COMMUNICATION CONTROL DEVICE, COMMUNICATION CONTROL METHOD, AND COMMUNICATION CONTROL PROGRAM

Abstract

A communication control device (10) comprises: a receiving unit (15a) that receives a switching instruction for an edge router in which a user terminal is accommodated; a deleting unit (15b) that deletes, on the basis of the switching instruction, an Address Resolution Protocol (ARP) cache held by a switching source edge router; an intercepting unit (15d) that intercepts an ARP protocol with respect to the switching source source edge router; and a submitting unit (15e) that submits user settings to a switching destination edge router.

Description

[Technical Field]

[0001] The present invention relates to a communication control device, a communication control method, and a communication control program. [Background technology]

[0002] In carrier networks, edge routers accommodating user terminals ("user terminals" or "terminals" as appropriate) are switched ("maintenance relocation" as appropriate) for maintenance purposes at the convenience of the telecommunications carrier. When switching edge routers, the user configuration information ("user configuration" as appropriate) currently accommodated is deleted from the edge router from which the switch is made ("source edge router" as appropriate), and the same information is then entered into the edge router to which the switch is made ("destination edge router" as appropriate). For security purposes, unicast reverse path forwarding (uRPF) may be applied to edge routers in carrier networks, and its application is recommended by the IETF (Internet Engineering Task Force), a standardization organization for Internet-related technologies.

[0003] As a conventional technology, a technology has been proposed in which, when performing maintenance and relocation of edge routers in a carrier network, the communication control system works in conjunction with a DHCP (Dynamic Host Configuration Protocol) server system to complete the switchover in a short time while minimizing the impact on user communications services. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Nishiguchi et al., "Edge Router Maintenance and Relocation Method to Minimize Communication Outages," Proceedings of the 2021 Institute of Electronics, Information and Communication Engineers General Conference, B-6-68, Mar. 2021. Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned conventional technologies make it difficult to effectively perform maintenance relocation of edge routers in IPv4 (Internet Protocol version 4) communications. For example, while many conventional technologies are based on IPv6 (Internet Protocol version 6) communications, there is no technology that safely relocates IPv4 communications without interruption. Furthermore, if user settings are randomly entered into the destination edge router, address duplication occurs, and if user settings are deleted from the destination edge router to avoid duplication, user communications are interrupted. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the communication control device of the present invention is characterized by comprising: a reception unit that receives a switching instruction for an edge router that accommodates a user terminal; a deletion unit that deletes an ARP (Address Resolution Protocol) cache held by the source edge router based on the switching instruction; a blocking unit that blocks the ARP protocol for the source edge router; and an input unit that inputs user settings to the destination edge router.

[0007] In addition, the communication control method of the present invention is a communication control method executed by a communication control device, and is characterized by including a reception step of receiving a switching instruction for an edge router accommodating a user terminal, a deletion step of deleting an ARP cache held by the source edge router based on the switching instruction, a blocking step of blocking the ARP protocol for the source edge router, and an input step of inputting user settings to the destination edge router.

[0008] In addition, the communication control program of the present invention is characterized in that it causes a computer to execute a reception procedure for receiving a switching instruction for an edge router that accommodates a user terminal, a deletion procedure for deleting an ARP cache held by the source edge router based on the switching instruction, a blocking procedure for blocking the ARP protocol for the source edge router, and an input procedure for inputting user settings to the destination edge router. [Effects of the Invention]

[0009] The present invention makes it possible to effectively perform maintenance relocation of edge routers in IPv4 communications. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a communication control system according to the first embodiment. [Figure 2] FIG. 2 is a diagram illustrating a conventional communication control process for IPv4 communication. [Figure 3] FIG. 3 is a diagram illustrating a conventional communication control process for IPv4 communication. [Figure 4] FIG. 4 is a block diagram illustrating an example of the configuration of the communication control device according to the first embodiment. [Figure 5] FIG. 5 is a sequence diagram showing an example of the flow of a communication control process according to the first embodiment. [Figure 6] FIG. 6 is a diagram illustrating a computer that executes a program. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A communication control device, a communication control method, and a communication control program according to embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below.

[0012] [First embodiment] The configuration of the communication control system according to the first embodiment, the configuration of the communication control device, and the flow of communication control processing will be explained below, and finally the effects of the first embodiment will be explained.

