KR950013138B1 - Method of program data transmission in classroom computer network - Google Patents

Abstract

determining whether programs each transmitted to a plurality of receiving side computers are same as each other; if the same programs are transmitted, transmitting a data packet in a broadcasting manner; transmitting confirmation data in one to one manner to check whether the receiving side computers receive the data packet; if only one receiving side computer is in a bad receiving state, returning to the data packet transmitting step; if the different programs are transmitted, receiving an execution packet and transmitting a program including a receiving program execution command to the receiving side computers in one to one manner; sequentially transmitting the execution packet to the receiving side computers; and if only one receiving side computer is in a bad receiving state of the execution packet, returning to the execution packet transmitting step.

Description

How to send a program in the classroom network

1 is a flowchart of a method for transmitting a program in a one-to-one manner in a conventional classroom network.

2 is a block diagram of a local area network card used in the present invention.

3 is a flowchart of a program transmission method in a classroom network according to the present invention.

* Explanation of symbols for main parts of the drawings

1: ISA bus L1, L2: Latch

2: Ethernet control circuit 3: Address generating circuit

4: Buffer 5: Bidirectional Buffer

The present invention relates to a classroom network that is spread in schools, and more particularly, to a program transmission method in a classroom network that improves transmission efficiency when transmitting the same program to a plurality of student computers.

The classroom network refers to a local area network (hereinafter referred to as a LAN) formed between a teacher computer and a plurality of student computers (typically 30 to 60) in a classroom environment. Computers that form the classroom network usually incorporate a LAN card with NOVELL's NE 1000 compatibility, and each LAN card is connected by a coaxial cable.

In such a classroom network environment, it is often necessary to transmit the same program from a teacher computer to a plurality of student computers, or different programs may be transmitted for each of them. However, in the case of transferring the same program to the student computer, there is no consideration of one-to-many program transmission in a typical local network, so in the classroom network, the program is individually transferred one-to-one from the teacher computer to the student computer. Should be. For one-to-one data transfer using the basic statement of NETBIOS, register the sender's user name by the ADD NAME command of the NETBIOS statement. Wait for the computer's CALL command.

After a session is established between the sending and receiving party by sending a call command from the sending computer and receiving a call command from the receiving computer, the receiving computer uses the send command of the sending computer in the receive command state. After receiving the transmission of information, the session is disconnected by HANG-UP and the received program is executed. At this time, the program transmitted by the sending computer transmits data packet by packet, and after transmitting one data packet, transmits an acknowledgment packet confirming the reception state of the data packet of the receiving computer. After sending the acknowledgment packet, if a packet indicating that the reception status is good is transmitted from the receiving side, the sending computer transmits the next data packet, but when the information indicating that the receiving status is bad is transmitted from the receiving side, the sending computer retransmits the transmitted data packet. Will be sent.

Therefore, if the information to be transmitted is formed of n data packets, the sending computer must perform at least n data packet transmission procedures and n confirmation packet major procedures.

FIG. 1 is a flowchart illustrating a method in which a teacher computer transmits data formed of n data packets to N student computers using a one-to-one data transmission method using a network BIOS statement. In the illustrated flowchart, a process of forming a session is omitted for ease of explanation.

As shown, the teacher computer sets the variable N in step S11 and increases the variable N by one. Then, in step S13, the teacher computer sets the variable n to 0, and then increases the variable n by one in step S14. After performing step S14, the teacher computer proceeds to step S15 to transmit the data packet designated in the student computer step S14 corresponding to the variable N specified in step S12. After the transmission of the data packet, the teacher computer transmits a confirmation packet in step S16, and determines the data reception state according to the packet transmitted from the student computer designated in step S17. As a result of the determination in step S17, if the reception state of the student computer is good, the process proceeds to step S18 to determine whether the data packet specified by the current variable N corresponds to the last data packet of the information to be transmitted. As a result of the determination, if it does not correspond to the last data packet, the teacher computer returns to step S14 to transmit the next data packet. As a result of the determination in step S18, if the transmitted data packet is the last data packet, the teacher computer proceeds to step S19 to determine whether the student computer specified by the current variable N is the last student computer. As a result of the determination in step S19, if it is not the last student computer, the teacher computer returns to step S12 to designate the next student computer to perform steps S12 to S19. At this time, if the determination in step S19 corresponds to the last student computer, the teacher computer will end all packet transmission process.

