WO2002101998A1

WO2002101998A1 - Routing software, communication program, communication method, and routing device

Info

Publication number: WO2002101998A1
Application number: PCT/JP2001/004795
Authority: WO
Inventors: Kuniaki Kondo
Original assignee: Kuniaki Kondo
Priority date: 2001-06-07
Filing date: 2001-06-07
Publication date: 2002-12-19
Also published as: JPWO2002101998A1

Abstract

A subaddress is assigned to a host connected to an internal network. In sending a packet to the host, the subaddress is set as a destination subaddress for the packet. To route such a packet to the internal network, a table of correspondence between sub-addresses and IP addresses is referenced to determine the IP address of the host to which the destination subaddress set to the packet has been assigned. The destination IP address of a packet is overwritten with the determined IP address.

Description

Description Routing software, communication program, communication method, and routing device

The present invention relates to a method for causing a computer to execute routing of a packet used for communication by the Internet protocol, software, an apparatus for performing the routing, and an Internet protocol. The present invention relates to a program for causing a computer to execute communication. Background art

Conventionally, communication using the Internet protocol has been widely used. In communication using the Internet protocol, a computer that performs communication (hereinafter referred to as “host”) is assigned a number represented by a 4-byte IP address. In order for one host to send data to another host (hereinafter referred to as “the other host”) by communication, the host obtains the IP address of the other host and transmits the data to be sent. The packet is divided into packets, and the IP address of the other host is set as the destination IP address in the header of the packet, and the IP address of the host is set as the source IP address in the packet. Send packets to the network.

The remote host may be connected to the same network as its own host, or may be connected to a different network. In order to communicate with a host connected to a different network, packet transfer must be controlled at the boundary of different networks. Controlling the transfer of buckets between these different networks is called "routing. Ning ".

When two different networks are connected, one may be called the "internal network" and the other as the "external network". In general, the smaller of the two different networks is called the internal network, and the larger one is called the external network. For example, when a home network is connected to a network called the Internet, the home network is called an internal network, and a network called the Internet is called an internal network. It will be called an external network.

The internal network and the external network are not always connected.For example, the internal network that is a home network and the external network such as the Internet are always connected. It is not connected. In such a case, assigning a different IP address to a host connected to the internal network than any host connected to the external network makes the IP address useless. Hosts connected to the internal network are assigned IP addresses that are classified as “private addressless” because they are wasteful and wasteful. A private address can uniquely identify a host only within the internal network, but uniquely identifies the host throughout the network, including the internal and external networks. Can not. In contrast, an IP address whose host is uniquely identified throughout the network is called a “global address”.

A host assigned a private address cannot be directly identified with a host connected to an external network because it is not uniquely identified throughout the network. Therefore, a method called “network address conversion (network address translation)” or “network address and port translation (network address translation)” is used. Used. This These methods assign a global address to the network interface on the external network side of the computer or device that routes packets between the internal network and the external network. When a device performing routing and routing transfers a bucket from an internal network to an external network, the source IP address of the bucket header is transferred to the routing computer or device. Routing is performed by overwriting with the assigned global address, and conversely, from the Internet to the network to which the host to which the private address is assigned is connected. When forwarding the bucket, the destination IP address is routed by harming the private address. . This enables communication between the host to which the private address is assigned and the host connected to the Internet.

However, even if the network-to-uniform-address translation, the network address and the port translation are used, communication must be started from a host connected to the internal network. The problem is that the host connected to the network cannot identify any host to which the private address is assigned and start communication. For this reason, depending on the communication protocol, some applications cannot be used on the host to which the private address is assigned, which is not preferable. Therefore, the present invention enables a host connected to an external network to identify a host connected to an internal network and start communication, and provides a communication protocol. The purpose is to ensure that all application programs are connected to the internal network and that private addresses can be used on the assigned host. Also, a host connected to the internal network may identify a host connected to another internal network via the external network and start communication. It is also an object of the present invention to be able to do so. Disclosure of the invention

In the present invention, a sub address is allocated to a host connected to the internal network, separately from the IP address. When a host connected to the external network sends a bucket to a specific host connected to the internal network, the packet header contains the subaddress assigned to that specific host. Set as destination subaddress.

