JP2003110738A - Method for controlling number of communication channels and dial-up router - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the use efficiency of an ISDN line at the time of file transfer is deteriorated since the transfer quantity of a whole file is not recognized by a dial-up router, and it is necessary to start the file transfer with the minimum number of communication channels (one B channel) even when the capacity of the whole file is sufficiently large. SOLUTION: This method comprises file capacity detection processing for detecting the capacity of a file to be notified before a file is transferred from a server, the optimal number of communication channel calculation processing for calculating the optimal number of communication channels according to a prescribed calculation formula based on the capacity of the file detected by the file capacity detection processing, and file transfer processing for connection processing of the lines in the optimal number of communication channels of lines to be charged for the server, and for transmitting files to be transferred from the server through lines in the optimal number of communication channels to the terminal.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an FTP (File T
When downloading file data from a ransfer protocol server, ISDN (Integrated Services Digi)
The present invention relates to a communication channel number control method for controlling the number of communication channels of a chargeable circuit such as a tal network) and a dial-up router to which the method is applied.

[0002]

2. Description of the Related Art A router is used to connect a LAN (Local Area Network) to an external communication line, and a dial-up router is often used especially when the LAN is connected to an ISDN line. The dial-up router is a router that has an interface for connecting a LAN and an interface for connecting an INSD line, and automatically performs dial-up via an ISDN line in response to a request from the LAN side and connects to the other party.

FIG. 5 is a system configuration diagram showing the configuration of a file transfer system using a dial-up router. In FIG. 5, PCs 1A and 1B are client-side personal computers that request file transfer from the FTP server 7 in the file transfer system. LAN cable 2 for PC1A and 1B
A LAN is constructed by being connected to each other by. PCs other than PCs 1A and 1B are included in the LAN.
May be connected.

The dial-up router 3 is connected to the FT.
Information such as the P server 7 (that is, the dial-up router 6) and the Internet service provider (not shown) is set in advance, and when packet data for accessing the outside from the PCs 1A, 1B on the LAN side is generated, the packet data is added It is a router that automatically makes a dial-up connection to the corresponding destination. This dial-up router 3
Is an interface (I / F) for connecting a LAN and an I
It has an interface for connecting NSD lines.
Some dial-up routers 3 have a built-in HUB function in addition to the routing function and dial-up function.

The ISDN line 4 is a network for converting all data including voices and images into digital signals for efficient transmission. The service (ISDN service) that uses the ISDN line 4 provided by the communication carrier is I
NS (Information Network System) net 64 and IN
There are two types of S-net 1500.

The INS 64 is composed of two B channels for communication (transmission rate of 64 Kbps) and one D channel for control communication (16 Kbps of the same) (Basic Rate Interface). In INS64, B
Up to 128 by using two channels at the same time
A communication speed of Kbps can be obtained. Meanwhile, INS
1500 has 23 B channels and D channels (64K
bps) 1 or 24 B channels (1
Next group velocity interface; Primary Rate Interfac
e). With INS 1500, the maximum is 1500 Kbps
A communication speed of (1.5 Mbps) can be obtained.

Generally, in a company, for example, when data communication is performed between a head office and a branch office, data communication is performed by the INS 1500 because the communication speed of the INS 64 is insufficient. In the file transfer system shown in FIG. 5, the ISDN service of the INS net 1500 is applied.

The exchange 5 performs packet switching (switching) in the ISDN line 4 network. The dial-up router 6 is the dial-up router 3 described above.
Similarly to the above, it is a router that automatically makes a dial-up connection by an ISDN line.

The FTP server 7 follows the client PCs 1A, 1 in accordance with FTP (File Transfer Protocol).
It is a server that transfers files to B. This FT
The P server 7 is connected to the dial-up router 6 as shown in FIG.

Next, the file transfer operation will be described. The operation of the user of the PC 1A starting the FTP client software in the PC 1A and downloading the file from the FTP server 7 will be described.