As can be seen from the above description, when taking a one-to-one transmission of information in the classroom network, the difference in the reception time of the data between the student computer first receiving the data from the teacher computer and the student computer finally receiving the data. Occurs so that a time difference between the computers receiving the program occurs.

For example, in a network card with a data transmission / reception rate of 10M bps, a network of 300K bytes in size with a effective transmission rate of 2M bps in consideration of various control frames and header bytes will be used for the first program. The difference in the reception time of the received computer and the computer that received the last program can be obtained as follows.

Time to transfer 300k bytes of program to one computer

t = 300 (k) * 8 (bits) / 2 (M b / s) = 1.2 seconds

Time to transfer 300k bytes of program to 30 computers

t = 300 (k) * 8 (bits) * 30 (large) / 2 (M b / s) = 36 seconds

Difference in reception time between the first computer and the last computer when sending a program of 300k bytes to 30 devices

t = 1.2 seconds * (30-1) = 34.8 seconds

Time to transfer 300k bytes of program to 60 computers

t = 300 (k) * 8 (bits) * 60 (large) / 2 (M b / s) = 72 seconds

Difference in reception time between the first computer and the last computer when sending a program of 300k bytes to 60 devices

t = 1.2 seconds * (60-1) = 71.8 seconds

This receiving time difference appeared as a great obstacle to the class environment, especially in the case of conducting a test using a computer or in the case of a computer class for lower grades, because the whole student cannot simultaneously perform the test and the class.

The conventional approach to solve this problem is to use the receive and send commands by RECEIVE BROADCAST DATAGRAM and SEND BROADCAST DATAGRAM with BROADCAST function supported by the network BIOS. will be. In these statements, broadcast means that the address (ADDRESS) of the packet is all set to "FF" (all six-byte addresses are set to "FFh") so that it can be received from one sending computer by all computers connected to the network. So that all computers connected to the network can receive this packet.

However, broadcast instructions are generally not used for important information delivery. The reason for this is that in the transmission and reception of the broadcast function, the receiver side does not reply whether or not all the computers connected to the network received or received the information transmitted in the SEND BROADCAST DATAGRAM. . Broadcast commands are therefore only used for the transmission of simple messages or non-critical information. In the classroom network, when a test is performed using such a broadcast function, a student computer may not be able to receive data about the test, which may cause a bigger problem than using a one-to-one transmission method. The network does not use the broadcast function to transmit important information.

The present invention is to solve the conventional problems that occur in the classroom network, an object of the present invention is to transmit a program to the classroom network that allows the entire student computer to run the program transmitted from the teacher computer in the classroom network environment at the same time. To provide.

