Protocol conversion apparatus between ipv4 terminal and ipv6 terminal or between one application program and another application program using mapping table and method, and generation method of mapping table of the protocol conversion apparatus

A protocol conversion apparatus and method between IPA terminals or applications using a mapping table, and a method for generating a mapping table of the protocol conversion apparatus {Protocol conversion apparatus between IPv4 terminal and IPv6 terminal or between one application program and another application program using mapping table and Method, and Generation method of mapping table of the Protocol conversion apparatus }

1 is a configuration diagram showing a network topology for performing a conventional protocol conversion;

2 is a configuration diagram showing an embodiment of a network topology when a protocol converter between IPv4/IPv6 terminals or applications using a mapping table according to the present invention is applied;

3 is a conceptual diagram illustrating a protocol converter having a dual stack according to the present invention, an address mapping table managed by the protocol converter, and an IPv4/IPv6 terminal connected to one interface and connected on the same physical network;

4 is a flowchart illustrating a procedure for communicating with an IPv6 terminal by starting communication from an IPv4 terminal connected to one interface of a protocol converter according to the present invention;

5 is a flowchart illustrating a procedure for communicating with an IPv4 terminal by starting communication from an IPv6 terminal connected to one interface of a protocol converter according to the present invention;

6 is a flowchart illustrating a procedure in which an IPv6 terminal connected to one interface of a protocol converter according to the present invention obtains a virtual address of an IPv4 terminal belonging to the same network using the domain name of the IPv4 terminal.

<Explanation of main symbols in the drawings>

2, 12 IPv4 networks 6, 18. IPv6 networks

1, 11, 17, 30, 100, 700. IPv4 terminal

7, 16, 40, 300, 500, 1000. IPv6 terminal

3, 5, 13, 15, 21, 24. Interface of protocol converter

4, 14, 20, 200, 600, 1200. Protocol converter

22, 240, 620, 1240. IPv4 Mapping Table

23, 220, 640, 1220. IPv6 Mapping Table

250, 610, 1260. IPv4 stack 210, 650, 1210. IPv6 stack

230, 630, 1230. Packet converter 1250. DNS ALG

1300. IPv4 DNS 1100. IPv6 DNS

<backgroundart><p>The present invention relates to a protocol support system and method for IPv4-IPv6 communication, and more particularly, to an apparatus and method for sharing a protocol function between an IPv4 terminal and an IPv6 terminal belonging to the same physical network or between application programs.</p><p>That is, when IPv4/IPv6 terminals coexist within one physical network or when the terminal supports IPv4/IPv6 dual stack but the application service supports only a specific protocol, protocol conversion apparatus and method that enable communication with each other through protocol conversion is about</p><p>A network protocol widely used and widely used based on the Internet is IPv4 (Internet Protocol version 4). The IPv4 protocol plays a decisive role in allowing numerous networks and users to be connected to one large network called the Internet in a short time. However, the IPv4 protocol has problems such as limitation in the number of IP addresses, inefficiency of packet routing, and difficulty in providing mobility and security.</p><p>To solve these problems, a new version of the protocol called Internet Protocol version 6 (IPv6) has appeared. IPv6 refers to a new IP address system developed to improve the shortcomings of IPv4, the currently used IP address system. As an official standard of the Internet Engineering Task Force (IETF), it is also called IPng (IP next generation) in the sense of the next-generation Internet communication protocol.</p><p>Unlike IPv4, IPv4 has 4.2 billion addresses in a 32-bit addressing system, and addresses are assigned using ABCD class CIDR (Classless Inter-Domain Routing). On the other hand, IPv6 has a 128-bit address system with about 30 times the number of addresses of IPv6, and addresses are allocated hierarchically based on CIDR.</p><p>As a result, IPv6-based networks are gradually emerging, and although the existing networks will be gradually replaced by IPv6, it is expected that it will be difficult in the short term to change many hosts and routers based on IPv4, which have been spread for decades, to IPv6 at once. will coexist with IPv4/IPv6.</p><p>Therefore, since most of the current Internet environment is configured based on IPv4 and IPv6 users must also connect to the IPv4 Internet, conversion between different protocols is essential. </p><p>Accordingly, many protocol conversion technologies have been standardized mainly by the Internet Engineering Task Force (IETF), and among these, the widely used technologies include NAT_PT (Network Address and Protocol Translation) and DSTM (Dual Stack Transition Mechanism) . Among them, DSTM is a technology that is considered when many IPv6 is introduced, and NAT-PT technology will be used a lot in the initial stage when IPv4 is widely used during the IPv4/IPv6 conversion stage.</p><p>As a specific example of use, the Korean Patent Application Laid-Open (Application No.: 10-2003-0005923), "Protocol function sharing method and device under IPv4 - IPv6 coexistence environment," states that each IPv4/IPv6 network is divided into different interfaces of the protocol converter. There is a problem in that protocol conversion is possible only when connected and separate networks are configured, but protocol conversion cannot be performed between IPv4/IPv6 terminals located in one physical network.</p><p>As described above, all of the previously disclosed protocol conversion techniques shown in FIG. 1 have a problem that is only possible when the IPv4/IPv6 network is physically divided into different networks according to the interface of the protocol converter.</p></backgroundart><abstractproblem><p>Accordingly, an object of the present invention has been achieved to solve the problems of the prior art, and an object of the present invention is not a protocol conversion method between physically separated IPv4/IPv6 networks, but IPv4/IPv4/IPv4/IPv6 existing in the same physical subnetwork. An apparatus and method for enabling protocol conversion between IPv6 terminals or between applications are provided.</p></abstractproblem>