Also, in order to route a bucket with the destination subaddress set in the header from the external network to the internal network, the IP address of the host to which the destination subaddress is assigned Overwrites the destination IP address of the packet with the packet and sends the packet to the internal network. In addition, in order for the internal network to be protected from the external network to the bucket where the destination subaddress is not set, the IP address of a specific host connected to the internal network is used. Overwrite the destination IP address of the bucket and send the packet to the internal network. To route buckets from the internal network to the external network,

Determines the host address of the host to which the IP address is assigned, sets it as the source address of the header and sends the packet to the outside, and the host with the sub address assigned. In order to communicate, it is necessary to know the subaddress assigned to the host, but by recording the subaddress on a specific record of the domain name server, the host Get to know the dress.

In addition, since the host connected to the internal network can be identified by a sub address in the internal network, the internal network Hosts connected to the network do not need to be assigned different IP addresses. Therefore, the same IP address is temporarily assigned to the host connected to the internal network, and the internal network is used to route the bucket between the internal network and the external network. When a global IP address is assigned to a host, the global IP address may be assigned as an official IP address to a host connected to the internal network. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows that the external network and the internal network are connected by a routing computer. Fig. 2 shows the structure of the first part of the packet used for communication. Fig. 3 shows the situation where the sub-address is assigned to the host connected to the internal network. Fig. 4 shows the IP address assigned to the host connected to the internal network. An example of a table showing the correspondence between dresses and sub-addresses is shown. FIG. 5 is a diagram showing an example in which the source subaddress and the destination address are set in the packet in order to set them in the optional portion of the bucket. Fig. 6 is a flowchart of a program that causes a computer to execute routing. FIG. 7 is a flowchart of a program for executing communication with a host to which a sub-address is assigned. Fig. 8 shows a state where the same temporary IP address is assigned to a host connected to the internal network. Fig. 9 shows an example of a table showing the correspondence between the MAC address and the subaddress of the host connected to the internal network. Figure 10 shows a state where a formal IP address is assigned to a host connected to the internal network. Fig. 11 shows that the same IP address is assigned to the host connected to the internal network and routing is performed with the external host. This is a flowchart of the processing to be performed. Fig. 12 shows the configuration of a device that assigns different IP addresses and different sub-addresses to hosts connected to the internal network and performs packet routing. FIG. 13 shows the configuration of a device that assigns the same IP address to a host connected to the internal network and performs packet routing. BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in more detail with reference to the accompanying drawings.

Fig. 1 shows that the routing computer 101 is connected to the external network 103 connected to the Internet 102 and the internal network 104, and to the internal network. This shows a state in which the hosts 105, 106, and 107 are connected, and the host 108 is connected to the external network. The internal network hosts 105, 106, and 107 have 192.16.80.0.2, 192.1.168.0.0.3, and 192, respectively. A private address of 16.8.0.4 is assigned, and the internal interface of the computer 101 that performs routing is connected to the network interface on the side of 104. The private address is assigned to 68.1.1, and the network interface on the external network 103 side is connected to the network interface on the 3rd side. Suppose that a global address is assigned.

Figure 2 shows the structure of a packet used by a host connected to the network to communicate. The first part of the bucket (called the “header”) contains 32 bits. It is divided as one unit, and the source IP address is set in the part of 201 and the destination IP address is set in the part of 202. The portion of 203 is called an option, and In the invention, it is used to store the source subaddress and the destination subaddress.

Fig. 3 shows the assignment of subaddresses 1, 2, and 3 to hosts 105, 106, and 107 connected to the internal network 104 in Fig. 1, respectively. FIG. When the sub-address is allocated in this way, the computer 101 performing the routing is allocated to the host connected to the internal network as shown in Table 401 shown in FIG. This will hold a table showing the correspondence between the given IP address and the subaddress.

The packet sent or received by the host to which the subaddress is assigned is set to the subaddress assigned to that host. One of the methods of setting is, for example, a method of setting in an optional part of a packet. Based on this method, FIG. 5 shows that the subaddress is set in the optional part 203 of the packet in order to set the subaddress to the packet transmitted or received by the host to which the subaddress is assigned. This shows a state where the data is stored. Assuming that the subaddress is represented by 16 bits, the first 16 bits of the optional part contain the source subaddress, which is the subaddress assigned to the host that sent the bucket. The next 16 bits are set to the destination subaddress, which is the subaddress assigned to the host to which the packet is going.

