JP2017034557A - Address changing system and address changing method - Google Patents

Abstract

An object of the present invention is to eliminate address duplication efficiently without reducing again the duplication once eliminated in the course of executing the procedure and reducing the processing time. A notification request unit 111 of an allocation device 10 requests a plurality of terminals to notify their own addresses. Further, the generation unit 113 of the allocation device 10 generates a new address that is not included in the notified address when there is a duplicate address among the addresses notified from the terminal. In addition, the transmission unit 114 of the assignment device 10 transmits a message including a new address with the address of the terminal having the notified address being duplicated as a transmission destination. Each L2SW functioning as a transfer unit transfers the message transmitted by the transmission unit 114 of the assignment device 10 to one of the terminals having overlapping addresses. [Selection] Figure 7

Description

  The present invention relates to an address change system and an address change method.

  With the development of cloud networks, there are increasing cases of constructing a large-scale layer 2 domain including a plurality of layer 2 domains by constructing layer 2 domains in different locations and connecting them via the Internet. In addition, with the spread of data centers and the development of network virtualization technology, there are examples of building data centers in remote locations and improving the efficiency of resources by sharing the built data centers with different layer 2 domains. .

  On the other hand, since it became possible to construct the layer 2 domain as described above, as shown in FIG. 1, the network that was previously a separate layer 2 domain was integrated at the time of organizational restructuring. An example of constructing a new organization's layer 2 domain can be considered. FIG. 1 is a diagram for explaining integration of subnets. In such a situation, a technology for integrating a plurality of subnets is required.

  With the development of server virtualization technology, as shown in FIG. 2, there has been a case where a virtualized server (VM: Virtual Machine) is operated in a data center that has been conventionally constructed using physical servers. This is because the servers used by different individuals and organizations are virtualized and operated on the same physical server, thereby reducing the number of necessary physical servers. FIG. 2 is a diagram illustrating a configuration of a physical server having a VM. In addition, as shown in FIG. 3, when a physical server is maintained, it is possible to maintain the physical server without stopping the operation of the VM by moving the operating VM to another physical server. . FIG. 3 is a diagram for explaining the movement of the VM.

  Here, when data is transferred between each terminal including a VM using Ethernet (registered trademark), a MAC address, for example, is assigned as an address of layer 2 to the interface of each terminal. When the interface is a physical interface, the MAC address is assigned by the management organization and the manufacturer so as not to overlap each other.

  On the other hand, when the terminal is a VM, an address is assigned in the range of an address group assigned to a software manufacturer for operating the VM. Therefore, when software that operates VMs is operating on different servers, there is a possibility that duplicate MAC addresses are allocated between VMs as shown in FIG. FIG. 4 is a diagram for explaining duplication of MAC addresses. Thus, as a method for avoiding duplication of MAC addresses in the same subnet when a new VM is installed, an address duplication avoiding method used by ORACLE VM Server is known (for example, Non-Patent Document 1). .

  In the address duplication avoiding method used by the ORACLE VM Server, software called LDM (Logical Domains Manager) that assigns a MAC address to a VM is used. The LDM assigns a temporary MAC address to the VM when the VM is newly constructed. Then, the LDM detects a VM that exists in the same subnet and uses an address to be allocated. If such a VM is not detected, the LDM uses the assigned temporary MAC as the VM's MAC address, and if detected, determines another MAC address. The LDM assigns an address that is not used by any VM to the VM while repeating the above-described detection operation and temporary address changing operation.

  An address duplication avoidance method using LDM will be described with reference to FIG. FIG. 20 is a diagram for explaining a conventional address duplication avoiding method. As shown in FIG. 20, as the temporary MAC address, 1 is assigned to the VM 501a, 3 is assigned to the VM 502a, and 1 is assigned to the VM 503a. At this time, the LDM 501 transmits, to each LDM, a message for confirming whether there is a VM having a MAC address of 1 by multicast. Then, since a message indicating that there is a VM whose MAC address is 1 is returned from the LDM, the MAC address of the VM 501a is changed to 2. The LDM repeats these processes until there is no overlap.

