JPH05344122A - Router - Google Patents

Abstract

PURPOSE:To enable direct communication with a normal address while using an abnormal address by providing a router and registering the abnormal address and the normal address on an address translation table while pairing those addresses. CONSTITUTION:At the router 1, an address translation table 21 and an address analyzing mechanism 3 are provided, networks are connected through the router 1, and the router 1 receives a packet transmitted from a certain network to the other network. The address extracted from the packet is translated by the address analyzing mechanism 3 while referring to the address translation table 21 and transmitted to the destination side network.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a router that translates addresses between networks and that connects a plurality of networks.

[0002]

2. Description of the Related Art IP (Internet Protocol) networks are being constructed all over the world, and these IP networks are connected one after another to form a huge network. In an IP network, the address space is 32
It is fixed to bits and there are only limited addresses. Therefore, in a large organization, there are cases where the addresses of all the networks in the organization cannot be made official addresses. Even if a machine on the network with such an unofficial address tries to communicate with a machine of another organization, the address information cannot be sent and communication is not possible, so the address information of the unofficial network is sent to another organization. There was a strong demand for technology that communicates without notification.

In order to solve this, a method is adopted in which a packet from a machine using an unofficial address on a certain network is once entered into the official machine and is newly connected to a machine on another network. It was

[0004]

However, in the method of once entering a machine on the network having a formal address,
The advantage of the network that enables direct one-to-one communication with machines around the world is greatly impaired, and there is a problem in that it is inconvenient to use. In addition, a network address whose address space is limited to 32 bits is a finite and valuable resource that should be shared all over the world, and it is difficult for one organization to acquire too many formal addresses. For this reason, there is a demand for a method of using an unofficial address but still communicating directly with a machine on the network of another organization.

The present invention solves these problems.
The purpose is to set up a router and register the unofficial address and the official address in a pair in the address conversion table to enable direct communication with the official address while using the unofficial address.

[0006]

FIG. 1 is a block diagram showing the principle of the present invention. In FIG. 1, the address conversion table 21 is for registering a pair of an unofficial address and a formal address, a reference count, a reference time, and a fixed flag.

The address analysis mechanism 3 converts an unofficial address into an official address or an official address into an unofficial address by referring to the address conversion table 21 with respect to the address extracted from the transmitted packet.

The address generation mechanism 4 refers to the address conversion table 21 for the address taken out from the packet and automatically generates and registers a pair of an unofficial address and a formal address when the address is not registered.

The reference count recording mechanism 5 includes an address conversion table 2
The reference count of 1 is updated. The reference time recording mechanism 6 updates the reference time of the address conversion table 21.

The item erasing mechanism 7 refers to the number of times of reference in the address conversion table 21 to erase an item less than a predetermined number of times, or refers to a reference time to erase an item which has passed a predetermined time. It is a thing.

The fixed flag is a flag for setting whether or not the deletion of items is prohibited.

[0012]

According to the present invention, as shown in FIG. 1, networks are connected to each other via the router 1, and the router 1 receives a packet transmitted from one network to another network, and an address analysis mechanism is provided. Address conversion table 2 for the addresses extracted by 3 from the packet
1 is referred to, the address is converted, and the data is transmitted to the destination network.

At this time, the address generation mechanism 4 is provided, the router 1 receives the transmitted packet, and the address analysis mechanism 3 analyzes the address extracted from the packet.
When it is determined that the address is not registered by referring to the address conversion table 21, the address generation mechanism 4 automatically generates a pair of an unofficial address and a formal address and registers it in the address conversion table 21.

Further, the reference count recording mechanism 5 and the item erasing mechanism 7 are provided, the router 1 receives the transmitted packet, and the address analysis mechanism 3 refers to the address conversion table 21 for the address extracted from the packet. The address translation / reference count recording mechanism 5 uses the address translation table 21.
The reference number of the address is transmitted and transmitted to the network on the destination side.
The number of times of reference is referred to and items less than a predetermined number of times are deleted.

Further, the reference time recording mechanism 6 and the item erasing mechanism 7 are provided so that the router 1 receives the transmitted packet and the address analysis mechanism 3 extracts the address from the packet by referring to the address conversion table 21. The address conversion / reference time recording mechanism 6 uses the address conversion table 21.
Of the address conversion table 21 is updated and transmitted to the destination network.
The reference time is referred to to delete the item that has passed the predetermined time.

