JP2012222542A - Ip address management system, dhcp converter, ip address management method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an IP address management system in which CPE allows connection with a WAN line and acquisition of an IP address automatically when starting communication of user data, and to obtain a DHCP converter, and an IP address management method and a program.SOLUTION: CPE 12 requests a DHCP server 11 to deliver an IP address, and obtains a DHCP offer containing a temporary IP address. WAN line connection request means 13d requests connection with a WAN line when data is sent from the CPE 12 toward the WAN line. Subsequently, the lease time of the IP address is updated, and while changing a MAC header of an IP packet other than the DHCP packet by a DHCP converter 103, user data is communicated between the CPE 12 and a WAN side DHCP server 104.

Description

  The present invention relates to an IP address management system, a DHCP conversion apparatus, an IP address management method, and a program that are connected to a WAN line and receive an IP address on the WAN line side.

  There is a WAN (Wide Area Network) as a communication network that operates over a wider range than a LAN (Local Area Network). When a WAN is constructed, CPE (Customer Premises Equipment) is arranged on each subscriber side, and the CPE is connected to the WAN line via the WAN line connection device. .

  In the related technology related to the present invention, in the WAN service communication network, the WAN line connection device always maintains the connection with the WAN line (for example, see Patent Document 1). For this reason, when the CPE is connected to the WAN line connection device using an Ethernet (registered trademark) cable, the CPE automatically activates DHCP (Dynamic Host Configuration Protocol) to obtain an IP address (Internet Protocol Address) Communication with the Internet becomes possible.

JP 2010-239591 (paragraph 0160, FIG. 20)

  According to this related technology, the CPE has the convenience that the IP address is automatically acquired and the communication state is obtained only by connecting the Ethernet (registered trademark) cable to the WAN line connection device. However, on the other hand, when the CPE is connected to the WAN line connection device using the Ethernet (registered trademark) cable, the process of transmitting and receiving the control packet for updating the IP address to and from the DHCP server on the WAN side is periodically performed. To be done. Therefore, when the CPE employs a pay-per-use system when connecting to the WAN line, there is a problem that the CPE user is charged more than the packet used for the original data communication. This is because the usage fee is charged according to the amount of packet communication in the pay-per-use system, and the control packet is also charged.

  Further, according to this related technique, since the CPE is connected to the WAN line via the WAN line connection device, there is a security problem that it is easy to receive attack packets from the WAN line side. Of course, the user can avoid the security problem by disconnecting the CPE from the WAN line other than the time for performing data communication by himself. However, this requires a user on the CPE side to manually perform WAN line connection processing and disconnection processing before and after communication, which is troublesome.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an IP address management system, a DHCP conversion device, an IP address management system capable of connecting to a WAN line and acquiring an IP address without user effort when the CPE starts communication of user data. It is to obtain an address management method and program.

  Another object of the present invention is to manage the IP address that can release the connection to the WAN line without the user's trouble when the CPE ends the communication of user data using the IP address acquired from the WAN line. A system, a DHCP converter, an IP address management method, and a program are obtained.

  In the present invention, (b) a DHCP (Dynamic Host Configuration Protocol) server that is arranged on the WAN (Wide Area Network) side and issues an IP address (Internet Protocol Address) to a requested device; A DHCP discover sending means for sending out a DHCP discover (DHCP DISCOVER) requesting delivery of an IP address to the own device to the DHCP server, and DHCP as a presentation condition for the DHCP discover sent out by the DHCP discover sending means A DHCP request sending means for accepting a condition for sending a DHCP request (DHCP REQUEST) to the DHCP server when the condition can be accepted when an offer (DHCP OFFER) is sent back, and accepting the condition Communication that allows data communication to be started using the IP address presented in the DHCP offer when a DHCP acknowledgment (DHCP ACK) is sent back in response to a DHCP request sent by the DHCP request sending means at the time of operation Starting means, lease time update DHCP request sending means for sending a lease time update DHCP request before the lease time elapses in order to update the lease time of the IP address presented in the DHCP offer, When the lease time update DHCP request is sent by the lease time update DHCP request sending means, when the DHCP negative acknowledgment rejecting the update request is returned, the IP address presented in the DHCP offer A CPE (Customer Premises Equipment) having an IP address discarding means to be discarded, and (c) a CPE and a WAN line to which the DHCP server is connected, and the connection to the WAN line is turned on. WAN line connection on / off means to be turned off, and when the above-mentioned CPE sends out the above-mentioned DHCP discover in a state where this WAN line connection on / off means is not connected to the above-mentioned WAN line, the above-mentioned DHCP server The proxy DHCP offer response means for issuing a temporary IP address received as a proxy of the request and replying the DHCP offer including the IP address to the CPE, and the CPE for the reply of the proxy DHCP offer response means When the above-mentioned DHCP request is sent, this is used as a proxy for the above-mentioned DHCP server. A proxy DHCP acknowledgment response means for receiving and responding to the above-mentioned CPE with a DHCP acknowledgment, and the above-mentioned WAN line connection on / off means when the data directed from the above-mentioned CPE to the above-mentioned WAN line is sent. A WAN line connection requesting means for making a transition to a state of waiting for data transmission without being connected to the WAN line and requesting the WAN line connection on / off means to connect to the WAN line, and this WAN This request is made when the CPE sends the DHCP request at the time of lease time update until the WAN line connection on / off means turns on the connection with the WAN line by the request of the line connection request means. Negative Acknowledgment Returning DHCP Negative Acknowledgment The above-mentioned DHCP request at the time of lease time update is not made until the predetermined time within the lease time presented by the DHCP server has passed after the WAN line connection on / off means has been connected by the above-described WAN line connection on / off means. The DHCP server-destined DHCP request transmitting means for transmitting a DHCP request on behalf of the above-mentioned CPE to the above-described DHCP server, and the DHCP server-destined DHCP request transmitted by the DHCP server-destined DHCP request transmitting means. And a DHCP acknowledgment return means for returning the DHCP acknowledgment to the CPE when the DHCP server returns a DHCP acknowledgment that means that the same IP address can be continuously issued. A DHCP conversion device IP address management system comprising a.

  In the present invention, (i) CPE (Customer Premises Equipment) requesting delivery of an IP address (Internet Protocol Address) and DHCP (Dynamic Host Configuration Protocol) delivering an IP address to the CPE in response to this request. WAN line connection on / off means that is arranged between a WAN (Wide Area Network) line to which the server is connected, and turns on / off the connection between the WAN line and its own device, and (b) this WAN line connection on When the above-mentioned CPE sends out a DHCP discover requesting the IP address to be issued to the above-mentioned DHCP server (DHCP DISCOVER) while the OFF means is not connected to the above-mentioned WAN line. Temporary IP address issue that receives and issues a temporary IP address as a proxy for the DHCP server. And (c) a proxy DHCP offer response that responds to the CPE with a DHCP offer (DHCP OFFER) as a presentation condition including the IP address issued by the temporary IP address issuing means to the DHCP discover described above. And (d) when a DHCP request (DHCP REQUEST) indicating that the above-mentioned CPE can accept the conditions indicated in the reply is sent in response to the reply of this proxy DHCP offer reply means, this is referred to as the DHCP server. Proxy DHCP acknowledgment response means for receiving a DHCP acknowledgment (DHCP ACK) to the above-mentioned CPE, and (e) when data directed from the above-mentioned CPE to the above-mentioned WAN line is sent. WAN line connection on / off means WAN line connection requesting means for making a transition to a state of waiting for data transmission without being connected to the WAN line and requesting the WAN line connection on / off means to connect to the WAN line; F) Until the above-mentioned WAN line connection on / off means turns on the connection to the WAN line in response to the request from the WAN line connection request means, the above-mentioned IP address presented by the above-mentioned DHCP offer by the above-mentioned CPE Negative acknowledgment return means for sending back a DHCP negative acknowledgment that rejects the request when a DHCP request is transmitted at the time of lease time update in order to update the lease time, and (g) WAN line connection ON as described above -The off means connected to the WAN line described above and the relay server presented by the DHCP server described above. A DHCP server-destined DHCP request transmitting means for transmitting a DHCP request on behalf of the CPE to the DHCP server when the DHCP request is sent for the first time after the lease time is renewed after a predetermined period of time elapses. (H) In response to the DHCP request addressed to the DHCP server sent by the DHCP server addressed DHCP request transmission means, the DHCP server returns a DHCP acknowledgment meaning that the same IP address can be continuously issued. The DHCP conversion device includes a DHCP acknowledgment return means for returning the DHCP acknowledgment to the CPE.