"Automatic or manual MAC address assignment", Oracle VM Server for SPARC 2.1 Administration Guide, [online], [Search July 21, 2015], Internet <http://docs.oracle.com/cd/E24622_01 /html/E23595/assignmacaddressesautomaticallyormanually.html>

  However, the conventional address duplication avoidance method using the LDM has a problem that the duplication once eliminated occurs again in the course of executing the procedure, and it takes time to eliminate all duplications, so that the efficiency is poor. .

  For example, when integrating different subnets, VMs using the same MAC address exist as many as the number of integrated subnets. In some cases, a plurality of MAC addresses are duplicated. Therefore, the following problem arises in the address duplication avoidance method using the conventional LDM.

  First, consider a situation where there are a plurality of subnets in which VMs using the same MAC address exist, and these subnets are integrated. Specifically, as shown in FIG. 21, there is a case where both the LDM 601 existing in the subnet 600 and the LDM 701 existing in the subnet 700 are provided with a VM having a MAC address of 1 and a VM having a MAC address of 2. It is done. 21 and 22 are diagrams for explaining a conventional address duplication avoiding method.

  In the example of FIG. 21, the LDM 601 includes a VM 601a whose MAC address is 1 and a VM 601b whose MAC address is 2. The LDM 701 includes a VM 701a whose MAC address is 1 and a VM 701b whose MAC address is 2. Thus, MAC addresses 1 and 2 are duplicated (step S501 in FIG. 22).

  In order to eliminate duplication, for example, the addresses of VMs 601a and 701a are changed to 3, and the addresses of VMs 601b and 602b are changed to 4. At this time, the two LDMs inquire about the existence of VMs using the MAC addresses 3 and 4 to the other LDM. If this inquiry occurs at the same time, and an inquiry from the other arrives before changing the MAC address of the VM, there is no VM using the MAC address described in the inquiry.

  Therefore, the LDM that has received the inquiry returns that there is no VM using the MAC addresses 3 and 4. Upon receiving the reply, both LDMs change the VM address of MAC address 1 to 3 and the VM address of MAC address 2 to 4 (step S502 in FIG. 22). Thereby, the MAC address is duplicated again (step S503 in FIG. 22).

  Further, the address deduplication process is executed for each address. For example, when address duplication occurs between address 1 and address 2, the process of eliminating duplication of address 1 and the process of eliminating duplication of address 2 operate independently. For this reason, when the address 2 deduplication process tries to use the address used by the address 1 deduplication process, the address 2 deduplication process must try to assign another address. For this reason, it takes time to eliminate all duplications.

  The address change system of the present invention, for a plurality of terminals, the notification request unit that requests to notify the address of the terminal itself, and when there are duplicate addresses among the addresses notified from the terminal, A new address allocating unit that generates a new address that is not included in the notified address, and that transmits a message including the new address, with the address of the terminal having the notified address being duplicated as a destination, and the message And a transfer unit that transfers the received address to one of the terminals having the same address.

  In addition, the address changing method of the present invention includes a notification requesting step for requesting a plurality of terminals to notify their own addresses, and when there are duplicate addresses among the addresses notified from the terminals. A new address assignment step of generating a new address not included in the notified address, and transmitting a message including the new address, with a destination address of the terminal having the notified address duplicated, And a transfer step of transferring the message to one of the terminals having the same notified address.

  According to the present invention, it is possible to efficiently eliminate address duplication without reducing again the duplication once eliminated in the process of executing the procedure and reducing the time required for processing.

