JPH10336243A - Inter-dialup router communication system and inter-dialup router communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inter-dialup router communication system and an inter-dialup router communication method that are executed through a terminal dialup IP service by an Internet service provider ISP at. a low communication cost without direct communication between a transmission terminal and a reception terminal. SOLUTION: A communication system between inter-dialup routers has a means by which one B channel 11 in two B channels 11, 12 of the ISDN is used to allow routers to make direct communication and which controls the other B channel 12 and exchanges information as to IP addresses acquired from ISPs 14, 15 of both the routers and as to IP address of a communication terminal. Furthermore, the other B channel 12 has a means that conducts communication via an ISP as an exclusive channel for data transmission reception.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system between dial-up routers and a communication method between dial-up routers. More particularly, the present invention relates to a terminal-type dial-up IP service provided by an Internet service provider (hereinafter referred to as an ISP). TECHNICAL FIELD The present invention relates to a communication system between dial-up routers and a communication method between dial-up routers to enable economical communication in the communication of the present invention.

[0002]

2. Description of the Related Art Conventionally, when there are two networks where a plurality of communication terminals are connected by LAN, router devices are prepared on each network, and the router devices use the B channel of the ISDN line. Direct connection, 2
A method of performing data communication between communication terminals between points is used.

For example, Japanese Patent Application Laid-Open No. 4-326226 discloses that the B channel of an ISDN terminal is directly connected to the B channel of an ISDN-LAN connection terminal, and the ISD
A technique is described in which N terminals and LAN terminals connected to ISDN-LAN terminals communicate data.

Generally, means for indirectly connecting router devices include an ISP and a LAN type dial-up IP.
A service is contracted, and communication is performed using an IP address fixedly assigned in advance by the ISP.

[0005]

Problems with the prior art are as follows.
The communication cost is very high.

[0006] Since the routers are directly connected using the B channel, there is a problem that the communication cost for a certain amount of communication data increases as the distance between the communication terminals becomes longer. Also, ISP LAN type dial-up IP
The service also has a problem that the contract fee for the ISP is expensive.

An object of the present invention is to provide a communication system between dial-up routers and a communication method between dial-up routers through a terminal type dial-up IP service of an ISP having a low communication cost without directly transmitting and receiving terminals. Is to provide.

[0008]

A communication system between dial-up routers according to the present invention includes a transmitting router, a receiving router, a transmitting terminal connected to a transmitting router, a receiving terminal connected to a receiving router, and an ISDN. And the sending router is IS
ISPa, which is an access point of an Internet service provider connectable through the DN, ISPb, which is an access point of the Internet service provider which the receiving router can connect through ISDN,
A communication system between dial-up routers composed of the Internet connected through SPa and ISPb, wherein a transmission router collects an IP address of a transmission terminal connected to the transmission router and uses the IP address of the transmission terminal as a terminal address. Creates a local host table for the sending router to be registered, and the receiving router collects the IP address of the receiving terminal connected to the receiving router, and
Create a local host table of the receiving router that registers the address as the terminal address, transmit the transmitting data from the transmitting terminal to the transmitting router, and at the beginning of the transmitting data, there is an Ethernet header that is the data link layer, Subsequently, there is an IP header of a network layer. The source IP address of the IP header indicates the IP address of the transmitting terminal, the destination IP address indicates the IP address of the receiving terminal, and then the transport layer. When the transmission data transmitted from the transmission terminal arrives at the transmission router, the transmission router transmits the ISDN.
A call is made to the receiving router using the control B channel, which is the first B channel, and the receiving router accepts the incoming call and confirms the connection with the transmitting router. The receiving router obtains a first IP address of the control B channel, the receiving router makes a call to ISPb to obtain a second IP address of the controlling B channel, and the transmitting router transmits the first IP address and the transmitting router. The local host table of the transmitting router becomes the remote host table of the receiving router, and the receiving router transmits the second IP address and the local host table of the receiving router to the transmitting router. The local host table of the receiving router becomes the remote host table of the transmitting router, where the control B channel is used. Is no longer needed, the sending router performs an IP header conversion process on the transmission data from the sending terminal, and the IP header conversion process uses the IP address of the sending terminal in the local host table of the sending router. -Refer to the entry and send the IP of the sending terminal
The terminal address is derived from the address and used as the source terminal address. The IP address entry of the receiving terminal in the remote host table of the transmitting router is referred to,
The terminal address is derived from the address and used as the destination terminal address, then the source IP address is replaced with the first IP address, the destination IP address is replaced with the second IP address, and then the source terminal address and the transmission This is processing for adding the destination terminal address to the option field of the IP header. The transmitting router transmits the transmission data after the IP header conversion processing to the data transfer B channel which is the second B channel of the ISDN. The transmission data after the conversion processing is received by the receiving router, and the receiving router performs an IP header conversion processing on the transmission data from the transmission router. The IP header conversion processing is performed in the remote host table of the receiving router. Referring to the IP address entry of the transmitting terminal, the IP address of the transmitting terminal is obtained from the source terminal address. A new transmission source terminal address out come,
IP of the receiving terminal in the local host table of the receiving router
With reference to the address entry, the IP address of the receiving terminal is derived from the destination terminal address as a new destination terminal address, and then the source terminal address and the destination terminal address included in the IP header are deleted. Replace the source IP address with the new source IP address, and
This is a process of replacing the address with the new destination IP address. The transmission data after the IP header conversion process is restored to the original transmission data output by the transmission terminal, and the reception terminal can receive the data, and the communication is completed. After completion, the transmitting router has a means for disconnecting the data transfer B channel between the transmitting router and the receiving router by detecting no communication from the transmitting terminal.

