JP2000250875A - Boot program distribution device and computer-readable storage medium storing program - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the efficiency of simultaneously delivering a boot program to a plurality of clients. A boot program distribution device that distributes a boot program (7) held by a server (2) to a client that starts up among clients (3 to 5) connected to the server (2) via a network (6). When a boot-up is detected in any of the clients 3 to 5, the boot program 7 stored in the server 2 is transmitted to the broadcast transmitting means 2b by broadcast communication, and the clients 3 to 5 are allocated. This is a boot program distribution device that includes broadcast receiving units 3b to 5b that receive the boot program 7 transmitted by the broadcast transmitting unit 2b when the clients 3 to 5 are started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boot program distribution device for transferring a boot program (startup program) via a network when starting up a computer, and a computer-readable storage medium storing the program.

[0002]

2. Description of the Related Art A general computer has a boot program for performing a start-up process in advance, and such a computer starts up independently.

On the other hand, for example, an X terminal, a diskless computer, a network computer (Network Compute)
Some computers such as r) have a CPU and a memory, but do not have a hard disk for holding a boot program. Therefore, some of these computers have a mechanism for acquiring a boot program necessary for startup from another computer via a network. Obtaining a boot program from another computer via a network in this way is called network boot.

[0004] Normal network boot is performed by performing one-to-one communication between a computer holding a boot program and a computer that starts up.

[0005] In this network boot, the contents after transmission are returned from the receiving side to the transmitting side again in order to check whether or not the correct boot program has been distributed to the booting computer.

Therefore, the communication amount required for the conventional network boot is obtained as shown in the following equation (1).

Communication volume = Boot program capacity × Number of computers to be started × (Response) 2 (1)

[0008]

As described above, in the conventional network boot, when a plurality of computers are started at the same time, the boot programs are independently executed between the plurality of computers and the computer having the boot program. Is communicated.

In recent years, computerization has been attempted in various industries, and among them, for example, a network boot of a plurality of computers may be performed simultaneously in synchronization with the start time of business.

In this case, if these computers are connected to the same network, the network may be saturated by the load due to the transfer of the program and congestion may occur.

[0011] Network congestion causes communication delay. Further, acquisition of a boot program may fail due to network congestion, and startup may be stopped.

The present invention has been made in view of the above circumstances, and transmits and receives a boot program using broadcast communication, thereby reducing network congestion, increasing the speed of boot program distribution and improving reliability. It is an object of the present invention to provide a boot program distribution device to be improved and a computer-readable storage medium storing a program.

[0013]

The gist of the present invention resides in that a boot program is distributed to a plurality of clients by using broadcast.

Hereinafter, specific means taken to realize the present invention will be described.

A first aspect of the present invention is a boot program distribution device that distributes a boot program held by a server to a client that starts up, of at least one client connected to the server via a network. A broadcast transmission means for transmitting a boot program held by the server by broadcast when detecting startup in any of the at least one client, and at least one of the clients, A boot program distribution device comprising at least one broadcast receiving means for receiving the boot program transmitted by the broadcast transmitting means when starting up the client.

In the boot program distribution device according to the first aspect of the present invention, the boot program is provided by broadcast to the client that starts up.

Therefore, even when a plurality of clients are started up at the same time, it is possible to reduce an increase in the communication amount due to the distribution of the boot program.

Therefore, network congestion is reduced,
The client can be started quickly. Further, the reliability of acquiring the boot program can be improved.

A second invention is the boot program distribution device according to the first invention, wherein the broadcast transmitting means broadcasts the boot program when detecting startup of any one of the at least one client. Is a boot program distribution device that transmits multiple times.

In the boot program distribution device of the second invention, the boot program is transmitted a plurality of times by broadcast communication.

Thus, even if the boot program cannot be normally received by the first broadcast communication, the boot program can be normally received by the subsequent broadcast communication. Therefore, the reliability of acquiring the boot program can be further improved.

Further, even if another client is started slightly after the start of one client, the other client can acquire the boot program.