  Further, in the present invention, (i) a DHCP (Dynamic Host Configuration Protocol) server that issues an IP address to the CPE in response to a request from a CPE (Customer Premises Equipment) that requests an IP address (Internet Protocol Address) is connected. The DHCP discover (DHCP DISCOVER) requesting the above-mentioned DHCP server to issue an IP address to the above-mentioned DHCP server in a state where the connection between the WAN (Wide Area Network) line and the own device is turned off. A temporary IP address issuing step for issuing a temporary IP address by receiving this as a proxy for the DHCP server when it is sent, and (b) a temporary IP address issuing step for the DHCP discover described above. DHCP offer as a presentation condition that includes the issued IP address A proxy DHCP offer reply step for replying (DHCP OFFER) to the above-mentioned CPE, and (c) a response made in this proxy DHCP offer reply step indicates that the above-mentioned CPE can accept the conditions indicated in the reply. A proxy DHCP acknowledgment reply step of receiving a DHCP request (DHCP REQUEST) as a proxy of the DHCP server and replying a DHCP acknowledgment (DHCP ACK) to the CPE; When data is sent from the CPE to the above-described WAN line, the state shifts to a state of waiting for data transmission while the connection between the WAN line and the own apparatus is off, and WAN line connection request request for device connection And (e) the above-mentioned IP address lease time presented by the above-mentioned DHCP offer by the above-mentioned CPE until the above-mentioned WAN line is connected to its own device by the request in this WAN line connection request step. When a lease time update DHCP request is sent for renewal, a negative acknowledgment return step of returning a DHCP negative acknowledgment rejecting this request, and (to) the WAN line connection request step described above. When a DHCP request is sent for the first time when the lease time is updated after the predetermined time within the lease time presented by the DHCP server has been connected with the WAN line and the above-mentioned DHCP server, the above-mentioned CPE is sent to the DHCP server. DH sending a DHCP request on behalf It is possible that the DHCP server described above can continue to issue the same IP address in response to the DHCP request addressed to the DHCP server sent in the DHCP request addressed to the DHCP server sent in the DHCP server addressed DHCP request sending step. The IP address management method includes a DHCP acknowledgment return step of returning the DHCP acknowledgment to the CPE when the DHCP acknowledgment meaning is returned.

  Furthermore, in the present invention, as an IP address (Internet Protocol Address) management program, (i) an IP address is issued to the CPE in response to a request from a CPE (Customer Premises Equipment) that requests the IP address to be issued. With the WAN (Wide Area Network) line connected to the DHCP (Dynamic Host Configuration Protocol) server connected to the own device, the CPE issues an IP address to the own device toward the DHCP server. A DHCP discover request (DHCP DISCOVER) is received as a proxy for the DHCP server and a temporary IP address issuance process for issuing a temporary IP address; and (b) for the DHCP discover described above. I issued by the temporary IP address issuing process described above Proxy DHCP offer response processing that responds to the above-mentioned CPE with a DHCP offer (DHCP OFFER) as a presentation condition including the P address, and (c) the above-mentioned CPE responds to the response made in this proxy DHCP offer response processing. Proxy DHCP Acknowledge that receives a DHCP request (DHCP REQUEST) indicating that the indicated condition is acceptable as a proxy of the DHCP server and returns a DHCP acknowledgment (DHCP ACK) to the CPE And (d) a state of waiting for data transmission in a state where the connection between the WAN line and the own apparatus is off when data is sent from the CPE to the WAN line. As well as the WAN line and own device WAN line connection request processing for requesting connection, and (e) the above-mentioned CPE is presented in the above-mentioned DHCP offer until the above-mentioned WAN line is connected to the own device by a request by this WAN line connection request processing. Negative acknowledgment return processing for returning a DHCP negative acknowledgment that rejects this request when a DHCP request is transmitted at the time of lease time update in order to renew the lease time of the IP address, and (to) the WAN described above The above-described DHCP request at the time of lease time renewal is sent for the first time after the predetermined time within the lease time presented by the DHCP server has passed after the WAN line is connected to the above-mentioned WAN line by the line connection request processing. DHCP request on behalf of the above-mentioned CPE to the DHCP server DHCP server-sending DHCP request sending process for sending a DHCP server and (g) DHCP server-sending DHCP request sent in the DHCP server-sending DHCP request sending process, the DHCP server continues to issue the same IP address. When a DHCP acknowledgment signifying that it is possible is returned, a DHCP acknowledgment return process for returning the DHCP acknowledgment to the CPE is executed.

  As described above, according to the present invention, the DHCP conversion apparatus is connected to the WAN line triggered by the start of user data communication of a CPE represented by an access router, a personal computer or the like that acquires an IP address using DHCP. The Therefore, it is possible to connect to the WAN line when necessary without individually connecting a special device to each CPE, so that not only the usage fee can be reduced but also the network traffic can be reduced. be able to. Further, since it is not necessary to always connect the CPE to the WAN line, the possibility of unauthorized access from the WAN line side can be reduced.

It is a claim correspondence diagram of the IP address management system of the present invention. It is a claim corresponding | compatible figure of the DHCP converter of this invention. It is a claim correspondence diagram of the IP address management method of the present invention. It is a claim correspondence diagram of the IP address management program of the present invention. 1 is a system configuration diagram showing an outline of a configuration of an IP address management system according to an embodiment of the present invention. It is sequence explanatory drawing showing the mode of the process performed between DHCP conversion apparatuses, when CPE starts in the IP address management system of this Embodiment. It is sequence explanatory drawing which showed the operation | movement when the DHCP converter in this Embodiment receives the user data which should be transmitted to a WAN line from CPE. It is sequence explanatory drawing showing the update process about the lease time of the IP address from a WAN side DHCP server in this Embodiment. It is a flowchart showing the process of the WAN connection part at the time of the completion | finish of transmission of user data in the DHCP converter of this Embodiment. It is the flowchart showing the mode of the transmission process of the DHCP release packet in the DHCP converter of this Embodiment. It is sequence explanatory drawing showing the mode of processing of the IP address management system when the DHCP converter of this Embodiment determines with the absence of transmission data. It is sequence explanatory drawing which showed the process of the IP address management system when the DHCP converter in the modification of this invention determines with transmission data absence.

  FIG. 1 is a diagram corresponding to claims of the IP address management system of the present invention. The IP address management system 10 of the present invention includes a DHCP (Dynamic Host Configuration Protocol) server 11, a CPE (Customer Premises Equipment) 12, and a DHCP conversion device 13. Here, the DHCP server 11 is arranged on the WAN (Wide Area Network) side, and issues an IP address (Internet Protocol Address) to the requested apparatus. The CPE 12 includes a DHCP discover sending means 12a, a DHCP request sending means 12b when conditions can be accepted, a communication start means 12c, a DHCP request sending means 12d when a lease time is updated, and an IP address discarding means 12e. The DHCP discover sending means 12a sends a DHCP discover (DHCP DISCOVER) requesting the DHCP server 11 to issue an IP address to itself. When the condition can be accepted, the DHCP request sending means 12b receives the DHCP offer (DHCP OFFER) as a presentation condition to the DHCP discover sent by the DHCP discover sending means 12a. A request (DHCP REQUEST) is sent to the DHCP server 11. The communication start means 12c uses the IP address presented in the DHCP offer when the DHCP acknowledgment (DHCP ACK) is sent back to the DHCP request sent by the DHCP request sending means 12b when the condition is acceptable. Data communication can be started. The lease time update DHCP request sending means 12d transmits a lease time update DHCP request before the lease time elapses in order to renew the lease time of the IP address presented in the DHCP offer. The IP address discarding unit 12e is configured to send the DHCP offer acknowledgment when the DHCP negative acknowledgment for rejecting the update request is returned when the lease time update DHCP request is sent by the lease time update DHCP request sending unit 12d. The IP address presented in is discarded. The DHCP converter 13 includes a WAN line connection on / off means 13a, a proxy DHCP offer reply means 13b, a proxy DHCP acknowledgment reply means 13c, a WAN line connection request means 13d, a negative acknowledgment reply means 13e, A DHCP server-addressed DHCP request transmission unit 13f and a DHCP acknowledgment return unit 13g are provided. The WAN line connection on / off means 13a is arranged between the CPE 12 and the WAN line to which the DHCP server 11 is connected, and turns on / off the connection with the WAN line. The proxy DHCP offer response means 13b receives the DHCP discover as a proxy of the DHCP server 11 when the CPE 12 sends out the DHCP discover when the WAN line connection on / off means 13a is not connected to the WAN line. A temporary IP address is issued and a DHCP offer including this IP address is returned to the CPE 12. The proxy DHCP acknowledgment reply means 13c receives the DHCP request as a proxy of the DHCP server 11 when the CPE 12 sends out the DHCP request in response to the reply of the proxy DHCP offer reply means 13b, and returns a DHCP acknowledgment to the CPE 12. . The WAN line connection request unit 13d waits for data transmission in a state in which the WAN line connection on / off unit 13a is not connected to the WAN line when data is sent from the CPE 12 to the WAN line. At the same time, the WAN line connection on / off means 13a is requested to connect to the WAN line. The negative acknowledgment reply means 13e is a DHCP request when the lease time is updated by the CPE 12 until the WAN line connection on / off means 13a turns on the connection to the WAN line in response to a request from the WAN line connection request means 13d. Is sent back, a DHCP negative acknowledgment that rejects this request is returned. The DHCP server-destined DHCP request transmission means 13f is the time when the lease time is updated for the first time after the WAN line connection on / off means 13a connects the WAN line described above and a predetermined time within the lease time presented by the DHCP server 11 has elapsed. When a DHCP request is sent, the DHCP request is transmitted to the DHCP server 11 on behalf of the CPE 12. The DHCP acknowledgment return means 13g means that the DHCP server 11 can continuously issue the same IP address in response to the DHCP server-addressed DHCP request sent from the DHCP server-addressed DHCP request transmission means 13f. When this message is returned, this DHCP acknowledgment is returned to the CPE 12.

