JP4331638B2 - Network control system and network control method - Google Patents

Description

  The present invention relates to a network control system having an IPv4 address for performing communication between an IPv4 (Internet Protocol version 4) device and an IPv6 (Internet Protocol version 6) device, and a translator for converting between IPv6 addresses. And a network control method.

  In an IP network in which an IPv4 device and an IPv6 device are connected together, the source address and the destination address are converted into a 32-bit IPv4 address and a 128-bit IPv6 address, respectively. A translator for performing the above is provided. A DNS (Domain Name System) server that obtains an IP address based on the domain name is also provided.

  The translator performs IP packet format conversion based on an IPv4 address / IPv6 address conversion table generated statically or dynamically. As a means for dynamically generating this address conversion table, a DNS proxy and Means for linking are known. For example, a network control system including an IPv4 client 41, an IPv6 server 42, a DNS server 43, a translator 44, and a DNS proxy 45 shown in FIG. 4 is known. In this case, when accessing the server 42 from the IPv4 client 41, the URL (Uniform Resource Locator) of the server 42 in the A record (IPv4 address record) is sent to the DNS proxy 45, for example, www. abc. com address request.

  The DNS proxy 45 makes an address request with the A record to the DNS server 43, but in the DNS server 43, www. abc. Since it only holds an IPv6 address for com, this address request fails. Therefore, the DNS proxy 45 requests an IPv6 address using an AAAA record (IPv6 address record). The DNS server 43 can be downloaded from www. abc. For example, an IPv6 address abc (ipv6) corresponding to com can be retrieved and extracted, and this IPv6 address abc (ipv6) is returned to the DNS proxy 45.

  The DNS proxy 45 notifies the translator 44 of the IPv6 address abc (ipv6) and makes a request for creating an address conversion table. The translator 44 selects one IPv4 address (for example, abc (ipv4)) from the pooled IPv4 address group. Then, an address conversion table between the IPv6 address abc (ipv6) and the selected IPv4 address abc (ipv4) is created and held for a predetermined period. The holding period is a fixed period or a period in which a TCP connection exists, and various periods are determined by the system configuration. Then, this IPv4 address abc (ipv4) is returned to the DNS proxy 45.

  The DNS proxy 45 notifies the client 41 of the IPv4 address abc (ipv4). The client 41 holds this IPv4 address abc (ipv4) as a DNS cache for a predetermined period. Then, the client 41 has www. abc. com server 42 is accessed by HTTP (Hyper Text Transfer Protocol). abc. The IPv4 address abc (ipv4) assigned by the translator 44 is used instead of the regular IPv6 address abc (ipv6) of the com.

  Then, the translator 44 converts the abc (ipv4) of the IPv4 address into the abc (ipv6) of the IPv6 address based on the address conversion table, and transmits the IP packet. As a result, the packet from the client 41 is transferred to the server 42. The server 42 sends it to the client 41 as an IPv6 address, but the translator 44 transfers it to the client 41 as an IPv4 address.

In addition, the above-mentioned translator is connected between the IPv4 network and the IPv6 network, and a plurality of translators are connected to the conversion server, and conversion information and the like due to the movement of the terminal are received by the translator via the conversion server. Means for performing address conversion is known (see, for example, Patent Document 1). There is also known means for enabling dynamic address generation by associating network access identifiers and IP addresses of various clients such as mobile terminals (for example, see Patent Document 2).
JP 2002-314618 A JP 2003-134145 A

  When the IPv4 client 41 accesses the IPv6 server 42, an address translation table is created in the translator 44 in conjunction with the DNS search. The DNS search is performed when the DNS cache of the IPv4 client 41 does not exist. When the DNS cache exists, the server 42 is accessed according to the contents of the DNS cache.

  If the DNS cache of this client 41 exists, but the address conversion table of abc (ipv4) / abc (ipv6) of the translator 44 is deleted due to elapse of a predetermined period, the access from the IPv4 client 41 to the server 42 is Since the address abc (ipv4) for the server 42 remaining in the DNS cache of the client 41 is used, it is routed to the translator 44. However, since the translator 44 does not have an address translation table for the addresses abc (ipv4) / abc (ipv6), the IP packet from the client 41 is discarded. There is a problem that such a state continues unless the DNS cache of the client 41 is deleted under some condition.

  An object of the present invention is to solve the problems of the above-described conventional example by controlling the lifetimes of the address conversion table and the DNS cache to be the same by relatively simple means.