FIG. 6 is a flowchart for explaining the operation of a program that causes the computer 101 that performs the routing to execute the routing. First, in step S601, the computer 1 1 is made to wait until a bucket is received. If a packet is received, control is transferred to the computer 101 in step S602, and the packet received from the external network 103 is received from the internal network 104. To determine whether If it is received from the network, the control is shifted to step S603, and if it is received from the internal network, the control is shifted to step S607. In step S6◦3, the calculator 101 determines whether the destination subaddress is set in the optional part of the packet, and if the destination subaddress is set, step S Transfer control to 604, if not set, step S 6

Transfer control to 06. Step 604 is a step of causing the computer 101 to acquire the IP address of the host that should receive the bucket 1 from the destination subaddress with reference to Table 401. In other words, this step is based on the correspondence between the IP address and the subaddress assigned to the host on the internal network and the packet received from the external network 103. This is a destination IP address resolution step for obtaining an IP address from a destination subaddress using the correspondence table. In step S605, the IP address obtained in step S604 is overwritten by the computer 101 as the destination IP address of the packet, and the bucket is routed. That is, in this step, the destination IP address in the header of the packet is overwritten with the IP end address obtained in the destination IP address resolution step, and the internal network 104 is executed. This is an inward routing step that routes packets. This destination

1 Destination address sub-address is assigned by the address resolution step and the inward routing step when the destination sub-address receives the specified packet from the external network. The bucket can reach the host connected to the specified internal network.

In step S603, the destination supplement is added to the packet. If it is determined that the IP address of the packet has not been set, control is transferred to step S606, and the IP address of the predetermined default host is changed to the destination IP address of the packet. Causes computer 101 to execute the default routing step that overwrites the address and routes to the internal network. Due to this default routing step, even if a bucket without a destination sub address is received from the external network, the default host that processes the bucket is sent to the default host. The ket can be reached.

In step S602, when a packet is received from the internal network 104, control is transferred to step S607, and the source IP address is changed to the IP address. The sub-address obtained by referring to the correspondence table of sub-addresses 401 is used as a source suapure and a bucket! , And causes the computer 101 to execute an external routing step for routing to the external network. Due to this external routing step, the packet sent from the host connected to the internal network 104 to the external network 103 always has the source subaddress set. Therefore, when a host connected to the external network receives the bucket, the host can know the sub-address of the host of the communication partner, and can use the sub-address. The response packet can be sent to the host.

By causing the computer 101 to execute a program consisting of such steps, the host 108 connected to the external network 103 is replaced with the host 108 connected to the internal network. The sub address assigned to the host is set as the destination address in the packet, and the packet can be sent to a specific host connected to the internal network. In addition, a computer connected to the internal network is connected to the computer 101 that performs routing. By sending the packet sent from the host to the external network with the subaddress assigned to the host connected to the internal network as the source subaddress. Then, the host connected to the external network can know the subaddress assigned to the host that sent the packet.

Fig. 7 shows that the host 108 connected to the external network 103 identifies the host connected to the internal network 104 and transmits first. This is a flowchart for explaining that the communication is started and the processing is performed. First, in step S701, the IP address and subaddress of the host to be communicated with are calculated by the host 108 as a computer. That is, step S701 is an address resolution step. If a private address is set for a host connected to the internal network, the host that can be specified by the private address cannot be uniquely identified. In this case, the global address assigned to the network interface connected to the external network 103 of the server is requested. To request this global address, there is a method such as referring to the A record of the domain name server. When receiving and starting communication, the host of the communication partner can be specified from the IP address and subaddress set in the packet that received the data. Further, the subaddress assigned to the host connected to the internal network may be obtained by referring to the subaddress recorded in a specific record of the domain name server. The HINFO record is an example of a specific record. In step S702, it is determined whether or not to transmit data. If data is to be transmitted, control is transferred to step S703, and if data is to be received, step S706 is performed. Transfer control. In step S703, The transmission data is generated, and in step S704, the transmission data is divided into packets, and the packet is obtained in step S701. The IP address and the subaddress are destined. Execute the destination IP address and destination sub address setting steps to set the destination IP address and destination sub address. Then, in step S705, a packet is transmitted, and in step S708, it is determined whether or not the communication has been completed. If the communication has been completed, the process is terminated. Step S702 Control is shifted. In step SO 2, if data is to be received, the control is shifted to step S 706 to execute the receiving process.In step S 707, the received data is processed. 8 Transfer control.