A feature of the present invention for achieving the above object is a method for transmitting a program in a classroom network, the process of determining whether the programs respectively transmitted to a plurality of receiving computers are the same program; A first step of transmitting a data packet in a broadcast manner when the same program is transmitted, a second step of confirming reception status of receiving computers by transmitting acknowledgment data in a one-to-one manner after transmission of the data packet, and Performing a third step of returning to the first step sequentially for all the data packets even when the receiving computer of the receiver receives a poor reception state; When different programs are transmitted to the receiving computer, a fourth step of transmitting a program including instructions for executing the receiving program to be received by the receiving computer in a one-to-one manner and receiving the execution packet; And a fifth step of sequentially transmitting to the second step, and a sixth step of returning to the fifth step when the reception packet of the execution packet is poor even in one receiving side computer.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of a local network card used in the present invention. As shown, the local network card is connected to the ISA bus 1 of the personal computer, which is an address bus, a system data bus, and a control bus. Then, the local network card has a first latch L1 for latching and transmitting data of the personal computer under the control of the personal computer via the ISA bus 1 and under the control of the Ethernet control circuit 2. The second latch L2, which latches data and applies it to the ISA bus 1, and the PROM to control the second lattice L2 according to the address generating circuit 3 generating the address and the received data, and controlling the input / output control. A third latch L3 and the ether for outputting a signal RD (WD) and an address signal and latching the Ethernet control circuit 2, the address signals A0 to A7 of the Ethernet control circuit 3; A buffer 4 is provided for storing and outputting data at an address corresponding to the address signal in accordance with the input / output control signal RD WD of the net control circuit 3. The buffer 4 may be composed of SRAM. The local network card is composed of a bidirectional buffer 5 and a conversion circuit 5 for converting parallel data in series and serial data in parallel, and an interface circuit 6 for data exchange with another personal computer. It is.

3 is a flowchart illustrating a program transmission method in a classroom network according to the present invention.

In general, there are cases in which the classroom network transmits the same program from the teacher computer to the student computers, and different programs are transmitted to each student computer. In this application, the teacher computer selectively performs two processes in preparation for such a case. That is, the teacher computer determines whether the programs to be transmitted to the student computers are the same or different programs in step S30. As a result of the determination in step 30, if the same program is transmitted, the process proceeds to step S31, and if different programs are transmitted to each student computer, the process proceeds to step S41. The teacher computer having proceeded to step S31 sets the first variable n to zero, and then increases the value of the variable n by one in step S32. Then, the teacher computer transmits the data packet of the program corresponding to the value of the variable N set in step S32 after setting the second variable N to 0 in step S33. When transmitting a data packet in a broadcast manner, as described above, all student computers forming a network with the teacher computer can receive the data packet transmitted from the teacher computer. In this case, each student local network card may not receive the transmitted data packet, and may receive the data packet in an error state. In preparation for such a case, the teacher computer proceeds to step S35 to increase the variable N by one, and then transmits a confirmation packet to the student computer corresponding to the variable N in step S36. The teacher computer then determines whether the student computer correctly received the data packet by the packet transmitted by the student computer corresponding to the variable N in response to the confirmation packet in step S37. If it is determined in step S37 that the student computer did not receive the transmitted data packet, the teacher computer returns to step S33 and retransmits the data packet in a broadcast manner.

If the student computer corresponding to the variable N has received the data packet correctly in step S37, the teacher computer proceeds to step S38, and the process proceeds to step S39 when the variable N corresponds to the last student computer. When the computer does not correspond to the last student computer, the process returns to step S35. That is, the teacher computer sequentially determines whether the student computers correctly received the transmitted data packet after transmitting the data packet by the steps S33 to S38, and if no student computer receives the data packet, the teacher computer transmits the data packet. The data packet is then retransmitted to the entire student computer in a broadcast manner.

If the result of the determination at step S38 corresponds to the last student computer, the teacher computer proceeds to step S39 since it means that all student computers constituting the classroom network correctly received the transmitted data packet. do. In step S39, the teacher computer determines whether the transmitted data packet corresponds to the last data packet of the plurality of data packets constituting the information to be transmitted. As a result of the determination in step S39, if the transmitted data packet does not correspond to the last data packet, the teacher computer returns to step S32 to increase the variable n by one, and in step S34 the variable n It sends a data packet corresponding to. That is, all data packets constituting the information by the steps S32 and S39 are sequentially transmitted to the student computer by the broadcast method.

However, if it is determined in step S30 that different programs are transmitted to the student computers, the teacher computer sequentially transfers the programs to the student computers by the same steps S41 to S49 as the first degree, and then proceeds to step S50. .