[0013] 1. Configuration of communication control system 100 The configuration of the communication control system 100 according to the first embodiment will be described in detail using Fig. 1. Fig. 1 is a diagram showing an example of the configuration of the communication control system 100 according to the first embodiment. Below, an example of the overall configuration of the communication control system 100 will be shown, and then each process will be described.

[0014] (1-1. Example of the overall configuration of the communication control system 100) The communication control system 100 includes a communication control device 10, edge routers 20 (20A, 20B), and a user terminal 30. The communication control device 10, the edge router 20, and the user terminal 30 are connected to each other via a predetermined communication network (not shown) so as to be able to communicate with each other via wired or wireless communication. The communication control system 100 shown in FIG. 1 may include a plurality of communication control devices 10 and a plurality of user terminals 30.

[0015] Figure 1 illustrates an example in which user communication is in progress between a user terminal 30 (ARP table: IPv4 address "AAAA", MAC (Media Access Control) address "aaaaaa", ARP timer "15") and a source edge router 20A (IPv4 address "AAAA", MAC address "aaaaaa"), and the communication is redirected to a destination edge router 20B (IPv4 address "AAAA", MAC address "bbbbbb").

[0016] (1-2. Processing of the communication control system 100) The following describes the processing of the communication control system 100: reaccommodation instruction processing, ARP cache deletion processing, ARP timer update processing, wait timer setting processing, ARP protocol blocking processing, user setting input processing, and GARP (Gratuitous ARP) transmission processing. Note that the following processing can also be executed in a different order. Also, some of the following processing may be omitted.

[0017] (1-2-1. Relocation instruction processing) The communication control device 10 receives a switching execution instruction from a maintenance person M who performs a maintenance relocation (step S1).

[0018] (1-2-2.ARP cache deletion process) The communication control device 10 clears the ARP cache held by the source edge router 20A (step S2). At this time, the ARP table held by the user terminal 30 is updated.

[0019] (1-2-3. ARP timer update process) The source edge router 20A updates the ARP timer included in the ARP table held by the user terminal 30 via an ARP request and an ARP reply exchanged with the user terminal 30 (step S3). In the example of Fig. 1, the timer in the ARP table of the user terminal 30 is updated to the maximum value of "999", and other entries remain unchanged.

[0020] (1-2-4. Waiting timer setting process) The communication control device 10 sets a wait timer to prevent the APR protocol from being shut down before the APR table is updated (step S4).

[0021] (1-2-5. ARP protocol blocking process) The communication control device 10 blocks the ARP protocol for the source edge router 20A (step S5). At this time, the communication control device 10 blocks the ARP protocol by setting a filter for IPv4 communication for the source edge router 20A.

[0022] (1-2-6. User setting input process) The communication control device 10 inputs the user setting to the switching destination edge router 20B (step S6). At this time, the IPv4 interface (IF) of the switching destination edge router 20B is enabled. In the example of Fig. 1, the communication control device 10 inputs the user setting including the IPv4 address "AAAA" of the user terminal 30.

[0023] (1-2-7. GARP transmission processing) The switching destination edge router 20B transmits a GARP to the user terminal 30 (step S7). At this time, the ARP table held by the user terminal 30 is updated. In the example of Fig. 1, the MAC address in the ARP table of the user terminal 30 is updated to "bbbbbb," which is the MAC address of the switching destination edge router 20B.

[0024] (1-3. Effects of the communication control system 100) Below, we will explain the problems with conventional communication control processing, and then provide a detailed explanation of the effects of the communication control system 100, which is a switching technology for transferring user-specific configuration information set in the edge router 20 to a backup edge router 20.

[0025] (1-3-1. Conventional communication control processing) The communication control process shown in Non-Patent Document 1 is a technology that performs switching without interrupting user communication by working with a DHCP server to update the lease timer of the address assigned to the user, assuming that an IPv6 address has been assigned in user communication. Furthermore, in conventional communication control processes related to IPv4 communication, in order to prevent communication interruption, switching can also be performed by inputting user settings for the switching destination edge router 20B while user settings exist in the switching source edge router 20A. Furthermore, in conventional communication control processes related to IPv4 communication, in order to prevent address duplication, switching can also be performed by deleting the user settings for the switching source edge router 20A and then inputting user settings for the switching destination edge router 20B.