A third invention is a boot program distribution device for distributing a boot program held by a server to a client that starts up, among at least one client connected to the server via a network, A broadcast transmitting unit configured to divide a boot program held by the server into a plurality of packets when the boot-up is detected in any one of at least one client, and to transmit a plurality of packets by broadcast communication;
When transmission of a plurality of packets by the broadcast transmission means is completed, retransmission permission means for transmitting a retransmission enable signal indicating that the packet can be retransmitted by broadcast communication to at least one client. Assigned and at least one broadcast receiving means for receiving a plurality of packets transmitted by the broadcast transmitting means when starting up the assigned client; and at least one assigned to each client and retransmission permission Upon receiving the retransmittable signal transmitted by the means, it detects the presence or absence of a packet that was not normally received by the broadcast receiving means assigned to the same client as itself, and the packet that was not received normally At least one retransmission request means for transmitting a retransmission request signal indicating that retransmission of the A packet retransmitting means for transmitting a packet indicated by the received retransmission request signal when a retransmission request signal is received from any one of the one retransmission request means; And at least one packet re-receiving means for receiving a packet retransmitted from the packet re-transmitting means because the packet was not normally received by the broadcast receiving means assigned to the same client. is there.

In the boot program distribution device according to the third aspect of the present invention, the boot program is divided into a plurality of packets and transmitted from the server to the client. However, only the packets that have not been normally received by the client are retransmitted. You.

Therefore, even if an abnormality occurs in the distribution of the boot program, the boot program can be repaired, so that the reliability of acquiring the boot program can be further improved.

Further, even if an abnormality occurs in the distribution of the boot program, the recovery is performed by communication in units of packets, so that the communication amount required for the recovery work can be reduced.

The fourth to sixth inventions are computer-readable storage media storing a program for realizing the functions of the boot program distribution device described in the first to third inventions by a computer.

By using a storage medium storing such a program, the above-described functions can be easily added to a server or a client that does not have the above-mentioned functions.

[0029]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) In this embodiment, a client booted up by the same boot program is connected to a network, and a boot program of a server is broadcasted when this client is booted up. A device that uses (broadcast) to distribute to a client will be described.

Incidentally, the broadcast communication is a communication system for simultaneously transmitting the same information and message from one place to a plurality of places.

FIG. 1 is a block diagram showing the configuration of a computer system provided with the boot program distribution device according to the present embodiment.

The computer system 1 is configured such that a server 2 and clients 3 to 5 are communicably connected via a network 6 capable of broadcasting.

The boot program distribution device according to the present embodiment has a broadcast transmitting section 2b provided in the server 2 and broadcast receiving sections 3b-5 provided in the clients 3-5.
b.

The server 2 includes a storage device 2a and a broadcast transmitting unit 2
b, and other functions (not shown) for realizing the function as a server. Note that this not-shown function is
The functions may be considered to be the same as the functions provided in the conventional server, and include, for example, a function of detecting that any one of the clients 3 to 5 is started.

The storage device 2a stores a boot program 7 for starting up the clients 3 to 5.

When the server 2 detects the activation of any of the clients 3 to 5, the broadcast transmitting unit 2b reads the boot program in the storage device 2a, divides the boot program into program fragments, and creates a packet. . And
The created packet is sent to the client 3 by using broadcast.
To 5.

The broadcast transmission unit 2b transmits the same packet a plurality of times (for example, about three times) in preparation for a failure in transmission and reception of the packet. Note that, for example, when the user confirms that all the clients to be started up or when the boot program 7 is distributed to all the clients to be started up, the same process is performed at that time. The transmission of the packet from the notification transmitting unit 2b may be stopped.

Each of the clients 3 to 5 is a computer such as an X terminal, a diskless computer, a network computer or the like which does not have a boot program, and is a computer which is started up by the same boot program 7.

Each of the clients 3 to 5 has a memory 3a to 5a, a broadcast receiving unit 3b to 5b, respectively, and other functions (not shown) for realizing a function as a client started by network boot. The function (not shown) may be considered to be the same as the function provided in the conventional client. For example, there is a function of notifying the server 2 that the self-startup is requested.

The memories 3a to 5a are devices for holding the distributed boot program 7. This memory 3
The execution of the boot program 7 stored in each of the clients a to 5a starts the clients 3 to 5.

The broadcast receiving units 3b to 5b are assigned to the clients 3 to 5 by being installed, respectively, and are used when the assigned clients 3 to 5 start up. Receive the packet transmitted by the broadcast communication. Then, the boot program 7 is synthesized from the received packet, and the memories 3 a to 5
Stored in a.