  The network control system of the present invention is a network control system including an IPv4 device, an IPv6 device, a translator that performs IPv4 address / IPv6 address translation, a DNS server, and a DNS proxy, wherein the translator translates an address from the DNS proxy. An address translation table is created in accordance with a table creation request, and means for holding the address translation table and the lifetime of the address translation table is provided. The DNS proxy sends to the DNS server in accordance with an address search request from the IPv4 device. An address search request is made for the address search request, it is determined whether or not address conversion is required based on the address of the search result from the DNS server for the address search request, and an address conversion table creation request is sent to the translator when address conversion is required. Before and Means for sending the translated address included in the address translation table creation response from the translator to the IPv4 apparatus and sending the same lifetime as the lifetime of the translator address translation table as the DNS cache lifetime of the IPv4 apparatus It has.

  In addition, the translator includes an address translation table creation response including means for creating the address translation table and determining a lifetime of the address translation table, an address translated by the address translation table, and the lifetime. Means for forwarding to the DNS proxy, and the DNS proxy has means for sending the address and the lifetime included in the address translation table creation response to the IPv4 apparatus.

  The network control method of the present invention is a network control method including an IPv4 device, an IPv6 device, a translator that performs IPv4 address / IPv6 address translation, a DNS server, and a DNS proxy, in accordance with an address search request from the IPv4 device. The DNS proxy makes an address search request to the DNS server, determines whether or not address conversion is necessary based on the address in accordance with the address search request from the DNS server, and sends an address conversion table to the translator when address conversion is required. Making a creation request, the translator creates an address translation table and determines the lifetime of the address translation table, and sends an address translation table creation response including an address translated by the address translation table to the DNS proxy. And the DNS proxy Wherein is intended to include a process of sending the address that has been converted at the translator for IPv4 device, the same lifetime and lifetime of the address translation table.

  Further, it may include a step of determining the lifetime of the address translation table in the translator created according to the address translation table creation request from the DNS proxy by negotiation with the DNS proxy.

  The lifetime of the address translation table created in accordance with the address translation table creation request from the DNS proxy is determined by the translator when there is no notification of the lifetime from the DNS proxy. Can include the process of

  When accessing the IPv6 apparatus from the IPv4 apparatus, the lifetime of the address conversion table created in the translator and the address converted by the address conversion table can be made the same by the cooperation control between the DNS proxy and the translator. Therefore, as long as the DNS cache of the IPv4 device exists, the translator's address translation table exists, so that the IP packet when the IPv4 device accesses the IPv6 device using the translated address is avoided from being discarded. Can do.

  Referring to FIG. 1, an IPv4 device (client 1), an IPv6 device, a translator 4 that performs IPv4 address / IPv6 address translation, a DNS server 3, and a DNS proxy 5 are included. A lifetime holding unit that creates an address conversion table by the functions of the address conversion control unit 16 and the address conversion table management unit 17 according to the address conversion table creation request, and holds the address conversion table and the lifetime of the address conversion table The DNS proxy 5 makes an address search request to the DNS server 3 according to the address search request from the IPv4 device (client 1), and searches from the DNS server 3 for this address search request. Based on the result address, whether or not address conversion is necessary It is determined by the less translation processing unit 11 and included in the address translation table creation response from the translator 4 and means such as the cooperative signal transmission processing unit 14 for sending an address translation table creation request to the translator 4 when address translation is required. DNS signal transmission for sending the translated address to the IPv4 device (client 1) and sending the same lifetime as the lifetime of the address translation table of the translator 4 as the lifetime of the DNS cache of the IPv4 device (client 1) And a processing unit 15 and the like.

  FIG. 1 is an explanatory diagram of a main part of the first embodiment of the present invention, in which an IPv4 client 1 (IPv4 apparatus), an IPv6 server (IPv6 apparatus) not shown, a DNS server 3, a translator 4, In the network control system including the DNS proxy 5, the DNS proxy 5 includes the address conversion processing unit 11, the DNS signal reception processing unit 12, the cooperative signal reception processing unit 13, the cooperative signal transmission processing unit 14, and the DNS. The translator 4 includes a signal transmission processing unit 15, and the translator 4 includes an address conversion table control unit 16, an address conversion management unit 17, a cooperative signal transmission processing unit 18, a cooperative signal reception processing unit 19, a life A time value holding unit (TTL; Time To Live) 20, and the server ( It shows the route for notifying the address of the IPv6 device.