  FIG. 2 shows a claim correspondence diagram of the Dynamic Host Configuration Protocol (DHCP) conversion apparatus of the present invention. The DHCP conversion apparatus 20 of the present invention includes a WAN (Wide Area Network) line connection on / off means 21, a temporary IP (Internet Protocol Address) address issuing means 22, a proxy DHCP offer response means 23, and a proxy DHCP acknowledgment. A reply means 24, a WAN line connection request means 25, a negative acknowledgment reply means 26, a DHCP server-addressed DHCP request transmission means 27, and a DHCP acknowledgment return means 28 are provided. Here, the WAN line connection on / off means 21 is a WAN line connected to a CPE (Customer Premises Equipment) that requests the IP address to be issued and a DHCP server that issues an IP address to the CPE in response to this request. And turns on / off the connection between the WAN line and its own device. Temporary IP address issuing means 22 requests the above-mentioned DHCP server to issue an IP address to its own DHCP server when the WAN line connection on / off means 21 is not connected to the WAN line. When a DHCP Discover to be sent is sent out, it is received as a proxy for the DHCP server and a temporary IP address is issued. The proxy DHCP offer response means 23 returns a DHCP offer (DHCP OFFER) as a presentation condition including the IP address issued by the temporary IP address issuing means 22 to the above-described DHCP discover. The proxy DHCP acknowledgment reply means 24 sends a DHCP request (DHCP REQUEST) indicating that the CPE can accept the condition indicated in the reply to the reply of the proxy DHCP offer reply means 23. Received as a proxy for the DHCP server, and returns a DHCP acknowledgment (DHCP ACK) to the CPE. The WAN line connection request unit 25 transmits data in a state in which the WAN line connection on / off unit 21 is not connected to the WAN line when data is sent from the CPE to the WAN line. While shifting to a standby state, the WAN line connection on / off means 21 is requested to connect to the WAN line. The negative acknowledgment reply means 26 presents the above-mentioned CPE in the above-mentioned DHCP offer until the WAN line connection on / off means 21 turns on the connection to the WAN line in response to a request from the WAN line connection request means 25. When a DHCP request is transmitted at the time of lease time update in order to renew the lease time of the IP address, a DHCP negative acknowledgment that rejects this request is returned. The DHCP server-destined DHCP request transmission means 27 is the DHCP server when the lease time is updated only after the WAN line connection on / off means 21 connects the WAN line described above and a predetermined time within the lease time presented by the DHCP server elapses. When a request is sent, a DHCP request is transmitted to the DHCP server on behalf of the CPE. The DHCP acknowledgment return means 28 is a DHCP acknowledge that means that the DHCP server can continuously issue the same IP address in response to the DHCP server-addressed DHCP request sent from the DHCP server-addressed DHCP request transmission means 27. This DHCP acknowledgment is returned to the above-mentioned CPE.

  FIG. 3 is a diagram corresponding to claims of the IP address management method of the present invention. The IP address (Internet Protocol Address) management method 30 of the present invention includes a provisional IP address issuing step 31, a proxy DHCP (Dynamic Host Configuration Protocol) offer response step 32, a proxy DHCP acknowledgment response step 33, a WAN (Wide) Area network) line connection request step 34, negative acknowledgment return step 35, DHCP server-addressed DHCP request transmission step 36, and DHCP acknowledgment return step 37. Here, in the provisional IP address issue step 31, the WAN line connected to the DHCP server that issues the IP address to the CPE in response to a request from the CPE (Customer Premises Equipment) that requests the IP address to be issued, and the own device. When the above-mentioned CPE sends out a DHCP Discover (DHCP DISCOVER) requesting to issue an IP address to its own device to the above-mentioned DHCP server in a state where the connection is off, this is represented by the above-mentioned DHCP server. And issue a temporary IP address. In the proxy DHCP offer response step 32, a DHCP offer (DHCP OFFER) as a presentation condition including the IP address issued in the provisional IP address issue step 31 is returned to the above-mentioned CPE for the DHCP discover described above. In the proxy DHCP acknowledgment response step 33, when a DHCP request (DHCP REQUEST) indicating that the above-mentioned CPE can accept the conditions indicated in the response to the response made in the proxy DHCP offer response step 32 is sent. As a proxy of the above-mentioned DHCP server, and a DHCP acknowledgment (DHCP ACK) is returned to the above-mentioned CPE. In the WAN line connection request step 34, when data is sent from the CPE to the WAN line, a state of waiting for data transmission in a state where the connection between the WAN line and the own apparatus is off. And a request for connection between the WAN line and the own apparatus is made. In the negative acknowledgment reply step 35, the above-mentioned CPE is leased the IP address presented in the DHCP offer until the above-mentioned WAN line is connected to the own device by the request in the WAN line connection request step 34. When a DHCP request is transmitted at the time of lease time update to update the time, a DHCP negative acknowledgment that rejects this request is returned. In the DHCP request transmission step 36 for the DHCP server, the lease time described above is the first time after a predetermined time within the lease time presented by the DHCP server has passed after the WAN line is connected to the own device in the WAN line connection request step 34. When a DHCP request is sent at the time of update, the DHCP request is transmitted to the above-described DHCP server on behalf of the above-mentioned CPE. In DHCP Acknowledgment Return Step 37, DHCP Acknowledgment means that the DHCP server can continue to issue the same IP address in response to the DHCP server-addressed DHCP request sent in DHCP server-addressed DHCP request. This DHCP acknowledgment is returned to the above-mentioned CPE.

  FIG. 4 shows a correspondence diagram of claims of the IP (Internet Protocol Address) address management program of the present invention. The IP address management program 40 of the present invention includes a temporary IP address issuing process 41, a proxy DHCP (Dynamic Host Configuration Protocol) offer response process 42, a proxy DHCP acknowledgment response process 43, and a WAN (Wide Area Network). ) A line connection request process 44, a negative acknowledgment return process 45, a DHCP server-addressed DHCP request transmission process 46, and a DHCP acknowledgment return process 47 are executed. Here, in the provisional IP address issuance process 41, the WAN line connected to the DHCP server that issues an IP address to the CPE in response to a request from a CPE (Customer Premises Equipment) that requests the IP address to be issued, and the own device. When the above-mentioned CPE sends out a DHCP Discover (DHCP DISCOVER) requesting to issue an IP address to its own device to the above-mentioned DHCP server in a state where the connection is off, this is represented by the above-mentioned DHCP server. And issue a temporary IP address. In the proxy DHCP offer response process 42, a DHCP offer (DHCP OFFER) as a presentation condition including the IP address issued in the temporary IP address issue process 41 is returned to the above-mentioned CPE for the above-described DHCP discover. In the proxy DHCP acknowledgment response processing 43, when a DHCP request (DHCP REQUEST) indicating that the above-mentioned CPE can accept the condition indicated in the response to the response made in the proxy DHCP offer response processing 42 is sent. As a proxy of the above-mentioned DHCP server, and a DHCP acknowledgment (DHCP ACK) is returned to the above-mentioned CPE. In the WAN line connection request processing 44, when data is sent from the CPE to the WAN line, a state of waiting for data transmission in a state where the connection between the WAN line and the own apparatus is off And a request for connection between the WAN line and the own apparatus is made. In the negative acknowledgment reply process 45, the above-mentioned IP address lease presented by the above-mentioned DHCP offer is provided until the above-mentioned CPE is connected to the above-mentioned WAN line by the request from the WAN line connection request process 44. When a DHCP request is transmitted at the time of lease time update to update the time, a DHCP negative acknowledgment that rejects this request is returned. In the DHCP server-addressed DHCP request transmission process 46, the above-mentioned lease time is only after a predetermined time within the lease time presented by the DHCP server has elapsed after the WAN line and the own apparatus are connected by the WAN line connection request process 44. When a DHCP request is sent at the time of update, the DHCP request is transmitted to the above-described DHCP server on behalf of the above-mentioned CPE. In the DHCP acknowledgment return process 47, the DHCP acknowledge means that the DHCP server can continuously issue the same IP address in response to the DHCP server-addressed DHCP request sent in the DHCP server-addressed DHCP request transmission process 46. This DHCP acknowledgment is returned to the above-mentioned CPE.

  <Embodiment of the Invention>

  Next, an embodiment of the present invention will be described.

  FIG. 5 shows an outline of the configuration of the IP address management system according to the embodiment of the present invention. This IP address management system 100 has a structure in which a DHCP converter 103 is arranged between a CPE 101 and a WAN line 102. A WAN side DHCP server 104 is connected to the WAN line 102. The WAN side DHCP server 104 is a device that issues an IP address in response to a request from the CPE 101 through the WAN line 102.

  The DHCP conversion apparatus 103 includes a control unit 111. The control unit 111 includes a CPU 112 and a memory 113 that stores a control program executed by the CPU 112, and controls the following units. In addition, at least a part of these units can be realized by software.

  First, the LAN connection unit 114 is an Ethernet (registered trademark) interface such as 100BASE-T standardized as IEEE (Institute of Electrical and Electronic Engineers) 802.3u, for example. The LAN connection unit 114 is connected to the CPE 101 via the LAN cable 105. Among these, the CPE 101 is a device that acquires an IP address using the WAN-side DHCP server 104 in the present embodiment, and is composed of, for example, an access router or a personal computer.

  The WAN connection unit 115 is connected to the WAN line 102 via a predetermined line cable 106. The transfer processing unit 116 passes the packet received from the LAN connection unit 114 to the WAN connection unit 115. Further, the transfer processing unit 116 transmits the packet received from the WAN connection unit 115 to the CPE 101 via the LAN connection unit 114.

  In addition to the LAN connection unit 114 and the WAN connection unit 115, the transfer processing unit 116 is connected to the DHCP detection unit 117, the transmission standby flag storage unit 118, the WAN connection processing unit 119, and the post-startup elapsed timer 120. Here, the DHCP detection unit 117 detects a DHCP packet for obtaining an IP address requested from the CPE 101.

  The DHCP processing unit 121 is connected to the DHCP detection unit 117. When the DHCP conversion apparatus 103 is not connected to the WAN line 102, the DHCP processing unit 121 performs a proxy response to the DHCP packet detected by the DHCP detection unit 117 to temporarily The IP address is issued to the CPE 101. In addition, when the DHCP conversion apparatus 103 is connected to the WAN line 102, the DHCP processing unit 121 performs a transfer process of the DHCP packet with the WAN side DHCP server 104. Then, the DHCP processing unit 121 transfers the DHCP packet sent from the CPE 101 to the WAN side DHCP server 104 on the WAN line 102.