The communication method between the dial-up routers according to the present invention includes a transmitting router, a receiving router, a transmitting terminal connected to the transmitting router, a receiving terminal connected to the receiving router, an ISDN, and an ISDN. ISPb which is an access point of an Internet service provider which can be connected through ISDN, ISPb which is an access point of an Internet service provider which can be connected through an ISDN, ISPa and ISP
b. A communication method between dial-up routers using a communication system between dial-up routers constituted by the Internet connected through b, wherein the transmitting router collects an IP address of a transmitting terminal connected to the transmitting router,
A local host table of the transmitting router that registers the IP address of the transmitting terminal as the terminal address is created, the receiving router collects the IP addresses of the receiving terminals connected to the receiving router, and registers the IP address of the receiving terminal as the terminal address. Creates a local host table for the receiving router, sends the sending data from the sending terminal to the sending router, and at the beginning of the sending data is an Ethernet header that is the data link layer, followed by the IP header of the network layer The source IP address of the IP header indicates the IP address of the transmitting terminal, the destination IP address indicates the IP address of the receiving terminal, followed by a header in the transport layer, Next, there is actual data, and when the transmission data transmitted from the transmission terminal arrives at the transmission router, the transmission router Using the control B channel, which is the first B channel of SDN, a call is made to the receiving router, and the receiving router accepts the incoming call and confirms the connection with the transmitting router. To obtain the first IP address of the control B channel, the receiving router makes a call to ISPb to obtain the second IP address of the control B channel, and the transmitting router sets the first I
P address and local host table of sending router,
Sends to the receiving router, the local host table of the sending router becomes the remote host table of the receiving router, and the receiving router sends the second IP address and the local host table of the receiving router to the transmitting router, and the local host of the receiving router The table becomes a remote host table of the transmitting router, where the control B channel is no longer needed, and is disconnected. The transmitting router performs an IP header conversion process on the transmission data from the transmitting terminal, In the conversion process, the terminal address is derived from the IP address of the transmitting terminal by referring to the IP address entry of the transmitting terminal in the local host table of the transmitting router, and is used as the source terminal address. Refer to the address entry, and The terminal address is derived from the IP address and set as the destination terminal address, then the source IP address is replaced with the first IP address, the destination IP address is replaced with the second IP address, and then the source terminal address and This is a process of adding a destination terminal address to an option field of an IP header.
The transmission data after the conversion processing of the IP header is transmitted to the second
The transmission data after the IP header conversion processing is received by the receiving router, and the receiving router performs the IP header conversion processing on the transmission data from the transmitting router. Then, the IP header conversion process refers to the IP address entry of the transmitting terminal in the remote host table of the receiving router, derives the IP address of the transmitting terminal from the source terminal address, sets it as the new source terminal address, and Referring to the IP address entry of the receiving terminal in the host table,
Deriving the IP address of the receiving terminal from the destination terminal address as a new destination terminal address, then deleting the source terminal address and destination terminal address contained in the IP header, and then newly transmitting the source IP address This is a process of replacing the source IP address with the source IP address and replacing the destination IP address with the new destination IP address. The transmission data after the IP header conversion process is restored to the original transmission data output by the transmission terminal and received by the reception terminal. Is completed, and the communication is completed. After the communication is completed, the transmitting router detects no communication from the transmitting terminal, and thus the B channel for data transfer between the transmitting router and the receiving router is disconnected.

That is, in the communication system between the dial-up routers of the present invention, the router devices directly communicate with each other using one of the two B channels of the ISDN, and control and control of the other B channel. , The IP address obtained from the ISP of both routers and the I
It has means for exchanging information about P address information.

The other B channel has means for performing communication via the ISP as a dedicated channel for transmitting and receiving data.

Further, the present invention has the following IP address conversion means for enabling communication using an ISP of a terminal type dial-up IP service for allocating a dynamic IP address to a router device. In the communication between the communication terminal a and the communication terminal b located at two remote locations, the router device a at the same position as the communication terminal a receives the data transmitted by the communication terminal a.
Converts the source IP address of the IP header into an IP address acquired by the router device a that transmits the data at the time of the 1SP connection, and converts the destination IP address into the IP address acquired by the router device b that receives the data at the time of the ISP connection. ,
The source IP address information and the destination IP address information transmitted by the communication terminal a are added to the IP header, and the ISDN
Send to Then, the router device b received from the ISDN adds the IP header source I to the received data.
The P address is converted to the original source IP address transmitted by the communication terminal a by referring to the source IP address information added above, and the destination IP address information obtained by adding the destination IP address to the IP header is The data is converted to the original transmission destination IP address transmitted by the communication terminal a with reference to the data, restored to the data transmitted by the communication terminal a, and can be received by the communication terminal b.

According to the above means, when one of the communication terminals transfers data, the routers directly communicate with each other using one B channel of the ISDN, and both routers establish a connection to the ISP. To the IP of the communication terminal
Exchanges the address information and the IP address obtained from the ISP. After exchanging the information, the B channel is disconnected, so that the direct communication between the router devices can be completed in a short time.

Next, actual data transmission / reception is performed on the other B channel connected to the ISP. At this time, the IP address of the data IP header is set to the ISP of the router device.
By converting to the IP address obtained from, the partner router device can be specified,
There is no need to allocate a fixed IP address like a type dial-up IP service. In addition, the I
By adding a unique number indicating the IP address of the source and destination communication terminals to the P header, data can be transmitted to a specific communication terminal connected to the router device.

[0015]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a network configuration of an ISDN and a LAN to which a communication system between dial-up routers according to the present invention is applied.

Referring to FIG. 1, an embodiment of the present invention comprises a transmitting router 28, a receiving router 27, a transmitting terminal 1 connected to the transmitting router 28, and a receiving terminal 17 connected to the receiving router 17. , ISDN13 and sending router 2
8 is an ISPal4 (access point of an Internet service provider) connectable through ISDN;
ISPb to which the receiving router 27 can connect via ISDN
15 (access point of an Internet service provider) and the Internet 16 connected through ISPal4 and ISPbl5.

The transmitting terminal 1 and the receiving terminal 17 are communication terminals such as a personal computer and a work station which implement a transmission control protocol / internet protocol (hereinafter, referred to as TCP / IP) which is a protocol for Internet communication. . The transmitting terminal 1 operates as a data transmitting side such as a file transfer protocol application operating on TCP / IP, and the receiving terminal 17 operates as a data receiving side such as a file transfer protocol application.

Next, the configuration of the transmitting router 28 and the receiving router 27, which is a feature of the present invention, will be described with reference to FIG.

The transmission router 28 includes a LAN interface unit 3, a routing control unit 4, an IP header conversion unit 5,
, An SDN interface unit 6, a terminal address collection unit 7, a local host table 8, a remote host table 9, and a channel control unit 10.

The LAN interface unit 3 converts the data transmitted from the transmitting terminal 1 into TCP / IP data as shown in FIG.
It functions to terminate the Ethernet of the first and second layers of the Internet hierarchy model 30 and pass it to the routing control unit 4.