FIG. 1 is a diagram for explaining integration of subnets. FIG. 2 is a diagram illustrating a configuration of a physical server having a VM. FIG. 3 is a diagram for explaining the movement of the VM. FIG. 4 is a diagram for explaining duplication of MAC addresses. FIG. 5 is a diagram showing an outline of an address changing method in the address changing system according to the first embodiment. FIG. 6 is a diagram showing an overview of subnet integration in the first embodiment. FIG. 7 is a block diagram illustrating the configuration of the allocation device of the address change system according to the first embodiment. FIG. 8 is a diagram illustrating a configuration of the address changing system according to the first embodiment. FIG. 9 is a diagram for explaining an address changing method of the address changing system according to the first embodiment. FIG. 10 is a diagram for explaining an address changing method of the address changing system according to the first embodiment. FIG. 11 is a diagram for explaining an address changing method of the address changing system according to the first embodiment. FIG. 12 is a diagram for explaining an address changing method of the address changing system according to the first embodiment. FIG. 13 is a diagram for explaining an address changing method of the address changing system according to the first embodiment. FIG. 14 is a diagram for explaining an address changing method of the address changing system according to the first embodiment. FIG. 15 is a diagram for explaining an address changing method of the address changing system according to the first embodiment. FIG. 16 is a diagram for explaining an address changing method of the address changing system according to the first embodiment. FIG. 17 is a flowchart showing processing of the assigning device of the address change system according to the first embodiment. FIG. 18 is a flowchart showing the processing of the L2 switch of the address change system according to the first embodiment. FIG. 19 is a diagram illustrating an example of a computer in which an allocation apparatus is realized by executing a program. FIG. 20 is a diagram for explaining a conventional address duplication avoiding method. FIG. 21 is a diagram for explaining a conventional address duplication avoiding method. FIG. 22 is a diagram for explaining a conventional address duplication avoiding method.

  Hereinafter, embodiments of an address change system and an address change method according to the present application will be described in detail with reference to the drawings. Note that the address change system and the address change method according to the present application are not limited by this embodiment.

[First Embodiment]
In the following embodiments, the configuration of each device and the flow of processing in the address change system according to the first embodiment will be described in order, and finally the effects of the first embodiment will be described.

  First, the outline of the first embodiment will be described with reference to FIG. FIG. 5 is a diagram showing an outline of an address changing method in the address changing system according to the first embodiment. As shown in FIG. 5, in the first embodiment, an address arbitration function is introduced so that the same address is not assigned between overlapping processes.

  Each network does not have a function corresponding to LDM. In the example of FIG. 5, for example, there are a plurality of VMs having a MAC address of A and a VM having a MAC address of B, and address duplication occurs. For this reason, the allocation function plays a role as an arbitrator and causes each VM to change the address in order.

  Then, as shown in FIG. 6, for example, when address duplication is eliminated by the assignment device 10 having an assignment function, each terminal functions as a terminal on an integrated layer 2 network. FIG. 6 is a diagram showing an overview of subnet integration in the first embodiment. The assignment function may be realized as a single device as shown in FIG. 6 or may be realized as a part of the function of a server or network device having other functions.

[Configuration of First Embodiment]
First, the configuration of the allocation device 10 included in the address change system will be described with reference to FIG. FIG. 7 is a block diagram illustrating the configuration of the allocation device of the address change system according to the first embodiment. As illustrated in FIG. 7, the assignment device 10 includes a control unit 11 and a storage unit 12. The control unit 11 includes a notification request unit 111, a table update unit 112, a generation unit 113, and a transmission unit 114. The storage unit 12 has an address management table 121.

  The notification request unit 111 requests a plurality of terminals to notify their own addresses. In addition, when there are duplicate addresses among the addresses notified from the terminal, the generation unit 113 generates a new address that is not included in the notified addresses. In addition, the table update unit 112 updates the address management table 121. In addition, the transmission unit 114 transmits a message including the new address, with the address of the terminal with the notified address being duplicated as the transmission destination. The address management table 121 stores addresses and the number of addresses. The generation unit 113 and the transmission unit 114 function as a new address assignment unit.