  When receiving a user data packet as a packet to be transmitted from the CPE 101 to the WAN line 102, the WAN connection processing unit 119 performs WAN line connection processing to the WAN line 102. The WAN connection processing unit 119 disconnects the connection between the DHCP conversion apparatus 103 and the WAN line 102 when there is no user data packet to be transmitted from the CPE 101 to the WAN line 102 for a certain period of time. The WAN connection unit 115 is a connection unit with the WAN line 102 that can issue an IP address by DHCP, and is connected to, for example, a WiMAX (Worldwide Interoperability for Microwave Access) network.

  The transmission standby flag storage unit 118 stores a software flag indicating that there is user data to be transmitted from the CPE 101 to the WAN line 102. The post-startup elapsed timer 120 is a counter that indicates an elapsed time since the CPE 101 was started up.

  FIG. 6 shows a state of processing performed with the DHCP conversion apparatus when the CPE is activated in the IP address management system configured as described above. This will be described with reference to FIG.

  When the DHCP conversion apparatus 103 is activated, the LAN connection unit 114 waits for reception of a packet from the CPE 101. Assume that the CPE 101 is connected to the DHCP conversion apparatus 103 in this state. In this connection state, the CPE 101 transmits a DHCP discover (DHCP DISCOVER) packet in order to acquire an IP address using the DHCP conversion apparatus 103. In the DHCP conversion apparatus 103, the LAN connection unit 114 receives the DHCP discover packet (step S201).

  The DHCP discover packet received by the LAN connection unit 114 is sent to the transfer processing unit 116. The DHCP detection unit 117 connected to the transfer processing unit 116 confirms the type of the transmitted packet. In this example, the DHCP detector 117 recognizes that the destination port number of the sent UDP (User Datagram Protocol) packet is the DHCP server (port number 67). When the DHCP detection unit 117 recognizes that the received packet is a DHCP-related packet, the DHCP detection unit 117 sends the packet to the DHCP processing unit 121.

  The DHCP processing unit 121 determines which type of packet in the DHCP the packet received from the DHCP detection unit 117 is. When recognizing that the received packet is the above-described DHCP discover packet, the DHCP processing unit 121 generates a DHCP OFFER packet for presenting the IP address delivery condition to the requesting CPE 101. The DHCP offer packet includes data such as a payout IP address, a default gateway, and a lease time.

  Here, as the payout IP address, a local address for temporary use by the CPE 101 is designated. Hereinafter, this local address designated for temporary use by the CPE 101 will be referred to as a “temporary IP address”. In the default gateway, an IP address for the LAN connection unit 114 of the DHCP conversion apparatus 103 used as a proxy for the WAN side DHCP server 104 in this embodiment is designated. The lease time specifies a time (for example, 10 seconds) that is considerably shorter than the lease time normally used in DHCP.

  The DHCP offer packet generated by the DHCP processing unit 121 is transmitted from the transfer processing unit 116 to the CPE 101 via the LAN connection unit 114 (step S202).

  The CPE 101 determines whether the condition presented in the DHCP offer packet received from the DHCP conversion apparatus 103 is acceptable. If it is acceptable, the CPE 101 transmits a DHCP request (DHCP REQUEST) packet with the content to the DHCP conversion apparatus 103 (step S203). The DHCP request packet is received by the LAN connection unit 114 of the DHCP conversion apparatus 103 and sent to the transfer processing unit 116. The DHCP detection unit 117 recognizes that the DHCP request packet sent to the transfer processing unit 116 is a DHCP packet, and sends this to the DHCP processing unit 121.

  If the conditions indicated in the DHCP request packet are the same as the contents presented in the DHCP offer packet in step S202, the DHCP processing unit 121 generates a DHCP acknowledgment (DHCP ACK; DHCP ACKnowledgement) packet and similarly to the CPE 101. A reply is made (step S204). The CPE 101 receives the DHCP acknowledgment, and adopts the presented temporary IP address as its own IP address.

  With the above operation, the temporary IP address is assigned to the CPE 101 by the DHCP conversion apparatus 103 acting as the proxy of the WAN side DHCP server 104. The CPE 101 normally transmits a DHCP request packet for updating the lease time after the half of the lease time has elapsed after receiving the DHCP acknowledgment packet. If the lease time is 10 seconds, the DHCP request packet is transmitted when 5 seconds have elapsed after receiving the DHCP acknowledgment packet. The DHCP request packet is also sent to the DHCP processing unit 121 via the LAN connection unit 114, the transfer processing unit 116, and the DHCP detection unit 117 of the DHCP conversion apparatus 103 (step S205).

  The DHCP processing unit 121 that has received the DHCP request packet generates a DHCP acknowledgment packet, and similarly returns it to the CPE 101 (step S206). While the DHCP conversion apparatus 103 does not transmit user data from the CPE 101 to the WAN line 102, every time a DHCP request packet is transmitted, a DHCP acknowledgment packet is generated and a reply to the DHCP acknowledgment packet is sent to the CPE 101. Is repeated (step S207, step S208).

  With the above operation, even when the WAN line 102 is not connected to the DHCP conversion apparatus 103, the temporary IP address can be assigned to the CPE 101.

  FIG. 7 shows an operation when the DHCP conversion apparatus receives user data to be transmitted from the CPE to the WAN line. This will be described with reference to FIG.

  When the user data to be transmitted from the CPE 101 to the WAN line 102 is received, the DHCP conversion apparatus 103 first executes a process for obtaining a formal IP address from the WAN side DHCP server 104 instead of the temporary IP address. User data transmitted from the CPE 101 to the WAN line 102 is first received by the LAN connection unit 114 of the DHCP conversion apparatus 103 (step S221). The LAN connection unit 114 passes this user data to the transfer processing unit 116.

  When the transfer processing unit 116 receives user data to be transmitted from the CPE 101 to the WAN line 102, the transfer processing unit 116 determines whether the WAN line 102 is unconnected, and if not connected, the transfer processing unit 116 sends the WAN line 102 to the WAN connection processing unit 119. Request connection with. In this case, the WAN connection processing unit 119 performs processing for connecting the line between the DHCP conversion apparatus 103 and the WAN line 102 (step S222).

  At this time, the source IP address of the user data transmitted from the CPE 101 to the WAN line 102 is a temporary IP address. For this reason, the transfer processing unit 116 discards the user data without transmitting it to the WAN line 102, and “1” indicating that the transmission standby flag stored in the transmission standby flag storage unit 118 is waiting for transmission. "Is set.

  When the CPE 101 transmits a DHCP request to update the lease time with the transmission waiting flag set to “1” in this way (step S223), the DHCP processing unit 121 rejects this request. A DHCP negative acknowledgment (DHCP NAK; DHCP Negative AcKnowledgement) is returned (step S224).

  When receiving the DHCPPP negative acknowledgment from the DHCP conversion apparatus 103 in this way, the CPE 101 discards the data such as the temporary IP address that has been paid up to that point, and transmits a DHCP discover packet again (step S225).

  On the other hand, when “1” is set in the transmission standby flag, the DHCP processing unit 121 does not make a proxy response to the DHCP discover received from the CPE 101. Then, the received DHCP discover packet is transferred as it is to the WAN side DHCP server 104 (step S226).

  When the DHCP discover packet is sent from the DHCP conversion apparatus 103, the WAN side DHCP server 104 sends back a DHCP offer packet in response thereto (step S227). This DHCP offer packet includes data such as a payout IP address, a default gateway, and a lease time.

  When the DHCP conversion apparatus 103 receives the DHCP offer packet, the DHCP processing unit 121 replaces the lease time in the DHCP offer packet with a time substantially smaller than the lease time presented from the WAN side. The lease time in the DHCP offer packet is usually 4 hours or 24 hours, but this is replaced with a time such as 10 seconds. When the contents of the DHCP offer packet are changed in this way, the checksum value of the packet also changes. Therefore, the DHCP processing unit 121 recalculates the checksum value of the DHCP offer packet and performs replacement, and then transfers this packet to the CPE 101 (step S228).

  When the DHCP request packet is sent from the CPE 101 in a state where the transmission standby flag is set to “1” (step S229), the DHCP processing unit 121 of the DHCP conversion device 103 does not perform a proxy response in this case as well. . Then, the DHCP processing unit 121 transfers the received DHCP request packet to the WAN side DHCP server 104 (step S230).

  When the WAN-side DHCP server 104 receives the DHCP request packet, the WAN-side DHCP server 104 returns a DHCP acknowledgment packet to the DHCP conversion apparatus 103 (step S231). The DHCP processing unit 121 in the DHCP conversion apparatus 103 changes the lease time included in the DHCP acknowledgment packet sent from the WAN side DHCP server 104 as in the case of the DHCP offer. As a result, the checksum value of the packet changes, so the DHCP processing unit 121 recalculates the checksum value of the DHCP request packet and performs replacement. Thereafter, the DHCP processing unit 121 transfers the DHCP request packet to the CPE 101 (step S232). After this transfer, the transfer processing unit 116 clears the transmission standby flag stored in the transmission standby flag storage unit 118 to “0”.

  When the CPE 101 receives the DHCP acknowledgment in step S232, the CPE 101 adopts the IP address included in the packet as its own LAN side IP address. As a result, the IP address issued from the WAN side DHCP server 104 is assigned to the CPE 101 as the originally requested IP address.