<p>The mapping table generation method of the protocol conversion device of the present invention for achieving the above object supports protocol conversion between IPv4/IPv6 terminals or applications in one physical network environment in which IPv4/IPv6 terminals or applications are mixed. In order to do this, an ARP table is allocated to the IPv4 terminal and a neighbor table is allocated to the IPv6 terminal, and a virtual IPv6 address is mapped to the real IP address of the IPv4 terminal existing in the ARP table, and the neighbor table The mapping table is generated by mapping the real IP address and the virtual IP address of the IPv4/IPv6 terminal by mapping the virtual IPv4 address to the real IP address of the IPv6 terminal existing in the .</p><p>In this mapping table, for the IPv4 terminal, the real IP address is an IPv4 format address, the virtual IP address is an IPv6 format address, and for the IPv6 terminal, the real IP address is an IPv6 format address, and the virtual IP address is an IPv4 format address. Create a mapping table characterized in that the address of.</p><p>On the other hand, the protocol conversion apparatus between IPv4/IPv6 terminals or applications using the mapping table of the present invention is a protocol conversion apparatus that supports protocol conversion between IPv4/IPv6 terminals or applications, and is equipped with an IPv4/IPv6 dual stack. Transmits and receives a communication request from an IPv4 or IPv6 terminal, and uses a mapping table in which the real IP address and the virtual IP address of the IPv4/IPv6 terminal are respectively mapped. It is characterized by supporting protocol conversion between IPv6 terminals or application programs.</p><p>The configuration of the protocol conversion device includes an IPv4 stack for receiving an ARP request message for a virtual IP address from the IPv4 terminal, a mapping table for mapping and storing real IP addresses and virtual IP addresses of each of the IPv4/IPv6 terminals, and the mapping A packet converter that converts packets between the IPv4/IPv6 terminals by applying a Simple IP and ICMP Transition (SIIT) algorithm based on the information in the table and an IPv6 stack for receiving a Neighbor Discovery Protocol (NDP) request message from the IPv6 terminal characterized by including.</p><p>In addition, the protocol conversion device is included in the payload for each application that includes an IP address in the payload, such as DNS (Domain Name Service), FTP (File Transfer Protocol), or SIP (Session Initiative Protocol). If the IP address matches the real IP address in the mapping table, each application layer gateway (ALG) according to the application modifies the IP address information in the payload to the value of the virtual IP address of the corresponding entry in the mapping table and transmits it to the terminal. ) is further included.</p><p>On the other hand, the protocol conversion method for supporting protocol conversion between IPv4/IPv6 terminals or applications using a mapping table is a method for supporting protocol conversion between IPv4/IPv6 terminals, in a single physical network in which IPv4/IPv6 is mixed. The IPv4/IPv6 dual stack receives and responds to a message for a communication request of the IPv4 or IPv6 terminal existing in the environment, and uses a mapping table in which the real IP addresses and virtual IP addresses of IPv4 and IPv6 are mapped respectively to the IPv4 It supports protocol conversion between /IPv6 terminals to perform communication between the IPv4/IPv6 terminals.</p><p>In addition, the protocol conversion method for supporting protocol conversion between IPv4/IPv6 terminals or applications using a mapping table includes Domain Name Service (DNS), File Transfer Protocol (FTP) or When an IP address is included in a payload including Session Initiative Protocol (SIP), the IP address included in the payload is matched with the actual IP address in the mapping table through an Application Layer Gateway (ALG) according to each application. If they match, the IP address information in the payload is modified with the value of the virtual IP address corresponding to the real IP address and transmitted to the terminal.