When the user requests the file transfer from the FTP server 7 with the FTP client software in the PC 1A, the PC 1A sends out the packet data of the FTP request. The packet data of this FTP request is the LAN
It is sent to the dial-up router 3 via the cable 2. The dial-up router 3 uses the FTP from the PC 1A.
When the request packet data is received, it is determined that the destination is the FTP server 7 based on the preset information of the destination. And the dial-up router 3
Dial transmission is performed by transmitting a dial signal to the FTP server 7.

The dial signal sent from the dial-up router 3 is sent to the dial-up router 6 via the ISDN line 4 and the exchange 5. When dial-up router 6 responds to the dial signal, one B-channel line of ISDN line 4 (23 B-channels) is connected between dial-up routers 3 and 6.

The dial-up router 3 sends out the packet data of the FTP request to the FTP server 7 when the dial-up router 6 on the other side responds and one B channel line of the ISDN line 4 is connected. The dial-up router 6 sends the F sent from the dial-up router 3.
When receiving the packet data of the TP request, the packet data is transmitted to the FTP server 7.

The FTP server 7 uses the FTP from the PC 1A.
By receiving the request packet data, PC1A
An FTP control connection is established between the server and the FTP server 7. When the user specifies a predetermined file from PC 1A and sends a GET command to the FTP server 7, F
The TP server 7 notifies the PC1A of the capacity of the file designated by the GET command in a response message, and transfers (downloads) the file to the PC1A. The file data is transferred to the PC via the dial-up router 6, ISDN line 4, exchange 5 and dial-up router 3.
1A is transferred.

The dial-up router 3 checks (monitors) the amount of data transferred during a fixed time while the file data is transferred from the FTP server 7 to the PC 1A. When the dial-up router 3 determines that the data transfer amount is large, the dial-up line connection is performed by dial-up to increase the number of communication channels (number of B channels) of the ISDN line 4 used for file transfer. This reduces the time required for file transfer.

When the dial-up router 3 determines that the data transfer amount has decreased, the dial-up line connection is disconnected and the number of communication channels of the ISDN line 4 used for file transfer (the number of B channels). )
To reduce.

[0017]

However, in the conventional communication channel number control method as described above, since the transfer amount of the entire file is not known in advance in the dial-up router 3, even if the capacity of the entire file is sufficiently large. The file transfer must be started with the minimum number of communication channels (one B channel), and the efficiency of use of the ISDN line 4 at the time of file transfer was poor.

The ISDN line 4 is a pay-per-use line and is charged (communication charge is determined) according to the line usage time (communication time) for each communication channel number (B channel). In the conventional communication channel number control method,
Since the unit time for charging the ISDN line 4 is not considered at all, depending on the number of communication channels and line use time, a very useless charge may be made (the communication charge may be high). There were challenges.

The present invention has been made to solve the above problems, and when a file is transferred, the file transfer time is shortened and the chargeable line (ISDN line) required for the file transfer is reduced. An object of the present invention is to obtain a communication channel number control method and a dial-up router that can simultaneously realize a reduction in communication charges.

[0020]

In order to achieve the above object, in the communication channel number control method and dial-up router according to the present invention, a dial-up router connected to a chargeable line composed of a LAN and multiple channels is provided. When the packet data of the file transfer request to the server is received from the terminal on the LAN side, the line connection process of the charged line to the server is performed, and the server access process of transmitting the packet data of the file transfer request to the server for access. Calculate the optimal number of communication channels according to a predetermined formula based on the file size detection process that detects the file size that is notified before the file is transferred from the server and the file size detected by the file size detection process To calculate the optimal number of communication channels to Performs line connection processing of the optimum number of communication channels of gold lines, in which a file transfer process to send the file to be transferred from the server to the terminal by the line of optimum number of communication channels.