The terminal address collection unit 7 collects in advance the IP address assigned to the transmission terminal 1 connected to the LAN interface unit 3 and stores it in the terminal IP address field in the table format of the local host table in FIG. A unique number called a pair of terminal addresses is assigned to the terminal IP address.

The routing control unit 4 receives the data from the LAN interface unit 3 and receives the data from the TCP / 1 shown in FIG.
Termination of the third layer IP of the P Internet hierarchical model 30 is performed. Further, based on the destination IP address indicated in the format of the IP header in FIG.
And a process of instructing the channel control unit to make a call to ISDN13.

In the channel control unit 10, the ISDN interface unit 6 responds to the request of the routing control unit 4.
Control the outgoing call of the B channel. Before transferring the packet to the opposing router, the control B channel 11 is directly connected to the control B channel 11 of the opposing router to control the outgoing call of the data transfer B channel 12 and to control the IP of the IP header conversion unit 5. IS of receiving router 27 required for header conversion
The IP address acquired from Pbl5 and the local host table 24 are acquired. Further, it transmits the IP address and the local host table 8 obtained from its own ISP to the receiving router 27.

The IP header converter 5 adds the IP header of the data transferred from the routing controller 4 to the IP header.
The terminal addresses of the local host table 8 and the remote host table 9 referenced from the source IP address and the destination IP address of the header are added to the IP header. Further, the source IP address and the destination IP address of the IP header are obtained by using the ISPal4
Address and the receiving router 27 are ISPb
The IP address is converted to the IP address obtained from 15.

The ISDN interface unit 6 converts the data from the IP header conversion unit 5 into the first layer ISDN and the second layer point-to-point protocol (hereinafter referred to as PPP) of the TCP / IP Internet layer model 30 of FIG. ) And transfer to ISDN13. Also,
Calls can be made to the two B channels of ISDN in response to a request from the channel control unit 10.

In the local host table 8, its own L
The IP address of the terminal connected to the AN interface unit 3 and the terminal address allocated by the terminal address collection unit 7 are stored.

The remote host table 9 stores the IP address and the terminal address of the LAN interface unit 19 of the receiving router 27 obtained from the receiving router 27 by the channel control unit 10.

The receiving router 27, like the transmitting router 28, includes a LAN interface 19, a routing control unit 20, an IP header conversion unit 21, an ISDN interface unit 22, a terminal address collection unit 23, and a local host table 24. And a remote host table 25,
A channel control unit 26 is provided.

In the ISDN interface section 22, IS
The data from the DN interface unit 22 is transmitted to T in FIG.
First layer IS of CP / IP Internet hierarchy model 30
The DN terminates the second layer point-to-point protocol (hereinafter, referred to as PPP) and transfers it to the IP header conversion unit. In addition, for an incoming call from two ISDN B channels, the information is reported to the channel control unit 26.

In response to a request from the ISDN interface unit 22, the channel control unit 26 controls permission for incoming calls on the B channel of one SDN. Also, it is directly connected to the control B channel 11 of the transmission router 28, and in response to a request from the channel control unit 10 of the transmission router 28, the data transfer B channel 11
Control of outgoing call of channel 12, sending router 28 is 1SP
The IP address acquired from al4 and the local host table 8 of the transmission router 8 are acquired. Also, their own IS
The IP address and the local host table 24 acquired from Pbl5 are transmitted to the transmission router 28.

In the IP header conversion unit 21, the local host table 24 referred to from the source terminal address and the destination terminal address of the IP header of the data shown in FIG.
Then, the IP address of the remote host table 25 is extracted, replaced with the source IP address and the destination IP address of the IP header, and transferred to the routing control unit 20.

The routing controller 20 receives the data from the IP header converter 21 and terminates the third layer IP of the TCP / IP Internet layer model 30 shown in FIG. Further, it determines whether or not to send data to the receiving terminal 17 based on the destination IP address shown in the format of the IP header in FIG.

The LAN interface unit 19 converts the data transmitted from the routing control unit 20 into the data shown in FIG.
Of the TCP / IP Internet Hierarchy Model 30
Terminate the Ethernet of the layer and the second layer, and
Work to pass to 7.

The terminal address collecting unit 23 collects in advance the IP address assigned to the receiving terminal 17 connected to the LAN interface unit 19 in the same manner as the terminal address collecting unit 7 of the transmitting router 28, and It is stored in a terminal IP address field in the table format of the host table, and a unique number called a pair of terminal addresses is assigned to the terminal IP address.

In the local host table 24, similarly to the local host table 8 of the transmission router 28, the IP address of the terminal connected to its own LAN interface unit 19 and the terminal address allocated by the terminal address collection unit 23 are stored. I have.

In the remote host table 25, the IP address and the terminal address of the terminal connected to the LAN interface unit 3 of the transmission router 28 acquired from the transmission router 28 by the channel control unit 26 are stored.

Next, the flowcharts of FIGS.
With reference to a sequence chart of 14, a description will be given of a communication method of the transmission router 28 and the reception router 27, which is a feature of the present invention, in the general data transfer on the TCP / IP between the transmission terminal 1 and the reception terminal 17.

The transmitting router 28 and the receiving router 27
Terminals 1, 1 connected to N interface units 3, 19
7 are collected, a table in which one IP address is assigned a unique terminal address as shown in FIG. 18 is created, and stored as a local address table in each router. IP of sending terminal 1
The address and the terminal address are stored in the local host table 8 of the transmission router 28 (Step Rl in FIG. 4).
The IP address and the terminal address of the receiving terminal 17 are stored in the local address table 24 of the receiving router 27 (Step Sl in FIG. 6).

First, the transmitting terminal 1 transmits a TCP connection request message to the receiving terminal 17 (step P in FIG. 2).
l). At this time, the format of the transmission data is shown in FIG.
Shown in According to this, the header of the data link layer is at the head of the data, followed by the IP header of the network layer. In the contents of the IP header, the IP address of the transmitting terminal 1 that has transmitted the data is indicated as the source IP address, and the 1P address of the receiving terminal 17 that is the transmission destination is indicated as the transmission destination 1P address. Next, there is a transport layer TCP header, followed by actual data.