In step S50, the variable N designating each student computer is set to 0 again, and the process proceeds to step S51, where " 1 "

In addition, the teacher computer proceeds to step S52 and transmits an execution packet for executing the received program to the student computer corresponding to the variable N. In addition, the teacher computer determines whether the student computer receives the execution packet in step S53. If the student computer fails to execute the execution packet, the teacher computer returns to step S52 to retransmit the execution packet, and the student computer If the execution packet has been performed, the process proceeds to step S54.

In step S54, the teacher computer determines whether the set variable N is equal to the total number of student computers forming the classroom network, and if it is the same, ends the transmission process of the program, but returns to step S51 if it is not the same. That is, the teacher computer determines whether the execution packet has been transmitted to all student computers in step S54, and if so, terminates the transmission process of the program, but returns to step S51 if it has not been transmitted to all student computers. The next time an unsent file is sent, the executable packet is sent to the student computer.

Student computers that receive the program from the student computer by the above-described transmission process will receive the execution packet only to execute the received program. At this time, the minimum packet size in Ethernet forms 64 bytes, and the difference in the reception time of the execution packet occurring between the student computer first receiving the execution packet and the student computer receiving the execution packet last can be obtained as follows. Can be. In the following example, there are 30 and 60 student computers that form the classroom network, and the effective transmission speed is 2M bps.

1) Time required for transmission to one computer for information transfer within 64 bytes (t1)

t = 64 * 8 (bits) / 2M bps = 0.00025 seconds.

Time to transfer programs within 64 bytes to 30 computers (t)

t = 0.00025 × 30 = 0.0075 seconds

Difference in the reception time between the first computer and the last computer when sending a program within 64 bytes to 30 devices

t = 0.00025 sec × (30-1) = 0.00725 sec

2) Time to transfer a program within 64 bytes to 60 computers

t = 0.00025 × 60 units

Received time difference between the computer that received the first time and the computer that received the last time when transferring programs within 64 bytes to 60 devices

t = 0.00025 sec × (60-1) = 0.007 sec

As can be seen from the above calculation, it can be seen that the time difference between receiving the execution packet from the teacher computer is small among the student computers. Since the student computers execute the program received from the teacher computer only after receiving the execution packet, the difference in the start time of execution of the student computers to execute the received program is greatly reduced as compared with the related art. That is, in the conventional case, as described above, when a 300 kilobyte program is transferred to 30 and 60 student computers, a maximum execution time difference of 30.8 seconds and 71.8 seconds occurs, but in this case, the execution start time of 0.00025 seconds and 0.007 seconds Only difference occurs.

As described above, when the same program is transmitted to the student computers, the program can be transmitted by broadcasting, and the transmission time of the program can be shortened by checking whether the student computer receives the program in a one-to-one manner. By shortening the time, it is possible to reduce the difference in time of receiving information between student computers.

In addition, in the present invention, when transmitting different programs to student computers, the execution packet must be received at the beginning of the program to insert a command to execute the received program, and then sequentially transmit the program to all the student computers, and then execute the program. By sequentially transmitting the packets to the student computers, the student computers execute the receiving program at about the same time, thereby improving the classroom environment in the classroom network.

Claims (1)

A method of transmitting a program in a classroom network, the method comprising: determining whether programs each transmitted to a plurality of receiving computers are identical to each other; A first step of transmitting a data packet by a broadcast method when the same program is transmitted, a second step of confirming reception status of receiving computers by transmitting acknowledgment data in a one-to-one manner after transmission of the data packet, and A step of sequentially performing a third step of returning to the first step for all data packets even when the receiving computer is in a poor reception state; When different programs are transmitted to the receiving computer, a fourth step of transmitting a program including instructions for executing the receiving program to be received by the receiving computer in a one-to-one manner and receiving the execution packet; And a sixth step of sequentially transmitting the data to the first step, and a sixth step of returning to the fifth step when the reception packet of the execution packet is poor even in one receiving computer. .