The program that causes the computer to execute the processing in FIG. 7 is not only the host 108 connected to the external network 103 but also the host connected to the internal network 104. It can also be used when communicating with a host connected to a network and to which a subaddress is assigned.

In step S704, not only the destination IP address and the destination subaddress are set in the packet, but also if the sub-address is set in the own host, the sub-address is set. Alternatively, a source subaddress setting step may be performed in which a packet is set as a source subaddress in a packet.

In the above, a different IP address is assigned to a host connected to the internal network, but the same IP address is assigned to a host connected to the internal network. May be used. Fig. 8 shows a state where the same IP address is assigned to the internal network, i.e., to the computer 801, which performs routing, to the Internet 8002. The connected external network 803 and the internal network 804 are connected, and the hosts 805, 806, 807 are connected to the internal network. The same IP address as the network interface on the internal network side of the computer 801 that performs routing with the host 805, 806, 807 19.2.168.0 1 is assigned to the network interface on the internal network side of the computer 801, which performs routing, and to the hosts 800, 806, and 807, respectively. 0, 1, 2, and 3 are assigned as addresses. In FIG. 8, the network interface on the internal network side of the computer 801 that performs the routing is shown. The IP address 0.0.0.0 is assigned, which indicates that the computer 801 that performs routing and the external network 803 are not connected. I have.

When the same IP address is assigned to the network interface on the internal network side of the host computer connected to the internal network and the computer that performs routing in this way In order to communicate within the internal network, the destination host is specified by the address in the physical layer. For example, when the internal network 804 is constructed using Ethernet, the host is specified by the MAC address. Therefore, as shown in Fig. 9, Table 901 correlating the MAC address with the sub-address is shown in Table 9 You will have it. In the following, it is assumed that the internal network is built on Ethernet, but the same applies to other physical networks.

Figure 10 shows a network interface on the external network side of the computer 801 that performs routing, where the computer 801 that performs routing and the external network 803 are connected. 1 3 9 .2 1 3 .9 4 A global address is assigned to the host 805, 806, 807 connected to the internal network. It is a diagram to which a global address of 94 is assigned. Even if the global address is assigned to the host connected to the internal network in this way, the sub address does not change.

Fig. 11 shows the routing to the computer 81 that performs routing when the same IP address is assigned to the host connected to the internal network in this way. This is a flowchart for explaining the operation of a program to be executed by a user. First, in step S111, a subaddress is assigned to the computer 801 for a host connected to the internal network. That is, step S111 is a sub-address assignment step. When this step is executed by the computer 801, it is possible to know which sub address is assigned to the host having which MAC address, and the MAC address as shown in Table 901 is obtained. A correspondence table between addresses and sub-addresses can be created. In step S111, the same IP address is assigned to the host connected to the internal network. In step S1103, the computer 801 causes the computer 81 to wait until a packet is received. In step S111, it is determined whether the received packet is received from the internal network 804. If the received packet is received from the internal network 804, Control is transferred to step S111, otherwise control is transferred to step S108. In step S1105, it is determined whether or not the IP address assigned in the subaddress assignment step in step S111 is a "temporary IP address". Execute the IP address determination step. A temporary IP address is an IP address that is not a “official IP address”, and a formal IP address is a computer that performs a notifying process. IP address assigned to the network interface on the external network 803 side of the computer 801 that performs routing when the external network 803 is connected to the external network 803 It is. Therefore, if the computer 801 performing the routing is not connected to the external network 803, the external network 8 of the computer 801 performing the routing is not connected.