The LAN interface unit 3 of the transmission router 28 that has received the data from the transmission terminal 1 transfers the data to the routing control unit 4. The routing control unit 4 determines that the destination IP address of the IP header is
7 is determined to be the receiving terminal 17 connected to
First, the data is temporarily stored (step R4 in FIG. 4).
It instructs the channel controller 10 to connect to the receiving router 27.

Upon receiving the instruction, the channel control unit 10 instructs the 1SDN interface unit to call the control B channel 11 to the receiving router 27. I was instructed
The SDN interface unit 6 performs a calling process to the receiving router 27 (step R5 in FIG. 4). The process of connecting the control B channel to the receiving router 27 is shown in steps B to C of FIG.

When the connection process is completed, the channel controller 10 checks the connection with the channel controller 26 of the receiving router 28 (step R7 in FIG. 4). The method of confirming the connection of the control B channel 11 uses a method called a three-way handshake, and the sequence is shown in steps C to D of FIG. According to the sequence, the channel control unit 10 of the transmission router 28 transmits a connection request message, and the channel control unit 26 of the reception router 27 that has received the message transmits a response message to the channel control unit 10 of the reception router 28. And
The channel control unit 10 that has received the response message further transmits a response confirmation message to the channel control unit 10. FIG. 17 shows a data format between the channel control unit 10 and the channel control unit 26. According to the data format, the data link layer uses PPP, the Internet layer uses IP, and the transport layer uses user datagrams (hereinafter referred to as UDP).
Use In the connection request message transmitted by the channel control unit 10, the message part is set to decimal "1", REQ / ACK is set to "1" indicating the request, and there is no data part. The response message transmitted by the channel control unit 26 indicates a connection request, and REQ / A
CK can take '2'. Also in this case, there is no data portion. Then, the response confirmation message returned by the channel control unit 10 to the channel control unit 26 responds in the same format as the response message returned by the channel control unit 26 to the channel control unit 10.

After confirming the connection of the control B channel 11, the transmitting router 28 and the receiving router 27
Channels are respectively ISPal4, ISPbl5
F, the connection is started (step R9 in FIG. 4, step S3 in FIG. 6). FIG. 1 shows a sequence in which a transmitting router 28 and a receiving router 27 connect a data transfer connection to an ISP.
Steps D to E of 0 are shown.

When the connection of the data transfer B channel 11 is completed, the ISDN of the transmitting router 28 and the receiving router 27
The interface units 6 and 22 attempt to connect the ISP to the data link layer by PPP (step R1 in FIG. 4).
1, step S9 in FIG. 6). When connecting to the ISP by the terminal type dial-up IP service, since a fixed IP address is not assigned to the transmission router 28 and the reception router 27, the Internet Protocol Control Protocol (hereinafter, referred to as IPCP) which is an option of PPP is used. To obtain an IP address from the ISP. P
Data link layer connection by PP to ICP by IPCP
The sequence until the P address is obtained is shown in steps F to G in FIG.

After completing the PPP connection and the acquisition of the IP address, the transmitting router 28 and the receiving router 27 exchange 1P addresses with each other through the control B channel (steps R13, R15, S15 in FIG. 5).
1, step Sl3). The IP address acquisition sequence is as shown in steps G to H in FIG.
From the IP address request message packet of the sending router 28, each other exchanges 1P addresses by a three-way handshake. The data format of the communication packet is as shown in FIG. 17, and the IP address acquired from the 1SP of the receiving router is placed in the data field of the response message of the IP address request of the transmitting router 28. The IP address obtained from the ISP of the transmitting router is placed in the response message of the receiving router 27 of the transmitting router 28 to the response.

Next, the transmitting router 28 and the receiving router 27 exchange their host tables through the control B channel in the same procedure as the exchange of the IP address (FIG. 5).
Step R14, Step R16, FIG. 7 Step Sl
2, step Sl4). The acquisition sequence of the local host table is as shown in steps H to I in FIG. 11, and the host tables are exchanged by a three-way handshake from the host table request message of the sending router 28. The data format of the communication packet is as shown in FIG. 17, and the local host table 24 of the receiving router 27 is placed in the data field of the response message packet of the local host table request of the transmitting router 28. The local host table 8 of the transmission router 28 is placed in a response message of the reception router 27 of the transmission router 28 to the response message. The exchanged local host tables are stored in the remote host tables 9 and 24 inside the transmission router 28 and the reception router 27.
Is stored as

Next, the channel control section 10 confirms the connection of the data transfer B channel 12 (step R in FIG. 5).
17, step S15 in FIG. 7). The connection confirmation sequence of the data transfer B channel 12 is shown in steps J to K of FIG. Describing this sequence, first, the transmitting router 28 transmits a connection message to the receiving router 27. Receiving router 27 that has received the message transmits a response message to the reception.
The transmitting router 28 that has received the response message from the receiving router 27 is established by a three-way handshake procedure of transmitting a response confirmation message to the response message. The packet format of the message uses the data format shown in FIG. 17, PPP is used for the data link layer, IP is used for the network layer, and UDP is used for the transport layer. In the case of a connection request, a '
Put '2' and put '1' in the REQ / ACK field. There is no data field.

Next, when the connection of the data transfer B channel 12 is confirmed, the connection of the control B channel 11 becomes unnecessary, and by the procedure shown in steps KL of FIG.
Disconnect from SDN13 (step R23 in FIG. 5, step S21 in FIG. 7).

After confirming the connection of the B channel 12 for data transfer, the routing controller 4 of the transmission router 28
The stored data of the transmission terminal 1 is converted into an IP header conversion unit 5
Pass the data to.

In the IP header converter 5 receiving the data,
The IP header is converted (step R1 in FIG. 5).
9), its operation will be described with reference to the flowchart of FIG. The packet sent to the IP header converter is shown in FIG.
9 is in the form of an IP header. The IP header conversion unit first retrieves the terminal address corresponding to the source IP address indicated in the IP header from the local host table 8 in the format shown in FIG. 18 and holds it as the source terminal address (step Tl in FIG. 8). ). Next, the terminal address corresponding to the transmission destination IP address indicated in the IP header is extracted from the remote host table 9 shown in FIG. 18 and is held as the transmission destination terminal address (step T2 in FIG. 8). Next, the source terminal address and the destination terminal address held earlier are listed in the option of the IP header format 32 in FIG. The option of the IP header is a field in which variable-length control data can be placed. The IP header format after placing the option is as shown in the option of the IP header in FIG. 20 (step T3 in FIG. 8). Next, the transmission source IP address is replaced by the 1P address acquired by the transmission router 28 from ISPal4 (step T4 in FIG. 8). Next, the destination IP address is replaced with the 1P address acquired by the receiving router 27 from the ISPb15 (step T5 in FIG. 8). Next, since the header length and the IP packet length of the original IP header are changed due to the above-described change of the IP header, the recalculation is performed and the results are replaced (step T in FIG. 8).
6). As the last processing in the IP address conversion unit, since the checksum of the TCP header shown in FIG. 16 matches the value of the IP header, the checksum is recalculated and replaced (step T7 in FIG. 8). When the IP header conversion process is completed, the IP header conversion unit sends the data to the ISDN interface unit.