</p><p>Hereinafter, an apparatus for converting an IPv4/IPv6 terminal or an application program protocol using a mapping table of the present invention will be described in detail with reference to the accompanying drawings.</p><p>2 shows an embodiment of a network topology in which an IPv4/IPv6 network is not divided according to an interface of the protocol converter centering on the protocol converter 14 having the IPv4/IPv6 dual stack. As shown in FIG. 2 , an environment in which IPv4/IPv6 networks 16 and 17 are mixed in a network connected to one interface 15 of the protocol converter 14 is not separated.</p><p>Therefore, in the present invention, in the network environment as shown in FIG. 2 , the protocol converter 14 having an IPv4/IPv6 dual stack maintains a mapping table in which real IP addresses and virtual IP addresses are mapped for each IPv4/IPv6 terminal. Enables communication between terminals and applications using the /IPv6 protocol. </p><p>Here, the actual IP address becomes an IPv4 address for an IPv4 terminal, and an IPv6 address for an IPv6 terminal. On the other hand, the virtual IP address becomes an address in the form of an IPv6 address for an IPv4 terminal, and becomes an address in the form of an IPv4 address for an IPv6 terminal. Virtual IP addresses are not addresses actually assigned to terminals, but addresses managed only by a protocol converter.</p><p>3 shows a protocol converter 20 equipped with an IPv4/IPv6 dual stack, address mapping tables 22 and 23 managed by the protocol converter 20, an IPv4 network connected thereto, and one interface 21 of the protocol converter 20. ) is a conceptual diagram illustrating a network in which IPv4/IPv6 terminals 30 and 40 connected to each other coexist. </p><p>Looking at the basic configuration of the present invention, as shown in FIG. 3 , the IPv4 terminal 30 and the IPv6 terminal 40 are connected together to one interface 21 of the protocol converter 20 equipped with an IPv4/IPv6 dual stack. become and exist</p><p>IPv4/IPv6 terminals operate transparently to the protocol versions of terminals they wish to communicate with. That is, in order for the IPv4 terminal to communicate with the IPv6 terminal, an ARP request message for the virtual IP address of the corresponding IPv6 terminal is broadcast to all terminals in the subnetwork according to the ARP (Address Resolution Protocol) procedure.</p><p>This ARP request message will be broadcast only within the IPv4 network, and the IPv4 stack of the dual-stack protocol converter receives the ARP request message, and the IP address required in the received ARP request message. Since is the virtual IP address of the mapping table managed by the protocol converter itself, it responds to the ARP request message with the protocol converter's own MAC address and a reply message. </p><p>The IPv4 terminal inputs the virtual IP address to the destination IP address of the packet to be transmitted, and inputs the MAC address of the protocol converter to the destination MAC address to transmit. The transmitted packet is received by the protocol converter, and the protocol converter converts the packet to the previously presented SIIT ( Simple IP and ICMP Transition) conversion technique is applied to convert the packet into an IPv6 packet, and then the packet is transmitted to the actual IPv6 terminal.</p><p>In order for an IPv6 terminal to transmit a packet to an IPv4 terminal, all operation methods are the same except that the Neighbor Discovery Protocol (NDP) protocol defined in IPv6 is used instead of the ARP protocol. </p><p>In addition, when an IP address is included in the payload, such as DNS (Domain Name Service), FTP (File Transfer Protocol), or SIP (Session Initiative Protocol), an ALG (Application Layer Gateway) function is provided separately for each case, and the payload It checks whether the IP address included in the inside matches the real IP address in the mapping table, and if it matches, the IP address information in the payload is modified with the value of the virtual IP address of the corresponding entry in the mapping table and transmitted to the terminal to communicate.