and after the sixteenth consecutive unsuccessful attempt to transmit a message block, it stops.

 When using this method, as shown by numerous studies and observations in real local Ethernet computing networks, with a network flow exceeding 1 / π of the maximum flow, which is about 3 Mbit / s for Ethernet networks with a clock frequency of 10 Mbit / s, it is possible an increase in the number of conflicts in the network, up to the development of a clinch, in which the throughput of the data bus drops to zero.

 The known method according to US patent N 4628311, in accordance with which each subscriber of the computer network is assigned a unique time interval for transmission delay, and during the operation of the computer network, these unique time intervals are redistributed according to the cyclic law. In each adapter, it is entered, starting after the end of the transmission of the message block on the computer network bus, counting a unique time interval and if the adapter has a message block ready for transmission and no transmission is registered in the bus during the counting of the unique time interval, the adapter initiates the transmission of the message block to the bus computer network.

 However, the use of this method is possible only after the manufacture of new adapters and their replacement of all old adapters of subscribers of the computer network.

SUMMARY OF THE INVENTION
The objective of the present invention is to provide such a method of delaying the transmission of a message block to a bus of a computer network, consisting of a bus and subscribers connected to it using adapters, which would improve the efficiency of resource management of the computer network by reducing the number of conflicts and increasing the allowable flow of information, in which the stability of the system is still maintained, with minimal alterations in the equipment.

 This problem is solved by the fact that a signal is generated in the adapter simulating bus occupancy of the computer network.

 This allows for minimal changes in equipment to drastically reduce the number of conflicts in the computer network and increase its throughput.

List of drawings
In the future, the patented invention is illustrated by descriptions of specific examples of its implementation and the accompanying drawings, in which:
- FIG. 1 schematically depicts a simplified configuration of a computer network according to the invention;
- FIG. 2 schematically depicts another simplified configuration of a computer network according to the invention;
- figure 3 schematically depicts a fragment of a computer network with a simplified block diagram of a network adapter, according to the invention;
- figure 4 schematically depicts a timing diagram of the sequence of transmission of message blocks to the bus of the computer network and the formation of signals in network adapters, according to the invention.

Information confirming the possibility of carrying out the invention
A simplified configuration of the local area network is shown in FIG. 1, where the following notation is accepted:
1 - bus computer network;
2 - network adapter A ₁ ;
3 - network adapter A ₂ ;
4 - network adapter A _i ;
5 - network adapter A _N ;
6 - subscriber A ₁ ;
7 - subscriber A ₂ ;
8 - subscriber A _i ;
9 - subscriber A _N.

 A patented method for delaying the transmission of a message block to a computer network bus is as follows.

A computer network consists of N subscribers A ₁ , A ₂ , ... A _i , ... A _N , each of which is connected via its adapter D ₁ , D ₂ , ..., D _i , ..., D _N with a computer network bus.

Subscribers A ₁ , A ₂ , ... A _i , ... A _N can be separate computers exchanging information with each other using network adapters D ₁ , D ₂ , ..., D _i , ..., D _N , node processors with which individual local area networks are combined into a larger network, functional units of a computer system, interconnected by a computer network bus, and so on.

 A computer network bus can be a coaxial cable, a radio channel, or any other means of signal transmission.

 The computer network bus can also be an internal trunk of a switch or hub with which network adapters are connected.

A simplified configuration of a local area network using a trunk of a switch or hub as a bus is shown in FIG. 2, where the following notation is used:
10 - switching part of the adapter D _1/2 ;
11 - subscriber part of the adapter D _1/1 ;
12 - switching part of the adapter D _2/2 ;
13 - subscriber part of the adapter D _2/1 ;
14 - switching part of the adapter D _{i / 2} ;
15 - subscriber part of the adapter D _{i / 1} ;
16 - switching part of the adapter D _{N / 2} ;
17 - subscriber part of the adapter D _{N / 1} ;
A computing network consists of N subscribers A ₁ , A ₂ , ... A _i , ... A _N , each of which through the subscriber part of its network adapter D _1/1 , D _2/1 , ..., D _{i / 1} , ..., D _{N / 1} is connected by a twisted pair of conductors, optical fiber, infrared radiation, a trunk or any other means of signal transmission with the switching part of its network adapter D _1/2 , D _2/2 , ..., D _{i / 2} , ..., D _{N / 2} , which is connected to trunk 1 of the switch or hub.

The procedure for access of subscribers A ₁ , A ₂ , ..., A _i , ..., A _N to the computer network bus is as follows.