The ISDN interface unit that has received the data packet adds a PPP header to the data packet, uses the B channel for data transfer, and uses the ISPbl4
(Step R20 in FIG. 5, steps L to
M). The packet format of the data at that time is as shown in FIG.

The data is sent to the ISDN of the receiving router 27 via the ISPbl4, the Internet 16, and the ISPb15.
The data is received by the interface unit 22. The ISDN interface unit that has received the data terminates the PPP, and
The data is transferred to the P header conversion unit 21.

Upon receiving the data, the IP header conversion unit 21
The IP header is converted (step S17 in FIG. 7).
The operation will be described with reference to FIG.

The IP header of the received data is the I header of FIG.
Although the format of the P header portion is used, first, an IP address corresponding to the destination terminal address indicated in the option of the IP header is extracted from the local host table 24 and set as a new destination IP address ( FIG. 9 step Ul). Next, an IP address corresponding to the source terminal address indicated in the option of the same IP header is extracted from the remote host table 25 and set as a new source IP address (step Ul in FIG. 9).
2). Next, the source terminal address and the destination terminal address added to the option of the IP header are deleted (step U3 in FIG. 9). Next, the destination IP address is replaced with the new destination IP address (step U4 in FIG. 9). Next, the source IP address is replaced with the new source IP address (step U5 in FIG. 9). Next, the IP header IP
The header length and the header checksum are calculated and replaced with the original values (step U6 in FIG. 9). Next, the checksum of the TCP header is calculated and replaced with the original value (step U7 in FIG. 9). When the above-described IP header conversion processing is completed, the packet is transferred to the routing control unit 20.

The routing controller 20 receiving the data
Determines whether to transfer from the transmission destination IP address of the IP header to the LAN interface unit 19. If it is determined that the data should be transferred, the LAN interface unit 1
9 to transfer the data.

Next, upon receiving the data, the LAN interface unit 19 adds an Ethernet header and transmits the data to the receiving terminal 17 (step S18 in FIG. 7). The format of the data at that time is as shown in FIG. 19, and is the same as the format of the data immediately after being transmitted from the transmitting terminal 1.

Through the above series of operations, the TCP connection request data arrives from the transmitting terminal 1 to the receiving terminal 17.

In the following, the remaining data transfer procedure of the terminal will be described, which is assumed to include the above-described operations of the transmitting router 28 and the receiving router 27.

Next, the TCP connection request data is received.
7 will be described according to steps U to M in FIG. The receiving terminal 17 waiting for the reception of the TCP connection request answers the request,
An ACK packet corresponding thereto is transmitted (step Q2 in FIG. 3). Upon receiving the ACK from the receiving terminal, the transmitting terminal 1 transmits a TCP connection status message to confirm the usability of the TCP connection (step P3 in FIG. 2).

Next, the procedure for the transmitting terminal 1 to continuously transmit TCP data to the receiving terminal 17 up to the final data is shown in FIG.
A description will be given according to Steps N to O of No. 3. The transmitting terminal 1 transmits the first TCP data (Step P4 in FIG. 2). The transmission router 28 converts the IP header in the router and transmits the data to the reception router 27 via the data transfer B channel 12 (steps R19 and R2 in FIG. 5).
0). The receiving router 27 that has received the TCP data,
The IP address conversion in the router is performed, and the receiving terminal 17
(Steps S17, S17 in FIG. 7)
8). The receiving terminal 17 having received the data packet,
An ACK for the received TCP data is transmitted to the transmitting terminal 1 (step Q6 in FIG. 3). The ACK data is first received by the receiving router 27, performs the same operation as the IP header conversion of the transmitting router 28 in the receiving router, and transmits the ACK data to the transmitting router 28. The transmitting router 28 having received the ACK data performs the same operation as the conversion of the IP head of the receiving router 27 and transmits the data to the transmitting terminal 1. Since the transmitting terminal 1 that has confirmed the ACK from the receiving terminal 17 (step P10 in FIG. 2) has not transmitted all the TCP data (step P5 in FIG. 2), the transmitting terminal 1 transmits the second data next. (Step P4 in FIG. 2). The transmitting router 28 and the receiving router 27 that have received the TCP data perform the above-described TCP data transmission processing, and the receiving terminal 17 that has received the data transmits an ACK to the transmitting terminal 1. Also for this ACK data, the receiving router 27 and the transmitting router 27 perform the same ACK data transmission processing as described above. Subsequently, the transmitting terminal 1 and the receiving terminal 17 transmit data up to the final data in the same procedure.

Next, the transmitting terminal 1 transmits all the transmitted TCP data.
The procedure from the transmission of the data to the completion of the disconnection from the TCP disconnection request to the completion of the disconnection will be described with reference to steps OP of FIG. The transmitting terminal 1 that has transmitted all TCP data is TCP
A disconnection request is transmitted (step P6 in FIG. 2). Upon receiving the TCP disconnection request, the receiving terminal responds to the TCP disconnection request with A
CK is transmitted (step Q7 in FIG. 3). During this time, the transmission router 28 and the reception router 27 perform the same IP header conversion processing as the above-described TCP data transmission and ACK transmission. Transmission terminal 1 that has received the TCP disconnection request ACK
Waits for the next reception of the TCP disconnection from the receiving terminal (step P8 in FIG. 2). The transmitting terminal 1 that has received the disconnection completion packet from the receiving terminal 17 (step 8 in FIG. 2) transmits a TCP disconnection request completion to the receiving terminal 17 (step P9 in FIG. 2). In the receiving terminal 17, the T
Upon receiving the completion of the CP disconnection request, the communication between the terminals is terminated.
The receiving terminal 17 is again in an idle state of waiting for receiving a TCP connection request (step Q1 in FIG. 3). Also in the communication during this time, the transmission router 28 and the reception router 27 perform the same IP header conversion processing as the above-described TCP data transmission and ACK transmission.