Further, a fixed flag is provided in the address conversion table 21, and the item erasing mechanism 7 causes the address conversion table 2 to operate as necessary.
When erasing an item less than a predetermined number of times or an item having passed a predetermined time or more with reference to the reference count or reference time of 1, the fixed flag is referred to so as not to delete when ON.

Therefore, the router 1 is provided, and an unofficial address and a formal address are paired and registered in the address conversion table 21, so that it is possible to directly communicate with the formal address while using the unofficial address. Become.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the construction and operation of an embodiment of the present invention will be sequentially described in detail with reference to FIGS.

FIG. 1 is a block diagram showing the principle of the present invention. Figure 1
In the above, the router 1 transmits a packet received from one network to another network, and at this time, refers to the address translation table 21 to translate an unofficial address into an official address or convert an official address into an unofficial address. It is used for conversion, and is composed of an address translation storage mechanism 2, an address analysis mechanism 3, an address generation mechanism 4, a reference count recording mechanism 5, a reference time recording mechanism 6, an item erasing mechanism 7, and the like. is there.

The address translation storage mechanism 2 comprises an address translation table 21 and an address translation registration mechanism 22,
For example, a pair of an unofficial address and an official address is registered in the address conversion table 21.

The address conversion table 21 is a table for registering and storing a pair of an unofficial address used in a certain network and an official address when viewed from another network. Initially, a pair of a non-official address and a formal address that are fixedly used regularly are registered, or at the time of communication, when the address generation mechanism 4 is not registered.
A pair of an unofficial address and a formal address generated by is registered and stored.

The address translation / registration mechanism 22 registers a pair of an unofficial address and a formal address in the address translation table 21, and further includes a fixed flag, a reference flag, a reference count,
The reference time is registered, updated, deleted, and so on.

The address analysis mechanism 3 extracts the address (transmission destination, transmission source) extracted from the received packet,
If it is registered with reference to the address conversion table 21, it is converted to a registered address and transmitted to the destination network, or if it is not registered, the address generation mechanism 4 is caused to generate a new address and the address conversion is performed. It is registered in the table 21 or the like (see FIGS. 2 and 7).

The address generation mechanism 4 automatically generates a new address and registers it in the address conversion table 21 when the address (destination, source) extracted from the received packet is not registered in the address conversion table 21. It is something to let you do.

The reference count recording mechanism 5 updates the reference count of the address conversion table 21 when the address (source, destination) extracted from the received packet is registered in the address conversion table 21, and updates the reference count. Is recorded.

The reference time recording mechanism 6 updates the reference time of the address conversion table 21 when the address (source, destination) extracted from the received packet is registered in the address conversion table 21, and finally. The reference time referred to is recorded.

The item erasing mechanism 7 refers to the number of times of reference in the address conversion table 21 to erase an item equal to or less than a predetermined number, or refers to a reference time to erase an item which has passed a predetermined time or more, as necessary. It is something to do. When deleting this item, the item whose fixed flag is set to ON is not deleted.

Next, the operation of the configuration shown in FIG. 1 will be described. Here, it is assumed that the network A is communicating using an unofficial address and the network B is communicating using an official address.

(1) The transmission packet 200 is transmitted from the network B using the unofficial address to the network B using the official address, and is received by the router 1. Here, ○ represents a formal address addressed to network B (destination), and ■ represents network A (source)
Represents an unofficial address of.

(2) Address analysis mechanism 3 of router 1
However, since the non-authoritative address (1) of the sender extracted from the transmission packet 200 is registered in the address conversion table 21, the formal address □ corresponding to this non-authoritative address (2) is retrieved.

(3) The transmission packet 200 'converted into the formal dress □ extracted in (2) is generated and transmitted to the network B (transmission destination). As described above, the transmission packet 20 in which the unofficial address (1) is set is converted by the router 1 into the formal address □ by referring to the address translation table 21.
0'is generated and transmitted to the destination network B. As a result, the unofficial address (1) is automatically converted into the official address □ by the router 1, and the transmission packet 200 from the machine with the unofficial address can be transmitted in a one-to-one correspondence with the machine with the official address. It will be possible.