Further, in the communication channel number control method and dial-up router according to the present invention, a file transfer request from the terminal on the LAN side to the FTP server is made by the dial-up router connected to the charged line consisting of LAN and multiple channels. When receiving the packet data of
Performs line connection processing of the billed line to the FTP server, and transfers packet transfer request packet data to the FTP.
Server access processing to send to the server for access,
Based on the file size detection processing that analyzes the protocol of the response message notified before the file is transferred from the FTP server and detects the file size in the response message, and the file size detected in the file size detection step. Then, the optimum communication channel number calculation step of calculating the optimum communication channel number according to a predetermined calculation formula, and the line connection processing of the optimum communication channel number of the billed line to the server are performed, And a file transfer process for sending the transferred file to the terminal.

Further, in the communication channel number control method and the dial-up router according to the present invention, in the optimum communication channel number calculation step, based on the file capacity,
The file transfer time is calculated by the first formula, and the number of communication channels that minimizes the communication charge derived by the second formula is determined as the optimum number of communication channels based on the file transfer time. It is a thing.

Further, in the communication channel number control method and the dial-up router according to the present invention, the optimum communication channel number calculated in the optimum communication channel number calculating step has a minimum number of channels in advance according to the file capacity. It is set as it is set.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below. Embodiment 1. FIG. 1 is a block diagram showing the configuration of the dial-up router of the present invention. In FIG. 1, the dial-up router 10 uses the FT of the other party as described above.
Information such as the P server 7 is set in advance, and the PC on the LAN side
This is a router that automatically makes a dial-up connection to the other party according to the packet data when the packet data for accessing the outside from the (terminal) 1A, 1B is generated.

In the dial-up router 10, LA
The NI / F unit (LAN interface unit) 11 is a PC
LAN built from 1A and 1B (LAN cable 2)
Is an interface for connecting to. The route control unit 12 is provided between the LAN I / F unit 11 and the line I / F unit 15, and based on preset information, IP of packet data sent from the LAN side and the ISDN line 4 side. The address is checked and the route is selected.

Protocol analysis unit (file capacity detection unit)
13 monitors the packet data passing through the route control unit 12, analyzes the protocol of the packet data, checks the response message from the FTP server 7, and determines the data capacity of the file transferred from the FTP server 7. Is to detect. The optimum communication channel number calculation unit (optimal communication channel number calculation unit) 14 calculates the number of files based on the data capacity of the file detected by the protocol analysis unit 13.
The optimum number of communication channels for file transfer is calculated by a predetermined calculation formula.

Line I / F unit (line interface unit)
Reference numeral 15 is an interface for connecting the ISDN line 4. The line I / F unit 15 has a function of controlling line connection by dial-up.

The file transfer system has the same configuration as that shown in FIG. Note that the dial-up router 6 on the FTP server 7 side in FIG. 5 also has the same configuration as the dial-up router 10 shown in FIG.
In the following description, the dial-up router 20 (not shown) is used. Further, the same components as those described with reference to FIG. 5 are designated by the same reference numerals, and redundant description will be omitted.

In the present invention, it is assumed that the INS net 1500 is applied as an ISDN service provided by a telecommunications carrier.

Next, the file transfer operation will be described. FIG. 2 is a sequence diagram for explaining the file transfer operation in the file transfer system. In addition, PC
The operation in which the user of 1A starts the FTP client software (S / W) in the PC 1A and downloads the file from the FTP server 7 will be described.

When the user requests the file transfer from the FTP server 7 with the FTP client software in the PC 1A, the packet data of the FTP request is sent to the PC 1A.
To the dial-up router 10 (step ST1).

In the dial-up router 10, FTP is used.
The request packet data is sent to the route control unit 12 through the LAN I / F unit 11. The route control unit 12 is the PC 1
When the packet data of the FTP request from A is received, the IP address of the packet data is read, and the destination is recognized as the FTP server 7 based on the preset information of the destination. Then, the route control unit 12
A line connection instruction is issued to the line I / F unit 15.