</p><p>Specifically, as shown in FIG. 3 , the upstream interface 24 of the protocol converter is connected to an IPv4 network, and the downstream interface 21 is connected to a network in which IPv4/IPv6 is mixed. The protocol converter 20 manages the mapping tables 22 and 23 mapping real IP addresses and virtual IP addresses for each protocol.</p><p>For IPv4 terminals, the real IP address is an IPv4 format address (eg 10.1.1.1), and the virtual IP address is an IPv6 format address (eg 2001:100:2e::1). Conversely, for IPv6 terminals, the real IP address is an IPv6 address (eg 2001:100:2e::1), and the virtual IP address is an IPv4 address (eg 10.1.1.1).</p><p>Here, in the method of generating the mapping tables 22 and 23, an ARP table exists for an IPv4 terminal and a neighbor table exists for an IPv6 terminal. The mapping tables 22 and 23 are created in such a way that virtual IPv6 addresses are mapped to respective IPv4 terminals present in the ARP table and virtual IPv4 addresses are mapped to respective IPv6 terminals present in the neighbor table.</p><p>In order for the IPv4 terminal 30 connected to the downstream interface 21 of the protocol converter 30 to communicate with the IPv4 terminal 30 connected to the upstream interface 24 and the IPv4 terminal belonging to the IPv4 network 50 connected to the upstream interface 24, the protocol converter 20 is an IPv4/IPv6 dual stack support, so the existing IPv4 protocol method can be used without any modification. </p><p>In addition, in order for the IPv6 terminal 40 connected to the downstream interface 21 to communicate with the IPv4 terminal belonging to the IPv4 network 50 connected to the upstream interface 24, the existing NAT-PT (Network Address Translation-Protocol Translation) ) technique or DSTM (Dual Stack Transition Mechanism).</p><p>Then, a protocol conversion method between IPv4/IPv6 terminals or applications using the mapping table of the present invention having the above configuration will be described with reference to FIGS. 4 to 6 .</p><p>4 is a flowchart illustrating a procedure for mutual communication by performing protocol conversion with an IPv6 terminal 300 connected to the same interface, starting with the IPv4 terminal 100 connected to one interface of the protocol converter 200 . </p><p>When the IPv4 terminal 100 connected to one interface of the protocol converter 200 wants to communicate with the IPv6 terminal 300 connected to the same interface, the ARP request message for the virtual IP address given to the IPv6 terminal 300 is sent to the same Broadcast to the network connected to the interface (401). </p><p>The corresponding ARP request message is received by all IPv4 terminals in the subnetwork, and the IPv4 stack 250 of the protocol converter 200 also receives the corresponding message. </p><p>The protocol converter 200 recognizes that the corresponding IP address of the ARP request message is the virtual IP address of the mapping table 220 it manages, and ARP along with the MAC address of the protocol converter 200 for this ARP request message. A response message is transmitted to the corresponding IPv4 terminal 100 (402).</p><p>Since the IPv4 terminal 100 knows the IP address and MAC address of the terminal with which it wants to communicate, it creates and transmits a frame (403). The destination MAC address of the transmitted frame is the MAC address of the protocol converter 200 obtained through the ARP request message, and the destination IP address is set to a virtual IP address given to the corresponding IPv6 terminal 300 .</p><p>The frame is received by the IPv4 stack 250 of the protocol converter 200, and the protocol converter 200 that has received the frame (403) searches the IPv6 mapping table 220 to determine the virtual IP address that it manages. After confirming that it matches the IP address of the mapping table 220 (404), it is sent to the packet conversion unit 230 and converted into an IPv6 packet by applying the SIIT algorithm based on the mapping table information (406) 200) to the IPv6 stack 210, and finally the packet is delivered to the destination IPv6 terminal 300 (408). Here, the packet conversion unit 230 follows the previously presented SIIT-based conversion method.