[0026] (1-3-2. Problems with conventional communication control processing) The following describes problems with conventional communication control processing related to IPv4 using Figures 2 and 3. Figures 2 and 3 are diagrams illustrating conventional communication control processing related to IPv4 communication. Figures 2 and 3 explain an example in which user communication is in progress between the user terminal 30 (ARP table: IPv4 address "AAAA", MAC address "aaaaaa", ARP timer "15") shown in Figures 2(1) and 3(1) and the switching source edge router 20A (IPv4 address "AAAA", MAC address "aaaaaa") shown in Figures 2(2) and 3(2), and the communication is re-accommodated to the switching destination edge router 20B (IPv4 address "AAAA", MAC address "bbbbbb") shown in Figures 2(5) and 3(6).

[0027] (1-3-2-1. Problem 1) As shown in Fig. 2, the conventional communication control device 10P inputs user settings to the switching destination edge router 20B (see Fig. 2(4)). The switching destination edge router 20B also transmits a GARP to the user terminal 30 (see Fig. 2(6)). At this time, since the user settings have not been deleted in the switching source edge router 20A, address duplication is detected (see Fig. 2(7)).

[0028] In other words, in order to prevent an IPv4 communication interruption, it is necessary to input the user settings to the destination edge router 20B while the user settings still exist in the source edge router 20A. However, in such a state, the same IPv4 address exists in the source edge router 20A and the destination edge router 20B, resulting in an address duplication state.

[0029] (1-3-2-2. Problem 2) As shown in Fig. 3, the conventional communication control device 10P deletes the user settings in the source edge router 20A (see Fig. 3(4)) and inputs the user settings to the destination edge router 20B (see Fig. 3(5)). The destination edge router 20B also transmits a GARP to the user terminal 30 (see Fig. 3(7)). At this time, a communication interruption occurs between the deletion of the user settings in the source edge router 20A and the transmission of the GARP (see Fig. 3(8)).

[0030] In other words, if the process is performed in the order of deleting the user settings from the source edge router 20A and then inputting the user settings to the destination edge router 20B in order to prevent IPv4 address duplication, a communication interruption will occur during the period from the deletion of the user settings to the input of the user settings.

[0031] (1-3-3. Overview of the communication control system 100) First, in the communication control system 100, before inputting user settings into the destination edge router 20B, the ARP cache of the source edge router 20A is cleared, and the ARP table is updated between the user terminal 30 and the edge router 20, thereby refreshing the ARP timer and preventing unintended ARP update requests from the user terminal 30 while the switching process is being performed.

[0032] Second, in the communication control system 100, when ARP protocol inhibition is executed after the ARP cache is cleared, a certain waiting timer is introduced to avoid any impact on the ARP processing that is performed in conjunction with the cache clearing, and then inhibition is executed.

[0033] Thirdly, by inputting the user settings to the switching destination edge router 20B after the above processing has been executed in advance in the switching source edge router 20A, switching of the edge router 20 is completed without causing address duplication or communication interruption.

[0034] (1-3-4. Effects of the communication control system 100) As a result, the communication control system 100 can execute the switching process of the edge router 20 without causing address duplication and interrupting communication for users' IPv4 communications. Furthermore, the communication control system 100 can execute the switching process safely even if the ARP protocol of the switching source edge router 20A is blocked. In other words, the communication control system 100 can execute the maintenance relocation effectively by safely switching the edge router 20 without interrupting communication for users with regard to IPv4 communications.

[0035] 2. Configuration of communication control device 10 An example of the configuration of the communication control device 10 according to the first embodiment will be described in detail using Fig. 4. Fig. 4 is a block diagram showing an example of the configuration of the communication control device 10 according to the first embodiment. The communication control device 10 has an input unit 11, an output unit 12, a communication unit 13, a storage unit 14, and a control unit 15.

[0036] (2-1. Input section 11) The input unit 11 controls input of various information to the communication control device 10. The input unit 11 is, for example, a mouse or a keyboard, and receives input of setting information and the like to the communication control device 10.

[0037] (2-2. Output section 12) The output unit 12 controls the output of various information from the communication control device 10. The output unit 12 is, for example, a display, and outputs setting information stored in the communication control device 10, etc.

[0038] (2-3. Communications Department 13) The communication unit 13 controls data communication with other devices. For example, the communication unit 13 performs data communication with each communication device. The communication unit 13 can also perform data communication with an operator's terminal (not shown).