Upon receiving the line connection instruction from the route control unit 12, the line I / F unit 15 uses one B channel of the ISDN line 4 to dial the FTP server 7 (that is, the dial-up router 20). Dial transmission is performed by transmitting a signal (step ST2).

The dial signal sent from the dial-up router 10 is sent to the dial-up router 20 via the ISDN line 4 and the exchange 5. When dial-up router 20 responds to the dial signal (step ST3), one B-channel line of ISDN line 4 (of 23 B-channels) is connected between dial-up routers 10 and 20.

The dial-up router 10 responds to the dial-up router 20 of the other party, and
When the B channel line of the book is connected, the packet data of the FTP request from the PC 1A is sent to the FTP server 7 (step ST4). Dial-up router 2
0 is the FTP sent from the dial-up router 10.
When the request packet data is received, the packet data is transmitted to the FTP server 7 by selecting a route. As a result, the packet data of the FTP request from the PC 1A reaches the FTP server 7.

The FTP server 7 uses the FTP from the PC 1A.
By receiving the request packet data, PC1A
The FTP control connection is established between the FTP server 7 and the FTP server 7, and the PC 1A can perform the FTP communication with the FTP server 7. Here, an example of the control command and the response message using the FTP control connection is shown in FIG.

To log in to the FTP server 7, the user inputs a password from the PC 1A and sends it to the FTP server 7 (step ST5). FTP server 7
Receives the password sent from PC1A,
User authentication is performed based on the password (step ST6), and the user is permitted to log in to the server (step ST7).

After logging in to the FTP server 7, the user designates a file in the FTP server 7 from the PC 1A and issues a GET command (step ST8). Figure 3
In the above example, a GET command (get pub) is issued by designating a file (tcpbook tar bookfile).
Upon receiving the GET command sent from the PC 1A, the FTP server 7 notifies (sends) the capacity of the file designated by the GET command to the PC 1A with a response message (step ST9). In the example of FIG. 3, the underlined (77897088 bytes) is the file size.

At this time, the protocol analysis unit 13 of the dial-up router 10 monitors the packet data passing through the route control unit 12 and checks the response message from the FTP server 7. Therefore, the protocol analysis unit 13 checks the response message notified from the FTP server 7 and detects the file size in the response message (step ST10). Then, the protocol analysis unit 13 notifies the optimum communication channel number calculation unit 14 of the detected file capacity.

The optimum communication channel number calculation unit 14 calculates the optimum number of communication channels by performing the following calculation from the file size notified from the protocol analysis unit 13 (step ST11). First, using the file capacity, the file transfer time T is calculated by the following calculation formula (1).
(Time required to transfer the entire file) is required.

[0041]   File transfer time T (sec) = file capacity F (bits) / {used communication c h number N × 6400 (bits / sec)} (1)

In this calculation formula (1), the transfer rate (speed) of one B channel of the ISDN line 4 is set to 64.
000 bps, the number of communication channels (ch) used for file transfer is N (N is 1 to 23), and the capacity of the file transferred from the FTP server 7 is F.

Next, using the file transfer time T, the communication charge C required for the file transfer when the number N of communication channels is used is obtained by the following calculation formula (2).

[0044] Communication charge C = (T * a) × b × N ... (2)

In this calculation formula (2), the unit time of charging determined by the communication carrier is a (sec), and the charging fee per unit time of the charging is b (yen). In addition, the calculation of T * a represents an integer obtained by dividing T by a and raising the first decimal place.

As the number N of communication channels in the equation (2), for example, as shown in FIG. 4, the minimum number of channels preset in association with the file capacity F is substituted. The reason why the minimum number of channels is substituted for the number of communication channels N is as follows.

If the number N of communication channels that minimizes the communication charge C is simply calculated by the equation (2), the number N of communication channels may be too small. In this case, the communication charge C is the minimum amount, but the file transfer time T may be significantly long. If the file transfer time T becomes long,
The waiting time of the user also becomes long. Therefore, even if the communication charge C is sacrificed to some extent, it is necessary to secure the file transfer time T shortened to some extent. Therefore, the minimum number of channels as shown in FIG. 4 is set as the number of communication channels N.