0 The IP address assigned to the network interface on the 3rd side becomes a temporary IP address. If it is determined in step S1105 that the temporary IP address has not been assigned, the control is transferred to step S1107, and the temporary IP address is assigned. If it is determined that the IP address is present, the control is transferred to step S1106, and the formal IP address is assigned to all the hosts connected to the internal network, and step S111 is performed. Transfer control to. In step S1107, an external routing step of overwriting the source IP address of the packet with the formal address assigned in the formal IP address allocation step is executed. This ensures that when a bucket is sent from the internal network 804 to the external network 803, the formal IP address is sourced.

A bucket with 1 P address is sent.

In step SI104, when a packet is received from an external network, an internal routine that sends the packet to the host to which the destination subaddress written in the packet is assigned. Perform the step. Thus, if a host connected to the external network 803 sets a destination subaddress in a packet, the packet reaches the host to which the destination subaddress is assigned. It can be done.

Note that, in step S107, the packets ⁰ and ⁰ are connected to the external network 8

0 3 When hosting, the host card with which MAC address It is also possible to check whether the packet has been transmitted, obtain the support address of the host from Table 901, and execute a source sub-address setting step of setting the source sub-address of the bucket. As a result, the host connected to the external network 803 that has received the packet transmitted from the host connected to the internal network 804 can assign any sub-address to the host connected to the external network 803. It is possible to know whether the packet is from a host connected to the internal network 804.In the case of a host connected to the internal network 804, its own host Own sub-address resolution step to acquire the sub-address of the local host, and the sub-address of the local host obtained by the local sub-address resolution step to the source sub-address of the packet to be transmitted. By running a program that causes a host, which is a computer, to execute the setting steps and, the host connected to the internal network 804 and the external network Connected host to 8 0 3 becomes cormorants I can communicate.

With such a configuration, it is possible to perform communication from a host connected to an external network to a host to which a subaddress is assigned.

Figure 12 shows the routing of buckets between the external network 1201 and the internal network 122 to which the host with the assigned subaddress is connected. FIG. 3 is a block diagram of a routing device 1200. The routing device 12000 includes a destination IP address resolution unit 1203, an inward routing unit 1204, a default routing unit 1205, and an external routing unit. It consists of a directional routing section 1206 and a force. The destination IP address resolution unit 1203 determines the IP address and subaddress assigned to the host connected to the internal network as shown in Table 401 of Figure 4. Refer to the table showing the correspondence, and Obtain the IP address of the host to which the destination subaddress is assigned from the destination subaddress of the bucket received from the work.

The internal routing unit overwrites the destination IP address of the bucket header with the IP address obtained by the destination IP address resolution unit 123 and routes it to the internal network. When the destination IP address resolution bucket 122 and the inbound routing unit receive a bucket with a destination subaddress from the external network 1221, the destination Packets can be routed to hosts connected to the internal network to which the naming subaddress is assigned. If the destination subaddress is not written in the bucket received from the external network 1221, the default hosting section 125 will use the IP address of the predetermined default host. Overwrite the address to the packet's destination IP address for internal network health protection. Thus, when a packet for which the destination subaddress is not set is received from the external network 1221, the packet is routed to the host that processes the packet. Can be.

The external routing unit 1206 receives the bucket from the internal network 122 and receives the bucket's source IP address from the internal network as shown in Table 401. The sub address obtained by referring to the table showing the correspondence between the IP address and the sub address assigned to the host connected to the work is set in the packet as the source sub address and externally set. Net ヮ —Kerting. At this time, the source IP address of the packet is transferred to the network interface on the external network 1221 side of the routing device. You may overwrite the IP address assigned to one face. The source routing address is always set for the packets that are protected from the internal network 122 to the external network 122 by this external routing unit 126. The host connected to the external network 1221 that has received such a bucket will be sent from any host connected to the internal network 122. It is possible to know whether the packet is sent or not, and it is possible to send a reply packet to the host.

With the routing device having such a configuration, it is possible to perform communication by specifying a host of the internal network from the external network.

Figure 13 is a block diagram of a routing device that routes buckets between the internal network and the external network to which hosts to which the same IP address is assigned are connected. . The routing device 1300 has a sub-address allocating section 1301, an IP address allocating section 1302, an IP address deciding section 133, and a formal IP address allocating section. It consists of an abutting section 13 04, an external routing section 13 05, a source subaddress setting means 13 06, and an internal routing section 13 07.

The sub-address allocating unit 1301 allocates a subaddress to a host connected to the internal network 1308.