[0039] (2-4. Storage section 14) The storage unit 14 stores various information referenced when the control unit 15 operates and various information acquired when the control unit 15 operates. Here, the storage unit 14 is, for example, a semiconductor memory element such as a random access memory (RAM) or a flash memory, or a storage device such as a hard disk or an optical disk. Note that, in the example of Fig. 4, the storage unit 14 is installed inside the communication control device 10, but it may be installed outside the communication control device 10, or multiple storage units may be installed.

[0040] (2-5. Control unit 15) The control unit 15 controls the entire communication control device 10. The control unit 15 has a reception unit 15a, a deletion unit 15b, a setting unit 15c, a cutoff unit 15d, and an insertion unit 15e. Here, the control unit 15 is, for example, an electronic circuit such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), or an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0041] (2-5-1. Reception section 15a) The reception unit 15a receives a switching instruction for the edge router 20 that accommodates a user terminal. For example, the reception unit 15a receives, from a maintenance person M who performs maintenance relocation, information on the switching source edge router 20A, information on the accommodated user terminal 30, information on the switching destination edge router 20B, the purpose of switching the edge router 20, the scheduled switching start time, the scheduled switching end time, etc. as a switching instruction. Meanwhile, the reception unit 15a may store the received switching instruction in the storage unit 14.

[0042] (2-5-2. Deletion section 15b) The deletion unit 15b deletes the ARP cache held by the source edge router 20A based on the switching instruction. For example, the deletion unit 15b deletes the ARP cache, updates the ARP tables held by the source edge router 20A and the user terminal 30, and updates the ARP timer included in the ARP table to its maximum value, thereby preventing the user terminal 30 from requesting an ARP update. At this time, the deletion unit 15b updates the ARP table via an ARP request and an ARP response between the source edge router 20A and the user terminal 30.

[0043] (2-5-3. Setting section 15c) The setting unit 15c sets a standby timer to prevent the ARP protocol from being cut off before the ARP tables held by the source edge router 20A and the user terminal 30 are updated.

[0044] (2-5-4. Breaking section 15d) The blocking unit 15d blocks the ARP protocol for the source edge router 20A. For example, the blocking unit 15d blocks the ARP protocol by filtering IPv4 communication after the ARP cache is deleted.

[0045] (2-5-5. Insertion section 15e) The input unit 15e inputs the user setting to the switching destination edge router. For example, the input unit 15e enables IPv4 communication of the switching destination edge router 20B by inputting the user setting including the IPv4 address after the ARP protocol is blocked.

[0046] [3. Flow of communication control processing] The flow of communication control processing according to the first embodiment will be described in detail with reference to Fig. 5. Fig. 5 is a sequence diagram showing an example of the flow of communication control processing according to the first embodiment. Below, the following will be described in order: reaccommodation instruction processing, ARP cache deletion processing, ARP timer update processing, standby timer setting processing, ARP protocol blocking processing, user setting input processing, and GARP transmission processing. Note that the processing of steps S101 to S115 described below can also be executed in a different order. Also, some of the processing of steps S101 to S115 described below may be omitted.

[0047] (3-1. Relocation Instruction Processing) The maintenance person M who is to perform the maintenance relocation transmits a relocation instruction to the switching source edge router 20A which is performing user communication with the user terminal 30 (step S101) (step S102).

[0048] (3-2.ARP cache deletion process) The communication control device 10 deletes the ARP cache held by the source edge router 20A (step S103). At this time, the ARP table held by the user terminal 30 is updated. The processing of step S103 above executes an ARP timer update process, which will be described later, and therefore it is possible to prevent ARP transmission from the user terminal 30 due to the expiration of the ARP timer before the user settings are input to the destination edge router 20B.

[0049] (3-3. ARP timer update process) The source edge router 20A sends an ARP request to the user terminal 30 (step S104). Meanwhile, the user terminal 30 sends an ARP response to the source edge router 20A (step S105). As a result, the ARP table held by the source edge router 20A is updated (step S107), and the ARP table held by the user terminal 30 is updated (step S108). Also, the ARP timer included in the ARP table is updated to the maximum value (e.g., 999), and other entries remain unchanged. Therefore, no ARP request is issued from the user terminal 30 for the time being.

[0050] (3-4. Waiting timer setting process) The communication control device 10 sets a wait timer to prevent the ARP protocol from being shut down before the ARP table is updated (step S106), which makes it possible to prevent the ARP protocol from being shut down before the ARP table is updated.