  Thereafter, the CPE 101 communicates user data with the WAN side DHCP server 104 (step S233). At this time, the source MAC address (Media Access Control address) and the destination MAC address of the IP packet change as follows.

  First, the source MAC address of transmission data transmitted from the CPE 101 to the WAN line 102 is the MAC address of the CPE 101, and the destination MAC address is the MAC address of the LAN connection unit 114 in the DHCP conversion device 103.

  The transfer processing unit 116 to which the data received from the LAN connection unit 114 is transferred replaces the MAC address as follows. First, the source MAC address is rewritten from the MAC address of the CPE 101 to the MAC address of the WAN connection unit 115 of the DHCP conversion apparatus 103. Next, the destination MAC address is rewritten from the MAC address of the LAN connection unit 114 to the MAC address of the default gateway on the WAN line 102 side.

  The transfer processing unit 116 of the DHCP conversion device 103 transmits the MAC address data rewritten in this way from the WAN connection unit 115 to the WAN line 102.

  On the other hand, the source MAC address of the data received from the WAN line 102 is the MAC address of the default gateway on the WAN line 102 side, and the destination MAC address is the MAC address of the WAN connection unit 115.

  The transfer processing unit 116 to which the data received from the WAN connection unit 115 is transferred replaces the MAC address as follows. First, for the source MAC address, the MAC address of the WAN gateway 102 side default gateway is rewritten to the MAC address of the LAN side interface of the DHCP conversion apparatus 103. Next, for the destination MAC address, the MAC address of the WAN connection unit 115 is rewritten to the MAC address of the CPE 101.

  The transfer processing unit 116 of the DHCP conversion device 103 transmits the MAC address data rewritten in this way from the LAN connection unit 114 to the CPE 101.

  In this way, by exchanging the MAC header of the IP packet other than the DHCP packet by the DHCP conversion apparatus 103, the user data communication shown as step S233 is performed between the CPE 101 and the WAN line 102.

  FIG. 8 shows an update process for the lease time of the IP address from the WAN-side DHCP server. This will be described with reference to FIG.

  After receiving the DHCP acknowledgment packet from the DHCP conversion apparatus 103 in step S206 of FIG. 6, the CPE 101 transmits a DHCP request packet for updating the lease time every half of the lease time. For example, if the lease time is 10 seconds, a DHCP request packet is transmitted from the CPE 101 to the DHCP conversion apparatus 103 every 5 seconds. The DHCP request packet is sent to the DHCP processing unit 121 via the LAN connection unit 114, the transfer processing unit 116, and the DHCP detection unit 117 of the DHCP conversion apparatus 103 (step S251).

  When receiving the DHCP request packet, the DHCP processing unit 121 generates a DHCP acknowledgment packet. The DHCP acknowledgment packet is returned from the DHCP conversion apparatus 103 to the CPE 101 (step S252).

  The response by step S251 and step S252 is repeated for a while. In this way, it is assumed that half of the lease time designated by the WAN-side DHCP server 104 has elapsed, and the DHCP request packet is sent from the CPE 101 to the DHCP conversion apparatus 103 for the first time after this time has elapsed (step S253). . The DHCP processing unit 121 does not perform a proxy response to the DHCP request packet, and transfers the received packet to the WAN side DHCP server 104 as it is (step S254).

  If the WAN-side DHCP server 104 can continue to issue the same IP address, it returns a DHCP acknowledgment to this DHCP request packet (step S255). When the DHCP processing unit 121 receives this DHCP acknowledgment, the DHCP processing unit 121 determines the lease time included therein in the same manner as the processing performed on the DHCP acknowledgment packet sent from the WAN side DHCP server 104 in step S231 in FIG. change. As a result, the checksum value of the packet changes. Therefore, the DHCP processing unit 121 recalculates and replaces the checksum value.

  Thereafter, the DHCP processing unit 121 transfers the DHCP acknowledgment packet whose lease time has been changed to the CPE 101 (step S256). As a result, the lease time of the IP address issued from the WAN-side DHCP server 104 is updated. Thereafter, this state continues until there is no user data to the WAN line 102 for a certain period of time. As described above, the DHCP conversion apparatus 103 repeatedly performs the IP address lease time update process with the CPE 101 on behalf of the WAN-side DHCP server 104 while changing the lease time.

  FIG. 9 shows the processing of the WAN connection unit at the end of transmission of user data in the DHCP converter. This will be described with reference to FIG.

  When the transmission of user data to the WAN line 102 is completed (step S271: Y), the WAN connection unit 115 saves the value of the elapsed timer 120 after activation (step S272) and ends the transmission process (end). In this way, every time the WAN connection unit 115 transmits user data to the WAN line 102, the elapsed time from the activation of the CPE 101 to the end of transmission is recorded.

  FIG. 10 shows a state of DHCP release packet transmission processing in the DHCP conversion apparatus. This will be described with reference to FIGS.

  When the WAN connection unit 115 of the DHCP conversion apparatus 103 elapses for a fixed time (for example, 10 seconds) since the previous activation (step S291: Y), the WAN connection unit 115 is activated and acquires the current value of the elapsed timer 120 after activation (step S291). S292). Then, the difference from the post-startup elapsed timer 120 value saved in step S272 of FIG. 9 is obtained (step S293).

  The WAN connection unit 115 compares whether the obtained difference is greater than the no-communication timer setting time (step S294). Here, the no-communication timer setting time is a time that the user can set within an arbitrary range, and is set to a time of about 10 minutes, for example. As a result of the comparison, when the difference obtained in step S293 is larger than the no-communication timer set time (Y), the WAN connection unit 115 determines that “transmission data is absent” to the WAN line 102. In this case, the WAN connection unit 115 generates a DHCP release (DHCP RELEASE) packet (step S295). Then, the DHCP release packet is transmitted to the WAN side DHCP server 104 (step S296).

  As a result, the IP address that has been paid out to the CPE 101 is returned to the WAN-side DHCP server 104 that has received the DHCP release packet. Thereafter, the WAN connection unit 115 disconnects the connection with the WAN line 102 (step S297), and ends a series of processing (end).

  On the other hand, when it is determined that the difference obtained in step S293 is equal to or less than the no-communication timer setting time (step S294: N), the WAN connection unit 115 returns the process to step S291. Then, when a certain period of time has passed, the process proceeds to step S292 and subsequent steps as described above.

  FIG. 11 shows a state of processing of the IP address management system when the DHCP converter determines that there is no transmission data. In FIG. 11, the same steps as those in FIGS. 6 and 10 are given the same step numbers. This will be described with reference to FIG.

  If the DHCP conversion apparatus 103 determines that “transmission data is absent” in step S295, the WAN connection unit 115 transmits a DHCP release packet to the WAN side DHCP server 104 using the WAN line 102 (step S296). Thereafter, the connection with the WAN line 102 is disconnected (step S297).

  Thereafter, it is assumed that a DHCP request packet is sent from the CPE 101 to the DHCP conversion apparatus 103 (step S311). At this point, the CPE 101 does not know that the DHCP conversion apparatus 103 has disconnected from the WAN line 102. Therefore, the DHCP processing unit 121 of the DHCP conversion apparatus 103 returns a DHCP negative acknowledgment (DHCP NAK) indicating that the request is rejected for the DHCP request packet (step S312). As a result, the CPE 101 knows that the connection with the WAN line 102 has been disconnected, and is in a state of not holding the IP address.

  Therefore, after this, when the CPE 101 tries to communicate user data with the WAN line 102, a DHCP discover packet is transmitted to the DHCP conversion apparatus 103 in order to obtain an IP address (step S201). Hereafter, it is as having demonstrated after step S202 of FIG.

  As described above, according to the IP address management system 100 of the present embodiment, as a first effect, when the user selects the pay-as-you-go system, the usage fee can be reduced. This is because in the present embodiment, the CPE 101 can be connected to the WAN line 102 only when it is necessary to transmit a packet. Conventionally, since processing for transmitting and receiving control packets for updating IP addresses has been performed periodically, there has been a drawback in that even control packets are charged.

  In the present embodiment, as a second effect, the possibility of unauthorized access from the WAN line 102 side can be reduced. This is because the CPE 101 is connected to the WAN line 102 via the DHCP conversion apparatus 103 only when it is necessary to transmit a packet, thereby reducing the chance of unauthorized access from the WAN side.

  <Deformability of invention>

  FIG. 12 shows another example of processing of the IP address management system when the DHCP conversion apparatus determines that there is no transmission data. In this modified IP address management system, the same parts as those in FIG. 11 are denoted by the same step numbers, and description thereof will be omitted as appropriate. This will be described with reference to FIG.

  When the DHCP conversion apparatus 103 determines that “transmission data is absent” in step S295, the WAN connection unit 115 transmits the DHCP release packet to the WAN side DHCP server 104 using the WAN line 102 (step S296), and then the WAN. The connection with the line 102 is disconnected (step S297).

  In the sequence when the WAN line 102 is disconnected, in this modification, the physical link of the LAN connection unit 114 is lowered for a certain period of time when the DHCP conversion apparatus 103 disconnects from the WAN line 102 (step S401). The time for bringing down the physical link is, for example, 10 seconds. Thereafter, the physical link of the LAN connection unit 114 is increased (step S402). As a result, the DHCP client of the CPE 101 is initialized and the IP address is released.

  As described with reference to FIG. 11, even when the DHCP processing unit 121 returns a DHCP negative acknowledgment at the time when the DHCP request packet is sent from the CPE 101 to the DHCP conversion apparatus 103 (step S311), the processing of the DHCP client is performed. Depending on the method, the CPE 101 may not return a DHCP discover packet. In such a case, a method for initializing the DHCP client of the CPE 101 as in the modification shown in FIG. 12 is effective.