Under the above conditions, the optimum communication channel number calculation unit 14 calculates the communication channel number N such that the communication charge C obtained by the calculation formula (2) becomes the minimum amount, and the communication channel number is calculated. Determine N as the optimal number of communication channels. The optimum communication channel number calculation unit 14 calculates the optimum communication channel number, and as a result, when there are a plurality of communication channels having the minimum communication charge C, the file transfer time T
In order to shorten the maximum number of communication channels, the number of communication channels with the largest number is determined as the optimum number of communication channels.

The optimum communication channel number calculation unit 14 notifies the calculated optimum communication channel number to the line I / F unit 15. The line I / F unit 15 disconnects the connected line once the optimum communication channel number is notified from the optimum communication channel number calculation unit 14 (step ST12). This allows
One B channel line of the ISDN line 4 is released. Immediately thereafter, the line I / F unit 15 determines that the optimum communication channel
B of the optimum number of communication channels notified from the number calculation unit 14
Dial transmission is performed by transmitting a dial signal from the FTP server 7 (that is, the dial-up router 20) using the channel (step ST13).

When the dial-up router 20 responds to the dial signal (step ST14), the B channel line having the optimum number of communication channels of the ISDN line 4 (of 23 B channels) is established between the dial-up routers 10 and 20. Connected.

After that, the FTP server 7 transfers the file designated by the GET command from the PC 1A to the PC 1A using the B channel line having the optimum number of communication channels (step ST15). PC1A is FT
When all the files from the P server 7 are transferred and the files are saved, the dial-up router 10 is notified of the end of the file transfer (step ST16).

The line I / F unit 15 of the dial-up router 10, when notified of the end of the file transfer from the PC 1A, disconnects all the B channels of the optimum number of communication channels of the ISDN line 4 (step ST17). As a result, all the B-channel lines having the optimum number of communication channels are released.

Although the PC 1A is configured to notify the dial-up router 10 of the end of the file transfer, the present invention is not limited to this, and the FTP server 7 notifies the dial-up router 20 of the end of the file transfer. The dial-up router 20 may be configured to disconnect the line.

As described above, in the first embodiment, the protocol analysis unit 13 causes the FT which passes through the route control unit 12.
The response message from the P server 7 is checked, the file capacity in the response message is detected, and the optimum communication channel
The number calculation unit 14 calculates the optimum number of communication channels according to a predetermined calculation formula based on the file capacity detected by the protocol analysis unit 13, and the line I / F unit 15 calculates the optimum communication channel number calculation unit 14. The dial-up line connection is performed with the optimum number of communication channels, and the file transfer from the FTP server 7 is performed using the line with the optimum number of communication channels. Therefore, when the file transfer is performed, the file transfer time T can be shortened and the communication charge C of the ISDN line 4 can be reduced at the same time.

Further, the optimum communication channel number calculation unit 14 calculates the file transfer time T by the predetermined calculation formula (1) based on the file capacity F, and based on the file transfer time T, the predetermined calculation formula (2 ), The number of communication channels that minimizes the communication charge C is determined as the optimum number of communication channels. Therefore, it is possible to simply and reliably calculate the optimum number of communication channels for file transfer for the user.

By setting a minimum number of channels in advance as the number of communication channels calculated as the optimum number of communication channels, it is possible to secure a minimum shortened file transfer time T and to communicate. Charge C
It is possible to realize a low price.

Embodiment 2. In the first embodiment, F
Although the number of communication channels is controlled when the file is downloaded from the TP server 7, the number of communication channels is not limited to this, and the number of communication channels is controlled when the file is uploaded from the FTP server 7. It doesn't matter. Even in this case, it is possible to simultaneously shorten the file transfer time when the file is transferred and reduce the communication charge of the ISDN line 4.