 All subscribers of the system exchange messages, passing them to their own adapters and further to the computer network bus.

Each time, when any subscriber A _i (1≤i≤N) forms a message block for transmission to the computer network bus, the subscriber transmits this prepared message block to the computer network adapter connected to the subscriber. If the bus of the computer network is currently busy sending a message block, the adapter waits for the bus to free. If the bus of the computer network at this moment is not busy sending a message block, i.e. is free, in order to delay the transmission of the message block, a signal is generated in the adapter simulating the busyness of the data bus, and the adapter waits for the signal to end. After the signal ends, if the data bus is free, the adapter starts transmitting the message block received from the subscriber.

 This signal can be a meander supplied to the input of the network adapter, or a voltage level supplied to the input of the network controller of the adapter, which informs the network controller about the bus occupancy of the computer network.

A fragment of a computer network with a simplified block diagram of a network adapter is shown in figure 3, where the following notation:
18 - transceiver P _i ;
19 - network controller With _i ;
20 - communication unit with the subscriber S _i .

The subscriber part of the network adapter D _{i / 2} consists of series-connected communication unit with the subscriber S _i , the network controller C _i and the transceiver P _i . The signals transmitted on the computer network bus or on the communication channel of the subscriber part D _{i / 1 of the} adapter with the switching part D _{i / 2 of the} adapter are converted by the transceiver P _i into data signals, clock signals and bus status signals of the computer network, which are transmitted to the network controller C _i .

Figure 4 shows the timing diagram of the sequence of transmission of message blocks to the bus of the computer network and the formation of signals in network adapters, where the following notation:
21 - bus status of the computer network;
22 - the state of the network adapter D _i ;
23 - the state of the network adapter D _j ;
24 - the state of the network adapter D _k ;
25 - message block transmitted over the computer network bus;
26 - block message of the subscriber A _i ;
27 - block message subscriber A _j ;
28 - block message subscriber A _k ;
29 is a signal generated in the adapter D _i ;
30 - signal generated in the adapter D _j ;
31 - signal generated in the adapter D _k ;
32 - time interval IFG;
33 - the moment of receipt in the adapter D _i of a message packet intended for transmission over the computer network bus;
34 - the moment of receipt in the adapter D _j of a message packet intended for transmission over the computer network bus;
35 - the moment of receipt in the adapter D _k of a message packet intended for transmission over the computer network bus.

 The message blocks are transmitted over bus 1 of the computer network.

If necessary, to delay in the network adapter D _{i the} transmission of the message block to the bus of the computing network 1 in the adapter form a signal 29 simulating bus occupancy. Moreover, if the subscriber A _i transmits a message block at the time 33 to the network adapter D _i connected to it, the adapter D _i waits for the message block 25 and signal 29 to be transmitted over the computer network bus, after which the time interval 32 is common for all network adapters starts sending message block 26.

If necessary, to delay in the network adapter D _{j the} transmission of the message block to the bus of the computer network 1 in the adapter form a signal 30 simulating bus occupancy. In this case, if the subscriber A _j transmits a message block to the associated network adapter D _j at time 34, the adapter D _j waits for the transmission of message block 25 and signal 30 via the computer network bus, after which the computer network bus is busy transmitting the message block 26 subscribers A _i . The adapter D _j waits for the end of the transmission on the computer network of the message block 26 and the signal 30, after which, after a time interval 32 common to all network adapters, it starts transmitting the message block 27.

If it is necessary to delay the transmission of a message block in the network adapter D _k , a signal 31 is simulated in the adapter simulating bus occupancy. In this case, similarly to the above, if the subscriber A _k transmits the message block at the time 35 to the network adapter D _k associated with it, the adapter D _k waits for the end of the transmission of the message block 26, 27 and signal 31 via the computer network, after which it will of all network adapters, time interval 32 starts sending message block 28.

 The signal can be a meander supplied to the input of the adapter, or a level fed to the input of the network controller of the adapter, informing the network controller about the busy data bus.

 The proposed method of delaying the transmission of a message block to a computer network bus can significantly reduce the number of conflicts, reduce the average and maximum delivery time of a message block in already operating computer networks. Moreover, the application of the proposed method is not associated with any changes in the mathematical software of the network.

Claims (1)

 A method of delaying the transmission of a message block to a bus of a computer network consisting of a bus and subscribers connected to it by means of adapters, which consists in the fact that a signal is simulated in the adapter simulating bus occupancy.

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