  The configuration of the address change system including the assignment device 10 will be described with reference to FIG. FIG. 8 is a diagram illustrating a configuration of the address changing system according to the first embodiment. As illustrated in FIG. 8, the assignment device 10 is connected to L2SWs (layer 2 switches) 21 to 24. Note that the L2SW 22 directly connected to the allocation device 10 functions as a transfer unit that transfers the message transmitted by the transmission unit 114 of the allocation device 10 to one of the terminals with overlapping addresses. .

  As shown in FIG. 8, each L2SW is connected to a VM to which a MAC address is assigned. The L2SW 21 is connected to the VM 211 whose MAC address is A. The L2SW 22 is connected to a VM 221 whose MAC address is A. The L2SW 23 is connected to a VM 231 whose MAC address is A and a VM 232 whose MAC address is B. The L2SW 24 is connected to a VM 241 whose MAC address is B.

  When each VM receives the forwarded message, each VM changes its own address to a new address included in the message. In addition, when the address is changed, each VM notifies the message including the address before the change by broadcasting. On the other hand, when a message including the address before change notified by another VM is received and the own address matches the address included in the message, the allocation device 10 is requested to transmit a new address. .

  Note that a message requesting transmission of a new address may be transmitted by broadcast, or the address of the allocation device 10 may be transmitted as a transmission destination. Further, each VM learns by storing a transmission source address when a message requesting notification of an address from the notification request unit 111 is transmitted, and the stored address may be used as the address of the allocation device 10. .

  In the example of FIG. 8, since the MAC addresses of VMs 211, 221 and 231 are all A, address duplication occurs. Further, since the addresses of the VMs 232 and 241 are both B, address duplication occurs. Note that the MAC address of the assignment device 10 is X.

  The details of the function of each unit of the assignment device 10 and the address change method in the address change system will be described with reference to FIGS. 9 to 16 are diagrams for explaining an address changing method of the address changing system according to the first embodiment.

  First, as illustrated in FIG. 9, the notification request unit 111 of the allocation device 10 transmits a message requesting that all VMs be notified of their own MAC addresses. At this time, the source address of the message is X, which is the MAC address of the assignment device 10. The transmission destination is a broadcast address. The message transmitted by the notification request unit 111 reaches each VM via each L2SW.

  Next, as illustrated in FIG. 10, when the VM receives the message transmitted by the notification request unit 111, the VM transmits a message including its own MAC address. At this time, the destination of the message transmitted by each VM is X, which is the MAC address of the assignment device 10. Further, the source of the message transmitted by each VM is the MAC address of each VM. For example, the VM 211 transmits a message including the MAC address A, where the transmission destination is X and the transmission source is A. Each VM may transmit a message with the broadcast address as a transmission destination instead of the MAC address of the allocation device 10.

  Then, as illustrated in FIG. 10, the assignment device 10 receives three messages including the MAC address A and two messages including the MAC address B. Here, the table updating unit 112 stores A and B as the MAC address of the terminal in the address management table 121, further stores 3 as the number of used terminals corresponding to the MAC address A, and the used terminal corresponding to the MAC address B Remember 2 as a number.

  Then, as illustrated in FIG. 11, the assignment device 10 determines that address duplication has occurred when there is a MAC address in which the number of used terminals stored in the address management table 121 is two or more. And run the deduplication process. The generation unit 113 of the allocation device 10 generates an address not included in the MAC address stored in the address management table 121 as a new MAC address.

  Then, the transmission unit 114 transmits a message requesting to use the new address generated by the generation unit 113, with the MAC address determined to be duplicated in the address management table 121 as a transmission destination. The transmission source of the message transmitted by the transmission unit 114 is the MAC address of the assignment device 10.

  For example, as illustrated in FIG. 11, the generation unit 113 generates MAC addresses C and D that are not included in A and B that are duplicate MAC addresses. Then, the transmission unit 114 transmits a message requesting to use the MAC address C with the MAC address A as a transmission destination. In addition, the transmission unit 114 transmits a message requesting to use the MAC address D with the MAC address B as a transmission destination.