(4) Next, the transmission packet 300 is transmitted from the network B using the formal address to the network A using the non-formal address, and is received by the router 1. Here, ◯ represents the formal address of the network B (transmission source), and □ represents the formal address of the network A (transmission destination).

(5) Address analysis mechanism 3 of router 1
However, since the formal address □ of the transmission destination extracted from the transmission packet 300 is registered in the address conversion table 21, the unofficial address □ corresponding to this formal address □ is extracted.

(6) The transmission packet 300 'converted into the unofficial address (3) extracted in (5) is generated and transmitted to the network A (transmission destination). As described above, the transmission packet 300 in which the formal address □ is set is referred to by the router 1 by referring to the address conversion table 21, and the transmission packet 30 in which the formal address □ is converted
0'is generated and transmitted to the destination network A. As a result, the formal address □ is automatically converted into the unofficial address ■ by the router 1, and the transmission packet 300 from the formal address machine can be transmitted in a one-to-one correspondence with the formal address machine. It will be possible.

Therefore, according to (1) to (3), the machine with the unofficial address (2) in the network A using the unofficial address sends the transmission packet 200 to the network B using the official address, and vice versa. By transmitting the transmission packet 300 to the network A using the unofficial address by the machine of the network B using the formal address, it becomes possible to send and receive packets between them to communicate with each other.

A detailed description will be given below with reference to FIGS. 2 to 11. FIG. 2 shows a block diagram of an embodiment of the present invention. This shows the overall configuration of the router 1.

In FIG. 2, the receiving mechanisms 12 and 14 receive packets flowing in the networks A and B. The transmission mechanisms 13 and 15 transmit the combined packets to the networks A and B.

The address extracting mechanism 10 includes a receiving mechanism 12,
14, the source and destination addresses and data are extracted from the packets received from the networks A and B.

The packet synthesizing mechanism 11 synthesizes the data passed from the address extracting mechanism 10 and the address (source, destination) passed from the address translation storage mechanism 2 to generate a packet.

The address analysis mechanism 3 converts the address (source, destination) passed from the address extraction mechanism 10 by referring to the address conversion table 21.

The address translation storage mechanism 2 translates addresses (source and destination), and refers to the address translation table 21 to perform address translation. The address generation mechanism 4 allocates and registers a new address when the address is not registered in the address conversion table 21.

Next, the operation of the configuration of FIG. 2 will be described in detail with reference to FIG. In FIG. 3, S1 transmits a packet from the network A which uses an unofficial address to the network B which uses an official address.

In S2, the router 1 searches the address conversion table. This is because the receiving mechanism 12 takes in the packet for the network B flowing in the network A of FIG. 2 and passes it to the address extracting mechanism 10. Address extraction mechanism 1
0 takes out an address (source: network A, destination: network B) from the packet and passes it to the address analysis mechanism 3. The address analysis mechanism 3 analyzes the address of the transmitted destination, determines here that it is destined for the network B, and the address translation table 2 in the address translation storage mechanism 2
Search for 1.

In S3, the address conversion table 21 is searched in S2, and it is found that the source address, which is an unofficial address, is registered here. Therefore, this unofficial address is converted into an official address. This is because the packet synthesizing mechanism 11 of FIG. 2 takes out the formal address corresponding to the unofficial address registered in the address translation table 21 of the address translation mechanism 2, and the packet synthesizing mechanism 11 fetches the data and this formal address ( The packet in which the (source) is set is combined, and the transmission mechanism 15 transmits the packet to the network B. As a result, when the formal address is registered in the address conversion table 21 in association with the non-formal address of the transmission source, the non-formal address of the transmission source of the packet is converted into the formal address, and the converted packet is converted into the network. Send to B.

In S4, the address conversion table 21 is searched in S2, and it is found that the source address, which is an unofficial address, is not registered here. Therefore, the official address corresponding to the unofficial address is generated by the address generation mechanism. 4 assigns this pair to the address translation table 21. Then, the packet synthesizing mechanism 11 in FIG. 2 synthesizes the data and the packet in which the formal address (source) assigned is set, and the transmitting mechanism 15 transmits the packet to the network B. Accordingly, when the formal address is not registered in the address conversion table 21 in association with the unofficial address of the transmission source, a new official address corresponding to the unofficial address is newly allocated and registered in the address conversion table 21. At the same time, the unofficial address of the transmission source is converted into an official address, and the converted packet is transmitted to the network B.