When a plurality of identical packets are received, the broadcast receiving units 3b to 5b select a normal packet from the same packets when synthesizing the boot program 7, and synthesize the boot program 7. Try. When the boot program 7 has been successfully synthesized, the completion of synthesis is notified to the broadcast transmitting unit 2b.

The operation of the computer system 1 including the boot program distribution device having the above configuration will be described below.

For example, it is assumed that the power of the clients 3 and 4 is newly turned on at the start of the business, but the client 5 has already been started or is in a stopped state.

In this case, a request for acquiring the boot program 7 is made by the clients 3 and 4 that start up, and this acquisition request is detected by the server 2.

Then, the broadcast transmitting unit 2b of the server 2 is started, and the boot program 7 in the storage device 2a is read by the broadcast transmitting unit 2b.

The boot program 7 read by the broadcast transmitting section 2b is decomposed into a plurality of pieces to form a packet, which is transmitted using a broadcast communication. This broadcast is executed a plurality of times.

The plurality of packets are transmitted by broadcast to the clients 3 to 5 that are started up by the boot program 7. For this reason, a plurality of packets can be received by any of the clients 3 to 5, but the broadcast receiving units 3b to 5b receive the plurality of packets only when starting up the assigned clients 3 to 5. Demonstrate function.

Therefore, a plurality of packets are received by the broadcast receiving units 3b and 4b of the clients 3 and 4 that start up.

In the broadcast receiving sections 3b and 4b, the boot program 7 is synthesized based on the plurality of received packets. When a plurality of the same packets are received at the time of combining, a normal packet is selected and combined.

The boot program 7 synthesized by the broadcast receiving units 3b and 4b in this manner is stored in the memories 3a and 3b.
b.

The broadcast receiving sections 3b and 4b detect that the boot program 7 has been normally synthesized, and if the boot programs 7 are normally synthesized, the broadcast receiving sections 3b and 4b
Causes the broadcast transmitting unit 2b to notify the completion of the synthesis of the boot program 7. In the broadcast transmitting unit 2b, the boot program 7
When the notification of the completion of the synthesis is received from all the acquisition request sources, the broadcast communication is stopped.

Thus, even when a packet is transmitted a plurality of times by broadcast communication, unnecessary communication can be eliminated.

The clients 3 and 4 communicate with the memories 3a,
Booting is performed using the boot program 7 in 3b.

As described above, in the boot program distribution device according to the present embodiment, the broadcast transmitting unit 2b
And the broadcast receivers 3b to 5b broadcast the boot program 7 via a network.

The amount of communication required when performing a network boot using this boot program distribution device is as follows:
Equation (2) is obtained even when the number is large.

Communication amount = Boot program capacity × Number of communication times (2) The communication amount obtained by the expression (2) is much larger than the communication amount required by the conventional network boot obtained by the expression (1). Has been reduced.

Therefore, by applying the boot program distribution device according to the present embodiment, it is possible to prevent the network from being saturated by the transfer of the boot program and causing congestion. In addition, it is possible to prevent communication delay, prevent an abnormal acquisition of a boot program, or fail to start a client, thereby improving reliability.

When the boot program distribution device according to the present embodiment is applied, since no response is sent from the client to the server, disturbance to communication can be reduced, and the specification of the network can be improved.

Furthermore, in the boot program distribution device according to the present embodiment, since the boot program is transmitted a plurality of times, the reliability of the boot program distribution can be further improved. Further, even when another client is started up slightly after the start-up of a certain client, the other client can acquire the boot program.

On the other hand, if the boot program is normally distributed, the communication volume can be further reduced by stopping the communication even before completing the transmission several times.

(Second Embodiment) In the present embodiment, a plurality of packets created by dividing a boot program are transferred by broadcast communication. A boot program distribution device that retransmits only this abnormal packet will be described.

FIG. 2 is a block diagram showing a configuration of a computer system provided with the boot program distribution device according to the present embodiment. In FIG. 2, the same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The computer system 8 has a configuration in which a server 9 and clients 101 to 10n are connected via a network 6 so as to be able to transmit and receive.