  The processing after the DHCP conversion apparatus 103 ups the physical link of the LAN connection unit 114 and the CPE 101 transmits the DHCP discover packet in step S201 is the same as in the previous embodiment even in this modification.

Therefore, in the IP address management system according to this modification, when the DHCP conversion apparatus 103 disconnects from the WAN line 102, the DHCP client transmits the DHCP discover packet for obtaining the IP address by the difference in the processing method of the DHCP client. Regardless of whether or not

  Some or all of the embodiments described above are described as in the following supplementary notes, but are not limited to the following descriptions.

(Appendix 1)
A DHCP (Dynamic Host Configuration Protocol) server that is arranged on the WAN (Wide Area Network) side and issues an IP address (Internet Protocol Address) to a requested device;
A DHCP discover sending means for sending out a DHCP discover (DHCP DISCOVER) requesting delivery of an IP address to the own device to the DHCP server, and DHCP as a presentation condition for the DHCP discover sent out by the DHCP discover sending means When this condition can be accepted when an offer (DHCP OFFER) is sent back, a condition accepting condition for sending a DHCP request (DHCP REQUEST) to the DHCP server, and a DHCP request sending means, and when this condition is acceptable When a DHCP acknowledgment (DHCP ACK) is sent back to the DHCP request sent out by the DHCP request sending means, the IP address presented in the DHCP offer is used. Communication start means for enabling data communication, and lease time for transmitting a DHCP request at the time of lease time update before the lease time elapses in order to update the lease time of the IP address presented by the DHCP offer When a DHCP negative acknowledgment that rejects the renewal request is sent back when the lease time renewal DHCP request is sent by the renewal DHCP request sending means and the lease time renewal DHCP request sending means, the DHCP offer CPE (Customer Premises Equipment) having an IP address discarding means for discarding the presented IP address;
WAN line connection on / off means that is arranged between the CPE and the WAN line to which the DHCP server is connected, and turns on / off the connection to the WAN line, and the WAN line connection on / off means includes the WAN When the CPE sends out the DHCP discover in a state where it is not connected to the line, it receives this as a proxy of the DHCP server, issues a temporary IP address, and returns a DHCP offer including this IP address to the CPE Proxy DHCP offer replying means, and when the CPE sends out the DHCP request in response to the reply of the proxy DHCP offer replying means, this is received as a proxy of the DHCP server and a DHCP acknowledgment is returned to the CPE. From the proxy DHCP acknowledgment response means and the CPE When the data for the WAN line is sent, the WAN line connection on / off means shifts to a state of waiting for data transmission in a state where it is not connected to the WAN line, and the WAN line connection on / off WAN line connection request means for requesting connection to the WAN line from the means, and until the WAN line connection on / off means turns on the connection to the WAN line in response to a request from the WAN line connection request means, When the CPE sends a DHCP request when the lease time is updated, negative acknowledgment reply means for returning a DHCP negative acknowledgment rejecting the request, and the WAN line connection on / off means connect the WAN line. Connected and started after a predetermined time within the lease time presented by the DHCP server has elapsed When the lease time is updated, a DHCP request is sent to the DHCP server on behalf of the CPE. A DHCP request transmission means for a DHCP server that sends a DHCP request to the DHCP server, and a DHCP server that is sent by the DHCP request transmission means for the DHCP server. DHCP acknowledgment return means for returning the DHCP acknowledgment to the CPE when the DHCP server returns a DHCP acknowledgment that means that the DHCP server can continue to issue the same IP address in response to a DHCP request. An IP address management system comprising: a DHCP conversion device provided.

(Appendix 2)
The DHCP conversion apparatus includes: a transmission data absence determination unit that determines that transmission data is absent when the CPE does not perform communication of the data for a predetermined time; and the transmission data absence determination unit detects the absence of transmission data. DHCP release transmission means for transmitting a DHCP release (DHCP RELEASE) for returning the IP address paid out when determined to the DHCP server; and after the DHCP release transmission means transmits the DHCP release, The IP address management system according to appendix 1, further comprising WAN line connection disconnection means for disconnecting the connection.

(Appendix 3)
The DHCP conversion apparatus rejects a DHCP negative acknowledgment when the DHCP request is sent from the CPE after the WAN line connection disconnection means disconnects the connection between the own apparatus and the WAN line. The IP address management system according to appendix 2, further comprising a DHCP negative acknowledgment replying means for replying.

(Appendix 4)
The DHCP conversion apparatus further comprises link down means for bringing the physical link between the CPE and the own apparatus down for a predetermined time after the WAN line connection / disconnection means disconnects the connection between the own apparatus and the WAN line. The IP address management system according to Supplementary Note 2, which is a feature.

(Appendix 5)
The DHCP acknowledgment return means changes the lease time included in the DHCP acknowledgment sent from the DHCP server to the DHCP conversion device to the lease time indicated by the own device to the CPE, and changes the CPE. The IP address management system according to appendix 1, further comprising release time changing means for making a DHCP acknowledgment to be returned to the server.

(Appendix 6)
2. The IP address according to claim 1, wherein the DHCP conversion device comprises a MAC address changing means for rewriting a MAC address of a packet not related to DHCP transmitted from the WAN line and transmitted to the CPE and transferring the packet to the CPE. Management system.

(Appendix 7)
A WAN (Wide Area Network) connected to a CPE (Customer Premises Equipment) requesting delivery of an IP address (Internet Protocol Address) and a DHCP (Dynamic Host Configuration Protocol) server that delivers an IP address to the CPE in response to the request. ) WAN line connection on / off means arranged between the line and for turning on / off the connection between the WAN line and the own device;
When the CPE sends out a DHCP discover requesting the IP address to be issued to the DHCP server to the DHCP server while the WAN line connection on / off means is not connected to the WAN line. Temporary IP address issuing means for receiving this as a proxy for the DHCP server and issuing a temporary IP address;
A proxy DHCP offer replying means for replying to the CPE a DHCP offer (DHCP OFFER) as a presentation condition including the IP address issued by the temporary IP address issuing means to the DHCP discover;
When a DHCP request (DHCP REQUEST) indicating that the CPE can accept the condition indicated in the reply is sent in response to the reply from the proxy DHCP offer reply means, the DHCP request is received as a proxy of the DHCP server and is received as a DHCP acknowledge. Proxy DHCP acknowledgment response means for responding to the CPE with a response (DHCP ACK);
When data is sent from the CPE to the WAN line, the WAN line connection on / off means shifts to a state of waiting for data transmission without being connected to the WAN line, and the WAN line connection WAN line connection request means for requesting connection to the WAN line to the on / off means;
The CPE renews the lease time of the IP address presented in the DHCP offer until the WAN line connection on / off means turns on the connection to the WAN line in response to a request from the WAN line connection request means. Negative acknowledgment return means for sending back a DHCP negative acknowledgment that rejects this request when sending a DHCP request at the time of lease time renewal,
When the WAN line connection on / off means connects the WAN line and a DHCP request at the time of lease time update is sent for the first time after a predetermined time within the lease time presented by the DHCP server has passed, the DHCP server is sent to the DHCP server. A DHCP server-addressed DHCP request transmitting means for transmitting a DHCP request on behalf of the CPE;
When the DHCP server returns a DHCP acknowledgment indicating that the DHCP server can continue to issue the same IP address in response to the DHCP server-addressed DHCP request sent by the DHCP server-addressed DHCP request transmission means, this DHCP acknowledge A DHCP acknowledgment returning means for returning a request to the CPE.

(Appendix 8)
Transmission data absence determining means for determining that the transmission data is absent when the CPE does not perform communication of the data for a predetermined time or more, and when the transmission data absence determining means determines the absence of the transmission data, A DHCP release transmission unit that transmits a DHCP release (DHCP RELEASE) for returning an IP address to the DHCP server, and a WAN that disconnects the connection to the WAN line after the DHCP release transmission unit transmits the DHCP release. The DHCP conversion apparatus according to appendix 7, further comprising a line connection disconnecting unit.

(Appendix 9)
After the WAN line connection disconnecting means disconnects the connection between the own apparatus and the WAN line, when the DHCP request is sent from the CPE, a DHCP negative acknowledgment that rejects this request is returned. The DHCP conversion apparatus according to appendix 8, further comprising an acknowledgment reply means.

(Appendix 10)
Item 8. The appendix 8 further comprising link down means for bringing the physical link between the CPE and the own apparatus down for a predetermined time after the WAN line connection disconnecting means disconnects the connection between the own apparatus and the WAN line. DHCP conversion device.

(Appendix 11)
The DHCP acknowledgment return means changes the lease time included in the DHCP acknowledgment sent from the DHCP server to the DHCP conversion device to the lease time indicated by the own device to the CPE, and changes the CPE. The DHCP conversion apparatus according to appendix 7, further comprising release time changing means for making a DHCP acknowledgment to be returned to the network.

(Appendix 12)
The DHCP conversion apparatus according to appendix 7, further comprising a MAC address changing unit that rewrites a MAC address of a packet that is received from the WAN line and is transmitted to the CPE and is not related to DHCP and transfers the packet to the CPE.