In S11, the packet is transmitted from the network B using the formal address to the network A using the non-formal address. In S12, the router 1 searches the address conversion table. In this case, the receiving mechanism 14 takes in the packet for the network A flowing in the network B of FIG. 2 and passes it to the address extracting mechanism 10. The address extraction mechanism 10 determines the address from the packet (source: network B, destination: network A).
Is taken out and passed to the address analysis mechanism 3. The address analysis mechanism 3 analyzes the passed address of the transmission destination, determines here that the address is for the network A, and searches the address conversion table 21 in the address conversion storage mechanism 2.

In step S13, the address conversion table 21 is searched in step S12, and it is found here that the destination address, which is an unofficial address, is registered. Therefore, the official address is converted into an unofficial address. This is because the packet synthesizing mechanism 11 of FIG. 2 takes out an unofficial address corresponding to the formal address registered in the address translation table 21 of the address translation mechanism 2, and the packet synthesizing mechanism 1
1 synthesizes the data and the packet in which this unofficial address (destination) is set, and the transmission mechanism 13 makes the network A
Send to. As a result, when an unofficial address is registered in the address translation table 21 in association with the official address of the destination, the official address of the destination of the packet is converted to an unofficial address, and the converted packet is converted. To network A.

In step S14, the address conversion table 21 is searched in step S12, and it is found here that the destination address, which is a formal address, is not registered. Therefore, the packet in which the destination unknown notification is set is transmitted to the network B. .. This is because the pair of the unofficial address and the official address is not registered in the address conversion table 21 even though the destination network A uses the unofficial address, so the destination cannot be determined. It is returned to the source machine of network B as unknown.

FIG. 4 shows an example of addresses according to the present invention. This indicates the address of the transmission destination and the address of the transmission source, which is an example of the address set in the packet. FIG. 4A shows an example of a formal address. This formal address is an example of the formal address of the IP network, and is composed of 32 bits, and the upper bits 0 to 15 are assigned to the F laboratory. The lower bits 16 to 31 are addresses that can be freely assigned internally.

FIG. 4B shows an example of an unofficial address. This unofficial address is freely assigned internally from bit 0 to bit 31. Figure 5
An example of an address conversion table of the present invention is shown. Address conversion table 21
Is an address (unofficial address), official address,
It is composed of entries having items such as a fixed flag, a reference count, and a reference time. Here, the reference count and reference time are
Either one.

The address is an unofficial address.
The official address is an official address that enables direct one-to-one communication. The fixed flag is for prohibiting the deletion of the entry of the item and made resident when it is turned on.

The reference count records the number of times an item in the address conversion table 21 is referenced. This is to erase the item (entry) when the reference count is equal to or less than a predetermined number, and to effectively use the address conversion table 21.

As the reference time, the reference time for referring to the item of the address conversion table 21 is recorded. The item (entry) when a predetermined time or more has passed from this reference time
For erasing and effectively using the address conversion table 21.

FIG. 6 is a block diagram (part 1) of the essential parts of another embodiment of the present invention. This is the configuration of the embodiment in which the reference count recording mechanism 5 and the item erasing mechanism 7 are added in the dotted frame in the upper right of FIG. (1) and (2) in FIG.
Connect to (1) and (2).

In FIG. 6, the reference count recording mechanism 5 refers to the address conversion table 21 and, for example, when an unofficial address is converted into a formal address, updates the reference count of FIG. Is recorded. This recording of the reference count is for erasing the entries that are not referenced.

The item erasing mechanism 7 is for erasing an item (entry) in the address conversion table 21. Next, the operation will be described.

(1) Update of the reference count: When the unofficial address is converted to the official address or the official address is converted to the unofficial address by referring to the address conversion table 21, the corresponding entry is referenced. The reference count recording mechanism 5 updates (+1) the count and records the reference count.

(2) Item deletion: This will be described with reference to the flowchart of FIG. In S21, the number of times the address conversion table is referred to is checked. This is because the item erasing mechanism 7 activated every certain time checks the reference count of the address conversion table 21.

In step S22, it is determined whether the reference count is less than a certain count. In the case of YES, it is found that the number of times of reference is less than or equal to a certain number of times. Therefore, the reference number is erased in S23. Erased, and if NO, do not erase to make it resident). On the other hand, in the case of NO, the reference count is found to be greater than or equal to a certain count, and therefore the process proceeds to S24 without being erased.