The IP address allocating unit 1302 allocates the same IP address to the host connected to the internal network 1308.

The IP address determining unit 133 determines whether the IP address assigned to the host connected to the internal network 1308 is “temporary”. The fact that an IP address is tentative is defined by not being an IP address force S “official”. An IP address is official if the IP address is a routing device. Is connected to the external network 1310, and is assigned to the network interface on the external network 1309 side of the routing device 130.0. It is defined by the condition that it is equal to the assigned IP address. Therefore, unless the routing device 1300 and the external network 1309 are connected, the network device on the external network 1309 side of the routing device 1300 is not connected. The IP address assigned to the interface will not be formal.

The formal IP address assignment unit 1304 performs assignment of the formal IP address to all the hosts connected to the network. In other words, the official IP address is assigned to all hosts connected to the network. Here, the “host connected to the network” is a host connected to the internal network 1308.

When the external routing unit 135 receives a packet from the internal network 1308, the formal IP address assigning unit 1344 routes the formal IP address to the network. Assigned to the host connected to the network, set the source IP address of the received packet to the formal IP address assigned by the formal IP address assigning unit 134, and configure the external network. Work 1 3 9 9Healing.

With the above configuration, when a packet is routed from the internal network 1308 to the external network 1309, the source IP address of the packet becomes an official IP address and becomes When a host connected to the external network 1309 receives a packet, it can send a reply packet.

The external routing section 135 is connected to the internal network 130. 8 may have a source sub address setting means 1306 for setting a sub address assigned to the host to a source sub address of a packet when receiving from a host connected to the host 8 . This ensures that packets routed to the external network 1309 have the source subaddress set, and packets sent from hosts connected to the internal network 1308. The host connected to the external network 1309 that received the packet can know from which host connected to the internal network 1308 the packet was sent. .

When the internal routing unit 1307 receives a packet with a designated destination address from the external network 1309, the sub address allocation unit 1301 sends the subaddress to the subroutine. Sends a packet to the host to which the address is assigned. This allows the host connected to the external network 1309 to specify the sub-address of the host connected to the internal network 1308, thereby making the internal network 1 3 0 Ri by 8 to the connected packet to a particular host in the routing device 1 3 0 _{0 c} with this Yo I Do arrangement consisting cormorants I can and child transmission, the internal network 1 Even if the same IP address is assigned to the host connected to 310, the host connected to the external network 1309 can specify the sub-address by specifying the sub-address. The host connected to the internal network 1308 can be identified, and communication with that host can be performed. Industrial applicability

As described above, according to the routing software, the communication program, the communication method, and the routing device according to the present invention, a host connected to an internal network and assigned a private address is provided. Can be identified by the host connected to the external network, Regardless of the communication protocol, all application programs can be used on the host assigned the private address. Also, even if the same IP address is assigned to a host connected to the internal network, a different subaddress is assigned, so that a host connected to an external network such as the Internet can be assigned. From this point, it becomes possible to specify the sub-address and specify the host connected to the internal network to perform communication. Also, from a host connected to the internal network, a host connected to another internal network can be specified via the external network and communication can be started.

Claims

Claims l. A routing program that causes a computer to route packets between the internal network and the external network, and is an IP address assigned to a host on the internal network. Destination address of the packet 1 received from the external network by referring to the correspondence table between the address and the sub address, and obtaining the IP address using the correspondence table from the destination sub address. Step and overwrite the destination IP address in the packet header with the IP address determined in the destination IP address resolution step and packet to the internal network. A routing program that causes the computer to execute an in-direction routing step and a routing routine.

2. If the destination received address is not written in the packet received from the external network, the IP address of the predetermined default host is changed to the destination IP address of the packet. The routing program according to claim 1, wherein the routing program causes a computer to execute a default routing step of overwriting an address and routing to an internal network.

3. When a packet is received from the internal network, the sub address obtained by referring to the above correspondence table from the source IP address is set in the bucket as the source address, and the packet is received from the external network. The routing program according to claim 1, which causes the computer to execute an external routing step for routing.

4. An address resolution step for obtaining the IP address and subaddress of the host to be communicated with, and the IP address obtained in the address resolution step is referred to as a destination IP address. And no. Set in the A communication program for causing a computer to execute a destination address setting step of setting a supplement address obtained in the address resolution step as a destination address in a packet.