The boot program distribution device according to the present embodiment includes a broadcast transmission unit 9b and a packet retransmission unit 9c provided in the server 9, and clients 101 to 10n.
, A broadcast receiving section 11 and a re-receiving mechanism 12 provided in the system. Here, the broadcast transmitting unit 9b includes a retransmission permitting unit 13, and the rereceiving mechanism 12 includes a retransmission requesting unit 14 and a packet rereceiving unit 15.

The client 10 shown in FIG.
1 to 10n are computers that are started by the same boot program 7, and have the same configuration and operation. Therefore, the following description will be made mainly using the client 101.

The broadcast transmitting section 9b is composed of the clients 101-101.
When any of the bootstraps 10n is detected, the boot program 7 is divided into a plurality of packets to create a packet, attach identification information to the packet, and transmit the packet using broadcast communication. Here, the division number of the boot program 7 and its order are used as the identification information. For example, when the boot program 7 is divided into 100 pieces, identification information “1/100”, “2/100”,..., “100/100” are added in order from the first packet.

After transmitting all the created packets, the broadcast transmitting section 9b transmits a retransmission permission signal by the retransmission permission section 13 by broadcast communication. This retransmission permission signal is a signal for notifying that the packet can be retransmitted.

The broadcast receiving section 11 is assigned to the client 101 by being installed, and is transmitted by broadcast when the assigned client 101 is started up. Receive the packet. In addition, an attempt is made to synthesize the boot program 7 from the received packet. Here, when there is a packet having a communication error such as a case where there is an unreceived packet or a case where the content of the received packet is abnormal, a normal packet is input from the packet re-receiving unit 15 and a normal packet is input. The boot program 7 is synthesized using only the small packets. Then, the synthesized boot program 7 is stored in the memory 3a.

The retransmission request unit 14
, The retransmission permission signal transmitted by the broadcast is received. When receiving the retransmission permission signal, the broadcast receiving unit 11 refers to the received packet and detects whether or not there is a communication abnormal packet in the packet. If there is a communication error, the identification information of the packet causing the error is included in the retransmission request signal, and the retransmission request signal is sent to the server 9.
To the packet retransmitting unit 9c.

The packet retransmitting section 9 c
When the retransmission request signal is received from the host 4, the boot program 7 is read and a packet is created by the same method as that of the broadcast transmission unit 9b. The packet related to the identification information included in the received retransmission request signal is transmitted to the client 101.
To the packet re-receiving unit 15.

The packet re-receiving unit 15 receives the re-transmitted packet from the packet re-transmitting unit 9c, and outputs the received re-transmitted packet to the broadcast receiving unit 11.

The operation of the computer system 8 including the boot program distribution device having the above configuration will be described below.

FIG. 3 shows the server 2a of this computer system.
FIG. 3 is a diagram illustrating an operation performed between a client and a client.

When the power is newly turned on in any of the clients 101 to 10n, first, the broadcast program 9b of the server 9 reads the boot program 7,
Packets “1/100” to “100/100” are created.

When the packets "1/100" to "100/100" are transmitted by the broadcast transmission by the broadcast transmission unit 9b on the server 9, the broadcast reception unit 11 on the client 101 side Is received at However, it is assumed that the packet “55/100” is lost during this communication.

After the packets "1/100" to "100/100" have been transmitted by the broadcast transmission section 9b of the server 9, a retransmission enable signal from the retransmission permission section 13 uses the broadcast communication. Sent.

The retransmission request unit 14 on the client 101 side
When the retransmission enabling signal is received by the retransmission request unit 14, the packets received by the broadcast receiving unit 11 are listed. As a result, the packet "55/10
The fact that “0” has been lost is detected by the retransmission request unit 14.

Then, a retransmission request signal for retransmitting the packet “55/100” is transmitted by the retransmission request unit 14 on the client 101 side.

On the server 9 side, the retransmission request signal is received by the packet retransmission unit 9c, and the packet “55/100” is retransmitted based on the retransmission request signal.

On the client 101 side, the retransmitted packet “55/100” is received by the packet re-receiving unit 15 and then output to the broadcast receiving unit 11.

Then, the packets received by the broadcast receiving section 11 are listed up again by the retransmission request section 14, and as a result, all the receptions are confirmed, and the broadcast receiving section 11 synthesizes the boot program 7.