In step S24, it is determined whether or not the process has ended. In the case of YES, the reference count is checked for all the entries in the address conversion table 21, and the process is ended (END). .. N
In the case of O, S21 and subsequent steps are repeated for the next entry.

As described above, the reference number recording mechanism 5 refers to the address conversion table 21 to record the reference number of the addresses converted, and the item erasing mechanism 7 activated every predetermined time.
Checks the reference count of the address conversion table 21 and erases the reference count less than the predetermined count. This makes it possible to erase unused items (entries of a pair of an unofficial address and a formal address) and use the address conversion table 21 efficiently.

FIG. 8 is a configuration diagram (No. 2) of the essential parts of another embodiment of the present invention. This is the configuration of the embodiment in which the reference time recording mechanism 6 and the item erasing mechanism 7 are added in the dotted frame in the upper right of FIG. (1) and (2) in FIG.
Connect to (1) and (2).

In FIG. 8, the reference time recording mechanism 6 updates the reference time shown in FIG. 5 by referring to the address conversion table 21 and, for example, when an unofficial address is converted into an official address, updates the latest reference time. It is to record. The recording of the reference time is for erasing the entries that are not referred to.

The item erasing mechanism 7 is for erasing an item (entry) in the address conversion table 21. Next, the operation will be described.

(1) Update of reference time: When an unofficial address is converted to an official address or an official address is converted to an unofficial address by referring to the address conversion table 21, the corresponding entry is referenced. The reference time recording mechanism 6 updates the time to the latest reference time and records the time.

(2) Item deletion: This will be described with reference to the flowchart of FIG. In S31, the reference time of the address conversion table is checked. This means that the item erasing mechanism 7 activated every certain time checks the reference time of the address conversion table 21.

In step S32, it is determined whether or not a certain time has elapsed from the reference time. In the case of YES, it is found that a certain time or more has elapsed from the reference time, so it is erased (note that according to the configuration of FIG. 11 described later, it is further determined in S35 whether the fixed flag is ON, and when YES In S33, it is erased, and if NO, it is made permanent so that it is not erased). On the other hand, in the case of NO, it is determined that a certain time or more has not elapsed from the reference time, so the process proceeds to S34 without erasing.

In S34, it is determined whether or not the process is finished. In the case of YES, the reference time is checked for all the entries of the address conversion table 21, and the process is ended (END). .. N
In the case of O, S31 and subsequent steps are repeated for the next entry.

As described above, the reference time recording mechanism 6 refers to the address conversion table 21 to update and record the reference time, and the item erasing mechanism 7 activated at every predetermined time causes the address conversion table 21 to be updated. Check the reference time of and delete only those that have passed a predetermined time or more. This makes it possible to erase unused items (entries of a pair of an unofficial address and a formal address) and use the address conversion table 21 efficiently.

FIG. 10 is a configuration diagram (No. 3) of the essential parts of another embodiment of the present invention. This is obtained by adding an input type storage mechanism 8 to the configuration of FIG. In FIG.
The input type storage mechanism 8 refers to the address conversion table 21 and sets a fixed flag to ON / OFF when, for example, an unofficial address is converted into a formal address, even if the reference count is less than a certain number of times. It is recorded whether the erasure of the entry is permitted or prohibited. It is possible to set this fixed flag to ON, prohibit erasure, and make it resident (see S25 in FIG. 7). ..

FIG. 11 is a schematic view (No. 4) of the essential parts of another embodiment of the present invention. This is obtained by adding an input type storage mechanism 8 to the configuration of FIG. In FIG.
The input type storage mechanism 8 refers to the address conversion table 21 and, for example, when a non-formal address is converted into a formal address, sets the fixed flag to ON / OFF, even if a certain time or more has elapsed from the reference time. It is recorded whether the erasure of the entry is permitted or prohibited. Set this fixed flag to ON, prohibit erasing,
It becomes possible to make it resident (see S35 in FIG. 9).

[0072]

As described above, according to the present invention,
Since the router 1 is provided and the unofficial address and the official address are paired and registered in the address conversion table 21 to communicate between the unofficial address and the official address, the unofficial address is used. However, one-to-one direct communication can be performed with the official address. As a result, (1) Even if the network uses an unofficial address, it is not necessary to notify other networks of the address information of the network, so that it is possible to connect to networks all over the world, and a soft network structure is realized. Can be kept.