(Appendix 13)
A WAN (Wide Area Network) line connected to a DHCP (Dynamic Host Configuration Protocol) server that issues an IP address to the CPE in response to a request from a CPE (Customer Premises Equipment) that requests an IP address (Internet Protocol Address) to be issued When the CPE sends out a DHCP discover requesting the IP address to be issued to the DHCP server (DHCP DISCOVER) to the DHCP server in a state where the connection of the own device is OFF And a temporary IP address issuing step for issuing a temporary IP address
Proxy DHCP offer response step of returning a DHCP offer (DHCP OFFER) as a presentation condition including the IP address issued in the temporary IP address issue step to the DHCP discover to the CPE;
When a DHCP request (DHCP REQUEST) indicating that the CPE can accept the conditions indicated in the reply is sent in response to the reply made in the proxy DHCP offer reply step, this is received as a proxy of the DHCP server. A proxy DHCP acknowledgment response step of returning a DHCP acknowledgment (DHCP ACK) to the CPE;
When data is sent from the CPE to the WAN line, the state shifts to a state of waiting for data transmission in a state in which the connection between the WAN line and the own apparatus is off, and the WAN line and the own apparatus WAN line connection requesting step for requesting connection;
Until the WAN line and its own apparatus are connected by the request in the WAN line connection request step, the CPE sends a DHCP request at the time of lease time update so as to renew the lease time of the IP address presented in the DHCP offer. A negative acknowledgment reply step for sending back a DHCP negative acknowledgment that rejects this request upon transmission;
When the WAN request is sent for the first time after the lease time renewal DHCP request is sent after the WAN line and the own apparatus are connected by the WAN line connection request step and a predetermined time within the lease time presented by the DHCP server has elapsed. A DHCP request addressed to a DHCP server that sends a DHCP request on behalf of the CPE to
When the DHCP server returns a DHCP acknowledgment that means that the DHCP server can continuously issue the same IP address in response to the DHCP request addressed to the DHCP server sent in the DHCP request addressed to the DHCP server, this DHCP acknowledge A DHCP acknowledgment return step for returning a request to the CPE.

(Appendix 14)
The transmission data absence determination step for determining that the transmission data is absent when the CPE does not perform communication of the data for a predetermined time or more, and the payout when the absence of transmission data is determined in the transmission data absence determination step A DHCP release transmission step of transmitting a DHCP release (DHCP RELEASE) for returning an IP address to the DHCP server, and a WAN that disconnects the connection to the WAN line after transmitting the DHCP release in the DHCP release transmission step 14. The IP address management method according to appendix 13, further comprising a line connection disconnecting step.

(Appendix 15)
After disconnecting the connection between the own apparatus and the WAN line in the WAN line connection disconnecting step, when the DHCP request is sent from the CPE, a DHCP negative acknowledgment that rejects this request is returned. 15. The IP address management method according to appendix 14, further comprising an acknowledgment reply step.

(Appendix 16)
15. The supplementary note 14 further comprising a link down step of down the physical link between the CPE and the own device for a predetermined time after the connection between the own device and the WAN line is cut off in the WAN line connection disconnecting step. IP address management method.

(Appendix 17)
In the DHCP acknowledgment return step, the lease time included in the DHCP acknowledgment sent by the DHCP server to the DHCP conversion device is changed to the lease time indicated by the own device to the CPE, and the CPE 14. The IP address management method according to appendix 13, further comprising a release time change step for setting a DHCP acknowledgment to be returned to the server.

(Appendix 18)
On the computer,
A WAN (Wide Area Network) line connected to a DHCP (Dynamic Host Configuration Protocol) server that issues an IP address to the CPE in response to a request from a CPE (Customer Premises Equipment) that requests an IP address (Internet Protocol Address) to be issued When the CPE sends out a DHCP discover requesting the IP address to be issued to the DHCP server (DHCP DISCOVER) to the DHCP server in a state where the connection of the own device is OFF And a temporary IP address issuing process for issuing a temporary IP address
Proxy DHCP offer response processing for returning a DHCP offer (DHCP OFFER) as a presentation condition including the IP address issued in the temporary IP address issue processing to the DHCP discover to the CPE;
When a DHCP request (DHCP REQUEST) indicating that the CPE can accept the condition shown in the reply is sent to the reply made in the proxy DHCP offer reply process, this is received as a substitute for the DHCP server. Proxy DHCP acknowledgment response processing for returning a DHCP acknowledgment (DHCP ACK) to the CPE;
When data is sent from the CPE to the WAN line, the state shifts to a state of waiting for data transmission in a state in which the connection between the WAN line and the own apparatus is off, and the WAN line and the own apparatus WAN line connection request processing for requesting connection;
Until the WAN line and its own apparatus are connected by the request by the WAN line connection request processing, the CPE sends a DHCP request at the time of lease time update in order to renew the lease time of the IP address presented in the DHCP offer. A negative acknowledgment reply process that returns a DHCP negative acknowledgment that rejects this request upon transmission;
When the WAN request is sent for the first time after a predetermined time within the lease time presented by the DHCP server after the WAN line is connected by the WAN line connection request processing and the DHCP server is sent, the DHCP server is sent. A DHCP request addressed to a DHCP server that sends a DHCP request on behalf of the CPE to
When the DHCP server returns a DHCP acknowledgment that means that the DHCP server can continue to pay out the same IP address in response to the DHCP request addressed to the DHCP server sent in the DHCP request addressed to the DHCP server, this DHCP acknowledge. An IP address management program for executing a DHCP acknowledgment return process for returning a request to the CPE.

(Appendix 19)
The transmission data absence determination process for determining that the transmission data is absent when the CPE does not perform communication of the data for a predetermined time or more, and the payout when the absence of transmission data is determined in the transmission data absence determination process A DHCP release transmission process for transmitting a DHCP release (DHCP RELEASE) for returning an IP address to the DHCP server, and a WAN for disconnecting the WAN line after transmitting the DHCP release in the DHCP release transmission process 19. The IP address management program according to appendix 18, further comprising a line connection disconnection process.

(Appendix 20)
After disconnecting the connection between the own apparatus and the WAN line in the WAN line connection disconnection process, when the DHCP request is sent from the CPE, a DHCP negative acknowledgment that rejects this request is returned. Item 20. The IP address management program according to appendix 19, further comprising executing an acknowledgment reply process.

(Appendix 21)
Appendix 19 wherein after the connection between the own apparatus and the WAN line is disconnected in the WAN line connection disconnection process, a link down process is further executed to bring down the physical link between the CPE and the own apparatus for a certain period of time. IP address management program.

(Appendix 22)
In the DHCP acknowledgment return process, the lease time included in the DHCP acknowledgment sent by the DHCP server to the DHCP conversion device is changed to the lease time indicated by the own device to the CPE, and the CPE 19. The IP address management program according to appendix 18, characterized in that a release time change process is performed as a DHCP acknowledgment returned to the server.

10, 100 IP address management system 11 DHCP server 12, 101 CPE
12a DHCP discover sending means 12b DHCP request sending means when conditions are acceptable 12c Communication start means 12d DHCP request sending means when lease time is updated 12e IP address discarding means 13, 103 DHCP converter 13a WAN line connection on / off means 13b Proxy DHCP offer Reply means 13c Proxy DHCP acknowledgment reply means 13d WAN line connection request means 13e Negative acknowledgment reply means 13f DHCP request transmission means to DHCP server 13g DHCP acknowledgment return means 20 DHCP converter 21 WAN line connection on / off means 22 Temporary IP address issuing means 23 Proxy DHCP offer reply means 24 Proxy DHCP acknowledgment reply means 25 WAN connection Continue request means 26 Negative acknowledgment reply means 27 DHCP server-addressed DHCP request transmission means 28 DHCP acknowledgment return means 30 IP address management method 31 Temporary IP address issue step 32 Proxy DHCP offer reply step 33 Proxy DHCP acknowledge reply step 34 WAN line connection request step 35 Negative acknowledgment return step 36 DHCP request transmission step to DHCP server 37 DHCP acknowledgment return step 40 IP address management program 41 Temporary IP address issue processing 42 Proxy DHCP offer response processing 43 Proxy DHCP acknowledge response Process 44 WAN line connection request process 45 Negative acknowledgment reply process 46 HCP server addressed DHCP request transmission processing 47 DHCP acknowledgment back process 102 WAN line 104 WAN side DHCP server 105 LAN cable 111 controller 112 CPU
DESCRIPTION OF SYMBOLS 113 Memory 114 LAN connection part 115 WAN connection part 116 Transfer process part 117 DHCP detection part 118 Transmission waiting flag storage part 119 WAN connection process part 120 Post-start elapsed timer 121 DHCP process part

Claims (10)