When the transmission of the TCP data from the transmitting terminal 1 is completed and the routing controller 4 of the transmitting router 28 detects that there is no communication for a predetermined time (step R2 in FIG. 5).
1), the routing control unit 4 transmits a request to disconnect the data transfer B channel 12 to the channel control unit 10.
The procedure for disconnecting the B channel for data communication will be described with reference to steps Q to R in FIG. According to this, the channel control unit 10 receiving the disconnection request transmits a disconnection message of the data transfer B channel to the receiving router 27 (step R22 in FIG. 5). The channel controller 26 of the receiving router 27 that has received the disconnection message transmits a response message to the channel controller 10 of the transmitting router 28. The channel control unit 10 of the transmission router that has received the response message further transmits the response message to the channel control unit 26 of the reception router 27. FIG. 17 shows the packet format of this message. In the case of a disconnection message from the sending router 28, '8' is entered in the message field. There is no data field.

Finally, the transmitting router 28 and the receiving router 27
Performs disconnection from ISPal4 and ISPbl5 according to the procedure shown in the sequence of steps S to T in FIG.

[0065]

Next, the operation of an embodiment of the present invention will be described in detail with reference to FIGS. 1, 21 and 22. FIG. In this example, the case where the transmitting terminal 1 transmits one piece of data to the receiving terminal 17 will be described step by step.

In FIG. 1, the IP address of the transmitting terminal 1 is “192.168.1.1”, and the I
It is assumed that the P address is “192.168.10.1”. ISPal4 has an IP of '202.55.55.1'.
Address can be assigned to the sending router 28, and ISP
bl5 can allocate an IP address of “202.66.6.1” to the receiving router 27. First, the transmission router 28 collects the IP addresses of the transmission terminals connected to the LAN interface unit 3 and creates a local host table as shown in FIG. According to this, the IP address' 192.168.
1.1 is registered as the terminal address “1”, and the IP addresses “192.168.
1.2 'is registered as the terminal address'2', and the IP address' 192.16.1.3.3 'of the transmitting terminal 39 is registered as the terminal address'3'.

The receiving router 27 also creates a local host table as shown in FIG. According to this, the IP address' 192.168.
10.1 'is registered as the terminal address'1', and the IP addresses' 192.168.1 'of the other receiving terminals 40 are registered.
0.2 'is registered as the terminal address'2', and the IP address' 192.168.10.3 'of the receiving terminal 41 is registered as the terminal address 3.

Next, from the transmitting terminal 1 to step V in FIG.
1 is transmitted to the transmission router 28. According to this, at the head of transmission data, there is an Ethernet header which is a data link layer, followed by a network layer IP header. The source IP address of the IP header indicates the IP address' 192.168.1.1 'of the transmitting terminal 1, and the destination IP address indicates the IP address' 192.
68.10.1 'is shown. Next, there is a header in the transport layer, followed by actual data.

When the data transmitted from the transmitting terminal 1 arrives at the transmitting router 28, the transmitting router 17 calls the receiving router 27 using the control B channel 11. The receiving router 27 accepts the incoming call, and the transmitting router 17
After confirming the connection, the sending router 28
4, the receiving router 27 makes a call to ISPbl5,
Attempt to obtain P address.

The sending router 28 and the receiving router 27 obtain the IP address from ISPal4 and ISPbl5, respectively. In this case, the sending router 28 obtains the IP address “202.55.55.1” from ISPal4, and 27 is the IP address '20 from ISPbl5
2.6.6.6.1 ′ is obtained.

Next, the transmitting router 28 and the receiving router 27
The IP address and the local host table of each control B channel are exchanged. The transmitting router 28 transmits the IP address “202.55.55.1” and the local host table shown in FIG. 21 to the receiving router 27. The receiving router 27 has the IP address' 202.66.66.
1 'and the local host table shown in FIG. The local host table transmitted by the transmitting router 28 becomes the remote host table shown in FIG. 22 on the receiving router 27, and the local host table transmitted by the receiving router 27 becomes the remote host table shown in FIG. 21 on the transmitting router 28. .

Here, the control B channel is cut off because it is no longer needed.

Next, the transmission router 27 converts the transmission data from the transmission terminal 1 into an IP header shown in FIG. First, the terminal address “1” is derived from the source IP address “192.168.1.1” (the IP address of the transmission terminal 1) by referring to the terminal IP address entry of the local host table in FIG. 21 ( This is the source terminal address). Next, referring to the terminal IP address entry of the remote host table of FIG.
From the destination IP address '192.168.10.1' (IP address of the receiving terminal 17), the terminal address '1'
(This is the destination terminal address). Next, the source IP address is the IP address obtained from ISPal4.
Replace with address '202.55.55.1'. Next, the receiving router 28 sets the destination IP address to ISPbl.
IP address' 202.66.66.
Replace with 1 '. Next, the source terminal address and the destination terminal address that were derived earlier are set in the destination I of the IP header.
Add to option field between P address and padding. The transmission data format after the above IP header conversion processing is in the form of step V2 in FIG. 21, and the transmission router 28 transmits the transmission data to the data transfer B channel.

Next, the transmission data is received by the receiving router 27. The receiving router 28 that has received the data performs the conversion processing of the IP header shown in FIG. First, referring to the remote host table shown in FIG.
1 ', the IP address' 192.16 of the transmitting terminal 1
8.1.1 '(this is the new source IP address). Next, referring to the local host table of FIG.
The P address '192.168.10.1' is derived (this is set as a new destination IP address). Next, the source terminal address and the destination terminal address included in the IP header are deleted. Next, the source IP address is replaced with the new source IP address derived previously, and the destination IP address is also replaced with the new destination IP address derived previously. The format of the transmission data after the above-described IP header conversion processing is in the form of step W2 in FIG. 21, is restored to the original transmission data (step V1 in FIG. 21) output by the transmission terminal 1, and the reception is performed by the reception terminal 17. It becomes possible and communication is completed. After the communication is completed, the transmission router 28 detects no communication from the transmission terminal 1, thereby disconnecting the data transfer B channel between the transmission router 28 and the reception router 27.