As described above, in the boot program distribution device according to the present embodiment, a plurality of packets are created from the boot program 7 and transmitted using broadcast communication. Here, when a packet that has not been normally communicated is detected, only the packet that has not been normally communicated is retransmitted from the server 9 to the client 101.

That is, when the communication of the boot program 7 has partially failed, the boot program distribution device requests only the packet in which the communication failed from the server 9. Here, the retransmission request from the client 101 is executed after the retransmission permission is transmitted from the server 9.

As described above, when the boot program distribution device according to the present embodiment is used, it is not necessary to repeat the transmission of the boot program 7 a plurality of times in order to secure normal communication, and only the packets having abnormal communication have been transmitted. Should be retransmitted.

Therefore, in the boot program distribution device according to the present embodiment, the communication amount can be further reduced as compared with the case described in the first embodiment, and disturbance by the client 101 can be prevented. . Also,
Thereby, the reliability of the start-up of the computer system can be further improved.

Note that the retransmission enable signal in the present embodiment may be used as “boot permission” for a client that has successfully completed packet communication.

In the present embodiment, the retransmission request unit 14 detects a transmission error by referring to the identification information of the packet received by the broadcast receiving unit 11.
However, instead of this, the broadcast receiving unit 11 and the retransmission request unit 1
4 may be able to receive the packet, and the retransmission request unit 14 may detect the communication abnormality using the identification information of the packet received by itself.

In each of the above embodiments, the case where each component of the boot program distribution device is incorporated in the server and the client constituting the computer system is described as an example. However, the present invention is not limited to this. Not
It may be external to the server and the client.

Further, in each of the above-mentioned embodiments, all the clients that start up with the same boot program are the transmission destinations of the broadcast communication. However, the present invention is not limited to this. For example, the boot program may be transmitted only to clients that are activated by the same boot program and that have been requested to be activated within a predetermined period of time.

(Third Embodiment) Each function of the boot program distribution device according to each embodiment described above is
Examples of programs that can be executed by a computer include a magnetic disk (floppy disk, hard disk, etc.) and an optical disk (CD-ROM, DVD
Etc.), it is also possible to write and apply to a storage medium such as a semiconductor memory or to transmit to a communication medium and apply to various devices. The computer that realizes each of the above functions is
The above-described processing is executed by reading the program stored in the storage medium and controlling the operation by the program.

For example, a first program for realizing the function of the broadcast transmitting section 2b shown in FIG. 1 and a second program for realizing the function of the broadcast receiving section 3b are stored in a storage medium.

The user installs the first program on the server 2 and installs the second program on each of the clients 3 to 5, so that the case where the boot program distribution device according to the first embodiment is applied can be obtained. A similar situation can be realized.

Further, for example, the retransmission permitting unit 1 shown in FIG.
The third program for realizing the function of the broadcast transmitting unit 9b including the third program, the fourth program for realizing the function of the packet retransmitting unit 9c, the fifth program for realizing the function of the broadcast receiving unit 11, re-reception A sixth program for realizing the function of the mechanism 12 is stored in a storage medium.

If the user installs the third and fourth programs on the server 9 and installs the fifth and sixth programs on each of the clients 101 to 10n, the boot program distribution according to the second embodiment is performed. The same situation as when the device is applied can be realized.

[0097]

As described above, in the present invention,
When booting a client that does not hold a boot program, the server distributes the boot program to the client by using broadcast communication.

Thus, when a large number of clients must be started up at the same time, the amount of communication can be reduced as compared with the case where a boot program is individually delivered to each client.

Therefore, it is possible to prevent the network from being saturated by the distribution of the boot program and causing congestion. In addition, it is possible to prevent a delay in communication due to network congestion and a failure in obtaining a boot program or a stop in startup of the boot program. Further, the distribution of the boot program for starting the client can be performed at high speed.

Further, in the present invention, by repeating the broadcast communication a plurality of times, the reliability of the startup of the client can be further improved.

Further, according to the present invention, a packet is created by dividing the boot program into a plurality of pieces, identification information is added to each packet, and the packet is transmitted by broadcast communication. Detect and retransmit only abnormal packets.

Thus, even if the communication of a part of the boot program fails, only the failed part needs to be retransmitted, and the broadcast communication need be performed only once. Therefore, the processing amount and the communication amount of the client and the server can be reduced, and disturbance by the client can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a computer system including a boot program distribution device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a computer system including a boot program distribution device according to a second embodiment of the present invention.