  The DNS proxy 5 makes an address search request to the DNS server 3 according to the address request of the destination server from the client 1. In this case as well, as described above, an address request is made to the DNS server 3 using an A record (IPv4 address record), but the DNS server 3 uses, for example, www. abc. Since it only holds an IPv6 address for com, this address request fails. Therefore, the DNS proxy 5 requests an IPv6 address using an AAAA record (IPv6 address record). The DNS server 3 can be downloaded from www. abc. Since the IPv6 address abc (ipv6) corresponding to com can be retrieved and extracted, the IPv6 address abc (ipv6) is returned to the DNS proxy 5.

  The DNS proxy 5 receives the DNS signal reception processing unit 12 and transfers the received DNS signal to the address conversion processing unit 11. The address conversion processing unit 11 determines whether or not address conversion is necessary. In this case, since it is necessary to convert the IPv6 address abc (ipv6) acquired from the DNS server 3 to the IPv4 address and notify the client 1, it is determined that the address conversion is necessary, and the address conversion processing unit 11 cooperates. An instruction to create an address conversion table is issued to the signal transmission processing unit 14. The cooperation signal transmission processing unit 14 sends an address conversion table creation request signal to the translator 4. The address conversion table creation request signal at this time can be notified including the lifetime of the DNS cache.

  The translator 4 receives the address conversion table creation request signal by the cooperation signal reception processing unit 19 and transfers it to the address conversion table control unit 16. The address conversion table control unit 16 instructs the address conversion management unit 17 that manages the address conversion table to create an address conversion table. Based on this, an address conversion table of IPv4 addresses and IPv6 addresses is created. At this time, based on the DNS cache lifetime notified from the DNS proxy 5 and the policy regarding the period for holding the address conversion table, the period for holding the address conversion table created this time is determined. It should be noted that the period (lifetime) for holding this address conversion table may be a value according to the lifetime from the DNS proxy 5. It is also possible to decide by negotiation.

  The address conversion processing unit 17 stores the period in which the created address conversion table for converting the IPv4 address / IPv6 address is stored in the lifetime value holding unit 20 as the lifetime of the DNS cache. That is, the lifetime corresponding to the created address conversion table is held by the lifetime value holding unit 20. Then, the response to the address conversion table creation request including the IPv4 address converted based on the address conversion table and the lifetime of the DNS cache held in the lifetime value holding unit 20 is linked through the address conversion table control unit 16. Instruct to transfer from the signal transmission processing unit 18 to the DNS proxy 5. When the same lifetime as the lifetime added to the address translation table creation request from the DNS proxy 5 is determined as the lifetime of the address translation table, the lifetime is not included in the address translation table creation response. In particular, the DNS proxy 5 can also recognize the lifetime sent by the DNS proxy 5 as the lifetime of the address translation table under the condition that the lifetime is not included in the response from the translator 4.

  The DNS proxy 5 receives the address conversion table creation response from the translator 4 by the cooperative signal reception processing unit 13 and transfers the response to the address conversion processing unit 11. The address translation processing unit 11 performs control to transfer the IPv4 address from the translator 4 and the lifetime of the DNS cache from the DNS signal transmission processing unit 15 to the client 1. The client 1 can transmit according to the IPv4 address from the DNS proxy 5 to the server. The DNS cache holding period for holding the IPv4 address is a period according to the notified lifetime.

  Therefore, the DNS cache of the client 1 and the lifetime of the address conversion table of the translator 4 are the same, and the IP packet sent to the server using the IPv4 address held in the DNS cache is sent to the IPv6 address by the translator 4. Therefore, the situation where the IP packet is discarded can be avoided.

  FIG. 2 is an operation explanatory diagram showing an outline of the information flow. In accordance with the server address request from the client 1, the ONS proxy 5 sends a server address search request based on the AAAA record to the DNS server 3, and the DNS server 3 The IPv6 address of the search result by the AAAA record and its lifetime (lifetime), for example, 7200 s are returned to the DNS proxy 5. The DNS proxy 5 determines that IPv4 / IPv6 address translation is necessary, and makes an address translation table creation request to the translator 4. At this time, the lifetime from the DNS server 3 can be added and transferred.

  The translator 4 creates an IPv4 address / IPv6 address translation table and determines the lifetime of the address translation table. In this case, if it is determined that the lifetime (lifetime) notified from the DNS server 3 is 7200 s (= 2 hours) and is too long for the number of IPv4 addresses managed by the translator 4, the policy is based on the policy of the translator 4. For example, the survival time (lifetime) can be set to 1800 s (= 30 minutes). Then, 1800 s of the determined survival time (lifetime) and the IPv4 address obtained by converting the IPv6 address by the address conversion table are transferred to the DNS proxy 5 as an address conversion table creation response.