Further, when the protocol analysis unit 13 detects the file size from the packet data of the response message transferred from the FTP server 7, the file size can be obtained (known) in advance by some means. It is possible to control the number of communication channels.
Also in this case, it is possible to realize the reduction of the file transfer time when the file is transferred and the reduction of the communication charge of the ISDN line 4 at the same time.

[0059]

As described above, according to the present invention, when a dial-up router connected to a charged line consisting of a LAN and multiple channels receives packet data of a file transfer request from a terminal on the LAN side to a server,
Performs line connection processing of the billed line to the server, detects server access processing that sends packet transfer request packet data to the server for access, and detects the file size notified before the file is transferred from the server File capacity detection processing, optimum communication channel number calculation processing that calculates the optimum communication channel number according to a predetermined calculation formula based on the file capacity detected by the file capacity detection processing, and optimum communication channel of the billed line to the server In addition to performing a number of line connection processes, a file transfer process of sending files transferred from the server by the line having the optimum number of communication channels to the terminal is provided. Therefore, at the time of file transfer, it is possible to realize the reduction of the file transfer time and the reduction of the communication charge of the chargeable line at the same time.

Further, according to the present invention, when the dial-up router connected to the chargeable line composed of the LAN and the multi-channel receives the packet data of the file transfer request to the FTP server from the terminal on the LAN side, the FT is performed.
Server access processing for performing line connection processing of the charged line to the P server, transmitting packet data of the file transfer request to the FTP server for access, and FT
Based on the file size detection processing that analyzes the protocol of the response message notified before the file is transferred from the P server and detects the file size in the response message, and the file size detected in the file size detection step. Then, the optimum communication channel number calculation step of calculating the optimum communication channel number according to a predetermined calculation formula, and the line connection processing of the optimum communication channel number of the billed line to the server are performed, And a file transfer process for sending the transferred file to the terminal. Therefore, in addition to the above effects, since the file size is described in the response message notified from the FTP server, the file size can be reliably detected from the description.

Further, according to the present invention, in the optimum communication channel number calculating step, the first communication channel number is calculated based on the file size.
Since the file transfer time is calculated by the formula, and the number of communication channels that minimizes the communication charge derived by the second formula is determined as the optimum number of communication channels based on the file transfer time. It is possible to easily and reliably calculate the optimum number of communication channels for file transfer for the user.

Further, according to the present invention, the optimum number of communication channels calculated in the optimum communication channel number calculating step is set to the minimum number of channels in advance according to the file size, so that the minimum number of channels is set in advance. Along with being able to secure a shortened file transfer time,
It is also possible to reduce the communication charge.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a dial-up router of the present invention.

FIG. 2 is a sequence diagram for explaining a file transfer operation in the file transfer system.

FIG. 3 is a diagram showing an example of a control command and a response message using an FTP control connection.

FIG. 4 is a diagram showing a relationship between a file capacity and the number of communication channels.

FIG. 5 is a system configuration diagram showing a configuration of a file transfer system using a dial-up router.

[Explanation of symbols]

1A, 1B PC (terminal) 4 ISDN line (charged line) 7 FTP server (server) 10 Dial-up router 11 LAN I / F unit (LAN interface unit) 12 Route control unit 13 Protocol analysis unit (file capacity detection unit) 14 Optimal communication channel number calculation unit (optimal communication channel number calculation unit) 15 Line I / F unit (line interface unit)

Claims (8)