[0051] (3-5. ARP protocol blocking process) The communication control device 10 blocks the ARP protocol for the source edge router 20A (step S109). At this time, the communication control device 10 blocks the ARP protocol by setting a filter for IPv4 communication for the source edge router 20A.

[0052] (3-6. User setting input process) The communication control device 10 inputs user settings (for example, the IPv4 address of the user terminal 30) to the switching destination edge router 20B (step S110). At this time, the IPv4 interface of the switching destination edge router 20B is enabled (step S111).

[0053] (3-7. GARP transmission processing) The switching destination edge router 20B transmits GARP to the user terminal 30 (step S112). On the other hand, the GARP transmitted to the switching source edge router 20A is blocked because ARP protocol blocking processing is being performed (step S113). At this time, the ARP table held by the user terminal 30 is updated (step S114), and the MAC address of the default gateway is updated to that of the switching destination edge router 20B. Then, user communication is performed between the user terminal 30 and the switching destination edge router 20B (step S115), and the processing ends.

[0054] 4. Effects of the First Embodiment Finally, the effects of the first embodiment will be described below: Effects 1 to 5 corresponding to the processing according to the first embodiment will be described below.

[0055] (4-1. Effect 1) In the first embodiment described above, a switching instruction is received from the edge router 20 that accommodates the user terminal, and the ARP cache held by the source edge router 20A is deleted based on the switching instruction, the ARP protocol is blocked for the source edge router 20A, and user settings are input to the destination edge router 20B. Therefore, in the first embodiment, maintenance relocation of the edge router 20 in IPv4 communication can be effectively performed.

[0056] (4-2. Effect 2) In the first embodiment described above, a predetermined timer is set to prevent the ARP protocol from being blocked before the ARP tables held by the source edge router and the user terminal 30 are updated. Therefore, in the first embodiment, the stability of the ARP protocol blocking is improved, making it possible to effectively perform maintenance relocation of the edge router 20 in IPv4 communication.

[0057] (4-3. Effect 3) In the first embodiment described above, the ARP cache is deleted, the ARP tables held by the source edge router 20A and the user terminal 30 are updated, and the ARP timer included in the ARP table is updated to its maximum value, thereby preventing the user terminal 30 from requesting an ARP update. Therefore, in the first embodiment, by preventing unintended ARP update requests from the user terminal 30, maintenance relocation of the edge router 20 in IPv4 communication can be effectively performed.

[0058] (4-4. Effect 4) In the first embodiment described above, the ARP protocol is blocked by filtering IPv4 communication after the ARP cache is deleted. Therefore, in the first embodiment, by avoiding an interruption of IPv4 communication, it is possible to effectively perform maintenance relocation of the edge router 20 in IPv4 communication.

[0059] (4-5. Effect 5) In the first embodiment described above, IPv4 communication of the switching destination edge router is enabled by inputting user settings including an IPv4 address after the ARP protocol is blocked. Therefore, in the first embodiment, duplication of IPv4 addresses can be avoided, thereby making it possible to effectively perform maintenance relocation of the edge router 20 in IPv4 communication.

[0060] [System configuration, etc.] The components of each device shown in the drawings according to the above embodiments are conceptual functional units and do not necessarily have to be physically configured as shown. In other words, the specific form of distribution and integration of each device is not limited to that shown, and all or part of each device can be functionally or physically distributed and integrated in any unit depending on various loads, usage conditions, etc. Furthermore, all or any part of the processing functions performed by each device can be realized by a CPU and a program analyzed and executed by the CPU, or can be realized as hardware using wired logic.

[0061] Furthermore, among the processes described in the above embodiments, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically using a known method.In addition, the information including the processing procedures, control procedures, specific names, various data and parameters shown in the above documents and drawings can be changed as desired unless otherwise specified.

[0062] 〔program〕 It is also possible to create a program written in a computer-executable language that describes the processes executed by the communication control device 10 described in the above embodiment. In this case, the same effects as those of the above embodiment can be achieved by having a computer execute the program. Furthermore, such a program may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read and executed by a computer to achieve the same processes as those of the above embodiment.

[0063] 6 is a diagram showing a computer that executes a program. As shown in the example of FIG. 6, a computer 1000 includes, for example, a memory 1010, a CPU 1020, 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, and these components are connected by a bus 1080.