</p><p>5 is a flowchart illustrating a procedure for communicating with an IPv4 terminal 700 connected to the same interface starting from the IPv6 terminal 500 connected to one interface of the protocol converter 600 by performing protocol conversion to communicate with each other.</p><p>When the IPv6 terminal 500 wants to communicate with the IPv4 terminal 700 located in the same subnetwork, it multicasts an NDP request message for the virtual IP address given to the IPv4 terminal 700 to the IPv6 terminals (801).</p><p>The corresponding NDP request message is received by all IPv6 terminals in the subnetwork, and the IPv6 stack 650 of the protocol converter 600 also receives the corresponding NDP request message. When the IP address in the NDP request message matches the virtual IP address information of the mapping table 620 managed by the protocol converter 600, the protocol converter 600 sends an NDP response message along with its own MAC address to the corresponding IPv6 terminal ( 500) (802).</p><p>The IPv6 terminal 500 creates a frame and transmits the IP address and MAC address of the terminal with which it wants to communicate (803). The destination MAC address of the transmitted frame is the MAC address of the protocol converter 600 obtained by NDP, and the destination IP address is set to a virtual IP address given to the corresponding IPv4 terminal 700 .</p><p>Upon receiving the frame (803), the protocol converter 600 searches the IPv4 mapping table 620 and confirms that the corresponding virtual IP address matches the IP address of the mapping table 620 that it manages (804), This is sent to the packet conversion unit 630, converted into an IPv4 packet based on the mapping table information (806), and then sent to the IPv4 stack 610 of the protocol converter 600 to finally deliver the packet to the destination IPv4 terminal 700. become (808). Here, the packet conversion unit 630 similarly follows the SIIT-based conversion method.</p><p>FIG. 6 shows a procedure in which the IPv6 terminal 1000 connected to one interface of the protocol converter 1200 obtains the IPv6 format virtual address of the IPv4 terminal 1300 with the DNS address of the IPv4 1300 belonging to the same network. It is a flow chart.</p><p>As shown in FIG. 6 , when an IP address is included in the payload, such as Domain Name Service (DNS), File Transfer Protocol (FTP), or Session Initiative Protocol (SIP), in each case, ALG (Application Layer Gateway) ) function, if the IP address included in the payload matches the actual IP address in the mapping table, the IP address information in the payload is modified with the value of the virtual IP address of the corresponding entry in the mapping table and transmitted to the terminal. </p><p>Specifically, in order for the IPv6 terminal 1000 to obtain a virtual IP address of an IPv4 terminal in the same network, it first queries the IPv6 DNS server 1100 in the same network for a domain name (eg, www.etri.re.kr). (1401). Upon receiving the query, the IPv6 DNS server 1100 recognizes that there is no corresponding domain name in its cache and transmits the virtual IP address of the IPv4 DNS server and the MAC address of the protocol converter to the protocol converter belonging to the same network ( 1402).</p><p>In this case, the destination address of the corresponding packet is the virtual IP address of the IPv4 DNS server, and the destination MAC address is set as the MAC address of the protocol converter. Here, the destination IP address is a virtual address of the IPv4 DNS server registered in advance in the IPv6 DNS server, and the destination MAC address is an address obtained through the method shown in FIG. 5 .