  The DNS proxy 5 sends to the client 1 an IPv4 address as the A record search result and 1800 s of the lifetime (lifetime) of the address conversion table. The client 1 accesses the server using the IPv4 address notified from the DNS proxy 5 as a transmission destination address, and uses the lifetime (lifetime) of the DNS cache that holds the IPv4 address as the lifetime (life) of the address conversion table. Time) of 1800 s. As a result, the address translation table of the translator 4 and the DNS cache of the client 1 are set to 1800 s with the same lifetime (lifetime), and are therefore deleted almost simultaneously.

  FIG. 3 is an explanatory diagram of the main part operation sequence of the first embodiment of the present invention, showing the operation between the DNS proxy and the translator, and from the DNS proxy to the DNS server (not shown) as described above. An address search request is sent out, and an IPv6 address and lifetime ttl # 1 are received from the DNS server as a response to this request. Then, an address conversion table creation request is made to the translator, and at that time, the lifetime tt1 # 1 is added.

  The translator creates an address translation table and determines the lifetime ttl # 2 of this address translation table. In this case, a state where ttl # ≠ ttl # 2 is shown, and in order to set the lifetime ttl # 2 as the lifetime tlt2 of the DNS cache of the client, as an address conversion table creation response to the DNS proxy, The translated IPv4 address and the lifetime ttl # 2 of the address translation table are transferred. The DNS proxy forwards the translated IPv4 address and the DNS cache lifetime ttl # 2 holding it to the client (not shown). Accordingly, since the lifetimes of the translator address translation table and the client DNS cache coincide with each other and are deleted almost simultaneously, the problem of discarding the IP packet sent from the client due to the deletion of only the translator address translation table can be solved. .

It is principal part explanatory drawing of Example 1 of this invention. It is operation | movement explanatory drawing of Example 1 of this invention. It is principal part operation | movement sequence explanatory drawing of Example 1 of this invention. It is explanatory drawing of a network control system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Client 3 DNS server 4 Translator 5 DNS proxy 11 Address conversion process part 12 DNS signal process part 13 Cooperation signal reception process part 14 Cooperation signal transmission process part 15 DNS signal transmission process part 16 Address conversion table control part 17 Address conversion management part 18 Cooperation signal transmission processing unit 19 Cooperation signal reception processing unit 20 Lifetime value holding unit (TTL)

Claims (5)

In a network control system including an IPv4 device, an IPv6 device, a translator that performs IPv4 address / IPv6 address translation, a DNS server, and a DNS proxy,
The translator has means for creating an address translation table in accordance with an address translation table creation request from the DNS proxy and holding the address translation table and the lifetime of the address translation table;
The DNS proxy makes an address search request to the DNS server in accordance with an address search request from the IPv4 device, and determines whether or not address conversion is necessary based on the address of the search result from the DNS server in response to the address search request. And means for sending an address translation table creation request to the translator when address translation is required, and sending the translated address included in the address translation table creation response from the translator to the IPv4 device and the address translation of the translator A network control system comprising: a lifetime that is the same as the lifetime of the table as a lifetime of the DNS cache of the IPv4 device.   The translator includes a means for creating the address translation table and determining a lifetime of the address translation table, an address translated by the address translation table, and an address translation table creation response including the lifetime And a means for forwarding the address and lifetime included in the address translation table creation response to the IPv4 device. The network control system according to 1. In a network control method including an IPv4 device, an IPv6 device, a translator that performs IPv4 address / IPv6 address translation, a DNS server, and a DNS proxy,
In accordance with the address search request from the IPv4 device, the DNS proxy makes an address search request to the DNS server, determines whether or not address conversion is necessary based on the address according to the address search request from the DNS server, and performs address conversion. When necessary, it makes an address translation table creation request to the translator, the translator creates an address translation table and determines the lifetime of the address translation table, and an address including the address translated by the address translation table A translation table creation response is sent to the DNS proxy, and the DNS proxy sends an address translated by the translator to the IPv4 device and a lifetime that is the same as the lifetime of the address translation table. A network control method characterized by including a process. 4. The process of determining the lifetime of an address translation table in the translator created according to an address translation table creation request from the DNS proxy by negotiation with the DNS proxy. Network control method . The lifetime of the address translation table in the translator created in accordance with the address translation table creation request from the DNS proxy is determined as the same lifetime as the lifetime added to the address translation table creation request, and the lifetime An address translation table response that does not include the lifetime is sent to the DNS proxy, and the DNS proxy uses the address translation table response that does not include the lifetime to display the lifetime added to the address translation table creation request in the address translation table. 4. The network control method according to claim 3, further comprising a process of setting a lifetime .

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