  Here, the routing protocol in the L2SW will be described with reference to FIG. Each L2SW uses, for example, a spanning tree protocol as a layer 2 routing protocol. When the spanning tree protocol is used, the L2SW confirms and stores the address of the transmission source of the packet that has arrived at the port. When a packet having a destination address as the address designated as the transmission source arrives, the packet is transmitted from the stored port.

  For example, as shown in FIG. 12A, all the packets transmitted by the VMs 211, 221 and 231 using the MAC address A pass through the L2SW 22. At this time, every time the packet passes, the port corresponding to the MAC address A is updated.

  For example, when a packet transmitted by the VM 231 passes through the L2SW 22, the port 22c is stored as a port corresponding to the MAC address A. Thereafter, when the packet transmitted by the VM 211 passes through the L2SW 22, the port corresponding to the MAC address A is updated to the port 22a. For this reason, as shown in FIG. 12B, there are a plurality of VMs using the MAC address A, and even when a packet is transferred toward the MAC address A, the VM to which the packet reaches is only the VM 211. .

  As shown in FIG. 11, the VMs 232 and 241 that use the MAC address B are connected to the L2SW 23 and the L2SW 24, respectively. For this reason, also in the L2SW 23 and the L2SW 24, it is necessary to perform packet transfer control by the spanning tree protocol as in the L2SW 22.

  A message having the broadcast address as a transmission destination is transmitted to all terminals in the network. The broadcast address is, for example, the MAC address “FF: FF: FF: FF: FF: FF”.

  As illustrated in FIG. 13, the L2SW 22 transfers a message with the MAC address A transmitted by the transmission unit 114 as a transmission destination to the VM 211 via the L2SW 21. At this time, the route reaching the VMs 221 and 231 is blocked. Then, as illustrated in FIG. 14, the VM 211 that has received the message changes its own MAC address to C.

  Thereafter, the VM 211 transmits a message indicating that the MAC address A is used with the broadcast address as the transmission destination and the MAC address C as the transmission source. This message is transmitted to each VM and the allocation device 10. Thereby, each VM and the allocation device 10 can detect that the address of the VM 211 has been changed.

  Here, as shown in FIG. 15, among the VMs that have received the message transmitted by the VM 211, the VMs whose MAC address matches the MAC address described in the message, that is, the VMs 221 and 231 are assigned to the allocation device 10. Request a new address. The transmission destination of this message is the MAC address X, and the transmission source is the MAC address A.

  Then, as shown in FIG. 16, the message requesting a new address indicates that the number of VMs whose MAC address is A is 2, so the table update unit 112 stores the MAC stored in the address management table 121. The number of terminals using address A is reduced from 3 to 2. Further, the generation unit 113 of the assignment device 10 generates the MAC address E.

  Then, the transmission unit 114 transmits a message requesting to use the MAC address E with the MAC address A as a transmission destination. This message is transferred to only one VM in the L2SW 22 as described above. For example, as illustrated in FIG. 16, when the message transmitted by the VM 221 passes through the L2SW 22 after the message transmitted by the VM 231, the message transmitted by the transmission unit 114 is transferred to the VM 221.

[Process of First Embodiment]
The processing of the assignment device 10 will be described using FIG. FIG. 17 is a flowchart showing processing of the assigning device of the address change system according to the first embodiment. As shown in FIG. 17, the notification request unit 111 requests each VM to notify its own MAC address (step S101). Next, the table update unit 112 updates the number of terminals used for each MAC address in the address management table 121 based on the received notification (step S102).

  Then, the generation unit 113 generates a MAC address to be assigned to a terminal having a duplicate MAC address (step S103). Note that the generation unit 113 generates a MAC address that is not stored in the address management table 121 or has a number of used terminals of 0 as a new MAC address. Here, the table updating unit 112 adds the generated MAC address to the address management table 121 (step S104).

  Then, the transmission unit 114 notifies the terminal having the duplicate MAC address of the new MAC address generated by the generation unit 113 (step S105). At this time, the message transmitted by the transmission unit 114 is transferred only to one of the VMs having the MAC address designated as the transmission destination. At this time, the number of terminals using the MAC address designated as the transmission destination stored in the address management table 121 may be reduced.