Further, the most suitable example to which this embodiment is applied is that the transmitting router 28 and ISPal 4 are located at a position where intra-area communication is applied in the ISDN13 charge system, and the receiving router 27 and ISPbl 5 are also in intra-area communication. Is in a position to which the transmission router 28, IS
The distance between Pal4 and the receiving router 27, ISPbl5 is 2
This is the case where they are separated by 0 km or more. For example, one hour of communication time is required, and the distance between them is 20 to 30 km.
In the daytime communication up to the time, when the conventional router directly communicates, 1 hour (3600 seconds) ６００45 seconds (20 seconds)
通信 30 km communication fee) × 10 yen = 800 yen. On the other hand, when the communication method of the present invention is applied, the following is performed. For the B channel for data communication, the communication fee from the router to the ISP is 1 hour (3600 seconds)
÷ 180 seconds (charge for intra-area communication) × 10 yen = 200 yen, which is applied to both the transmission router 28 and the reception router 27, and thus 200 yen × 2 = 400 yen. For the control B channel, the routers communicate directly with each other, but the communication time is expected to be within 30 seconds because the communication time is limited to the waiting time until the router connects to the ISP and the short time between transmission of the IP address and the local host cable. Is done. When the charge of the control B channel is calculated based on the time, 30
Seconds ÷ 45 seconds × 10 yen ≒ 10 yen (rounded up).
Therefore, the total amount of money when the communication method of the present invention is applied is 410 yen, which is about half the cost of the conventional communication method.

Further, as a case where the effect is greatest, a case where the distance exceeds 160 km is compared.
In the case of the conventional communication method, one hour (3600 seconds) ÷ 1
6.5 seconds (communication charge for over 160km) x 10
Yen = 2190 yen. On the other hand, in the case of the present communication system, one hour (3 hours) is required for the B channel for data transfer.
600 seconds) ÷ 180 seconds (communication charges within the area) × 10 yen =
It is 200 yen, which is applied to both the transmission router 28 and the reception router 27, so that 200 yen × 2 = 400 yen.
For the control B channel, 30 seconds ÷ 16.5 seconds ×
10 yen ≒ 20 yen (rounded up). Therefore, the total amount in the case of the present communication system is 420 yen, and communication can be performed at one fifth of the cost of the conventional communication system.

[0077]

As described above, according to the present invention, the communication used for data transfer requires a relatively low contract fee.
By using the line of the terminal type dial-up IP service of the SP, there is an effect that the communication cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a network configuration of an ISDN and a LAN to which a communication system between dial-up routers according to the present invention is applied.

FIG. 2 is a flowchart illustrating a transmission process of the terminal in FIG. 1;

FIG. 3 is a flowchart illustrating a reception process of the terminal in FIG. 1;

FIG. 4 is a flowchart 1 showing a transmission process of the router of FIG. 1;

FIG. 5 is a flowchart 2 showing a transmission process of the router of FIG. 1;

FIG. 6 is a flowchart 1 showing a receiving process of the router of FIG. 1;

FIG. 7 is a flowchart 2 showing a receiving process of the router of FIG. 1;

FIG. 8 is a flowchart showing details of an IP address conversion in a transmission process of the router of FIG. 5;

9 is a flowchart showing details of IP address conversion in a reception process of the router of FIG. 7;

FIG. 10 shows the terminal, router, control B channel of FIG.
FIG. 3 is a diagram showing a sequence chart 1 showing an operation of a data transfer B channel.

FIG. 11 is a diagram illustrating the Rizue, router, control B channel,
FIG. 7 is a diagram showing a sequence chart 2 illustrating an operation of a data transfer B channel.

FIG. 12 shows the terminal, router, control B channel,
FIG. 9 is a diagram showing a sequence chart 3 illustrating an operation of a data transfer B channel.

FIG. 13 shows the terminal, router, control B channel,
FIG. 9 is a diagram showing a sequence chart 4 showing the operation of the data transfer B channel.

FIG. 14 shows the terminal, router, control B channel,
FIG. 9 is a diagram showing a sequence chart 5 showing the operation of the data transfer B channel.

FIG. 15 is a diagram showing a 7-layer reference model of 0SI and a TCP / IP Internet layer model.

FIG. 16 is a diagram showing a format of an Internet data packet, a format of an IP header corresponding thereto, and a format of a TCP header.

FIG. 17 is a diagram showing a data format on a control B channel of FIG. 1;

FIG. 18 is a diagram showing table formats of a local host table and a remote host table.

FIG. 19 is a diagram showing a format of data on a data transfer B channel of FIG. 1;

FIG. 20 is a diagram showing a format of data on the LAN in FIG. 1;

FIG. 21 is a diagram illustrating conversion of an IP header of a transmission router.

FIG. 22 is a diagram illustrating conversion of an IP header of a receiving router.

[Explanation of symbols]

1, 38, 39 Transmission terminal 2, 18 LAN 3, 19 LAN interface unit 4, 20 Routing control unit 5, 21 IP header conversion unit 6, 22 ISDN interface unit 7, 23 Terminal address collection unit 8, 24 Local host table 9 , 25 remote host table 10, 26 channel control unit 11 control B channel 12 data transfer B channel 13 ISDN 14 ISPa 15 ISPb 16 Internet 17, 40, 41 receiving terminal 27 receiving router 28 transmitting router 29 ISO 7 layer reference model Reference Signs List 30 Internet hierarchical model 31 Internet data packet format 32 IP header 33 TCP header format 34 Data format on control B channel 35 Local host table and resource Over preparative host table format 36 de on the LAN - data format 37 data transfer data format on B-channel

Claims (2)