[Claims] 1. When a dial-up router connected to a charged line composed of a LAN and multiple channels receives packet data of a file transfer request from the terminal on the LAN side to the server, the charged line to the server is connected. A server access step of performing line connection processing and transmitting the packet data of the file transfer request to the server for access, and the file of the file notified before the file is transferred from the server by the dial-up router. A file capacity detecting step of detecting a capacity; and an optimum communication channel number calculation for calculating an optimum communication channel number according to a predetermined calculation formula based on the file capacity detected by the dial-up router in the file capacity detecting step. Step and above A file transfer step of performing line connection processing of the optimum number of communication channels of the billed line to the server by the earl up router and sending the file transferred from the server to the terminal by the line of the optimum communication channel number. And a method for controlling the number of communication channels. 2. When a dial-up router connected to a charged line composed of a LAN and multiple channels receives packet data of a file transfer request from the terminal on the LAN side to the FTP server, the charged charge is applied to the FTP server. The line connection processing of the line is performed and the packet data of the file transfer request is transmitted to the FT.
A server access step of transmitting to a P server for access, analyzing a protocol of a response message notified by the dial-up router before the file is transferred from the FTP server, and determining a capacity of the file in the response message. And a file capacity detecting step for detecting an optimum communication channel number according to a predetermined formula based on the file capacity detected by the dial-up router in the file capacity detecting step. And the dial-up router performs line connection processing of the optimum communication channel number of the billed line to the server and sends the file transferred from the FTP server to the terminal by the line of the optimum communication channel number. Number of communication channel control method is characterized in that a Airu transfer step. 3. In the optimum communication channel number calculating step, the file transfer time is calculated by the first calculation formula based on the file capacity, and the communication charge derived by the second calculation formula is calculated based on the file transfer time. The communication channel number control method according to claim 1 or 2, wherein the number of communication channels that minimizes is determined as the optimum number of communication channels. 4. The optimum number of communication channels calculated in the optimum communication channel number calculating step is set to a minimum number of channels in advance according to the file capacity. 4. The method for controlling the number of communication channels according to any one of 3. 5. A LAN interface unit for connecting a LAN, and a chargeable line comprising multiple channels are connected to form the LAN.
When transmitting the packet data of the file transfer request from the terminal on the side to the server, the connection process of the chargeable line to the server is performed, and the packet data of the file transfer request is transmitted to the server for access. A line interface unit that performs line connection processing for the optimum number of communication channels of the billed line to the server when a file is transferred from the server; and a line interface unit that is provided between the LAN interface unit and the line interface unit and set in advance. A route control unit that checks the IP address of the packet data sent from the LAN side and the billed line side to select a route based on the obtained information, and monitors the packet data that passes through the route control unit. Then
A file capacity detection unit that detects the capacity of the file that is notified before the file is transferred from the server, and the optimum capacity according to a predetermined calculation formula based on the capacity of the file that is detected by the file capacity detection unit. A dial-up router comprising: an optimum communication channel number calculation unit that calculates the number of communication channels. 6. A LAN interface unit for connecting a LAN, and a chargeable line comprising multiple channels are connected to said LAN.
When transmitting the packet data of the file transfer request from the terminal on the side to the FTP server, the line connection processing of the charged line to the FTP server is performed, and the packet data of the file transfer request is transmitted to the FTP server for access. Between the LAN interface unit and the line interface unit, which performs line connection processing for the optimum number of communication channels of the billed line to the FTP server when transferring a file from the FTP server. A route control unit provided to check the IP address of the packet data sent from the LAN side and the charged line side based on preset information and to select a route; and to pass the route control unit. Monitor the packet data to
A protocol analysis unit that analyzes the protocol of the response message notified before the file is transferred from the FTP server, and detects the capacity of the file in the response message; and a file of the file detected by the protocol analysis unit. A dial-up router comprising: an optimum communication channel number calculation unit that calculates the optimum communication channel number based on a capacity according to a predetermined calculation formula. 7. The optimum communication channel number calculation unit,
Calculate the file transfer time by the first formula based on the file capacity, and based on the file transfer time,
7. The dial-up router according to claim 5 or 6, wherein the number of communication channels that minimizes the communication charge derived by the second calculation formula is determined as the optimum number of communication channels. 8. The minimum number of channels is preset as the optimum number of communication channels calculated by the optimum number of communication channels calculation unit according to the capacity of the file. Any one of seven
Dial-up router described in section.