  Here, VMs with duplicate addresses may also notify a message requesting an address. Further, when there are MAC addresses having two or more terminals in use, the notification request unit 111 may further request each VM to notify its own MAC address. If the allocation device 10 further receives a notification, the allocation device 10 returns to step S102 and repeats the process (step S106, Yes). Moreover, the allocation apparatus 10 complete | finishes a process, when not receiving notification (step S106, No).

  Next, the processing of each L2SW will be described using the L2SW 22 as an example with reference to FIG. FIG. 18 is a flowchart showing the processing of the L2 switch of the address change system according to the first embodiment.

  First, when the L2SW 22 receives a message having the MAC address A as the transmission source and the MAC address X as the transmission destination from the port 22c (step S201), the port corresponding to the MAC address A is set to the port 22c (step S202). The message is transferred to the port corresponding to the MAC address X (step S203).

  Next, when the L2SW 22 receives a message having the MAC address A as the transmission source and the MAC address X as the transmission destination from the port 22b (step S204), the port corresponding to the MAC address A is set to the port 22b (step S205). ), The message is transferred to the port corresponding to the MAC address X (step S206).

  When the L2SW 22 receives a message having the MAC address A as the transmission source and the MAC address X as the transmission destination from the port 22a (step S207), the port corresponding to the MAC address A is set to the port 22a (step S208). The message is transferred to the port corresponding to the MAC address X (step S209).

  Here, when the L2SW 22 receives the message having the MAC address A as the transmission destination (step S210), the port corresponding to the current MAC address A is set to the port 22a, and therefore the message is transferred to the port 22a. (Step S211).

[Effect of the first embodiment]
The notification request unit 111 of the allocating device 10 requests a plurality of terminals to notify their own addresses. Further, the generation unit 113 of the allocation device 10 generates a new address that is not included in the notified address when there is a duplicate address among the addresses notified from the terminal. In addition, the transmission unit 114 of the assignment device 10 transmits a message including a new address with the address of the terminal having the notified address being duplicated as a transmission destination. Each L2SW functioning as a transfer unit transfers the message transmitted by the transmission unit 114 of the assignment device 10 to one of the terminals having overlapping addresses.

  As a result, the address of each terminal can be centrally managed by the assigning device 10 and address duplication can be eliminated one by one. For this reason, it is possible to efficiently eliminate the duplication of addresses without causing the duplication once eliminated in the process of executing the procedure, reducing the time required for processing.

[System configuration, etc.]
Further, each component of each illustrated apparatus is functionally conceptual, and does not necessarily need to be physically configured as illustrated. In other words, the specific form of distribution / integration of each device is not limited to that shown in the figure, and all or a part thereof may be functionally or physically distributed or arbitrarily distributed in arbitrary units according to various loads or usage conditions. Can be integrated and configured. Further, all or any part of each processing function performed in each device is realized by a CPU (Central Processing Unit) and a program analyzed and executed by the CPU, or hardware by wired logic. Can be realized as

  In addition, among the processes described in the present embodiment, all or part of the processes described as being automatically performed can be manually performed, or the processes described as being manually performed can be performed. All or a part can be automatically performed by a known method. In addition, the processing procedure, control procedure, specific name, and information including various data and parameters shown in the above-described document and drawings can be arbitrarily changed unless otherwise specified.

[program]
FIG. 19 is a diagram illustrating an example of a computer in which the assignment device 10 is realized by executing a program. The computer 1000 includes a memory 1010 and a CPU 1020, for example. The computer 1000 also includes a hard disk drive interface 1030, a disk drive interface 1040, a serial port interface 1050, a video adapter 1060, and a network interface 1070. These units are connected by a bus 1080.