[0064] As shown in FIG. 6, the memory 1010 includes a ROM (Read Only Memory) 1011 and a RAM 1012. The ROM 1011 stores a boot program such as a BIOS (Basic Input Output System). The hard disk drive interface 1030 is connected to a hard disk drive 1090 as shown in FIG. 6. The disk drive interface 1040 is connected to a disk drive 1100 as shown in FIG. 6. 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 as shown in FIG. 6. The video adapter 1060 is connected to a display 1130 as shown in FIG. 6.

[0065] 6, 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, the above programs are stored, for example, on the hard disk drive 1090 as program modules in which instructions to be executed by the computer 1000 are written.

[0066] The various data described in the above embodiment are stored as program data, for example, in the memory 1010 or the hard disk drive 1090. The CPU 1020 then reads the program module 1093 and the program data 1094 stored in the memory 1010 or the hard disk drive 1090 into the RAM 1012 as needed, and executes various processing procedures.

[0067] Note that the program module 1093 and program data 1094 related to the program are not limited to being stored in the hard disk drive 1090, and may be stored in, for example, a removable storage medium and read by the CPU 1020 via a disk drive or the like. Alternatively, the program module 1093 and program data 1094 related to the program may be stored in another computer connected via a network (such as a LAN (Local Area Network) or WAN (Wide Area Network)) and read by the CPU 1020 via the network interface 1070.

[0068] The above-described embodiments and their modifications are included in the technology disclosed in this application, as well as in the scope of the invention described in the claims and their equivalents. [Explanation of symbols]

[0069] 10. Communication control device 11 Input section 12 Output section 13 Communications Department 14 Storage section 15 Control Unit 15a Reception 15b Deleted section 15c Setting section 15d Breaker 15e Input section 20, 20A, 20B Edge Router 30 User terminals 100 Communication Control System

Claims

1. a receiving unit that receives a switching instruction from a source edge router that accommodates a user terminal to a destination edge router; a deletion unit that deletes an Address Resolution Protocol (ARP) cache held by the source edge router based on the switching instruction and continues data communication that executes an ARP request and an ARP response between the user terminal and the source edge router; a blocking unit that blocks an ARP protocol for the switching source edge router after the ARP cache is deleted, thereby preventing detection of address duplication; an input unit that inputs a user setting to the destination edge router after the ARP protocol is blocked; A communication control device comprising:

2. a setting unit that sets a predetermined timer to prevent the ARP protocol from being blocked before the ARP tables held by the switching source edge router and the user terminal are updated; 2. The communication control device according to claim 1, further comprising:

3. The deletion unit deleting the ARP cache, updating the ARP tables held by the switching source edge router and the user terminal, and updating the ARP timer included in the ARP table to a maximum value, thereby preventing the user terminal from requesting an ARP update; 3. The communication control device according to claim 1, wherein:

4. The interrupter is blocking the ARP protocol by filtering IPv4 (Internet Protocol version 4) communications after the ARP cache is deleted; 3. The communication control device according to claim 1, wherein:

5. The input unit is After the ARP protocol is blocked, the user settings including an IPv4 address are input to enable IPv4 communication of the destination edge router.

3. The communication control device according to claim 1, wherein:

6. A communication control method executed by a communication control device, a receiving step of receiving a switching instruction from a source edge router accommodating a user terminal to a destination edge router; a deletion step of deleting an ARP cache held by the switching source edge router based on the switching instruction, and continuing data communication in which an ARP request and an ARP response are executed between the user terminal and the switching source edge router; a blocking step of blocking the ARP protocol for the switching source edge router after the ARP cache is deleted, thereby avoiding detection of address duplication; an input step of inputting a user setting to the destination edge router after the ARP protocol is blocked; A communication control method comprising:

7. a receiving procedure for receiving a switching instruction from a source edge router accommodating a user terminal to a destination edge router; a deletion procedure for deleting an ARP cache held by the switching source edge router based on the switching instruction, and continuing data communication for executing ARP requests and ARP responses between the user terminal and the switching source edge router; a blocking procedure for blocking the ARP protocol for the switching source edge router after the ARP cache is deleted, thereby avoiding detection of address duplication; an input procedure for inputting a user setting to the destination edge router after the ARP protocol is blocked; A communication control program that causes a computer to execute the above.

Images