Patent Publication Number: US-2003225911-A1

Title: Method and apparatus for communicating data between IPv4 and IPv6

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001] This application claims the priority of Korean Patent Application No. 2002-29954, filed May 29, 2002, which is incorporated herein in its entirety by reference.  
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The present invention relates to an Internet Protocol version 4 (IPv4)-Internet Protocol version 6 (IPv6) communication system, and more particularly, to a method and apparatus for allowing IPv6 devices in an IPv6 home network to communicate with an IPv4 host.  
       [0004] 2. Description of the Related Art  
       [0005] IPv6 Internet addresses have a size of 128 bits to extend addressing capability. In addition, IPv6 can process multimedia data in real time using a flow labeling function. IPv6 also has an enhanced security capability to support authentication and data confidentiality.  
       [0006] However, current Internet networks usually employ an IPv4 format, so devices allocated IPv6 addresses in a home network cannot use most of the Internet employing the IPv4 format. Therefore, network systems for allowing the current IPv6 networks to communicate with the IPv4 protocol have been developed.  
       [0007]FIG. 1 is a diagram of a conventional network system for IPv4-IPv6 communication. Referring to FIG. 1, a dual stack transition mechanism (DSTM) host  130  is a host having an IPv4/IPv6 dual stack. A dynamic host configuration protocol version 6 (DHCPv6) server  140  allocates global IPv4 addresses and tunnel end point (TEP) addresses. A router  160  relays connection between the IPv4 host  180  and the DSTM host  130 . When the DSTM host  130  accesses first and second domain name systems (DNSs)  150  and  170  using a domain name, the first and second DNSs  150  and  170  convert the domain name into an IPv4 address.  
       [0008] In operation, the DSTM host  130  in an IPv6 network  110  inquires for an IPv4 address corresponding to the domain name from the first and second DNSs  150  and  170  to acquire the address of an IPv4 host  180 . Next, the DSTM host  130  needs an IPv4 address, so it is allocated an IPv4 address and a TEP address through the DHCPv6 server  140 . Thereafter, the DSTM host  130  transmits an IPv6 packet including an IPv4 packet to the router  160  through a dynamic tunneling interface (DTI)  190 . Subsequently, the router  160  transmits the IPv6 packet to a destination, i.e., the IPv4 host  180  in an IPv4 network. Here, the router  160  stores the IPv6 address and IPv4 address of the DSTM host  130 .  
       [0009] However, the conventional network system shown in FIG. 1 has a very complex DSTM and must include elements, i.e., DNS, DHCPv6, DTI, and router, which are not standardized. In particular, the conventional network system shown in FIG. 1 needs DNSs, i.e., the first and second DNSs  150  and  170 , in order to check both IPv6 address and IPv4 address. In addition, since the DHCPv6 server  140  must always have a global IPv4 address, the conventional network system shown in FIG. 1 cannot fundamentally overcome a shortage of addresses.  
       SUMMARY OF THE INVENTION  
       [0010] The present invention provides an Internet Protocol version 4 (IPv4)-Internet Protocol version 6 (IPv6) communication method for allowing devices in an IPv6 home network to communicate with an IPv4 host in an IPv4 network by installing a dual stack proxy server having both an IPv4 address and an IPv6 address between the IPv6 home network and the IPv4 network.  
       [0011] The present invention also provides an IPv4-IPv6 communication apparatus using the above IPv4-IPv6 communication method.  
       [0012] According to an aspect of the present invention, there is provided an IPv4-IPv6 communication method for allowing IPv6 devices of an IPv6 home network to communicate with an IPv4 host. The IPv4-IPv6 communication method includes upon receiving a web address from an IPv6 device of the IPv6 home network, inquiring for an IPv4 address corresponding to the web address from a domain name system (DNS); upon receiving the inquired IPv4 address, mapping the IPv4 address to an IPv6 address, storing the mapped IPv4/IPv6 addresses, and setting a connection to the IPv4 host; receiving data of a web page corresponding to the web address from the connected IPv4 host; and transmitting the received data of the web page to the IPv6 device by referring to the mapped IPv4/IPv6 addresses.  
       [0013] According to another aspect of the present invention, there is provided an IPv4-IPv6 communication apparatus for allowing IPv6 devices of an IPv6 home network to communicate with an IPv4 host. The IPv4-IPv6 communication apparatus includes a cache section storing received data of a web page; a table section mapping an IPv4 address to an IPv6 address and storing the mapped IPv4/IPv6 addresses; and a protocol controller section, which inquires for an IPv4 address corresponding to a web address received from an IPv6 device of the IPv6 home network from a DNS, maps the inquired IPv4 address to an IPv6 address to connect with the IPv4 host, receives data of a web page corresponding to the web address from the IPv4 host, stores the data in the cache section, and transmits the data of the web page stored in the cache section to the IPv6 device by referring to the mapped IPv4/IPv6 addresses. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0014] The above features and advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings in which:  
     [0015]FIG. 1 is a diagram of a conventional network system for Internet Protocol version 4 (IPv4)-Internet Protocol version 6 (IPv6) communication;  
     [0016]FIG. 2 is a diagram of a network system for IPv4-IPv6 communication according to an embodiment of the present invention;  
     [0017]FIG. 3 is a detailed diagram of a dual stack proxy server (DSPS) shown in FIG. 2; and  
     [0018]FIG. 4 is a flowchart of an IPv4-IPv6 communication method according to an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0019] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.  