  The memory 1010 includes a ROM (Read Only Memory) 1011 and a RAM (Random Access Memory) 1012. The ROM 1011 stores a boot program such as BIOS (Basic Input Output System). The hard disk drive interface 1030 is connected to the hard disk drive 1090. The disk drive interface 1040 is connected to the disk drive 1100. For example, a removable storage medium such as a magnetic disk or an optical disk is inserted into the disk drive 1100. The serial port interface 1050 is connected to a mouse 1110 and a keyboard 1120, for example. The video adapter 1060 is connected to the display 1130, for example.

  The hard disk drive 1090 stores, for example, an OS 1091, an application program 1092, a program module 1093, and program data 1094. That is, a program that defines each process of the assignment device 10 is implemented as a program module 1093 in which a code executable by a computer is described. The program module 1093 is stored in the hard disk drive 1090, for example. For example, a program module 1093 for executing processing similar to the functional configuration in the assignment device 10 is stored in the hard disk drive 1090. The hard disk drive 1090 may be replaced by an SSD (Solid State Drive).

  The setting data used in the processing of the above-described embodiment is stored as program data 1094 in, for example, the memory 1010 or the hard disk drive 1090. Then, the CPU 1020 reads the program module 1093 and the program data 1094 stored in the memory 1010 and the hard disk drive 1090 to the RAM 1012 and executes them as necessary.

  The program module 1093 and the program data 1094 are not limited to being stored in the hard disk drive 1090, but may be stored in, for example, a removable storage medium and read out by the CPU 1020 via the disk drive 1100 or the like. Alternatively, the program module 1093 and the program data 1094 may be stored in another computer connected via a network (LAN (Local Area Network), WAN (Wide Area Network), etc.). The program module 1093 and the program data 1094 may be read by the CPU 1020 from another computer via the network interface 1070.

10 Allocation device 11 Control unit 12 Storage unit 21, 22, 23, 24 L2SW
22a, 22b, 22c Port 111 Notification request unit 112 Table update unit 113 Generation unit 114 Transmission unit 121 Address management tables 211, 221, 231, 232, 241 VM

Claims (7)

A notification request unit that requests a plurality of terminals to notify the address of the terminal itself;
If a duplicate address exists among the addresses notified from the terminal, a new address not included in the notified address is generated, and the address of the terminal where the notified address is duplicated is set as a transmission destination. A new address assignment unit for transmitting a message including the new address;
A transfer unit that transfers the message to one of the terminals having the notified address duplicated;
An address change system comprising:   2. The address change system according to claim 1, wherein the transfer unit transfers the message to a terminal that has last notified an address among terminals having the notified address duplicated.   The new address allocating unit assigns a new address not included in the notified address when the address notified from the terminal is duplicated every time an address is notified from the terminal included in the plurality of terminals. The address change system according to claim 1 or 2, wherein a message including the new address is transmitted with the address of a terminal that is generated and the notified address is duplicated as a transmission destination. Each terminal of the plurality of terminals is
A change unit that changes the address of the terminal to a new address included in the message when the message transferred by the transfer unit is received;
When the address is changed by the changing unit, a notification unit that broadcasts a message including the address before the change, and
A request unit that transmits a message requesting transmission of a new address when the address of the terminal matches the address included in the message including the address before change notified by a terminal other than the terminal. When,
The address change system according to claim 1, wherein the address change system includes:   The address change system according to claim 4, wherein the request unit transmits a message requesting transmission of a new address by broadcast. Each terminal of the plurality of terminals is
A learning unit that stores an address of a request transmission source to notify the address of the terminal itself transmitted from the notification request unit;
The address change system according to claim 4, wherein the request unit transmits a message requesting to transmit a new address to the address stored by the learning unit. A notification requesting step for requesting a plurality of terminals to notify the address of the terminal itself;
If a duplicate address exists among the addresses notified from the terminal, a new address not included in the notified address is generated, and the address of the terminal where the notified address is duplicated is set as a transmission destination. A new address assignment step for transmitting a message including the new address;
A transfer step of transferring the message to one of the terminals having the notified address duplicated;
A method for changing an address, comprising:

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