</p><p>The protocol converter searches a mapping table in which real IP addresses and virtual IP addresses of IPv4/IPv6 are mapped to match the transmitted virtual IP address and MAC address (1403), and as a result of the check, the received virtual IP address If the packet matches one of the registered virtual IP addresses in the mapping table, protocol conversion is performed (1405) and the DNS query message is transmitted to the IPv4 DNS server belonging to the same network (1406, 1407).</p><p>Upon receiving the DNS query, the IPv4 DNS server searches for the query (1408), and transmits a packet including the corresponding IP address value to the protocol converter (1409). The IPv4 stack of the protocol converter receives the packet, recognizes that the packet is a DNS response packet, and transmits the packet to the DNS ALG 1250 ( 1410 ). The DNS ALG (1250) recognizes that the IPv4 format address value located in the payload matches the actual IP address entry in the mapping table it manages, and then replaces it with the IPv6 format virtual IP address of the corresponding entry (1411).</p><p>The next procedure is converted into IPv6 packets as described in FIG. 5 (1412, 1413, 1414, 1415), and finally informs the IPv6 terminal of the IP address of the corresponding IPv4 terminal as an IPv6 virtual IP address ( 1416). The subsequent process is consistent with the contents of FIGS. 5 and 6 .</p><p>The reverse process, the process in which the IPv4 terminal obtains the virtual IP address of the IPv6 terminal, is performed in the same manner as in the reverse process.</p><p>Specifically, when a DNS query is transmitted to an IPv4 DNS server in the same network, the IPv4 DNS server receiving the query recognizes that the corresponding domain name does not exist in its cache, and sets the virtual IP address of the IPv4 DNS server and the protocol converter. 's MAC address is sent to the protocol converter. In this case, the virtual IP address of the IPv4 DNS server is the destination address of the corresponding packet, and the MAC address of the protocol converter is set as the destination MAC address. Here, the destination IP address is a virtual address of the IPv6 DNS server registered in advance in the IPv4 DNS server, and the destination MAC address is an address obtained through the method shown in FIG. 5 .</p><p>The protocol converter searches a mapping table in which real IP addresses and virtual IP addresses of IPv4/IPv6 are mapped to match the transmitted virtual IP address and MAC address, and as a result of the check, the received virtual IP packet is mapped If it matches one item of the registered virtual IP address in the table, protocol conversion is performed and the DNS query message is transmitted to the IPv6 DNS server belonging to the same network.</p><p>Upon receiving the DNS query, the IPv6 DNS server searches for the query and transmits a packet containing the corresponding IP address to the protocol converter, which receives the packet, recognizes that the corresponding packet is a DNS response packet, and DNS ALG send the packet to The DNS ALG recognizes that the IPv6 format address value located in the payload matches the actual IP address entry in the mapping table it manages, replaces it with the IPv4 format virtual IP address of the corresponding entry, and converts it into an IPv4 packet. An IPv4 virtual IP address of the corresponding IPv6 terminal is transmitted to the IPv4 terminal.</p><p>Although the present invention has been described in more detail with reference to several embodiments above, the present invention is not necessarily limited to these embodiments, and various modifications may be made within the scope without departing from the technical spirit of the present invention.</p>

<p>As described above, according to the present invention, IPv4/IPv6 terminals located in one physical subnet, such as a home network domain, use the existing Simple IP and A protocol conversion method such as ICMP Transition) can be used, and the IP protocol version can be transparently communicated with each other. In addition, it can be used with a terminal located in an external network without any modification through an existing protocol or protocol conversion technique.</p>