     [0020]FIG. 2 is a diagram of a network system for Internet Protocol version 4 (IPv4)-Internet Protocol version 6 (IPv6) communication according to an embodiment of the present invention. The network system shown in FIG. 2 includes an IPv6 home network  210  including IPv6 devices  212 ,  214 ,  216 , and  218  and an IPv4 network  230  including a domain name system (DNS)  232  and an IPv4 host  234 . In addition, the network system includes a dual stack proxy server  220 , which relays communication between the IPv6 devices  212 ,  214 ,  216 , and  218  of the IPv6 home network  210  and the IPv4 host  234  of the IPv4 network  230 .  
     [0021] Referring to FIG. 2, the IPv6 devices  212 ,  214 ,  216 , and  218  of the IPv6 home network  210  must use IPv6 applications. The DNS  232  of the IPv4 network  230  converts a domain name requested by the DSPS  220  into an IPv4 address. The DSPS  220  inquires for an IPv4 address, which corresponds to a uniform resource locator (URL) received from an IPv6 devices  212 ,  214 ,  216 , or  218  of the IPv6 home network  210 , from the DNS  232 ; maps the inquired IPv4 address to an IPv6 address; connects with the IPv4 host  234 ; receives data of a web page at the URL from the IPv4 host  234 ; and transmits the web page data to the IPv6 device  212 ,  214 ,  216 , or  218 .  
     [0022]FIG. 3 is a detailed diagram of the DSPS  220 . Referring to FIG. 3, a cache section  340  stores data of web pages received from the IPv4 host  234 . The mapping table section  330  maps an IPv4 address to an IPv6 address and stores the mapped IPv4/IPv6 addresses. A protocol controller section  310  inquires IPv4 addresses corresponding to URLs received from the IPv6 devices  212 ,  214 ,  216 , and  218  of the home network  210  from the DNS  232 , maps the inquired IPv4 addresses to IPv6 addresses, and stores the result of mapping. In addition, the protocol controller section  310  receives data of web pages at the URLs from the IPv4 host  234 , stores the data in the cache section  340 , and transmits the data stored in the cache section  340  to the relevant IPv6 devices  212 ,  214 ,  216 , and  218  referring to the mapped IPv4/IPv6 addresses stored in the mapping table section  330 .  
     [0023]FIG. 4 is a flowchart of an IPv4-IPv6 communication method according to an embodiment of the present invention. Here, it is assumed that the IPv6 host  212  among the IPv6 devices  212 ,  214 ,  216 , and  218  of the IPv6 home network  210  intends to acquire a web page of the IPv4 host  234  of the IPv4 network  230 .  
     [0024] The IPv6 host  212  tries to connect with the IPv4 host  234  in operation  410 . For example, the IPv6 host  212  inputs a URL to be accessed through a web browser. Next, the IPv6 host  212  transmits a URL to the DSPS  220  in operation  420 .  
     [0025] Next, the DSPS  220  inquires for an IPv4 address corresponding to the URL from the DNS  232  in operation  430 . Then, the DNS  232  transmits the inquired IPv4 address to the DSPS  220  in operation  440 . For example, the DNS  232  informs the DSPS  220  of the IPv4 address  211 . 115 . 109 . 7  corresponding to the URL www.yahoo.com.  
     [0026] Next, the DSPS  220  maps the IPv4 address received from the DNS  232  to a corresponding IPv6 address and stores the mapped IPv4/IPv6 addresses in the mapping table section  330  in operation  450 . Here, the connection between the DSPS  220  and the IPv4 host  234  is set.  
     [0027] Next, the DSPS  220  transmits the URL to the IPv4 host  234  in operation  460 . For example, the DSPS  220  transmits a packet including information on its own IPv4 address corresponding to a source and the IPv4 address of the IPv4 host  234  corresponding to a destination to the IPv4 host  234 .  
     [0028] Next, the IPv4 host  234  transmits the data of a web page corresponding to the URL to the DSPS  220  in operation  470 . Then, the DSPS  220  stores the data of the web page received from the IPv4 host  234  in the cache section  340  in operation  480 . Next, the DSPS  220  transmits the data stored in the cache section  340  to the IPv6 host  212  of the IPv6 home network  210  referring to the mapped IPv4/IPv6 addresses stored in the mapping table section  330  in operation  490 .  
     [0029] Consequently, by installing the DSPS  220 , which stores both an IPv4 address and an IPv6 address between the IPv6 home network  210  and the IPv4 network  230 , each of the devices  212 ,  214 ,  216 , and  218  of the IPv6 home network  210  can communicate with the IPv4 host  234  of the IPv4 network  230 .  
     [0030] The present invention can be realized as a code which is recorded on a computer readable recording medium and can be read by a computer. The computer readable recording medium may be any type on which data which can be read by a computer system can be recorded, for example, a ROM, a RAM, a CD-ROM, a magnetic tape, a hard disc, a floppy disc, a flash memory, or an optical data storage device. The present invention can also be realized as carrier waves (for example, transmitted through Internet). Alternatively, computer readable recording media are distributed among computer systems connected through a network so that the present invention can be realized as a code which is stored in the recording media and can be read and executed in the computers.  
     [0031] As described above, the present invention provides a DSPS having both an IPv4 address and an IPv6 address between an IPv6 home network and an IPv4 network so that each device of the IPv6 home network can communicate with a host of the IPv4 network. In addition, since the devices of the IPv6 home network use IPv6 addresses, a shortage of IPv4 addresses can be overcome. Moreover, IPv4 host content that is frequently accessed is stored in the DSPS, so the traffic between the IPv4 host and the DSPS can be reduced.  
     [0032] The present invention is not restricted to the above-described embodiments, and it will be apparent that various changes can be made by those skilled in the art without departing from the spirit of the invention.