A DHCP (Dynamic Host Configuration Protocol) server that is arranged on the WAN (Wide Area Network) side and issues an IP address (Internet Protocol Address) to a requested device;
A DHCP discover sending means for sending out a DHCP discover (DHCP DISCOVER) requesting delivery of an IP address to the own device to the DHCP server, and DHCP as a presentation condition for the DHCP discover sent out by the DHCP discover sending means When this condition can be accepted when an offer (DHCP OFFER) is sent back, a condition accepting condition for sending a DHCP request (DHCP REQUEST) to the DHCP server, and a DHCP request sending means, and when this condition is acceptable When a DHCP acknowledgment (DHCP ACK) is sent back to the DHCP request sent out by the DHCP request sending means, the IP address presented in the DHCP offer is used. Communication start means for enabling data communication, and lease time for transmitting a DHCP request at the time of lease time update before the lease time elapses in order to update the lease time of the IP address presented by the DHCP offer When a DHCP negative acknowledgment that rejects the renewal request is sent back when the lease time renewal DHCP request is sent by the renewal DHCP request sending means and the lease time renewal DHCP request sending means, the DHCP offer CPE (Customer Premises Equipment) having an IP address discarding means for discarding the presented IP address;
WAN line connection on / off means that is arranged between the CPE and the WAN line to which the DHCP server is connected, and turns on / off the connection to the WAN line, and the WAN line connection on / off means includes the WAN When the CPE sends out the DHCP discover in a state where it is not connected to the line, it receives this as a proxy of the DHCP server, issues a temporary IP address, and returns a DHCP offer including this IP address to the CPE Proxy DHCP offer replying means, and when the CPE sends out the DHCP request in response to the reply of the proxy DHCP offer replying means, this is received as a proxy of the DHCP server and a DHCP acknowledgment is returned to the CPE. From the proxy DHCP acknowledgment response means and the CPE When the data for the WAN line is sent, the WAN line connection on / off means shifts to a state of waiting for data transmission in a state where it is not connected to the WAN line, and the WAN line connection on / off WAN line connection request means for requesting connection to the WAN line from the means, and until the WAN line connection on / off means turns on the connection to the WAN line in response to a request from the WAN line connection request means, When the CPE sends a DHCP request when the lease time is updated, negative acknowledgment reply means for returning a DHCP negative acknowledgment rejecting the request, and the WAN line connection on / off means connect the WAN line. Connected and started after a predetermined time within the lease time presented by the DHCP server has elapsed When the lease time is updated, a DHCP request is sent to the DHCP server on behalf of the CPE, and a DHCP request transmission means for the DHCP server that sends the DHCP request to the DHCP server, DHCP acknowledgment return means for returning the DHCP acknowledgment to the CPE when the DHCP server returns a DHCP acknowledgment that means that the DHCP server can continue to issue the same IP address in response to a DHCP request. An IP address management system comprising: a DHCP conversion device provided.   The DHCP conversion apparatus includes: a transmission data absence determination unit that determines that transmission data is absent when the CPE does not perform communication of the data for a predetermined time; and the transmission data absence determination unit detects the absence of transmission data. DHCP release transmission means for transmitting a DHCP release (DHCP RELEASE) for returning the IP address paid out when determined to the DHCP server; and after the DHCP release transmission means transmits the DHCP release, 2. The IP address management system according to claim 1, further comprising WAN line connection disconnecting means for disconnecting the connection.   The DHCP conversion apparatus rejects a DHCP negative acknowledgment when the DHCP request is sent from the CPE after the WAN line connection disconnection means disconnects the connection between the own apparatus and the WAN line. 3. The IP address management system according to claim 2, further comprising a DHCP negative acknowledgment reply means for replying.   The DHCP conversion apparatus further comprises link down means for bringing the physical link between the CPE and the own apparatus down for a predetermined time after the WAN line connection / disconnection means disconnects the connection between the own apparatus and the WAN line. The IP address management system according to claim 2, wherein:   The DHCP acknowledgment return means changes the lease time included in the DHCP acknowledgment sent from the DHCP server to the DHCP conversion device to the lease time indicated by the own device to the CPE, and changes the CPE. 2. The IP address management system according to claim 1, further comprising release time changing means for making a DHCP acknowledgment to be returned to the network.   2. The IP address according to claim 1, wherein the DHCP conversion device comprises a MAC address changing unit that rewrites a MAC address of a packet not related to DHCP that is received from the WAN line and transmitted to the CPE, and forwards the packet to the CPE. Address management system. A WAN (Wide Area Network) connected to a CPE (Customer Premises Equipment) requesting delivery of an IP address (Internet Protocol Address) and a DHCP (Dynamic Host Configuration Protocol) server that delivers an IP address to the CPE in response to the request. ) WAN line connection on / off means arranged between the line and for turning on / off the connection between the WAN line and the own device;
When the CPE sends out a DHCP discover requesting the IP address to be issued to the DHCP server to the DHCP server while the WAN line connection on / off means is not connected to the WAN line. Temporary IP address issuing means for receiving this as a proxy for the DHCP server and issuing a temporary IP address;
A proxy DHCP offer replying means for replying to the CPE a DHCP offer (DHCP OFFER) as a presentation condition including the IP address issued by the temporary IP address issuing means to the DHCP discover;
When a DHCP request (DHCP REQUEST) indicating that the CPE can accept the condition indicated in the reply is sent in response to the reply from the proxy DHCP offer reply means, the DHCP request is received as a proxy of the DHCP server and is received as a DHCP acknowledge. Proxy DHCP acknowledgment response means for responding to the CPE with a response (DHCP ACK);
When data is sent from the CPE to the WAN line, the WAN line connection on / off means shifts to a state of waiting for data transmission without being connected to the WAN line, and the WAN line connection WAN line connection request means for requesting connection to the WAN line to the on / off means;
The CPE renews the lease time of the IP address presented in the DHCP offer until the WAN line connection on / off means turns on the connection to the WAN line in response to a request from the WAN line connection request means. Negative acknowledgment return means for sending back a DHCP negative acknowledgment that rejects this request when sending a DHCP request at the time of lease time renewal,
When the WAN line connection on / off means connects the WAN line and a DHCP request at the time of lease time update is sent for the first time after a predetermined time within the lease time presented by the DHCP server has passed, the DHCP server is sent to the DHCP server. A DHCP server-addressed DHCP request transmitting means for transmitting a DHCP request on behalf of the CPE;
When the DHCP server returns a DHCP acknowledgment indicating that the DHCP server can continue to issue the same IP address in response to the DHCP server-addressed DHCP request sent by the DHCP server-addressed DHCP request transmission means, this DHCP acknowledge A DHCP acknowledgment returning means for returning a request to the CPE.   8. The DHCP conversion apparatus according to claim 7, further comprising a MAC address changing unit that rewrites a MAC address of a packet that is received from the WAN line and is transmitted to the CPE and is not related to DHCP and transfers the packet to the CPE. A WAN (Wide Area Network) line connected to a DHCP (Dynamic Host Configuration Protocol) server that issues an IP address to the CPE in response to a request from a CPE (Customer Premises Equipment) that requests an IP address (Internet Protocol Address) to be issued When the CPE sends out a DHCP discover requesting the IP address to be issued to the DHCP server (DHCP DISCOVER) to the DHCP server in a state where the connection of the own device is OFF And a temporary IP address issuing step for issuing a temporary IP address
Proxy DHCP offer response step of returning a DHCP offer (DHCP OFFER) as a presentation condition including the IP address issued in the temporary IP address issue step to the DHCP discover to the CPE;
When a DHCP request (DHCP REQUEST) indicating that the CPE can accept the conditions indicated in the reply is sent in response to the reply made in the proxy DHCP offer reply step, this is received as a proxy of the DHCP server. A proxy DHCP acknowledgment response step of returning a DHCP acknowledgment (DHCP ACK) to the CPE;
When data is sent from the CPE to the WAN line, the state shifts to a state of waiting for data transmission in a state in which the connection between the WAN line and the own apparatus is off, and the WAN line and the own apparatus WAN line connection requesting step for requesting connection;
Until the WAN line and its own apparatus are connected by the request in the WAN line connection request step, the CPE sends a DHCP request at the time of lease time update so as to renew the lease time of the IP address presented in the DHCP offer. A negative acknowledgment reply step for sending back a DHCP negative acknowledgment that rejects this request upon transmission;
When the WAN request is sent for the first time after the lease time renewal DHCP request is sent after the WAN line and the own apparatus are connected by the WAN line connection request step and a predetermined time within the lease time presented by the DHCP server has elapsed. A DHCP request addressed to a DHCP server that sends a DHCP request on behalf of the CPE to
When the DHCP server returns a DHCP acknowledgment that means that the DHCP server can continuously issue the same IP address in response to the DHCP request addressed to the DHCP server sent in the DHCP request addressed to the DHCP server, this DHCP acknowledge A DHCP acknowledgment return step for returning a request to the CPE. On the computer,
A WAN (Wide Area Network) line connected to a DHCP (Dynamic Host Configuration Protocol) server that issues an IP address to the CPE in response to a request from a CPE (Customer Premises Equipment) that requests an IP address (Internet Protocol Address) to be issued When the CPE sends out a DHCP discover requesting the IP address to be issued to the DHCP server (DHCP DISCOVER) to the DHCP server in a state where the connection of the own device is OFF And a temporary IP address issuing process for issuing a temporary IP address
Proxy DHCP offer response processing for returning a DHCP offer (DHCP OFFER) as a presentation condition including the IP address issued in the temporary IP address issue processing to the DHCP discover to the CPE;
When a DHCP request (DHCP REQUEST) indicating that the CPE can accept the condition shown in the reply is sent to the reply made in the proxy DHCP offer reply process, this is received as a substitute for the DHCP server. Proxy DHCP acknowledgment response processing for returning a DHCP acknowledgment (DHCP ACK) to the CPE;
When data is sent from the CPE to the WAN line, the state shifts to a state of waiting for data transmission in a state in which the connection between the WAN line and the own apparatus is off, and the WAN line and the own apparatus WAN line connection request processing for requesting connection;
Until the WAN line and its own apparatus are connected by the request by the WAN line connection request processing, the CPE sends a DHCP request at the time of lease time update in order to renew the lease time of the IP address presented in the DHCP offer. A negative acknowledgment reply process that returns a DHCP negative acknowledgment that rejects this request upon transmission;
When the WAN request is sent for the first time after a predetermined time within the lease time presented by the DHCP server after the WAN line is connected by the WAN line connection request processing and the DHCP server is sent, the DHCP server is sent. A DHCP request addressed to a DHCP server that sends a DHCP request on behalf of the CPE to
When the DHCP server returns a DHCP acknowledgment that means that the DHCP server can continue to pay out the same IP address in response to the DHCP request addressed to the DHCP server sent in the DHCP request addressed to the DHCP server, this DHCP acknowledge. An IP address management program for executing a DHCP acknowledgment return process for returning a request to the CPE.

Images