[Claims] 1. A transmitting router, a receiving router, a transmitting terminal connected to the transmitting router, a receiving terminal connected to the receiving router, an ISDN, and the transmitting router being an ISDN.
ISPa, which is an access point of an Internet service provider connectable through ISDN, ISPb, which is an access point of an Internet service provider connectable by the receiving router through ISDN,
A communication system between dial-up routers configured by the Internet connected through SPa and ISPb, wherein the transmitting router collects an IP address of a transmitting terminal connected to the transmitting router and changes an IP address of the transmitting terminal. Creating a local host table of the transmitting router to be registered as a terminal address, the receiving router collecting an IP address of a receiving terminal connected to the receiving router, and registering the IP address of the receiving terminal as a terminal address; A local host table of the router is created, and the transmission data is transmitted from the transmission terminal to the transmission router. At the head of the transmission data, there is an Ethernet header which is a data link layer. There is an IP header, and the source IP address of the IP header is IP address of the transmitting terminal is shown, destination I
The P address indicates the IP address of the receiving terminal, followed by a header in the transport layer, followed by actual data, and the transmission data transmitted from the transmitting terminal is transmitted by the transmission terminal. When arriving at the router, the transmitting router uses the control B channel, which is the first B channel of ISDN, to make a call to the receiving router, the receiving router accepts an incoming call, and establishes a connection with the transmitting router. After confirming, the transmitting router makes a call to ISPa and performs the control B
A first IP address of a channel is obtained, the receiving router makes a call to ISPb to obtain a second IP address of the control B channel, and the transmitting router transmits the first IP address and the transmission Transmitting a local host table of a router to the receiving router; the local host table of the transmitting router becomes a remote host table of the receiving router; and the receiving router is configured to store the second IP address and the local host table of the receiving router. Is transmitted to the transmitting router, and the local host table of the receiving router becomes a remote host table of the transmitting router. Here, the control B channel is disconnected because it is no longer required. A conversion process of the IP header with respect to the transmission data from the terminal. The IP header conversion process refers to an IP address entry of the transmitting terminal in the local host table of the transmitting router, derives a terminal address from the IP address of the transmitting terminal, sets the terminal address as a source terminal address, Referring to the IP address entry of the receiving terminal in the remote host table of the router, derive a terminal address from the IP address of the receiving terminal as a destination terminal address, and then set the source IP address to the first IP address And replacing the destination IP address with the second IP address, and then adding the source terminal address and the destination terminal address to an option field of the IP header. The transmission data after the conversion processing of the IP header is The data is transmitted to the B channel for data transfer, which is a B channel. The transmission data after the conversion processing of the IP header is received by the reception router. The reception router responds to the transmission data from the transmission router by the IP. The header is converted and the IP
The header conversion process refers to the IP address entry of the transmitting terminal in the remote host table of the receiving router, and calculates the IP address of the transmitting terminal from the source terminal address.
Address of the receiving terminal in the local host table of the receiving router.
With reference to the P address entry, the IP address of the receiving terminal is derived from the destination terminal address and set as a new destination terminal address. Next, the source terminal address and the destination terminal address included in the IP header are Delete and then replace the source IP address with the new source IP
Replacing the destination IP address with the new destination IP address. The transmission data after the IP header conversion process is restored to the original transmission data output by the transmission terminal, and the The terminal is ready to receive and the communication is completed. After the communication is completed, the transmitting router detects no communication from the transmitting terminal, so that the data transfer B channel of the transmitting router and the receiving router is disconnected. A communication system between dial-up routers. 2. A transmitting router, a receiving router, a transmitting terminal connected to the transmitting router, a receiving terminal connected to the receiving router, an ISDN, and the transmitting router being an ISDN.
ISPa, which is an access point of an Internet service provider connectable through ISDN, ISPb, which is an access point of an Internet service provider connectable by the receiving router through ISDN,
A communication method between dial-up routers using a communication system between dial-up routers constituted by the Internet connected through SPa and ISPb, wherein the transmitting router assigns an IP address of a transmitting terminal connected to the transmitting router. Collecting, creating a local host table of the transmitting router that registers the IP address of the transmitting terminal as a terminal address, the receiving router collecting the IP address of the receiving terminal connected to the receiving router, Creates a local host table of the receiving router that registers an IP address as a terminal address, transmits transmission data from the transmission terminal to the transmission router, and, at the beginning of the transmission data, transmits data to an Ethernet of a data link layer. Followed by a network layer IP header The source IP address of the IP header, the IP address of the transmitting terminal is shown, destination I
The P address indicates the IP address of the receiving terminal, followed by a header in the transport layer, followed by actual data, and the transmission data transmitted from the transmitting terminal is transmitted by the transmission terminal. When arriving at the router, the transmitting router uses the control B channel, which is the first B channel of ISDN, to make a call to the receiving router, the receiving router accepts an incoming call, and establishes a connection with the transmitting router. After confirming, the transmitting router makes a call to ISPa and performs the control B
A first IP address of a channel is obtained, the receiving router makes a call to ISPb to obtain a second IP address of the control B channel, and the transmitting router transmits the first IP address and the transmission Transmitting a local host table of a router to the receiving router; the local host table of the transmitting router becomes a remote host table of the receiving router; and the receiving router is configured to store the second IP address and the local host table of the receiving router. Is transmitted to the transmitting router, and the local host table of the receiving router becomes a remote host table of the transmitting router. Here, the control B channel is disconnected because it is no longer required. A conversion process of the IP header with respect to the transmission data from the terminal. The IP header conversion process refers to an IP address entry of the transmitting terminal in the local host table of the transmitting router, derives a terminal address from the IP address of the transmitting terminal, sets the terminal address as a source terminal address, Referring to the IP address entry of the receiving terminal in the remote host table of the router, derive a terminal address from the IP address of the receiving terminal as a destination terminal address, and then set the source IP address to the first IP address And replacing the destination IP address with the second IP address, and then adding the source terminal address and the destination terminal address to an option field of the IP header. The transmission data after the conversion processing of the IP header is The data is transmitted to the B channel for data transfer, which is a B channel. The transmission data after the conversion processing of the IP header is received by the reception router. The reception router responds to the transmission data from the transmission router by the IP. The header is converted and the IP
The header conversion process refers to the IP address entry of the transmitting terminal in the remote host table of the receiving router, and calculates the IP address of the transmitting terminal from the source terminal address.
Address of the receiving terminal in the local host table of the receiving router.
With reference to the P address entry, the IP address of the receiving terminal is derived from the destination terminal address and set as a new destination terminal address. Next, the source terminal address and the destination terminal address included in the IP header are Delete and then replace the source IP address with the new source IP
Replacing the destination IP address with the new destination IP address. The transmission data after the IP header conversion process is restored to the original transmission data output by the transmission terminal, and the The terminal is ready to receive and the communication is completed. After the communication is completed, the transmitting router detects no communication from the transmitting terminal, so that the data transfer B channel of the transmitting router and the receiving router is disconnected. A communication method between dial-up routers.