5. The method according to claim 4, wherein, in the address resolution step, a subaddress of a host to be communicated with is determined by a subaddress recorded in a specific record of the domain name server. Communication program.

6. The communication program according to claim 4, further comprising causing the computer to execute a source sub-address setting step of setting a sub-address of the host as a source address of the packet.

7. A communication method in which a source sub-address and a sub-address are set in an IP bucket, and communication is performed between hosts determined by the IP address and the sub-address.

8. The communication method according to claim 7, wherein the source sub-address and the sub-address are set in an optional part of a header of an IP packet. 9. The communication method according to claim 7, wherein the sub-address is recorded in a specific record of a domain name server to resolve the sub-address.

10. The sub-address assignment step to assign a sub-address to a host connected to the internal network, and the same IP address to all hosts connected to the internal network IP address assignment step to assign IP addresses and IP address judgment to determine whether the IP address assigned to the host connected to the internal network is a temporary IP address When the step and the IP address assigned in the IP address assignment step are determined to be a temporary IP address by the IP address determination step Includes a formal IP address assignment step that assigns an official IP address to all hosts connected to the network, and an internal network address. 1.When a bucket is received from the work, the source IP address of the packet is assigned in the formal IP address assignment step together with the formal IP address assignment step. A routing program that causes the computer to execute an external routing step that overwrites the official IP address that was set.

1 1. When a bucket is received from a host connected to the internal network, the subaddress assigned to the host is changed to the source subaddress of the bucket in the subaddress assignment step. 10. The routing program according to claim 10, wherein the source sub-address setting step for setting a dress is executed by a computer.

1 2. When a destination subaddress is received from the external network, the destination subaddress is assigned to the destination subaddress by the above-mentioned subaddress allocation step. 10. The routing program according to claim 10, wherein said routing program causes a computer to execute an internal routing step of transmitting a packet.

1 3. Self-address resolution step for acquiring the sub-address of the own host, and self-address for setting the sub-address acquired in the self-address resolution step to the source sub-address of the packet to be transmitted. A communication program that causes a computer to execute the setting steps and.

14 4. A routing device that routes the bucket between the internal network and the external network, and the IP address and subaddress assigned to the host on the internal network. Refers to the correspondence table with the address and obtains the IP address from the destination supplement address of the packet received from the external network using the correspondence table.Destination IP address resolution And the destination IP address of the bucket's header as the IP address determined in the destination IP address resolution step. Routing device that overwrites the address and routes the bucket to the internal network.

15 5. If the destination sub address is not written in the packet received from the external network, the IP address of the predetermined default host is changed to the destination of the packet. 15. The routing device according to claim 14, further comprising a default routing unit that overwrites an IP address and routes to an internal network.

16 6. When a packet is received from the internal network, the sub address obtained by referring to the above correspondence table from the source IP address is set in the bucket as the source sub address, and the packet is received from the external network. 15. The routing device according to claim 14, further comprising an external routing portion for performing work-healing.

1 7. Assign the same IP address to the sub-address allocating unit that allocates sub-addresses to the hosts connected to the internal network, and all the hosts connected to the internal network. An IP address assignment unit, an IP address determination unit that determines whether the IP addresses assigned to all the hosts connected to the internal network are temporary IP addresses, and an internal If the IP addresses assigned to all the hosts connected to the network are determined to be temporary IP addresses in the IP address determination step, a formal IP address is assigned to the network. Formal IP address assignment unit assigned to all hosts connected to the network, and when a bucket is received from the internal network, the official IP address assignment unit assigns the official IP address. External routing that allocates the address and overwrites the source IP address of the socket with the formal IP address assigned by the formal IP address assignment unit. A routing device with a part and a part.

18. When the external routing unit receives a bucket from a host connected to the internal network, the external routing unit sets the sub address assigned to the host to the source sub address of the packet. The routing device according to claim 17, further comprising a dress setting means.

19. When receiving a bucket with a destination sub-address specified from an external network, the sub-address allocating unit sends a bucket to the host to which the destination sub-address is allocated. The routing device according to claim 17, further comprising an internal routing unit for transmitting a route.