FIG. 3 is an exemplary view showing an operation performed between a server and a client of the computer system including the boot program distribution device according to the embodiment.

[Explanation of symbols]

 1, 8 ... Computer system 2, 9 ... Server 2a ... Storage device 2b, 11 ... Broadcasting transmission unit 3-5, 101-10n ... Client 3a-5a ... Memory 3b-5b ... Broadcast receiving unit 6 ... Network 7 ... Boot program 9c Packet retransmitting unit 12 Retransmission mechanism 13 Retransmission permitting unit 14 Retransmission requesting unit 15 Packet rereceiving unit

Claims (6)

[Claims] 1. A boot program distribution device that distributes a boot program held by the server to a client that starts up, among at least one client connected to the server via a network, Upon detecting startup in any one of the clients, a broadcast transmission unit that transmits a boot program held by the server by broadcast, and is assigned to the at least one client,
A boot program distribution device, comprising: at least one broadcast receiving means for receiving the boot program transmitted by the broadcast transmitting means when starting up the assigned client. 2. The boot program distribution device according to claim 1, wherein the broadcast transmitting unit broadcasts the boot program by broadcast when detecting a start-up in any of the at least one client. A boot program distribution device for transmitting a plurality of times. 3. A boot program distribution device that distributes a boot program held by the server to a client that starts up, among at least one client connected to the server via a network, A broadcast transmitting unit configured to divide a boot program held by the server into a plurality of packets when the boot program is detected in any one of the clients, and to transmit the plurality of packets by broadcast communication; Retransmission permitting means for transmitting, by broadcast communication, a retransmission enable signal indicating that retransmission of the packet is possible when transmission of the plurality of packets by the broadcast transmission means is completed, and the at least one client Assigned to
When starting up the assigned client, at least one broadcast receiving unit that receives a plurality of packets transmitted by the broadcast transmitting unit, and is assigned to each of the at least one client,
Upon receiving the retransmission enable signal transmitted by the retransmission permitting means, detecting the presence or absence of a packet that has not been normally received by the broadcast receiving means assigned to the same client as itself and receiving the packet normally. At least one retransmission request unit for transmitting a retransmission request signal indicating that retransmission of a packet that has not been performed is requested, and when a retransmission request signal is received from any of the at least one retransmission request unit. Packet retransmission means for transmitting a packet indicated by the received retransmission request signal, assigned to each of the at least one client,
At least one packet re-receiving means for receiving a packet retransmitted from the packet re-transmitting means because the packet was not normally received by the broadcast receiving means allocated to the same client as the self-client. Boot program distribution device. 4. A broadcast transmission function for transmitting a boot program held by a server by broadcast communication when a start-up of any one of at least one client is detected, and a client assigned to the computer. A computer-readable storage medium storing a program for realizing a broadcast receiving function of receiving a boot program transmitted by the broadcast transmitting function when starting up. 5. A computer-readable storage medium storing the program according to claim 4, wherein the broadcast transmission function is configured to execute the boot program upon detecting startup in any one of the at least one client. A computer-readable storage medium storing a program, wherein the program is transmitted a plurality of times by broadcast communication. 6. A computer, when detecting startup of at least one of the clients, divides a boot program held by the server into a plurality of packets, and transmits the plurality of packets by broadcast communication. A broadcast transmission function, and a retransmission permitting function of transmitting, by broadcast, a retransmission enable signal indicating that the packet can be retransmitted when transmission of the plurality of packets by the broadcast transmission function is completed. And when starting up the client to which it is assigned, a broadcast receiving function for receiving a plurality of packets transmitted by the broadcast transmitting function; and a retransmission enable signal transmitted by the retransmission permitting function. Upon reception, the broadcast receiving function detects the presence or absence of a packet that has not been received normally, and A retransmission request function for transmitting a retransmission request signal indicating that a packet retransmission is requested; and when the retransmission request signal transmitted by the retransmission request function is received, the retransmission request signal A program for realizing a packet retransmission function for transmitting a packet to be transmitted and a packet retransmission function for receiving a packet retransmitted from the packet retransmission function because the packet was not normally received by the broadcast reception function. A stored computer-readable storage medium.