(2) Further, the address conversion table 21 is provided with a predetermined number of reference times, reference times, and fixed flags, and a pair of an unofficial address and a formal address is registered and recorded together, so that the address conversion table 21 is predetermined. Check every hour to delete entries with a reference count less than a predetermined number, delete entries that have passed a predetermined time or more than the reference time, and set a fixed flag to ON to prohibit deletion of entries However, it is possible to erase unnecessary entries in the address translation table 21 to use them efficiently and to make necessary entries resident.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a configuration diagram of an embodiment of the present invention.

FIG. 3 is an operation explanatory diagram of the present invention.

FIG. 4 is an example of addresses according to the present invention.

FIG. 5 is an example of an address conversion table of the present invention.

FIG. 6 is a configuration diagram (part 1) of a main part of another embodiment of the present invention.

FIG. 7 is an item deletion flowchart of the present invention (reference count).
Is.

FIG. 8 is a configuration diagram (part 2) of a main part of another embodiment of the present invention.

FIG. 9 is an item deletion flowchart of the present invention (reference time).
Is.

FIG. 10 is a configuration diagram (Part 3) of the main parts of another embodiment of the present invention.

FIG. 11 is a configuration diagram (Part 4) of the main parts of another embodiment of the present invention.

[Explanation of symbols]

 1: Router 2: Address conversion storage mechanism 21: Address conversion table 22: Address conversion registration mechanism 3: Address analysis mechanism 4: Address generation mechanism 5: Reference count recording mechanism 6: Reference time recording mechanism 7: Item erasing mechanism 8: Input Type storage mechanism 10: Address extraction mechanism 11: Packet synthesis mechanism 12, 14: Reception mechanism 13, 15: Transmission mechanism

Claims (5)

[Claims] 1. A router for connecting between networks, an address conversion table (21) for registering a pair of an unofficial address and an official address, and an address conversion table (21) for an address extracted from a transmitted packet. The router (1) is provided with an address parsing mechanism (3) for converting an unofficial address to an official address or an official address to an unofficial address by referring to, and connecting the network to the network through the router (1), The router (1) receives a packet transmitted from one network to another network, and the address analysis mechanism (3) refers to the address conversion table (21) for the address extracted from the packet. Configured to perform address translation and send to the destination network A router characterized by that. 2. An address generation mechanism (4) is provided in the router (1), the networks are connected via the router (1), and packets transmitted from one network to another network are transmitted. When the address received by the router (1) and extracted from the packet is not registered by referring to the address conversion table (21), the address generation mechanism (4) sends an unofficial address and an official address. The router according to claim 1, wherein the pair is automatically generated and registered, converted into the registered address, and transmitted to the destination network. 3. The router (1) is provided with a reference count recording mechanism (5) and an item erasing mechanism (7), and the networks are connected to each other via the router (1), and from one network to another. The router (1) receives the packet transmitted toward the address, converts the address extracted from the packet by referring to the address conversion table (21), and causes the reference count recording mechanism (5) to convert the address. The reference count of the conversion table (21) is updated and transmitted to the destination side network, and the item deletion mechanism (7) causes the address conversion table (2
The router according to claim 1 or 2, wherein the router is configured to delete an item less than a predetermined number of times by referring to the reference number of 1). 4. The router (1) is provided with a reference time recording mechanism (6) and an item erasing mechanism (7), the networks are connected to each other via the router (1), and from one network to another. The router (1) receives the packet transmitted toward the address, converts the address extracted from the packet by referring to the address conversion table (21), and causes the reference time recording mechanism (6) to convert the address. The reference time in the conversion table (21) is updated and transmitted to the destination network, and the item deletion mechanism (7) causes the address conversion table (2
An item which is configured to erase an item which has passed a predetermined time or more with reference to the reference time of 1).
A router according to claim 2 and claim 3. 5. An address conversion table (2) for the router (1).
A fixed flag is provided in 1), and the item erasing mechanism (7) refers to the reference count or reference time of the address conversion table (21) as necessary, and the item is equal to or less than a predetermined number of times or has passed a predetermined time 5. The router according to claim 3, wherein the router is configured so as not to be erased when it is turned on by referring to the fixed flag when erasing.